Note: Descriptions are shown in the official language in which they were submitted.
~4~9
BACKGROUND OF T~E INVENTION
2 The present invention is directed to a process
3 for preparing a metal~oxygen composition which composition
4 is capable of dehydrocoupling toluene to stilbene.
Styrene is currently commercially produced from
6 benzene in a two-step process. In the first step benzene
7 is alkylated with ethylene to for~ ethylbenzene, and in
8 the second step, the ethylbenzene is dehydrogenated to
g form styrene.
One of the known alternative routes for forming
11 styrene in~olves the oxidati~e coupling of toluene to form
12 1, 2-diphenyl e~hylene ~stilbene) followed by the dispro-
13 portionation of the stilbene with ethylene in ~he presence
14 Of a catalyst to ~orm styrene. The economic significance
o the overall procesg scheme o the toluene-stilbene route
16 is that styrene can be produced from 0.5 mole of ethylene
17 and one mole of toluene. This compar~s with the con~en-
18 tional ethylbenzene route wherein styrene is produced from one
19 mole of ethylene and one mole of benzene. In light o~ the
rising costs of benzene and ethylene and the environmental
21 problems of benæene, the toluene-based process will become
22 a more attractive route than the existing ben2ene-based
23 process ~or styrene manuf-acture.
24 In addition to its utility as an intermediate in
production of styrene, stilbene, because of its unsaturated
26 character, iS very reactive and may be employed in various
27 organic synthesss. Derivatives of stilbene are useful in
28 the production of chemicals which may be used in the manu-
2gi facture of dyes, paints, and resins. It is also use~ul in
optical bri~hteners, in pharmaceutic~ls and as an organic
31 intermediate~
32 Thus, there is substantial economic incantive to
develop an economical process for producing stilbene.
34 The oxidative coupling o toluene to 1, 2-diphenyl
etbane (i.e., bibenzyl) and sti}bene has bee~ known for
36 many years.
;
., ~
.:. . ..
. ., :.- ' . ~
~24~
1 The ideal reaction to stilbene from toluene is
2 the direct dehydrocoupling reaction summarized as follows:
6 H3+0,-~ ~ CH=CH ~ +~2 (eq.l)
toluene stilbene
Such a selective reaction in practice is difficult to
9 achieve. More often, the overall reaction involves the
dehydrocoupling of toluene to stilbene as well as bibenzyl~
11 Bibenzyl however can be dehydrogenated to stilbene. Thus,
12 a commercial process for producing stilbene could include
13 an overall reaction scheme summarized as follows:
14
16 4 ~ C~3 ........ ~ ~ 82-CH ~
~:: 17 ~ Bibenzyl (eq.2)
- ~ S ilben
2i
22 although the greater selectivity of the reaction to stil-
23 bene, the more ef~icient the process.
24 The reaction of Equation 1, employing oxygen as
the oxidant in the ab5:ence of a catalyst, is extremely
26 inefficient because of the preponderance of non-selective
27 free-radical reactions~le:ading to complete combustion of.
28 the h.ydrocarbons and the formation of oxygenated by-products.
29 Consequently, attempts:have been made to improve the selec-
tivity of the reaction:using oxidants, such as metal or
31 non-metal oxides as stoichiometric reactants~providing
32 lattice oxygen which is depleted during the reaction.
33 Such metal oxides can also function as catalysts for a
~ 34 prima.ry oxidant such as oxyg:en. Becau5e of the oxyge:n
:`~ 35 depletion.of metal oxide stoichiometric oxidantsi their
.
~z~9
1 use requires that they be either very inexpensive and
2 therefore disposable, or they must be capable of being
3 regenerated by replacing the lattice oxygen l~st during
4 the reaction. Since many o~ the conventional stoichio-
metric metal oxide oxidants are expensive, their use re-
6 quires extensive plant equipment and engineering design to
7 provide proper regeneration. This has led to two alter-
8 native approaches; namely, fixed bed and fluidized bed
9 sy~tems. In the fixed bed system, two or three reactors
1~ with staggered cycles typically are employed to achieve
11 continuous operation. This system is very costly in terms
12 of plant equipment. In the fluidized system a single
13 reactor can be ~mployed and a portion of the metal-oxide
14 can be constantly removed, regeneratedl and returned to
the reactor. Fluidi~ed systems, however, lead to attrition
16 of the metal oxide and in many instances the metal of the
17 metal oxide can be lost as fines which coat the walls of
18 the reactors.
19 Another difficulty with stoichiometric oxidants
and/or catalysts is t~lat those producing relatively good
21 selectivity usually result in a slow reaction rate. In
22 addition the oxygen-carrying capacity is usually very low
23 leading to a short active life.
24 Representative examples of conventional metal
oxide oxidants and/or catalysts are disclosed in U.S.
26 Patent Nos. 3,694,518; 3,739,038; 3,868,427; 3,965,206;
27 3,980,580; 4,091jO44; 4,183,828; 4,243,825; 4,247,~27;
~8 4,254,293; 4,255,60`2; 4,255,603; 4,255,604; 4,268,703;
29 4,268,704; 4,278,824; 4,278,825; and 4/278,826. These
patents disclose various metal/oxide compositions which can
31 be p~epared by a variety of methods. For example, the sim-
32 plest me*hod involves intimately mixing the powdered metal
33 oxides in the dry state and calcining. Another method i~-
34 volves adding the metal oxides to water with stirring, fil-
tering to remove excess water or, alternatively, heating to
36 evaporate the water, drying, and calcining. In ¬her
37 method of pre~aration, the powdered metal ~xides ca-n be
'``'
~2~
1 intimately mixed before fonming a paste with water and fur-
2 ther mixing the paste. The paste can be dried in air, after
3 which it can be calcined in air. The calcined product can
4 then be crushed and sieved to the desired mesh size. In
still another method o~ preparation, the powdered metal ox-
6 ides can be mixed in the dry state together. A further
7 method of preparation involves intLmately mixing the pow-
8 dered metal oxides in water and spray drying the resulting
9 sLurry or solution to produce relatively dust-free a~d free-
flowing ~pherical particles which are also calcined prior
11 to use. In an alternative method of preparation, suitable in-
12 organic metal/oxygen composition precursor salts such as
13 nitrates, carbonates,and acetates are intimately mixed or
14 dissolved in water or nitric acid and heated to thenmally
decompose the precursor salts to form the corresponding ox
16 ides and/or oxygen complexe The oxides and/or oxygen com-
17 plexes can then be treated as described hereinabove prior
18~ to use.
1~ - Thus, a majority of these preparative methods
employ water and are referred to herein as aqueous pre-
21 parations. None of these patents disclose th~ use of
22 organic liquids to prepare the metal oxide compositions.
23 ?he metal oxide compositions disclosed in these
24 patents prepared by an aqueous method exibit an extremely
short active life. For example, Example 6 in U.S. Patent
26 No. 4,091,044 illustrates the use of a Sb/Pb/Bi oxide
27 oxidant prepared by the aqueous method. When run for 1
28 minute at 580C (run 3, Table 6) the conversion is 47.3~
2;9 and a selectivity for cis and trans stilbene plus bibenzyl
is 81.2~. However, after 7 minutes reaction time (run 6,
31 Table 6) the conversion drops to 9.7~ at a corresponding
32 selectivity of 87.5~. The substantial drop in conversion
3~3 over a period of S minutes indicates that the oxidant is
34 quic~ly dea¢tivated and implies that it is not an efficient
oxygen carrier. It is for this reason that the oxidant
36 is typicalIy regenerated for 30 to 60 minutes after each
37 one-minute run (iee Exam~le 1, lines 34 et. s;eq.). Thus,
,~
~4~
l not only is the oxidant quickly deactivated but its regen-
2 eration time is also ~uite long.
3 It is known that vanadium phosphorus oxygen
catalysts for the oxidat~on o~ hydrocarbons, e.g. butane,
to form, for example, maleic anhydride, can be prepared
6 using an organic medium, such as isobutanol, as illustrated
7 by U.S. Patent Nos. 3,864,280; 4,132,670 and commonly
8 assigned U.S. Patent ~o. 4,392,986. However these
9 catalyst~ are not employed for the conversion of
toluene to stilbene.
11 The search has there~ore continued for metal
12 oxide compositions for use in conjunction with the conver-
13 sion o toluene by oxidative dehydrocoupling to stilbene
14 which possess the characteristics of (1) high activity and
15 selectivity ~o minimize toluene recycle and loss to unde-
16 sired by-products, (2) high oxygen-carrying capacity, (3)
`~ 17 high reoxidation or regeneration rate to minimize the
18 amount of composition employed, ~4) high a~trition resis-
19 tance under`c~n~itions o~ repeated oxidation a~d reduction,
20 a~ (g~) h~i~h; reaction r~te. The present invention was de-
2~ veloped in.~e~spo,n~e to thi~. se&rch.
'.~
.,
.
. ~' ' ~ ' ~ ,' .
4~
- 6 -
1 S W ARY OF THE INVENTION
2 In one aspect of the present invention there is
3 provided a process for preparing a precursor metal oxygen
4 composition capable of dehydrocoupling toluene when calcined
which comprises:
6 (i) reacting a mixture of metal oxides in the
7 presence of at least one organic media comprising
8 at least one member selected from the group
g consisting of organic: alcohol~ aldehyde, ketone,
ether, amine, amide and thiol, to form a metal
11 oxygen precursor composition the metals of said
12 ~etal oxide mixture having (a) at least one
13 member selected from the group consisting of Tl,
14 . Bi, Pb, Co, and Th and (b) at least one member
lS selected from the group consisting of Li, Na, K,
16 Rb, Cs, Fr, Be, Mg, Ca, Sr, ~a, Ra, In, Tl, Ge,
17 P, As, Sb, Ag, Au, ~u, Zn, Cd, Hg, Sc, Y, La,
1.8 Ac, Ti, Zr, ~f, ~b, Ta, Mn, Tc, Re, Fe, Ru, Os,
19 Rh, Ir, Ni, Pd, ~t, Ce, Pr, Nd, Pm, Sm, Eu, Gd,
. Tb, Py, Er, Tm, Yb, ~u, and U;
21 ~ii) se~parating the precursor composition from
22 the organic media-
23 In another aspect of the present invention there
24 is provided a psocess for preparing a metal oxygen compo-
sition capable of dehydrocoupling toluene which comprises
26 ca}cining the above described precursor metal oxygen compo-
27 sition.
28 In a further aspect of the present invention there
29 is provided a process for dehydrocoupling toluene and/or
toluene derivatives using the metal oxygen composition pre-
pared by the aQredescribed process.
32 }n still another aspect of:the present invention
33 there is provi~ed a metal oxy$en composition prepared by
:4 the afore:de~scribe.~ p~r~ee$s..
.
~ ~ .
.
s
~.. , ~ `' .
