Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
TITLE
Zeolite Rho as Cataly~t for
Conve~ion of Methanol and
~mmonia to Dimethyla~ine
BACKGROUND OF THE INV~NTION
This invention ~nvol~es a proce~s fo~ making
amine~, particularly dimethylamine, in which methanol
andior dimethylethe~ and ammonia a~e con~acted in the
presence of a ~elected zeolite cat~ly6t.
Methylamines are genelally prepared în
indu~t~ial quanti~ies by continuou~ ~eac~ion of
1~ methanol and ammonia in the pr~ence of a
~ilica-alu~ina catalyst. The ~eactants are typically
combined in the vapor pha~e, at temperature~ in the
~ange of 300 to 500C, and at elevated pressure~.
Trimethylamine is the ~rincipal component of the
ce~ulting product ~tream, accompanied by le66er
amount6 of monomet~ylamine and dimethylamine. From a
comme~cial ~tandpoint, the mo~t valued producC of the
reaction i~ dimethylamine, in view of itfi wide6pread
~ndustrial use a~ a chemical intermediate.
Acco~dingly, a major objectiYe of tho~e seeking to
enhance the commercial efficiency of this process ~a~
been to improve overall yields of dimethylamine, and
to a le~er extent, monomethylamine, rel~tive to tri-
methylamine. Among the app~oaches taken to mee~ thi~
Z5 objective a~e recycling of trimethylamine, adju~t~ent
of the ratio of methanol to ammonia react~nt6, and
use o~ 6elected dehydrating or aminating ~a~aly6t
specie~. Due to the com~e~c~al imeortance of the
proces~, a rather exten~ive compendium of patent~ and
o~her contributions to the ~echnical literature ha6
resulted. Re~re~entati~e referen~es gQne~ally
rele~ant to ~he field of ~he plefient inYentio~ ar~
~ummariz~d in She follcwing parayra~h~.
CR-8142 35
~.
~;.;s~Y
, ~
Swallen, U.S. Pa~nt 1.926,6910 di~clo~e~ a
p~oce6~ for producing dimethylamine by di~propo~tion-
a~ing monomethylamine over dehyd~ating or aminating
cataly~t~ ~uch afi alumina, silica. thocia. aluminum
6ilicate or partially dehydrated aluminum trihydrate.
ALnold, U.S. Pa~ent 1~9~2.9'~5, des~ribe~ a
proce~s for catalytic syn~hesi~ o~ amine~ from
alcohols and ammonia which employs as cataly~t a -
dehyd~a~ing oxide, e.g., alumina, depo~i~ed on the
~urface of a pOlOU~, rigid gel, e.g., ~ilica gel.
Arnold, V.S. Paten~ Re. 19,632, disclo~es a proce~6
improvement in which trimethylamine i~ introduced
with the methanol and ammonia reactant~ to ~hift
reaction equilibrium in favor of dimethylamine
production.
John~on, B~iti6h Patent No. 422,563, cli~-
clo~e~ a proca~s fo~ p~oducing aliphatic amine~
involving heating an alcohol or ether under a
pres~ure oE more than about 50 atmosphe~es in the
presence of a "cataly6t capable of 6plitting off
water" ~e.g., alumina), with an exce~s of ammonia and
optionally with addition of ~rimary amine to the
reaction mixture.
Go~horn, U.S. Patent 2,349,222. discloses
u~e of gLanular alumina coated with one or mo~e
oxide~ of nickel, cobalt, or chromium a6 a cataly~t
for alkylation of ammonia to p~oduce alkyl amine6.
Go~horn, V.S. Pa~ents 2.394,515 and 2,394.516,
di~clo~e6 u~e as cataly6t of an aluminum salt or
oxide coated with 6ilica and vanadium or molybdenum
oxide.
Smi~h, U.S0 Patent Z,456,599, di~clo~es a
proce~6 improvement wherein water i~ added eo a
re~ctant feed mixtu~e of methanol and am~onia to
repre~ formatlon of tertiary amine in ~avor of
3s primary and secondary amine.
~ ,,.~
~2~
Markiewitz, U.S. Patent 3,278,598, disclo~e~
use of a rhodium, palladium, or ruthenium cocataly~t
in conjunction with Raney metal~ ~o i~rease produc-
ti~n ~f ~econdary amine~ from ~e reaction o~
alcohol~ and ammonia.