39
- 7 -
1 DESCRIPTION OF PREFERRED EMBODIMENTS
-
2 A majority of the metals employed to prepare the
3 metal oxide composition capable of dehydrocoupling toluene
4 to stilbene are conventional in the ~rt. More specifically,
5 the inorganic metal oxide composition prepared in accor-
6 dance with the present invention comprises a material which
7 can be represented by the empirical formula:
9 Aa~bx (I)
11
12 wherein ~ is at least one metal selected from the group
13 consisting of Tl, Bi, Pb, Co, and Th; and B at least one
14 ~etal selected from the group consisting of Li, Na, K, Rb,
Cs, and Fr of Group lA (of the periodic chart) Be, Mg, Ca,
16 Sr, Ba, and Ra of Group 2a; In, and Tl of Group 3a; Ge of
17 Group 4a; P, As~ and Sb, o~ Group SA; Ag~ Au, and Cu, of
18 Group Ib; Zn, Cd, and ~ of Group 2b; Sc, Y, La, and Ac of
19 Group 3b; Ti, Zr~ and Hf of Group 4b; Nb and Ta of Group
Sb; Mn, Tc, and Re of Group 7b; Fe, Ru, Os, Rh, Ir, ~i, Pd,
21 and Pt of Group 8; Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Er,
22 Tm, Yb, and Lu, of the Lanthanides or rare earths; and Th
23 and U of the actinides. Also in formula I, "a" is a num- -
24 ber o~ about l, "b" is a number of from about .01 to about
100, preferably from about .01 to 10, most pre~erably .1
26 to 10; and "x" is a numbe~ taken to satisfy the average
27 valences of metals A and B in the oxidation states in which
28 they exi-qt in the composition.
29 It is~ to be understood that while the abov2 ~for-
3Q mula Iand formulae which ~ollow hereinafter are referred
31 to ~s empirical formulae, they are not considered to be
32 em~irical formulae in the conventional sense. The precise
33 structure of the metal oxide catalysts of the present
34 invention has not yet been determined and X in these ~ormu-
3; lae in fact has no fixed deteminate value since it can
3~ vary widely de~ending on the various possible co~binations
37 within the cata~lyst. l~hat there is oxygen present is-kno~n
,
4~9~
1 a~d the x in these formulae is representative of this.
Z However, these formulae are significant in that they repre-
3 sent the gram atom ratio of the metal components of the
4 catalvst.
Subgeneric classes of suita~ble metal oxide compo-
6 sitions falling wi~hin the ~cope of formula I include those
7 represented by the following ~mpirical formulae:
8 Al~lOX CII)
wherein Al is Tl (o Group 3a); Bl is at least one member
11 selected from the group consisting of Sc, Y, La, Ac (of
12 Group 3b); Ti, Zr, and H~ (of Group 4b); N~, and Ta ~of
13 Group 5~); Mn, Tc, Re (of Group 7b)7 As and Sb (of &roup
14 5a); Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Er, Tm, Yb,
and Lu (of the Lanthanides or rare earths); Th, and U
16 (of the actinides); preerably ~1 is selected from Ta,
17 Sb, Ti, Zr, and Hf and mixtures; "a" is a number of about
18 1, ~b" is a number of from about .01 to about 10; preferably
19 from about .05 to about 5, and "x~ is as described above;
. ~ B~Ox (III)
2:2 wherein A2 is Bi; 82 is at least one member selected
23 from the group consisting of Be, Mg, Ca, Sr, Ba, and
24 Ra (of Group 2a); In (of Group 3a); ~g (of Group lb);
preferably 32 is Ag, Mg, Ca, Sr or Ba and mixtures thereof;
26 "h" is a numbe~r of about I, "j" is a number of from about
27 .01 to about I00, preferably from about Ool to about
2~8. 10, and ~x" is: as described above;
29 3 3
AkBl x (IV)
31 wherein A3 is Bi; B3 is at least one mèmber selected
3~ from the group consisting of Li~ Na, K, Rb, Cs, and Fr
33 (of Group la); Sc, Y, La~, and Ac (of Group 3b); Ti, Zr,
3:4 and Hf (of.Gr~up 4b); Fe, Ru, Os, Co, Rh, Ir, Ni, ~d,
and Pt (of Goup 8), Zn~(of Group 2b); Ge (of Group 4a);
.
'
-;
. . .:
. . :,
:. ' ' ~:,
.. :. ..... .
99
1 Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Er, Tm, Yb, and Lu
2 (of the Lanthanides or rare earths); Th (of the actinides);
3 preferably 83 is selected from Zn, Ce, Li, Na, K, Cs,
4 and Zr and mixtures; "k" is a number of about 1, "1"
5 is a number of from about 0.01 to about 10, preferably
6 from about O.S to about S, and "x" is as described above;
8 AmBnOX (V)
10 wherein A4 is cobalt, B4 is La, "m" is a number of about 1,
11 "b" is a number of from about 1 ~o about 10, preferably
12 from about 1 to about S, and "x" is as described above:
13
i4 AoBSOx (VI)
16 wherein A5 iq Th; ~5 is at least one member selected from
17 the group consisting of Cu (of Group lb); Zn, Cd, and Hg
18 (of Group 2b); preferably B5 is Zn; "o" is a number of about
19 1, "p" ig a number of from about 0.01 to about 10, prefer-
20 ably from abo~t 0.5 to about 5; and "x" is as described
21 above;
23 A696O tVII)
24 wherein A6 is~ Pb; B6 is at least one member selected
25 from the group consisting of Li, Na, R, Rb, C9, Fr (of
26 Group la); Sc, Y, La, and Ac (of Group 3b); Ti, Zr, and
27 Hf (of Group 4b); Fe~, Ru, Qs, Co, Rh, Ir, Ni, Pd, and
28 Pt (of Group 8), kg (of Group lb); Zn (o Group 2b);
23 Ge (of Group 4a), P.and As (of Group Sa); Ce, Pr, Nd,
3a Pm, Sm, Eu, Gd, Tb, Py, Er, Tm~ Yb, and Lu tof the Lan~ha-
31 ni~es or rare earths); Th (of the actinides); (preferably
32 B6 is se}ected from Ag, Zn, As, Li, Na, g, Rb, Cs, Zr,
33 and mixtures, most preferably Ag, Zn, K, and Zr); "g~
34 is a number of about 1, "r" is a~number of from ahout
35 .01 to about lQ, pre~fera~b.ly from about 0.5 to about S,
36 a~nd "x" is a;s described a~ove;
"': ' ' .
.';. ' .:
....
., '.,~: .,.,. ~ `
~2~4~
-- 10 --
1 ~ 7
AsBtx (VIII)
3 wherein A7 is Pb; B7 is at least one member selected
4 from the group consisting of Be, Mg, Ca, Sr, Ba, Ra (of
Group 2a); Tl (of Group 3a) (preferably B7 is selected
6 from Ba, Ca, Sr and mixtures); ~s" is a number of about
7 ,; "t" is a number of from about 0.01 to about 10, preferably
8 from about 0.5 to about 5; and ~x'l is as described above;
Sbc d ie x (IX)
1~ wherein "c" is a number of about 1, "d" is a number of from
12 ~bout 0.1 to about 10, preferably from about 0.5 to about
13 5, ne" is a number from about O ~o about 5, preferably from
14 about O to about 1, and "x" is as defined in co~nection with
formula I as it pertains to the oxidation state of Sb, Pb,
16 and Bi metals in the formula; and
17 DuEvSbyBizx (X)
18
19 wherein D is at least one member selected ~rom the group
23 consisting of Li, Na, R, Rb, Cs, Fr, ae, ~g, Ca, Sr, Ba, and
2:1 Ra; preferably D is Cs; E is at least one member selected
22 from the group consisting of Pb, Au, Agj Pt, Pd, Cu, Zn, Cd,
23 and Hg; preferably E is Pb, Au, or Cu; most ~referably ~u; "u"
24 is a number which can vary rom about O to a-bout 10, pre-
ferably from about 0.5 to about 5; "v" is a number which
26 can vary from about O to about 10, pre~erably from about
27 0.5 to about 5; "y" is a~number which can vary from about O
28 to about 10, pre~feFaby` from abou~ 0.5 to about 5; ''z" is a
29 number which can vary from about 0.01 to about 10, prefe~r-
3~ ably from:about .01 to about 5; and ''x" is as aefined in
31 connection:with formula I as it pertains to the oxldation
32 state o~ D, E, Sb, and BL.
33 Representative~examples of empirical formulas
34. (based on formula I) of metal oxygen compositions which can
3~s be prepared in accordance with the present invention are
36 d~scribed below. The l~-tters "a" and "b" in each formula
37 co~llectively repr~s:en~ the gra~m atom ratios o each m~tal
,
i: .: .. ,.,,,.,.. , ~ ~ :
", ; ~ ~
1 in the composition. The letter "x" of each of these formu-
2 las is as described above is indeterminate although its the-
3 oretical value can be calculated from the representative ox-
4 idation states o~ each metal as also provided. Futhermore,
the o~idation states of each of the metals of the calcined
6 metal oxygen composition may vary between the highest and
7 lowes~ pcssible oxidation states in a sin~le composition.
....... ........
:
,
:: ~ :
. ~....... .
~ :- :
, . , ~: :
~az24~
13~s~i3g~ a b
+3 ~3
2 Tl S~ o 1 .3
a bx
3 1 .5
4 n
1 2
6 n 1 3
7 Tl Ti40 1 . 2
a b x
8 1 .3
n 1 . 5
W
}I . n 1 ;~
12 ~I 1 3
13 Tl~3T +50
a }~ x
14 Tla 3M~b2o
}5 Tl 31;ab30x
16 Tla3Ub50X ~1. 5
17 Bi l 3Cab20x 10.1
18 n 10~3
19 n 10.5
20` n
21 n
22 ~ 1 lQ
23 ~ ` 1lOa
;
. ~ - . ..
::,. ::
: , ,
~2;;~
-- l3_
1E:mpirical Formula a b
2Bi+3Srb x 1 . 3
~ - n 1 5
4 "
5 1~ 1 4
Bi+3I +30
a b x
7Bia3AgblO 1 . l
n 1 ~16
9 n 1 ~2
n 1 ~3
11 I~ 1 ~5
B~i 3Ca 2Ag lx l . 3
1Bi+3C;a~2Inb30 1Ca- . 3, In~ . 8
L4~3i t 3Cab25~2ox 1. S
+2 +2 l .1
a~ b x
16 " 1 . 3
17 n 1 5
18 n
Lg n 1 2
n 1 3
P~+2Mg+20
22Pb+2~ab20 x
2_Pb~a2'rl~ x 1 2
2.4 Bi 3Znb20 l .1
~5` '` 1 .I7
26 " 1 . 2S
~7 " 1 .5
28~
.
., .
, . -
2~ 9
- 14 --
Empirical Fo~mula a b
2 l 2
3 n l 3
4 Bi~ R~; x 1 . 013
n l .2I
6 1 .43
7 n
8Bi 1 3Nib2o x 1 . 2
n l 3
n l 5
11 n
12 n 1 2
~ ~ n 1 3
14Bi+3Zr.b4OX 1 .17
lS n. 1 .3
16
17 1 2
1~ n 1 3
lg Bi ~eb 1 .17
2Q n ~ l .7
21 1~ 1 3. Q
2~ Bi Ceb40 : l .1 ?
2 3 n ~ 1 .- 3 3
24 ni 1 .S
n
:
21~ n 1 2
r 1 3
,~ ~
-
- , ., - -
.
~2~4~9~
-- 15 -- .
L ~irical Fors~ula A b
2 B~+3Lab3~ 1 .3
3 1~ 1 .5
4 n
- 5 1 1
6 n 1 2
7 1- 1 3
3i31'h 4æ 1 . 3
a
9 ~ 1 .5
"
n 1 2
2 ~ 1 3
1-3 Bi~3mb4Zn~2OX 1 ~h- .16,Zn~ . 5
14 8i+3~,a+3X I lo 1 La~ . 5
a b b x
~i+3Geb4Nib20 1 Gec . 25,2~i~ . 5
16 ~1~3Zn+2Zr+4O 1 Zn= 1, Zr- 1
a b b x
17 Bi+3Ce~4m 1 Ce- .~, m-
a b b x
18 Co 6Lab3O
19 " 1 2
20 " 1 3
+4; +2
21 ~ Z~ O 1 .3
a b x
2~2 ~ ~ ~5
2 3
~4. " 1. 2
n . 1 3
25Th+4CU~20~ 1 1
a ~. x
:; :
.
.. .,: , , .
: . :.~. , :,
... .
~z~ 9
-- i6 --
E~npi~ical For;nula a b
2 Th~4cd+20
a b x
3 pb+2z~+40 1 . 3
a b x
3 1 .5
4 n
1 2
6 n 1 3
7 pb+2~+10 1 2
a b x
8 pb+2y+30 1 . 3
a b x
n 1 5
1 01 n
11 n 1 6
~:
12 n 1 10
.13 Pb 2Co~2o
a b x
14.p~;l 2T~40
a b x
lS a b x 1 . 2
: n 1 .-3
16
n 1 D5
17
1~ `
l g n 1 2
1~ 1 3
~3
21 1 5
22 Pb 2P+50X
a b
23 Pb 2Asb;O x
` 24 Pb ~A~b10 x` 1 .1
: .~ 1 . ~ 3
. 2~
n ` 1 .17
~6
.
. -. .
,
~Z;~4~
- 17 -
1 E~irical Formula a b
1 .2S
3 " 1 ~
4 Pba2AgblZrb4Ox 1 Ag= .7, Zr- .3
5 pb+2K+lzr+4O g= .8, Zr-- .3
a b b x
6 Pb~2Yb32rb4Ox Y= .3, Zr= .35
7 Pb+2Zn+2Th+4O Zn= .4, Th= .01
8 Pb~2Znb2Cob2ox Zn= .3, Co= .17
Representative examples of empirical formulas of
11 metal oxide compositions, based on formula IX, are illus-
12 trated below. In these formulas, the letters "c", ~d" and
13 ~e" as provided collectively represent gram atom ratios of
14 the respective metals. The letter "x" is as described
above.
16 Empirical Formula c d e
17sbc3pb~2~i~3~ I 1.5 0
18 ~ 1 2 .~5
19 ~` 1 2 0
2~0 " 1 3 0
21 " 1 4 0
22 " 1 5 0
23 " 1 1.5 .25
24 Representative examples of empirical formulas of
metal cxide comDositions, based on structural formula X
26 are illustrated below. In these formulas the letters "u",
27 "v", "y" and "z", collectively represent gram atom ratios
28 of the respective metals. The letter "x" is às described
29 above.
30 Em~irical Por ~ a u v ~ z
31 SbyBizOX
32 " 0 0 0.25
33 " 0 0 1.0 0.25
34 CsuSbyBizOx 0-05 1.0 0.25
35- ~ 0.1 0 1.0 0.25
36 " 0.5 0 1.0 0.25
37 " 1.0 0 1.0 0.25
'~
.
~2~ 9
- 18 ~
1 Em~irical Formula u v ~ z
2CsuPbvShyBizOx .S 1.51.0 0.25
3 " 0.1 1.51.0 0.25
4 " 0.5 1.51.0 0.25
" 1.0 1.51.0 0.25
6CuvSbyBizOx 0 0.251.0 0.25
7 " 0 0.51.0 0.25
8 n 0 0.51. 0 0.5
9 n 0 0.5O.S 1.0
10AuvSbyBizOx 0 0.051.0 0.25
11 " 0 0.051.0 0.50
12 " 0 0.11.0 0.25
13 " 0 0.11.0 0.50
14CSuCUvSbyBizx .S 0.250 1.0
n 0.1 0~250 1.0
16 " 0.5 0.250 1.0
17 1.0 0.250 1.0
18KvSbyBizOx 0.051.0 0.25
19 " 0 0.11.0 0.25
" 0 ~.5 0 1.0
21 n O 1.0 0 1.0
22RbuAu~SbyBizOx 0.05 0. 05 1. O O . 25
2~3 " 0.1 0.051.0 0.25
24 " 0.5 0.051.0 0.25
" 1.0 0.0S1.0 0.25
26 Representative starting materials in metal oxide
27 form, from which the metal oxide composltion of the present
28 invention can be prepared include Sb2O3,PbO, Bi2O3, T12O3,
2 5 23' T12O3, U3O8, CaO, In2O3, SrO, BaO MgO ZnO
ZrO2, GeO3~ CeO2~ Y2O3-
31 However, included within the ~erm metal oxides
32 are precursors~of said metal oxide such as nitrates, car-
33 bonates, and acetates which can be converted to their cor-
34 re-spon~ing metal oxides by heat treatment~
Representative illustrations of such precursor
36 metal oxide,s include l~n(NO3)2, Bi(NO3)3, AgN03, ~h(NO3)4,
3 3)2' CU(~3)2~ Na~¢o3, Na2Co3,
..
`' ,
` . ~' ,
. . .
,
~" ,.'. ~
4~9
-- 19 --
1 The process for preparing the metal oxide compo-
~ si~ions o~ the ~resent invention is conducted by reacting
3 at least two of the oxides of said metals in the presence
4 of at least one organic media, e.g., alcohol, under condi-
tions and in a manner sufficient to ~orm a catalyst pre-
6 cursor co~position. m e term "media" i used herein in a
7 collective sense to signi~y singular and/or plural.
8 When an alcohol is em~loyed as the liquid organic
9 media, water and other organio by-products, such as ethexs,
esters and the like, are formed as a result of this reaction
ll and there are essentially no other detectable by-products
12 therefrom. While not wishing to be bound by any particular
13 theory, thiC occurence has led to the conclusion that the
14 organic alcohol participates in thi~ reaction, although to
an undetermined extent, through the hydroxy functional
16 group thereby releasing water. More specifically, it is
17 fu~ther believed that the alcohol may react with at least
18 the qur~ace o tha metal oxide particles to form an alkoxide
19 which in turn may become an active intermediate for further
reaction to form the complex metal oxide catalyst matrix.
21 An organic media with reducing properties may facilitate
22 this intermediate forming reaction.
23 In any event, the metal oxides are eventually
24 reacted with each o~her and the precursor catalyst com-
position is not belie~ed to be a mere mixture of oxides.
26 The above rea~tion can be conducted bv admixing
27 at least two of said metal oxides with at least one orga~ic
28 media and heating t~e admixture. Since most metal oxide~
29 a~e generally at ieast partially insoluble in the organic
media, a slurry or suspension will result and the reaction
31 is conducted in a heterogeneous phase. However, an organic
32 media whi¢h dis~solves the met~l oxides can also be employed
33 although this complicates the recovery procedure. Accord-
34 ingly, it is contemplated to employ-organic metal oxides
such as~a~timony butoxide and ma;gnesium methaxide which are
36 s~-luble i~ the o~r~anic ~è~ia, a~s starting materials in the
37 process of the present in~e~nti3~.
: .
:
. .
.:: '' ' ; '
~Z~4~9~
- 20 -
1 ~hus, the organi~ media functions as a solvent and/or
2 suspending medium for the metal oxides, as a solvent and/or
3 suspending agent for the catalyst precursor composition, as
4 a medium for providing uniform heating of the metal oxides,
and optionally as a reactant.
6 The organic m~dia is comprised of carbon, hydrogen,
7 and at least one hetero-atom such as oxygen, nitrogen or
8 sulfur.
9 Included within the scope of organic media are
alcohols, aldehydes, ketones, ethers, amines, arnides,
11 and thiols, and mixtures thereof, containing typically
12 from about 1 to about 20, preferably ~rom about 1 to
13 about 10, and most preferably from about 1 to about 5
14 carbon atoms.
lS More specifically, the organic moiety to which
16 the alcohol, aldehyde, ketone, ether, amine, amide, and
17 thiol functional groups can be attached includes alkyl,
18 typically about Cl to about C20, preferahly Cl to C10,
19 most preferably Cl to C5 alkyl; aryl, typically about
C6 to a~out CI4, preferably about C6 to about C10, most
21 preferably C6 aryl, cycloalkyl, typically about C4 to
22 about Czo~ preferably about C6 to about C12, most preferably
23 about C6 to C10 cycloalkyl, aralkyl and alkaryl wherein
24 the alkyI and aryl groups thereof are described above.
Each class o liquid organic media can contain
26 one or more, typically 1 to 3, functional groups.
27 The preferred organic compounds are the primary
2~ and secondary alcohols. AlcohoIs which con~ain 1, 2
29 or 3 hydroxyl substituent groups are especially preferred
3a because these, in general, are readily liquiied at useful
31 temperatures in the process range. Representative hydro~y-
32~ lic compounds useful in the process include monoalcohols,
33 such as methanol, ethanol, isopropanol, }-propanol, 1-
34 butanol, isobutanol, 2-butanol, t-butan~ Pentanol,
cyclohexanol, 1-o¢tanol, 2-octanol, 3-octanol , 4-octanol,
36 2-hexadecanal, 2-eicosanol, ~-ethyl-l- hexanol,
37 phenol, ~en~yl alcohol, etc.; di-alcohols, such as ethylene
,.
,
.
,:
. . . . . .
.-. -~ ., ~
; ,. ., - ' :
: . ~ , : ~
~Z2~9
.
- 21 -
} glycol, 1,4-butanediol, 1,2-propanediol; trialcohol suoh
2 as glycerine, 2,2-dimethylol ~ propanol; ether alcohols
3 such as diethylene glycol, triethylene glycol, 2-butoxy-
4 ethanol, 4-methoxybutanol, tetrahydrofurfuryl alcohol;
and mixtures thereof.
6 Representative aldehydes include benzaldehyde,
7 formaldehyde, acetaldehyde, propionaldehyde, m-~olualdehyde,
8 2-ethylh~anol, trioxane, valeraldehyde and mixtures
g thereof.