Rostelli et al., A. I. Ch. E. Journal 12:292
(1966~ de~cribe studies of transmethylation reaction~
of monome~hrlamine and dimethyl~mine over ~ontmoril-
lonite, a hydrated magnesium or calcium oxide-
containing aluminosilicate having a porous la~tice
structure. For trans~ethylation of ~onomethylami~e,
thi~ work indicated that ~eaction ~a~te wa6 directly
proportional to reac~ant partial pre~ure, indica~ing
that the rate-determining event i~ adsorption of
reactant to the cataly~t surface.
Hamilton, U.S. Patent 3,384,667, de6cribes
alkylation of ammonia in the pre~ence of a dehydrated
crystalline alimino~ilicate catalyst having pores of
a diamete~ peEmitting ab60rption of primar~ and
~econdary, but not tectiary, amine product6.
Leonard, U.S. Patent 3,387,032, disclose6 a
eroce6s foc reacting a~monia with methanol and~or
; dimethyl ether in the ~re~ence of a cataly~t consi6t-
ing of a silica gel ba~e impraynated with 10-15%
alumina which is first ~team-deac~ivat~d and then
treated with ~ilver, chenium, molybdenum. or cobalt
ion~ to peomote 6electivity for dimethyla~ine.
Kaeding, U.S. Patent 4,082,805, disclo~es
ufie of a c~y6talline aluminosilicate or zeolite
cataly~t having the ~tructure of ZSM-5, ~SM-ll or
ZS~-21 in a process for producing amine~ by eeaction
; of ammo~ia w~th Cl-C5 al~ohols at elevated
temperatu~e~ and pre~sure6.
: Parker et al., U.S. Patent 4,191.709,
de6ccibe use of a hydrogen form of zeolite FU-l or
.
lZ9L~
zeolite FU-l in which sGme or all of the proton~ have
been ~eplaced by bivalen~ or ~rivalent cations.
. Weigert, U.S. Patent 4,25~,061. di~clo~e~ a
prOCe~8 in which ~roduction of monomethylamine i8
enhanced by reacting methanol and ammonia in amounts
~ufficient to provide a CtN ratio of 0.5 to 1.5 over
a cataly~t 6elected from
~a) mordenite wherein ~he primary cation i~
Li, Na, HNa having at leas~ 2~ Na by
weight, K, Ca, Sr, Ba, Ce, Zn or Cr:
(b~ ferrierite ~herein the primary metal
~ation i~ Li, Na, K, Ca. Sr, Ba, Ce or
Fe;
(c) erionite ore;
(d) calcium ecionite, and
(e~ clinoptilolite oce
at a temperature of 250-475C and a presfiure of
7-7000 kPa. a contact time, normalized to 7 kPa, of
0,1 So 60 ~e~ond~, and a methanol conver6ion of
15-95%.
A~hina et al., JapaAese published Patent
Application No. 56-53887, and ~ochida et al., Journal
of CatalY 6 32:313 (1981~, also disclose u~e of
mvrdenite zeolite~ to enhance pcoduction of di~ethyl-
amine i~ ~lo~ely related variants of the proce~s
di~clo6ed by Weigert.
We~gert, U.S. Patent 4,313,0~3, di~closes an
improved proce~ for di~propor~ionating monomethyl
amine to dime~hylamine and ammonia, comprising
2a5~in~ monomethylamlne over a cry6talline
alumino~licate cataly~t ~elected from
(a~ mordenite wherQin the primaLy cation i~
Na, HNa having at least 2t Na, ~g, Ca,
Sr or Ba;
q
` :..
6~
(b~ ferrierite wherein ~he p~imary me~al
cation i~ Na, K, ~g, Ca, Sr or Ba;
(c) clinoptiloli~e and
(d) phillipsi~e:
at a temperature of 250-475C and a pre~sure of
7-7000 kPa . at a feed rate of 0.1-10 ~ram~ of
~onomethylamine per g~am of cataly6t per hour, at a
monomethylamine conver6ion of 15-75%.
Coch~an et al., U.S. Patent 4,398,041,
de~cribe ~ proce~ fol converting Cl-C4 alcoh~ls to a
non-equilibrium controlled di~tribu~ion of primary.
~econdary, and tertiary alkylamine~. The procefi6
di6clo~ed involvefi paE~ing a mixture of reactant
alcohol~ and ammonia into a first conversion zone
containing a i'~hape-selective" ceystalline
alumino6ilicate cataly~t having a pore ~ize ~elective
for monoand di~ub~tituted alkylamine products:
dividing the resulting product stream: pa~6ing one
portion of thi~ product ~tream to a 6econd conversion
zone ~ontaining another c~taly~t having a diffelent
pore ~ize di~tribution; and combining the remaini~g
portion of the fir6t product ~tream with the product
stream of the second conversion zone to yield a
non-equilibrium controlled product distributlon. The
zeolite cataly6t6 di~closed by thi~ ceference include
5A æeolite. REY zeolite, H-chabazite-erionite.