Representative ketones include acetone, methyl-
11 ethylketone, cyclohexanone, dimethyl ketone, diethyl
12 ketone, dibutyl ketone, methyl isopropyl ketone, methyl
13 sec butyl ketone, benzophenone, and mixtures thereof.
14 Representative ethers include diethyl ether,
lS di~utyl ether, tetrahydrofuran, anisole, dioctyl ether,
16 1,2-dimethoxyethane, 1,4~-dimethoxybutane, diethylene
17 ether, and mixtures thereof.
18 Representative amines include ethylene diamine,
19 hexylamine, cyclohexyl a~ine, diethylamine, 1,3 butadia~ine
ethylene triamine, n-phenylbenzamine and mixtures thereof.
21 Representative amides include formamide~, dimethyl
22 ormam~ide, acetamide, 3-butaneamide, n-phenyl acetamide,
23 azacyclohexan-2-one, hexanediamide and mixtures thereof.
24 Representative thiols include phenylmethanethiol,
ethanethiol, pentanethiol, 1,4-butanedithiol, cyclohexane-
26 thiol, benzylthiol, l,S-pentane dithiol; and mixtures
27 thereof.
28 The~primary and secondary alkanols (ROH~ having
29 a carbon atom content in the range from 3 to 6 are a
prefe-rred class of liquid organic media for reason or
31 cost and~avàil~ability and because of their convenient
32 boiling points. I-sobutanol is the optimum liquid.
3-3 In sh~rt, any~ of the aforenoted organic compounds
34 a~lone or in any~combïn-ation can be~employed as the organic
3S media.
T~e o~ga~ic m~diia may als~ contain non-oxygenated
~7 unreactive dil~ents w~hich-a~re in the liquid ~has~e at
. :.
:~
, .. -:
.
, . .. . . ..
:~ - :.,
:. ,,, .:.
. ~ . ~ : :
~Z~ 9~
- 22 --
1 reaction temperature. The5e include hydrocarbons, mono-
2 and polychlorinated hydrocarbons, and the like diluents.
3 The diluents which can be most advantageously
4 employed are less expensive than the organic media and help
to reduce the cost o the overall process. However, a min-
6 imum amount of hetoro-atom containing organic media is
7 employed as described herein to form the precursor com-
8 position.
g Repre entative compounds which can function as a
ln diluent in the organic media include hexane, heptane,
11 octane, cyclohexane, methylcyclopentane, 2,2,4-trimethylpen-
12 tane, dodecane, 2-ethylhexane, 3-octene, cyclohexene; ben-
13 zene, toluene, o-xylene, m-xylene, p-xylene, ethylbenzene,
14 trimethylbenzene, 2-propylbenzene; methylene chloride,
chloroform, carbon tetrabromide, carbon tetrachloride 3-
16 ahlorohexane, 2,3-dichlorooctane, chlorocyclohexane, 1,2-
l? dichloropentane, 1,2-dichloroheptane, 1,1,2-trichloroethane;
18 chlorobenzene, bromobenzene, o-dichlorobenzene, p-dichloro-
19 benzene, 2-chlorotoluene, 4-chlorotoluene, 2,4-dichloro-
- 2:0 toluene, 1,3-dimethyI-4-chlorobenzene, butyl bromide, and
21 the like hydrocarbons and halogenated hydrocarbons.
22 The proportion of each metal oxide added to the
23 reaction mixture i9 selected to achieve the gram atom
24 metal ratios employed to yield a metal oxygen composition
caRable of dehydrocoupling toluene such as described above
26 in the final composition in conjunction with the a~ore-
27` mentione~d formulas.I and II~
28 Thè amount of` orqanic madia which is admixed with
29 the metal:oxides i~ any amount suffi~ient to permit uniform
heating and mixing. o the reaction mixture and formation of
31 the precursor comFosition. Generally, the number of moles
32 of organic med`ia is at lea~st equal t~ the sum of the number
33 of moles of each met21 in the me.tal oxide mixture multiPlied
34 by the oxidation state of each metal in said mixture. Thus,
while any effe~tive amount of organic media can be employed,
36 su¢h efi~etive amQunts will: constitute a ratio of moles of
37 me--tal iB the metal= ox-ide mi~tu;~e pe~ mole of oLganic media o
,:
: : :
`' "
.
:
~Z~24~
- 23 -
1 typically at leas~ 1:1, preferably at least 1:3, and most
2 preferably at lea~t 1:8. The preferred amount of organic
3 media i9 calculated according to the formula:
4 ~oles of organic media = ~i Mi x Vmax,i
5 wherein Mi is the moles of ith metal in the catalyst system
6 and U max,i is the maximum possible oxidation state of metal
7 M. Most preferably about 5 to about 10 times the moles of
8 organic media calculated from the above equation is employed
g initially and the excess over the calcula~ed quantity is
gradually rem~ved.
11 Alternatively, the amount of organic media and
12 metal oxides can be expressed as a percentage of the reaction
13 mixture. Thus, the reaction mlxture wiLl comprise typically
14 from about 1 to about 60%, preferably from about 10 to about
50%, and most pxe~erably from about 10 to about 30~, by
16 weight, metal oxides, and typically from about 40 to about
17 99%, preferably from about 50 to about 90~, and mQst:pre-
18 fe~ably from about~70 to ~out gQ%, by ~eight~ organic media,19 based on the weight of the reaction mixture.
The reaction mixture comprising organic media and
21 metal oxides is heated to any temperature sufficient to form
22 the precursor composition. ~hus, while any effective temper-
23 ature may be employed, such e~fective temperatures typicaLly
24 wLll be at least 20C, preferably at least 75C, and most
pre~erably at least 105C, and can vary typically from about
26 20 to about 200C, preferably from about 75 to about 150C,
27 a~d most pre~ferably from about 100 to about 110C.
28 Preferably, the organic media is selected so tnat
29 it will ~oil at the sA}ected reaction temperature. This
permits ref}uxing of the reaction mixture.
31 During heating of the reaction mix~ure, an~
3~ wa~er and/or volatile organic by-products such as es~ers,
33 ethers, aldehydes~, ketones and acids~ formed in-situ are pre-
34 ferably removed, for exampIet by azeotropic distillation.
Thus, the rea~tion mixture is preferably heated ~nder s~b-
36 stæntially ain~hYdirous ~onditions.
37 3y "~ubst-anitially aDhy~rous~" as u~ed herein is meant
.- ,, . :. .
: '' '~ ' ~
. ~ .- . .
~,.; - .
.: -
,; . . .
:. .; , :' ' .
-
~2Z~9
1 typically less than about 10~, preferably less than about
2 5%, and most preferably less than about 1~, by weight water,
3 based on the weight of the organic media in the reaction mix-
4 ture.
As stated above,the reaction r~uxture typically
6 will axist as a slurry or suspended material during heating.
7 The term "slurry" as used in connection with the
8 cataLy5t precursor forming step is defined herein to mean a
g suspension wherein the solid components thereof are present
therein at a solids content of typically not greater than
11 about 60, preferably not greater than about 40, and most
12 preferably not greater than about 2S~, by weight, based on
13 the weight of the suspension.
14 The order of addition of the metal oxides to the
organic me~ia is not critical.
16 The reaction time is selected in conjunction with
17 the reaction temperature to permit substantially complete
18 reaction at the above reaction temperatures. Such reaction
19 times typically will ~ary from about 2 to about 48 hours,
preerably from about 10 to about 30 hours, and most pre-
21 fsrably from about 16 to about 24 hours.
22 Upon completion of the reaction,the precurqor
23 composition is separated from the reaction mixture by any
24 means capable of achieviNg this goal. Since the precursor
composition typically is insoluble in the reaction mixture,
26 bulk se~aration can be accomplished by simple filtration
27 techniques. Alternately, the residual organic media can
28 be distiIled to orm a wet paste. Residual liquid is pre-
29 ferably removed from the filtrand ~i.e., the insoluble
m~ate~rial removed from the filtrate) or paste by drying the
31 same, tvpically at temperatures of from about 25 to about
32 210C, preferably from about 80 to about 160C, and most
33 preferably from about 100 to about 150C.
34 The isolated precuxsor composition is then cal-
cined to form the metal oxygen composition capable of de-
36 hydrocoupling toluene. Calcination ca~ be conduct~d in a
3~ sepa~ate step or in-situ in the reactor and involve~s
:..... : ~.
- 25 -
1 heating the metal oxygen com~osition to at least reaction
2 temperature.
3 Accordingly, calcination is conducted at tem-
4 peratures of ty~ic~lly from about 300 to about 1200C, pre-
ferably from about 400 to about 1000C (e.g. 500 to 1000C),
and most preferably from about 600 to about 900C for a
7 period of typically from about 0.5 to about 24 hours, pre-
8 ferably from about 1 to about 10 hours, and most preferably
9 from about 1 to about 4 hours.
The atmospheDe under which calcinationis conducted
11 is capable of oxadizing, where possible, the metal(s) in
12 the metal oxygen composition. Such atmospheres include
13 oxygen or an oxygen containing gas s~ch as air; a gaseous
14 mixture of air and minor amounts of at least one of the
inert gases such as helium, argon and the like; and a
16 mixture of air and minor amounts of at least one other
17 gas such as CO2~ CO, H2, and hydrocarbon (e.g. toluene).
l8 The preferred calcination atmosphere is air. While the
l9 calcination atmosphere may be passed as a moving stream
~0 over the precursor composition, it is preferred that the
21 ca}cination atmosphere be static in nature.
22 A~ter calcination is conducted the metal oxygen
23 composition can optionally be activated. Activation in-
2~ volves preconditioning the metal oxygen composition with
2~ ~ir or other atmosphere descr~bed in connection with
2; calcination beore selecting the final operating conditions.
27 Activation is therefore typically conducted by contacting
23 the metal oxygen com~osition with said gaseous atmosphere
2~ at temperatures of t~pically from about 350 to about 700,
30 oreferably from about 400 to about 650, and most preferably
3l from about 400 to about 600C.
32 Acti~ation times can vary typically from about l
33 to about 24, pre~erably from about 2 to about 20, and most
3I preferably from akout lO to about 16 hours. While activa-
3~ tion may be conducted in a static atmos~here it is pre-
ferred that sueh atmosi~here~be dynamic and pass over the
-:, ..
:
.
., ': ~ ~.' '
. ~' . ... ':~ ,.: .
~4~9~
- 26 -
1 the catalyst as a fluid tream.
2 The attrition resistance of the metal oxide com-
3 position can be sub~tantially improved by incorporating at
4 least one: alkali or alkaline earth metal oxide, prefer-
S ably alkali metal oxide, most Dreferably cesium oxide into
6 the final composition. This can be achieved by selecting
7 the a~propriate alkali or alkaline earth metal oxide as one
8 of the initial metal oxides which i9 admixed with the
9 organic media. Alternatively, and most preferably, ~he
10 appropriate metal oxide is impregnated into the precursor
11 composition after removal of the organic media therefrom
12 by any suitable method. In accordanca with the preferred
13 me~hod of impregnationO the appropriate alkali or alkaline
14 earth metal oxide is dissolved in water to form a solution,
15 e.g., of CsO~/~20, and the precursor composition is admixed
16 with the solution to form a slurry.
17 The resulting slurry is then stirred ~or a time
18 of typically from about 1 to about 24, preferably from
19- about 2 to 16, and most preferably from about 4 to about 10
20 h~urs, at temperatures of typically from about 2S to about
21 lU0, preferably ~rom abou* 60 to about 80, and most pre-
22 ferably from about 65 to ahout 7SC to effect impregnation.
23 The impresnated precur~or composition solids are
24 then recovered by, for example, evaporating the water to
25 form a thick paste which i5 then dried in an oven at the
26 aforedescribed drying temPeratureS. The impregnated pre-
27 c~rsor composition is then calcined as deRcribed herein.
28 The attrition resistance effect has been found to
29 be imparted to the final composition by the alkali or alka~
3~ line earth metal oxide when pre~ent ~herein in amounts of
31 typicallv from about 0.01 to about 100, pre~erably 0.1 to
32 about 10, and most preferably from about 1.0 to about 5.0
33 mole ~ a;ttrition resistance modifying metal, based on the
34 total number of moles of metals in the metal oxygen com-
35 position.
36 ~he s~urfaee ar~ea of the metal oxide composition
37 after calcination typic~llv will vary from ahout 0.1 to
... :.: .
,: .: .,: ,
.
~Z~
- 27 -
1 about 10, preferably from about 0.1 to about 2.0, and most
2 preferably from about 0.1 to about 1.0 m2/gm, as de~ermined
3 by the B.E,T. method.
4 The metal oxide composition resulting after caL-
cination exhibits improved activity and selectivity vis-a-
6 vis the dehydrocoupling of toluene to stilbene relative to
7 metal oxide composition derived from similar metal oxides
8 prepared by prior art techniques, particularly the aqueou~
9 slurry techniques discussed above. In addition, the metal
oxide composition of the present invention deactivates at
11 a slower rate than those prepared by prior art techniques .
12 and is more attrition resistant. Thus, while the metal
13 oxide compocition of the present invention may possess an
14 ampirical formula similar to that of the prior art, the
particular method of preparation described herein is
16 believed to alter both the precursor and final composition's
17 basic physical and/or chemical characteristics in terms of
18 crystal structure, porosity and surface area relative to
19 prior art com~ositions to the extent that improved effects
are obser~ed as described herein.
21 The inorganic metal oxygen composition of the
22 present invention can function in a catalytic mode, a
23 stoichiometric mode ~also referred to herein as the cyclic
24 mode because of the need for regeneration o~ lattice oxygen)
as an oxidant or oxygen carrier, or a combined catalytic/
26 stoichiometric mode for the dehydrocoupling of toluene~
27 In the catalytic mode of operation, oxygen-or an
28 oxyqen-containing gas such as air or oxygen-enriched air is
29 reacted with toluene in an amount suficient for the dehy-
drocoupling reaction,said reaction being catalyzed by and
31 conductedin the presence of the metal oxygen composition.
32 In the stoichiometric mode of operation, the
33 metal oxygen composition is the sole source of oxygen.
34 That is, in the latter instance the dehydrocoupling of
toluene is conducted in the substantial absence of added
36 free oxygen such as would be obtained from air. Consequently,
37 the metal oxygen composition when operating in this mode is
'
: - -
.. - "', ~' ~ :
:: . . ,~, .
~ .: : ' :
4~
1 eventually depleted of oxygen and must be regenerated as
2 described hereinafter.
3 I~ the combined catalytic/stoichiometric mode of
4 operation, oxygen or an oxygen-containing gas is added as a
reactant in a manner similar to that noted herelnabove for
6 the catalytic mode of operation. However, the amount of
7 added oxygen i- not suficient by itself to meet the
8 stoichiometric oxygen re~uirements of the d~hydrocoupling
9 reaction. Conqequently, additional oxygen must be supplied
by the inorganic metal oxygen compo~ition. The amount of
11 added free oxygen is typical~y controlled and limited by
12 diluting the atmosphere in contact with the metal o~ygen
13 composition with a suitable inert gas such as nitrogen.
14 Of these three modes of operation, the stoichio-
metric mode is generally preerred although this preference
16 may change depending on the particular metal oxygen com-
17 position elected.
18 The term "dehydrocoupling n and related terms
19 are employed herein to mean that the toluene molecules
are coupled or dimerized, with carbon-carbon bond formation
21 occurring between the methyl group carbons, and the coupled
22 molecules have lost eLther one or two hydrogen atoms
23 from the ~ethyl group of each toluene molecule. When
24 two hydrogen atoms per molecule of toluene are lost r
the carbon-carbon bond at the coupling or dimerization
26 site is uns~aturated as by dehydrogenation, that is, stilbene
27 is the product. On the other hand, bibenzyl, having
28 a saturated carbon-carbon bond at the coupling site,
29 is the product when only one hydrogen atom per molecule
o toluene is lost.
31 In general, the production of stilbene as the
32 dehydrocoupled toluene product is preferred over the
33 production of bibenzyl. This stated preference is due
34 to the unsaturated character of stilbene as opposed to
the saturated character of bibenzyl. As is well
36 known in the art, the presence of the unsaturated olefinic
37 carbon-carbon double bond causes the stilbene to exhibit
.
- 2~ -
1 high reactivity, thereby facilitating its direct use
2 as an organic intermediate in numerous organic syntheses.
3 The process of this invention is conveniently
4 carried out in an apparatus of the type suitable for
carrying out chemical reactions in the vapor phase.
6 It can be conducted in a single reactor or in multiple
7 reactors using either a fixed bed, a moving bed, or a
8 fluidized bed system to effect contacting of the reactant
g or reactants and metal oxygen composition. The reactant
toluene or toluene derivatives will generally be heated
11 and introduced into the reactor as a vapor. However,
12 the reactant may be introduced to the reactor as a liquid
13 and then vaporized.
14 The oxidative dehydrocoupling reaction is prefer-
ably carried out in the vaDor ~hase and under the influence
l; of heat. The temperature ranqe under which the reaction can
17 be carried out ranges from about 300 to about 650C, te.g.
18 400 to 650C), preferablY from about 450 to about 600C,
19 and mo~t preferably from about 500 to about 580C.
2~ Pressure is not critical in the dehydrocoupling
21 process of this invention. The reaction ma~ be carried
Z2 out at subat spheric, atmospheric, or superatmospheric
23 pressures as desired. It will be generally preferred,
24 however, to conduct the reaction at or near atmospheric
pressure. Generally, pressures from about 1 to about
2S 10, preferably from about 1 to about 5, and most prefer-
27 ably from about I to about 2 atmospheres can be conveniently
2~ employed.
29 The reaction time for the contact of the reactant
3~ with the metal oxygen composition in the present invention
31 may be selected from a broad`operab}e range which may
32 vary from about 0.5 to about 10, preferably from about
33 1 to about 8, and most preferably from about 1 to about
34 4 seconds. The reaction time maY be defined as the
length of time in seconds which the reactant gasses
36 measured under reaction conditions are in ~ontact with
37 the inorganic metal oxygen com~osition in the reactor.
. .
.
'
~z~
- 30 -
1 The sele¢ted reaction time may vary depending upon the re-
2 actio~ temperature and the de~ired toluene conversion level.
3 At higher temperatures and lower toluene conversion levels,
4 shorter contact times are required.
In addition to the toluene and/or toluene deriva-
6 tives, other inert substances such as nitrogen, helium and
7 the like may be present inthe reactor~ Such inert materials
8 may be introduced to the process alone or may be combined
9 with ~he other materials as feed.
Water has been found to play a signi~icant role
11 in the dehydrocoupling process. ~igher toluene conversions
12 and selectivities to desired products can be obtained by
13 including water, preferably in the form of steam,in the
14 t~luene feed stream. However, care should be taken to
avoid introducing too much steam, since steam cracking of
16 tha toluene can occur thereby yie}ding a product effluent
17 having an undesirably hi~gh benzene and C02 by-product con-
18 tent. Thus,~ suitable steam to hydrocarbon mole ratios~ in
19 the feed stream are selected in conjunction with a p~rticu-
2n lar metal oxygen composition to effect improved selectivi-
21 tie~s to stilbene and diphenylethane, and toluene conversions
22 relative to the absence of steam. Accordingly, while any
23 effe~tive steam-to-hydrocarbon mole ratios may be employed
24 it is contemplated that such mole ratios constitute typically
from about 0:1 to about 10:1, preferably 1:1 to about 5:1,
2~6 and most preferably 2:1 to about 4:1.
27 ~he metal oxygen composition may be employed in
28 the present invention alone or in association with a support
29 or carrier. The use of a support may be particularly ad-
vantageous to further improve attrition resistance during
3-1 reactor charging and/ox under reaction conditions encoun-
32 tered during the course of the re~ction process. Suitable
33 su~ports, typically employed in sphe~rical, tablet, or cylin-
34 drical form, for the composition are, for example, siL-ca,
aIumina, silica-alumina, metal aluminates such as magnesium
36 alumina~e, calcium aluminate, titania, zirconia, acti~ated
37 car~on, zeolites~ a~d the li~e.
,~
., ~ : .... . ,: .
. . .
.. .... ..
. ::. .
4~
- 31 -
1 As noted hereinabove, the dehydrocoupling reaction
2 may be conducted in the presence or absence of added
3 free oxygen. When oxygen is not added to the system,
4 that is, the reaction is conducted in the stoichiometric
mode of operatïon; the oxygen required for the reaction
6 is provided by the metal oxygen composition which enters
7 into the reaction and is consequently reduced (or, in
8 actual practice, partially reduced~ during the course
9 of the reaction. This necessitates rPgeneration or reoxida-
tion which can be easily effected by heating the material
11 in an oxygen containin~ gas such as air or oxygen at reac-
12 tion temperatures reci~ed herein, e.g. prefera~ly from about
13 500C ~o about 600C for a period of time ranging fromabout
14 5 minutes to about 2 hours. In a semi-continuous operation,
regeneration can be effected by periodic interruption
16 of the reaction for reoxidation of the reduced composition,
17 that is, periods of reaction are ~ycled with perlodq
18 of regeneration. Operation, howeqer, can be on a continuou~
19 basis whereby a portion of the metal oxygen composition
can be continuously or intermittently removed, reoxidized
2~ and the reoxidized material can ~hereafter be continuously
22 or intermittently returned to the reaction. The latter
23 method is particularly adapted to operations in which
24 the metal oxygen composition is fed in the form of a
fluidized bed or a moving bed system.