H-erionite, H-~ordenite~ and H-Y zQolite. Deeba et
al.~ publi~hed European Patent ~pplication 008S408,
disclo~e a method for improving methanol ~onversion
rates co~pri~ing reacting ~ethanol and a~monia over a
3~ highly acidic dehydrated alumino6ilicate satalyfi~
having a silicon to aluminum ratl~ of at lea6t 2.0
: and mani~e~ing microporous diffu~ivity or
methylamînes. Deeba et al., ~.S. 4,434,300 di~close
a ~ethod for imeroving ~ethanol conver~ion rates in
:
the reaction of methanol and ammonia to produce
methylamine~ which compri~e~ effecting the reaction
in the presence of a ~ac~oporou~, highly a~idic
aluminosilicate.
Tomp~ett, U.S. Patent ~,436,938, di~clo6e6 a
p~oce6~ for making methylamines compri~ing reacting
methanol and/or dime~hyl ether over a binderles~
zeolite A cataly~t. pLeferably a binde~les~ zeolite
5A cata ly5 t .
Currently, methylamine6 are produced using
an adiabatic plug flow reac~ol. Although ~pecific
condit;ons do va~y depending upon ammonia feed ra~io
and am~unt of product recycle, reactor inlet
temperatures are yenerally maintaîned ~rom about
310C ~o 340C, and outlet temperature~ generally cun
15 f~om about 400~C to about 430C. The difference
between inlet and outlet temperatures i8 due to
exothermicity of the reaction and i~ moderated by
recycling o~ ammonia and tri~ethylamine. The
foregoing temparature~ Lepre~ent a compromi~e between
increa6ing production rates at a given reacto~ ~ize,
which is favo~ed at higher react;on temperature~, and
reducing catalyst deactivation, which i6 minimized at
lower reaction temperatur26. ~ ~ore ~ctive ~ataly~t
wGuld permit operation at lower reaction ~empera-
ture6, increa6ing cataly~t life~ime and/or decrea6ingthe need to ~ecycle ammonia or trimethylamine.
A~ the foregoing di~cu6sion 8ugge6t6, new
process improvement~ which optimize dimethylamine
yield~ and ~uppress production of trimethylamine and
which allow lower reaction temperature~ while
maintaining reactor throughput in thi~
widely-practiced procefi~ are of 6ignificant ;nte~e~t
to the chemical indu~try.
3~
,;
SUMMARY OF THE INVENTION
The pre6en~ invention provides a proce~s for
p~odu~ing dimethylamine compri~ing reac~ing ~ethanol
and/or dimethylether and ammonia, in amoun~6
sufficient ~o provide a carbon~nitrogen (C/N~ ~atio
from about 0.2 to about 1.5, at a tem~erature from
about 250C to about 450C, in the pre~ence of a
catalytic amoun~ of an acidie zeolite rho.
DETAILED DESCRIPTION OF THE [NVENTION
Zeolite~ can be generically described as
~omplex alumino6ilicate~ characterized by a
three-dimensional framework fitructure enclosing
cavitie~ occupied by ion~ and water ~olecule6, all of
which can move with ~ignificant freedom within the
zeolite ~atri~. In commercially u~eful zeolite~, the
water molecules can be removed fco~ or replaced
within the f~amewor~ withou~ ~e6~roying its
geometry. Zeol~te6 can be represented by the
following formula:
M2/n A12O3 ~ x SiOz y H O
wherein ~ is a cation of valence n, x >2, and y is a
number determined by the porosity and the hydration
6tate of the zeolite, senerally from 2 to ~. In
na~urally-occurring zeolites, M is princip~lly
represented by Na, Ca~ K, Mg and ~a in proportion6
u6ually reflecting thei~ app~oximate geochemical
abundance. The cation6 M are 1008ely bound to t~e
st~uc~ure and can f~equently be co~eletely or
par~ially replaced with other cations by convention~l
ion exchanye.