26 The~metai oxygen compositlon typically can be oper-
27 ated~at conversions of from about 1 to about 40~ a~d selectivi-
28i ties to stilbene and bibenzyl o~ from aDOUt 10 to abou~ 95%, ior
~9 periods of ~rom about 5 to ahout 40 minutes, preferably from
about l0 to about 30 minutes, and most preferably from
31 abou~ 20 to about 30 minutes before having to be regener-
32 ate~. ~
j3 When oxygen is employed as a reactant, the reac-
34 tion may be conducted in~either a catalytic mode or opera-
tion or a combined catalytic/stoichiometric mode of opera-
36 tion, depending on the amount of oxygen supplied. In the
catalytie mode of o~eratiQn, oxysen is sup~lied in an amount
38 su~icie~nt f~r the dehydrocou~ling rea¢tion. The actu~l am~u~t
: ; ~
`' ~ `, ' ;, .: ' '`
;;. :; . .. .
~;224~
1 of oxygen supplied m2y be specified as a function o the
2 amount of the toluene o~ other suitable hydrocarbon com-
3 ponent. On this basis the amount of oxygen supplied is
4 ordinarily selected to provide a hydrocarbon-to-oxygen mole
ratio from about 0.2:1 to about 10:1, preferably from
6 about 0.5:1 to about 5:1, and most preferably from about
7 0.8:1 to about 2:1.
8 In the combined catalytic/stoichiometric mode
9 of operation, the amount of oxygen supplied as a reactant
is not sufficient for the dehydrocoupling reaction, thereby
11 requiring an additional source of oxygen. The required
12 additional oxygen will be supplied by the metal oxygen
13 compogition, that is, the composition will serve as the
14 additional source of oxygen. As a result, the metal
oxygen composition enters into the reaction a~d is conse-
16 quently reduced during the course of the reaction. This
17 necessitates regeneration or reoxidation of the reduced
18 composition which can be easily effected as described
19 hereinabove for the stoichiometric mode of operation.
In either mode of operation employing added oxygen
21 as a reaatant, w~ether catalytic or combined catalvtic~
22 stoichiometric, the added free oxygen may be supplied
23 either as oxygen or an oxygen~containing gas such as
24 air or oxygen-enriched air.
The dehydrocoupled toluene products, stilbene
26 and bibenzyl, may be recovered and purified by any appropri-
27 ate method and means known to the art. As noted previously,
2~ stil~ene, of course, is the preferred product. If desired,
29 bibenzyl can subsequently be converted to stilbene also
30 b~ ~ethods well known In the art or recycle~ back to the
31 toluene coupling reactor.
3-2 The followin~ examples are given as specific
33 illustrations of the claimed invention. It should be un~er-
34 stood, however, that the invention is not limited to the
35 specific details set forth in the examples. All parts and
36 percentages in the examples as well as in the remainder of
37 the q~ecification are by wei~ht u~less otherwise sipecified.
, ' : ,:~
`.
~4~9
- 33 -
l Futhermore, while the following examples may be written in
2 the present tense it is to be understood that such examples
3 represent-wor~ actually per~ormed.
4 In the following examples, selectiYity and con-
version are calculated as follows:
6 . gms. of cArbon of desired product
96 selectlvity ~ x 100
~ms~ of car~on o feed
% conve~sion , gms- of carbon in feed reacted x 100
~ gms. of carbo~ in feed
9 All product analysis is conducted by gas chroma-
tography
11 While the present in~ention i9 described in con-
12 junction with the dehydrocoupling Or toluene, it will be
13 understood by thase sXilled in the art that methyl substi-
14 tuted derivatives of toluene can also be employed as the
hydrocarbon feed s~urce. Thus, the hydrocarbon feed source
16 which can be employed in the process of the present inven-
17 tion comprises at least~o~e compound represented by he
I8 5tructural formula ~
~ (C~3)n ~XI)
21 wherein n is a number from 1 to 6, preferably l to 4, most
22 preferably l to about 3 (e.~. 2). Representative examples
23 of such hydrocarbon feed sources in addition to toluene,
24 include, o-xylene, m-xylene, p-xylene, 1,3,5-trimethyl-
benzene, 1,2,4-trimethylbenzene, 1,2,4,6-tetramethylbenzene,
26 hexamethylbenzene, pentamethylbenzene and the like. The
27 most preferred toluene derivatives are the xylenes.
28 Generally, when a hydrocarbon feed source other
29 than toluene is employed the dehydrocoupled product will
3~ be the appro~riate methyl substituted stilbene or diphenyl
31 ethane products, e.g. the methyl groups in excess of 1 are
32 carrie~ along and rem~i~ une~ected by the dehydrocoupling
33 reactions.
34 The term "toluene~ derivative" is therefore de~ined
herein to be at least one compound represented by formula
36 X~I w~herein n is betwee~ 2 and 6.
37 The followin~ examples illust~ate the per~orma~ce
", .~ , ..
. .
~',',. '', -: ~ , `
:. ~
- 34 -
1 of the metal oxygen composition when operating in either
2 the stoichiometric mode, the catalytic mode or combined
3 catalytic/stoichiometric mode. As described above, when
4 operating in the stoichiometric mode, the metal oxygen
composition is allowed to contact with toluene, steam
6 and nitrogen for a certain length of time during which the
7 oxygen of the metal oxygen composition depletes due to it~
8 stoichiometric reaction with toluene in the coupling proces~.
g The mstal oxygen composition, therefore, would need to be
regenerated in air (or oxygen) in-situ cyclically between
11 tests when employed commercially in this mode.-Consequently,
12 some of the runs pro~ided herein illustrate the per~ormance
13 of the metal oxygen composition ater regeneration.
I4 To illustrate the performance of the metal oxygen
lS com~osition when operating in the catalytic mode, said
16 composition is allowed to contact continually with toluene,
17 steam and air. Sufficient air is supplied in the feed to
18 maintai~ the oxygen content of the composition needed for
19 efficient dehydrogenation. Consequently, the metal oxygen
composition actg as a catalyst in the toluene dehydrocoupl-
21 ing process and its cyclic regeneration in air is no longer
22 necessary.
23 Nhen reporting the data in Table 1, an asterisk
24 in the column reporting toluene conversion signifies the
run is within the scope of the present invention.
26 EXAMPLE 1
27 A slurry is prepared by adding 58.3~ Sb2O3, 134.0g
28 PbO; and 23.3g Bi203 sequentially to 200 ml o~ iso~utanol
29 in a suitable container at room temperature. The resuIting
slurry is heated, stirred and refluxed at 108C ror 24
31 hours to remo~e water as it is formed. Durlng the reflux,
32 the color of the slurry changes from light yellow to orange.
33 The mix~ure is then cooled to room temperature (about 25C)
34 filtered, and the filter cake air dried at rOQm temperature
for about l6 hours. The resulting air dried ~ilter cake is
36 then further drisd in air at 150C for 48 hours in an oven.
37 The resulting precursor composition is then calcined in air
38 at 900 for 2 hours and sleved to a -12+20 mQsh size (U.S.
39 Sie~e Series).
~ .
, , ~
~z~ 9
- 35 -
1 Forty grams of the sieved metal oxygen composi-
2 tion are then placed in a 20 cc stainless steel U-shaped
3 reactor tube (OoD~ 3~8n, I.D. 5/16") immersed in a sand
4 bath to supply heat to the reactor. The inlet portion of
the reactor tube is horizontal, located in the sand bath,
6 and of sufficient length to vaporize the li~uid toluene
7 and any water before it is introduced into the reactor
8 portion. The empty heated horizon~al inlet tube therefore
9 functions as a preheating zone. The composition is then
heated in the reactor tube at 450C while passing air
ll through the tube at a flow rate sufficient to achleve a
12 contact time of about 2 sec., for a period o~ about 16
13 hours to activate the composition. During activation, re-
14 sidual moisture and volatile impurities are removed from
the metal oxygen composition and the metal oxidation states
16 are elevated to impart cptimum activity. A liquid mixture
17 con~aining toluene, ~2~ and ~2 in a I:2:1 molar ratio is
18 then introduced into the preheating zone of the reactor
I9 tube whereupon the toluene and water are vaporized. The
gaseous mixture is then passed through the remainder o~
21 the reacto~ tube.
22 The flow rate through the reactor is sufficient
23 to achieve a contact time with the metal oxygen composition
24 o 4.2 seconds. The temperature of the reactor during the
25 contact is 565C. The gaseous mixture is allowed to flow
~6 through the reactor for a period deRignated by "on-stream
27 time" before product samples are removed for ~nalysis.
28 Several runs are conducted in series and in each run
29 reactor effluent is scrubbed for 30 minutes with an ace-
tone trap at 0C. The metal oxygen composition i9 not
31 regenerated between each run. Samples for analysis are
32 removed fr~m the reactor ef~luent after 0.5, 1.0, and 2.0
33 hours of on-stream time.
34 The results are ;summari ed in Table 1 (runs 3-5)
sele~tivity to stilbene plus diphenyl ethane (i.e., DPE)
36 ran~es ~rom 81.7~ to 84.8~ at toluene conversions of 13.6%
37 and 16.2% resPectively.
, .
.
~ ,
..
. ~ ;
4~
36 -
1 EXAMPLE 2
2 Example 1 i~ repeat~d with the exception that
3 the contact time between the feed gas mixture and the metal
4 oxygen composition is reduced to 3.5 seconds, and the feed
gas contains a small amount of air sufficient to provide ~
6 molar ratio between toluene-stream-~2 and air of 1:2sl;0.87
7 respectively. This example is therefore conducted in the
8 combined catalytic/stoichiometric mode. On-stream time
9 before removing a product sample for analysis is two hours.
The results are summari~ed at Table 1, (run 9). Selectivity
11 to stilbene plus DPE is 72.2~ at a toluene conversion of
12 10.3~.
13 ~XAMPLE 3
14 A metal oxygen composition is prepared in accordance
with Example 1 (including drying, calcination and activation
16 conditions), and tested in accordance with the same with the
17 exception that before each recovery run is made, the metal
18 oxygen composition is regeneraged at reaction temperature~
19 (560-565C~ by passin~ air through the reactor for 30 minutes
at about 200 cc per minute. The re3ults are summarized
~i at Table l,truns 11 and 12). Selectivity to stilbene plus
22 DPE range~s from 90.4% to 89.7~ at respective toluene con-
23 versions of L7.3% and 15.6% with respective on-stream times
24 o~ 0.5 in 1 hour.
EXAMPLE 4
26 ~he me-tal oxygen composition employed in this
27 example is prepared in aocordance with the proc@dure de-
28 scribed in Example 1 (including drying, and activation) with
29 the exception tha~ the composition is caIcined at 600C for
2 hours. 9.0g of the metal oxysen composition are evaluated
31 in a 5cc micnsreactor immersed in a heated salt bath at553C.
32 The same feed stream employed in Example 1 is used and the
33 contact time is control}ed ~o be about 1.7 seconds. The
34 catalyst is regenerated in air at 553C for 0.5 hours prior
to each recovery run. The~ reactor effluent is scrubbed in
dual traps at ice temperature (OC). Samples of reactor
37 ef1ue~nt are removed~ after on-stream times of 0.5, 1.0, and
.