Zeolite ~tructure eon~ist~ of corner-llnked
teerah~dra with Al or Si ato~s at center~ of
tatrahedra and oxygen a~om6 at ~orners. Such
: 7
,,
~2~6g~
te~rahedra are combined in a well-defined repea~ing
~tructure co~pri~ing variou~ combina~ion~ of 4-, 6-,
8-, 10-, and 12-membered ring~. The re6ulti~g
framewoLk consi6~s of regular channel~ and cage6,
which impart a u~eful pore structure for catalys;s.
Pore dimen~ions are de~ermined by the geometry of ~he
alumino~ilicate tetrahedra forming the zeolite
channels or cage~, with nominal opening~ of 2.6 ~ for
6-ringfi, 4.0 A for 8-ring~, and 5.5 A for 10-ring~.
Pore dimensionfi are critical to catalytic
performance, ~ince thi6 characteristic determine~
whether reactant ~oleculex can enter and produc~
mole~ules can exi~ the zeolite framework~ In
practice, it ha~ been observed that very slight
decrea6e~ in ring dimen6ion~ can effectively hinder
or block movement of particular ~eactant6 or product
wi~hin a zeolite ~tructure.
The pore dimen6ion6 which control acce6~ to
the interior of the zeolite are determined not only
by the tetrahedra forming the pore opening, but al60
zo by the pre~ence or abfience of ionfi in or near the
pore. In ~he cafie of zeolite A, or example, acce~
can be restricted by monovalent ion6, ~uch a6 Na~ or
K~, which are ~ituated in or near 8-ring opening~ a~
well a~ 6-~ing openingfi. Acce~ i6 enhanced by
divalent ion~, fiuch a~ Ca2+, which are ~ituated only
in or near 6-ri~gfi. Thufi KA and NaA exhibit
effective pore opening6 of about 0.3 nm and 0.4 nm
re~pectively, wherea6 CaA ha~ an effective po~e
opening o 0.5 nm.
Useful refe~eQce~ generally relating to
zeolite ~t~ucture and characteri~ation include the
following:
~eier et al., Atlas of Zeolite Structure Types
3S (International Zeolite A~n. 1978);
; , 8
~6~j~2
Mumpton, "~a~ural Zeolite~" in Reviews in
M~e~L~l~Y 14:1 (lg77);
Smi~h, "OLigin and S~ructure of Zeolite6" in
Zeoli~e Che~is~y and ICatalysi~. ACS
Monograph 171 (American Chemic21
Society, 1976).
General_Characteri~tic~ of Zeolite Rho
Zeoli~e ~ho, ~he zeol te 6pecie~ employ2d in
the p~oce~ of the pre~ent invention, is a ~mall-pore
~ynthe~ic zeolite ~hich can be de~cribed by the
formula
~Na.C6)1~A1125i~6096 44 ~2~-
The 6tructure and 6ynthe~i~ of thi6 6ynthetic zeolite
are de~cribed by Rob~on et al., "5ynthesis and
Cry6tal Structu~e oS Zeolite R~o - A ne~ Zeolite
Related to Linde Type A", Advances in Chemi6try
Selies 121 (A~erican Chemical Society 1973), and
:Rob60n, U.S. Pa~ent 3,904,738.
The cationic ~pe~ie~ Na~ and C6~ present in
rho zeolites can be exchanged for protons an a
conventional ion exchange with ~4 or ~y conver~ion to
: an ammoniated for~ ~NH4-rho) whi~h i~ subgequently
conYerted to the acid fo~m by calcination at elevatad
eemperature~.
Acld ~orm~ of zeolite~ can be prepared by a
variety of technique~ including ammonium ex~nge
~ollowed by calcination, direct exchange of alkali
ions fo~ protons u&ing mineral acid~ or ion
exchan~arg, and by int~oduction of polyvalent ion~
r a di~uz~ion of acid 6ite~ in ~eol~e6, ~ee J.
Dwye~, UZeolite S~ructure. Compo6~tion and Cataly~i6"
:
~ : ~
in Chemi6trY and Industry, April 2, 1984). The acid
site~ produced are generally believed to be of the
Bron~ted (p~oton donating) type or of the Lewi~
(electron pai~ accepting~ type. Bron~ted ~ite~ are
generally produced by deammoniation at low
~empera~ures, exchanqe with protons, or hydroly~i6 of
polyvalent cations. Lewi~ ~ite~ are believed to
arise from dehydLoxylation of the H-xeolite~ or from
the presence of polyvalent ion~. In the acidic
zeoli~e catalygts of the pre~ent invention, Bron~ted
10 and/or Lewi~ ~ite~ can be pre~ent.
The c~y6~al ~t~ucture of zeolite rho i~
characterized by large cuboctahedral cages linked by
douhle 8-ring6, defining pore opening~ of
app~oximately 3.9 A by 5.1 A ~0.39 x 0.51 n~). One
unu~ual characteri6tic of the 6tructure of zeolite
rho i~ the presence of two independent
3-dimen~ionally-connected 6ystem~ of ~hannel6.
further unique 6~ructur~1 Eeature, described by
Parise et al., J. PhYs. 5hem. ~8:1635 (1984) i~ a
structural change occurring upon dehydration which
re6ult6 in an inCLea~e in ellipticiey of ~he
aforementioned 8-ring pore opening6. If a dehydrated
~ample of zeolite ~ho 1~ heated further, an increa~e
in unit cell dimensions re~ult6, accompanied by a
decrease in elliptici~y of the 8-ring pore opening~.
It ~hould be noted that catalytic
6electivity fo~ dimethylamine pro~ided by zeolite rho
cannot be at~ribueed ~olely t~ it~ geometry. Other
factors, for exa~ple, the number and nature of acid
30 ~ite6 on internal and external surface~, cry~alllte
6ize, external surface modifier~, and contaminant~
can al60 be expected to af~ect ~electivity for
dimethylamine.
.
:
" . ~
~2~
11
For example, introduction of alkali metal or
alkaline earth metal cation6 into th~e ~tructure of
zeolite ~ho by ion exchange can alte~ the effective
~ize of channel~ and thus facilitate or hinder
pa6~age of reactant or product molecule6 duLing a
reaction. Thu6, cation exchange can be employed as a
means of enhancing selectivity of 2eolite rho for
dimethylamine.
A cciterion ba~ed upon empirical
ob6ervation~ of zeolite ~orpeion characteri6tic~ ha6
been devi~ed in order to a~es~ the utili~y of
variou~ ~mall-pore zeolite6 a~ catalys~ for
conver~ion of methanol and ammonia to dimethylamine.
Thi~ c~iterion, which i6 hereîn denominated the
geometric selectivity index ~or dimethylamine, or
GSI, i6 defined a~ net solption of methanol (~eOH)
divided by net ~orption of n-propanol (n-PrOH), each
mea~ured a~ 25C following 20 hour6' expo~ure to
sorbate vapor. Sorption i6 expre~sed in weight
percent (gramE ~orbate per 100 gram~ ~eolite).
Sorption mea~urement~ are made using an
apparatu~ sub6tantially analogou~ to that de~cribed
by Landolt, Anal! Chem. 43:613 (19713. In a typical
experiment, 0.4 ~o 1 g of zeolite i8 pre~6ed at
300-loOo p~i into a self-~upporting ~ylinder,
in6erted in~o a pre-weighed sa~ple holder, evacuated,
heated to 425C, cooled, and the~ weighed in the
~ample holder. The re6ulting ~ample i~ then expo~ed
to ~orbate vapor at 10-50% o~ its vapo~ ~res6ure at
25C in a ~orption manifold, removed from the
60rption ~anifold, and weighed a~ain to determi~e
~o~tiO~ .
Small-pore zeoli~e~ other than zeoliSe H-rho
demon~t~ate incr~a~ed ~ele~tivity for dime~hylamine
with increased GSI . Su~pri6ingly, however, zeol~te
12
H-rho doe~ not 6how ~uch a correlation. GSI observed
for zeolite H-rho ~ample6 remain~ nearly cDn6tant
with ~ignificant increa6e6 in selectivity.
Catal~st Preparat_ n
Zeoli~e rho i6 ~ynthe~ized Ln a Na-C6 form
~ubstantially according ~o the procedurQ of Robson,
U.S. Patent 3,904,738. In one met~od of preparing
the H-form employed in the process of thi~ invention,
Na~ and C~ ions are exchanged for NlH4+ ion6 and the
re6ulting NH4~ form i~ deammoniated by calcination at
400C to 800~C. Although ion exchange of ammonium
fo~ Na~ and C~+ ion~ may be incomplete in any given
experiment, ~ypically leaving 0.5-1.0 C8 per unit
cell, the produc~ of ion-exchange i~ ~efeered ~o
he~ein a~ NH4-~ho. Similarly9 although deammoniation
of NH~-rho may not re6ult in co~plete conver~ion o~
all NH4~ to H+ or other acid 6ites. pa~ticularly when
a sample i6 calcined at lower temperature6, t~e
resulting ploduct i6 ~efe~red to he~ein as "zeolite
H-