, ' :
.,
'. ~ `' " '`' ,-:
: - :
- .
~29~
- 37 -
1 2.0 hours for analysis. The reRults are summa~ized at
2 Table 1, (runs 15-18). Selectivity to stilbene plus DPE
3 ranges from 88.8 to 91.0~ at toluene conversions at from
4 18.4 to 17.5% respectively.
5 EXAMPLE S
-
6 The metal oxygen com~osition for this example is
7 prepared in accordance with the procedures of Example 4 with
8 the exception that the precursor composition after drying
9 in accordance with Example 1 is placed in a ball mill jax
and ball-milled for four hours. The ball mill precursor
11 composition is then calcined at 6~0C for two hours in an
12 oven and sieved to a mesh size of -20+40 (U.S. Series).
13 ~all-milliny is employed to improve the uniformity of the
14 metal oxygen precursor composition. The metal oxygen com-
position is activated in accordance with Example 1, and
16 tested in accoraance with the procedures of Example 4. On-
17 stream times are varied from 5 to 20 minutes and regenera-
18 tion in air at 553C for 0.5 hours,at 2 sec. contact time
19 i~ conducted before each recovery run. The results are
20 summarized at Table 1, runs 21 to 24. Selectivity to stil-
21 bene plus DPE ranges from 85.1 to 86.9% a~ respective
22 toluene c~nversions of 32.8 and 20.8%.
23 EX~UPLE 6
24 The metal oxygen composition prepared and tested
in accordance with Example 5 tincluding drying, activation,
26 and regeneration) using a feed stream compri ing toluene,
27 water and nitrogen at a molar ratio of 1:3:1 and 2 seconds
28 contact time. Two runs are conducted with on-stream times
29 of 20 minutes for each run. The results are summarized at
Table 1, lruns 25-2~). The average selectivity to stilbene
31 plus DPE of these runs- is 84.1~ and an average toluene con-
32 version of 26.1%. Comparing these results with selectivity
33 and con~ersion obtained in run 24, it can be seen that the
34 use of additional water in the feed stream improves toluene
conversion substantially from 20.8% to 26.15% while the
36 stilbene plus DPE selec~ivity i5 reduce~ only slightly fro~
37 86.9% to 84.1%.
:,
,
.
,
~lZ2~
- 38 -
1 EX~PLE_7
2 Par~ A
3 ln this example, attrition resistance of the
4 metal oxygen composi~ion is improved by impregnating
the same with cesium hydroxide while maintaining stilbene
6 selectivity a~ moderately high levels. More specifically,
7 the metal oxygen precursor prepared in accordance with
8 Example 1 after being dried but uncalcined is impregnated
9 with cesium hydroxide in the following manner. In a
l-liter beaker, 2.56g of CsOH is added to 250 cc of ~2
11 and the mixture is stirred~to yield a uniform solution.
12 A slurry is made by adding to this CsOH solution, 150 g
13 of the dried metal oxide precursor. The slurry is constantly
14 stirred while it is heated for about five ho~rs and finally
evaporated to a thick paste. The paste is dried in the
16 oven at 150C for about 48 hours. The resulting metal
17 oxygen composition slurry is boiled down to a paste and
18 dried at 150C for about 48 hours. The dry composition
19 is then calcined in air at 600C ~or two hours. The re-
sulting calcined composition pos~esses the empirical formula:
21 ~90,o3~ Pbl.0' S~0.67' Bio.l7~ O4 5~ and a bulk density of
22 2.02 g/cc.
23 A portion of this composition is then tested for
24 attrition resistance in the following manner:
A~ter sieving the composition to a mesh size of
26 -20+40 (U.S. Series), 10 g of the composition are dropped
27 through a 10 ft. pipe of 1/2" I.D. onto a hzrd surface. The
28 particles are then sieved through a 20 mesh screen (U.S.
29 Series) and the particles los~ throu~h the screen is
between about 2 to 5~, based on the total initial weight.
31 The remainder of the metal oxygen composition not
32 tested for attrition resistance is then sieved to a mesh
33 size of -20+40 (U.5. Sieve~ Series).
34 Part ~
10.1 g of the -20+40 sie~ed metal oxygen composi-
3~ tion is then placed into the reactor employed in Example 1,
37 activated for 15 hrs. in air at 450C, 2 sec. contact ti~e
.
"
... .
.:
.- .~ , .
~2Z431 ~39
- 39 -
1 and then contacted *ith a vaporized feed mixture of toluene:
2 ~2O:N2 (1:2:1 mo}ar ratio) which is passed thr~ugh the re-
3 actor tube at 550C and 2 second contact time. Before
4 recovering product for analysis, the composition is regener-
at~d in air in accordance with Example 4. The reaction
6 conditions and results are summarized at Table 1, run 41.
7 The products are scrubbed in acetone traps at ice tempera-
8 ture and non-condensibles are collected in a sampling tube.
9 The products are analyzed by means of gas chromatography.
The same metal oxygen composition of run 41 after
11 regeneration and sample testing,are tested again after an
12 additional on-stream time of 20 minutes at 512C reaction
13 temperature, 2 second contact time, using a vaporized feed
14 mlxture of toluene:H20:N2 (1:4:1 molar ratio). Before pro^
duct recovery and analysis, the composition is regeneratad
16 in ~ccordance with Example 4. The reaction conditions and
17 results are summarized at Table 1, run 42.
18 The above procedure of run 42 is repeated again
19 at 522C reaction temperature, 2 second contact time,with
a vaporized feed mixture of toluene:H2O:N2 (1:5:1 molar
21 ratio). The reaction condi*ions, and results are summarized
22 at Table 1, run 43. As may be seen from the results of runs
23 41 to 43, increasing the amount of steam in the feed gas
24 results in increased selectivity to desired products with
only slight decreases in conversion upon regenexation.
26 Part C
27 To illustrate the performance of the metal oxyyen
28 composition when operating in the catalytic mode, 10.1 g
29 of the used and regene~aged metal oxygen composition from
run 43~, Part B is contacted with a vaporized feed mixture
31 of toluene:~2O:air (1:4:1 molar ratio) which is continuously
32 passed through the tube at a reaction temperature of 550C
33 and 2 second contact time until a steady state is attained,
34 i.e., about 3 hours. Product is then recovexed without
regeneration by the aforedescribed scrubbing procedure for
36 an additional 20 minutes and analyzed. The reaction is then
37 allowe~ to proceed until the to~al on-stream tim~ is about
~,:
:`
' . ,. ''
:~LZ~4
- 40 -
1 9 hour5. At thi5 tLme, the product is recovered without
2 regeneration by the scrubbing technique and analyzed. The
3 reaction conditions and test results are summarized at
4 Table 1 runs 44 and 45 respectively.
As may be seen from the data of runs 44 and 45
6 while the conversion drops to some extent relative to the
7 cyclic mode, the com~ined stilbene and DPE selectivity re-
8 mains high, i.e. about 80%.
9 EXAMPLE 8
The metal oxygen composition of this example
11 is prepared and tested in general acco~dance with the
12 procedures described in Example 1. However, in this
13 example 135.09 Bi2O3 and 94.5g ZnO are introduced into
14 and slurried with 500 cc of isobutanol. The resulting
slurry is heated and refluxed at 107.5C for 20 hours.
16 The mixture i5 then cooled to a temperature of 25C,
17 filtered and the filter cake dried in an over at }10C for
1~ 24 hours. The dry precursor composition i5 then calcined
1~ at 400C ~or two hours and 800C for one hour in an oven.
2b The calcined composition i~ then crushed and sieved to
21 a ~ 20 mesh size (U.S. Series) and placed in a 20cc stain-
22 less steel reac~or using a sand bath as a heat source. The
23 comDosition is then activated in air at 450C for 16 hr3.
24 'rhe ~ed mixture of toluene, H2O and N2 employed in ~xample
1 is then Passed throu~h the reactor which is maintained at
26 550C. Con~act time of the Seed gas with the metal oxygen
27 ¢omPosition is 4 seconds. The reactor effluent is scrubbed
28 in acetone for 30 minutes a~ter each run. Two runs are con-
29 duc~ed and samples are removed immediately after start-up
and after 0.5 hours of on-stream tLme for analysis. In
31 between each o these runs, the catalyst is regenerated in
32 air at a temperature of 550~ for a period of 0.5 hours.
33 Results are summarized at Table 1.(runs 27-28).
34 ~XAMPLES 9-12
A metal oxygen composition is prepared and tested
36 in accordance with Example 4. Such com~osition is use~ to
37 conduGt several runs at varying toluene:water:N2 molar
' `' ' ~ '
` :
'' ' ' ` :'
-` ~:
~LZ~4L31 ~39
- 41 -
1 ratios. Thus, in Example 9 (runs 31-32), such ratio is 1:0:
2 1; in Example 10 (runs 33, 34, 36),1:1:1; in Example 11
3 (runs 37-38), 1:2:1: and in Exampla 12 (runs 39-40), 1:3:1.
4 The test conditions and results of Examples 9-12 are sum-
S marized at Table 1 (runs 31-40). The on-stream time before
6 product analysis is taken for each of these runs is twenty
7 minutes. Except for run 35 of EY.amP1e 10, each of the runs
8 31 to 40 are conducted in the cyclic mode. Run 35, however,
9 is conducted in the catalytic mode using air in place of N2
but because of an obviously incorrect material balance, the
11 product~ were not properly recovere~ and the results had to
12 be ignored. All of runs 31 to 40 are conducted on the same
13 metal oxygen composition, and upon completion of each run
14 co~ducted in the cyclic mdde the composition is regenerated
in air fQX 0.5 hours at 553C prior to sample recovery. As
16 may be seen rom the data of ~uns 31 to 34, and 36-40, in-
17 creasing- tbe steam content substantially improves both the
18 selectivity to desired products and conversion of toluene.
19 The following comparative examples are intended
to illustrate the difference in results obtainable by com-
21 paring metal oxygen compositions prepared in accordance with
22 the aqueous procedures described in the prior art. U.S.
23 Patent No~. 4,091,044 and 4,254,293 are used to illustrate
24 the aqueous preparation.
COMPARATIVE EX~MPLE 1
26 Example 6 of U.S. Patent No. 4,091,04~ is repeated
27 using the~ same amaunts o Sb203, PbO, and ~i203 employed
28 in Example 1 (described above) with the exception that each
2;9 of these components are sequentially added to 250 ml of
watsr. The resulting slurry is heated with constant stir-
31 ring and boiled down to a paste, which is then dried in an
32 oYe~ at 110C for 24 hours. The dried product possesses a
33 light green color-. A p~rtion of the dried product is
3-4 calcined at 900C for 2 hours~ and the calcined catalyst
sieved to -12+20 mesh sizè (U.S. Sieve Series) for evalua-
36 tion. 20cc of the resulting mixed oxide composition are
37 evaluate~ in the 2Qcc stainless steel reactor tube of
-: , :;, '`: ' ,:. :
~- ... ., ~ : - .
.~ ~: .: :
. ", ' ~
'~2Z9~
- 42 -
1 Example 1 using a sand bath to sup~ly heat. Toluene, steam,
~ and N2 in a 1:2O1 molar ratio are fed throu~h and vaporized
3 in the reactor, said reactor being at 565C, while control-
4 ling the flow rate to achieve a contact time of 1.4 seconds.
5 Two runs are conducte~ at on-stream tLmes of 0.5 and 1.0 hour
6 and after each recovery run, the reactor effluent is scrubbed
7 for 30 minutes in acetone. The metal oxygen composition is
8 not regenerated between each of these runs. The results
9 are summarized in Table 1 (runs 1 and 2).
iO COr~PARATIVE EXAMPLE 2
11 The metal oxygen composition of this example is
12 Prepared in accordance with with the procedures of Compara-
13 tive Example 1 with the exception that the compo~ition is
14 activated in air at 450ac for 16 hours, 2 second contact
time and eva~uation of the same is conducted in accordance
16 with the procedures of Example 1 to obtain a comparison.
17 The re ults are summarized at Table 1 (run~ 6-8).
18 COMPARATIV~ _XAMPLE 3
19 A me~al oxvgen composition is Drepared in accord-
2~0 ance with the procedures of ComDarative Example Z. Prior
21 to ~roduct analysis, however, the composition is allowed
22 to remain on-stream without regeneration prior to the re-
23 covery run for a period of 2 hours. Reactor testing
24 pro¢edure is conducted in accordance with the procedure o~
Example 2. The results are summarized at Table 1 (run 10).
26 CO~ARATIVE EXAMPLE 4
27 A metal oxygen composition i5 prepared in accord-
28 ance with Comparative Example I with the exception that
29 activation is conducted in accordance wi~h Comparative
Example 2. The raactor testing and regeneration procedure
31 is conducted in accordance with Exam~le 3 to ~rovide a
32 basi~ o~ a comparison therewith The results are summarized
33 at Table 1 (runs 13 and 14).
34 COMPARATIVL EX~MPLE 5
A metal oxygen com~osition is prepared in accord-
36 ance with the procedures or Comparati~e Example 1 with the
37 e~ce~tion that calcination is conducted at 60QC for 2 hours
~ .,
. . ,
-
,
- , ~
- 43 -
l and activation is conducted in accordance with Comparati~e
2 Example 2. The resultins composition is tested in accord-
3 ance with the procedures of Example 4 to provide a basis
4 for comparison ~herewith. The results are summarized at
Table 1 (ru~s 19 and 20).
6 ~
7 A metal oxygen romposition is prepared in accord-
8 ance with U.S. Patent No. 4,254,293 by slurrying 135.0g
9 Bi2O3 and 94.5g ZnO with 500cc of water, The resulting
slurry is constantly stirred while being boiled down to a
11 ~aste. The paste is then dried in an oven at 110C for 24
12 hours. The dried produc~ is calcined at 400C for 2 hours
13 and subsequently at 800C for 1 hour. The calcined catalyst
14 is crushed and sieved to a -1~+20 mesh size (U.S. ~ieve
Series) for evalu~tion. Testing of the metal oxygen comr
16 position in a 20cc reactor is conducted in accordance with
17 the procedure~ of Example 8,including activation,to provide
18 a basis fo~ comparison therewith. Results are s~mmarized
19 at ~able 1 ~runs 24-30~.
SUMMARY OF EX~MP~ES AND COMPA~ATIVE EXAMPLES
21 The following is a summary of the conclusions
22 which can be drawn from the various examples and comparative
23 examples provided in Table 1.
74 Comparing runs 3, 4 and 5 (Example 1) with runs
~5 6, 7, and 8 (Comparative Example 2) respectively it can
Z6 be seen that at comparable on-stream times metal oxygen
27 compositions prepared by the organic method yield substan-
28 tially better stilbene selectivities than metal oxygen
2~ composi~ions prepared by the aqueous procedure, e.g.,
49.8~ vs. 29.8~, 47.8~ vs. 27.4% and 50.6% vs. 19.0%.
31 Furthermore, as on-stream time increases to 2 hours the
32 activity of the compositions prepared by the aqueous
33 method is reduced by more than 50% (toluene conversion
34 drops from 6.4~ to 2.9~) and a major proportion of this
reduction is due to a substantial dro~ in stilbene selectlv-
36 ity (i.e., ~electivity drops from 29.8~ to 19.0%). In con-
37 ~rast, the organicallv prepared compositions of the present
'
. ~ ,.... .. . . , :
- .;. - ~
. , , . .. : : -, :
::: ~,. . .:
: : .. - ' : - .
'~' ": . :
4~
- 44 -
1 invention yield only a slight drop in conversion (19.6% to
2 16.2~) and an increase in stilbene selectivity ti.e., 49.8%
3 ~o 50.6%).
4 Comparing run 9 (Example 2) with run 10 (Compara-
tive Example 3) wherein a minor quantity o~ air is added
6 to the feed s~ream and contact time i9 reduced to 3.5 sec-
7 onds, it can be seen that stilbene selectivity of the or-
8 ganicall-y prepared compositions is higher than the aqueous
9 preparation (i.e., 72.2% vs. 60.9%). These runs therefore
illustrate the superior performance of compositions pre-
11 pared by the organic method when run in the catalytic/
12 stoichiometric mode.
13 Comparing runs 11 and 12 (Example 3) with runs
14 1~ and 14 (Comparative Example 4) it can be seen that
lS after regene~ration, ~tilbene selectivities of runs 11 and
16 12 remain higher than runs 13 and 14 ~i.e., 49.0~ vs.
17 43.3%, and 49.9% vs. 44.0~ at re~pective on-stream times
18 of 0.5 and 1 hours).
I9 Comparing runs 15 and 16 (Example 4) with runs
19 and 20 (Comparative Example 5) at on-stream times of
21 0.5 and 1.0 hour respectively and a calcination temperature
22 of 600C, it can be seen that stilbene selectivities,
23 toluene conv~rsions, and stilbene and DPE selectivities of
24 ~he organically prepared compositions are or the most
part substantially better than those of the aqueous pre-
26 pared compositions (i.e., stilbene salectivities: 65~9% vs.
27 46.6%, 66.1~ V5. 46.6~; toluene conversions: 18.4~ vs.
28 6.6~, 20.2% vs~. 8.6~, stilbene and D~E selectivities: 88.8
z9 vs. 85.1%, ~0.2% vs. 91.1%).
Comparing runs 27 and 28 (Example 8) with xuns 29
31 and 30 ~Comparative Example 6). It can be seen that an
32 even greater improvement in perfo~mance of the organically
33 prepared metal oxygen compositions is achieved using a
34 Bi/Zn metal oxygen composition.
For example~, the above noted runs yield the
36 ~ollowing com~aris~ns:
..
.: -
:~ .... .
. . " ~ , .. ~
- 45 -
1 Stilbene selectivity: 28.3~ vs. 11.5%
2 48.q% vs. 11.6%
3 Stilbene + DP 93.2~ vs. 72.3%
4 se}ectivity 92.7% vs. 77.,5%
Toluene Conversion: 3.6~ vs. 2.6%
3.1% vs. 3.4
,
,:
,
'` ~
.~
'.~
., , ~
.
.
.
~ . :
,.: : :-:
- ; ::~ -:
: ~., ~ : :. - ,
- ' : '~:': ' ': ,` '
~z~
-- 46 --
I ~ ~ ! ~ _ _ r
~ O~ ~ O . _ ~ ~ æ _ 7 rO~
~i _ _ _ _ ~0 10 ~ _ _ r~ ~i, N
~~ h I!i ~ ~~ ~ a -- i æ ~ ~ ~
~ I ~ O ~ _ G. r~ 0 u~ _ o ~ r ¦~ ~
_ _ ~ c ¦-- ~ 3
o 3 ~ _ ~ ~ N N W 10 N 0 4~ ~ " I N "
:; _. _ I__ IA 0 0 _ ¦ ~ O _ ~ N N O ~_ ~ Cl _ ~ _ _ O _
~1 ~ U~ 1- ~ 0~ '.0 0 1 0 ~ 8
,, ~ ~ 0 ~' ~ _ N ~ ~1 ~ 11 In 10 1 N ~ I . 8 o ~ 8 ~ a,
~ 2 ~i ¦ ~ . . ~ . ~
~ ~ ~ ~
Z 1~ ~ ~
0 -- N _ I .
, ~ ~ """ ' ~' ' .. .:
,'"~;'"~,, ,, ' ' ,
~1 224~ 99
~. ~ ~ 3~ la ~
~^ I ~ ;a ~ 3
_ _____'A O, l~n _IIN Q ~0 _ Jo~ o ~O ~O ~a
~e I ~ ~ ~ A ~ 0
~~~ ~ ~ 1~o!o a 0 ~ ~ .
~ ~ o 31_~ , ~ ~ a7 ~ n i 4~' r~ ~ ~ ~ ~ ~ ~ ,
æ ~ ~cV u . ~ ~ . .
O ~ . . . . . . ~ s3c~ . .
ut ~ ~ ~ ~ t~l ~ ~ ~ ~ ~ ~ _ . ~ r~ ~ 0,, 0
., ~ 3 ~ ~a 33 ~ I a a~ a~
1!_ ~. ~ j o o ~ ~ 5~ S i o 3 _ ~ O~
~ ~ I' ~ 30 ~ C~ o
` z ~C' 1~ ~ - ~ - 2 ~ a R ~. ~ .o ~ c~ g
.- . . : . .~ ` :.,` .:
.. - . . .~ ~ : ..
L9
-- 48 --
-
,le / ~ ,' 1 `
'1- 1~ ~ 3~ i i~
~ ,,,' ~,:, ,Oo-,~l , . : , '
~ ~ ~ ~ S X
-- 49 --
~ .
~ _~ 2. o o. ~ ~
~ ~ ~ ~ _ ~ .
M ~ W ~0 O d ~ 'O
, o ~ 3 ~ ~
~o~ ~`
.~ oL~-~ ~ ~, ~ ......... ~ .
~io ~ ~-
. ~o ~ V~
. ~ ~,~c a 9 ~ & 5--
~
~ W~ . . ~ . ~ .
~ ~ ~ Y ~ C
. ~ ~ o~Y~ _ ~ 3 ~ ~ ,, .
~ ~ 1~ 9 ~I ~ il~
____ . j~
_ '-~;! ~ ~ . ~ ~ o
:~ :~
. e .~ '~' .~ '~' V~
24~
- 50 -
1 The principles, preferred embodiments, and modes
2 of operation of the present invention have been described
3 in the foregoing specification. The invention which
4 is intended to be protected herein, however, i5 not .o
be construed as limited to the particular forms disclosed,
6 since these are to be regarded as illustrative rather
7 ~han restrictive. Variations and cbanges may be made
8 by those s~il}ed in the a,rt without depar~ing from the
9 spirit of the i~vention.
.
, ~
, ,:
:
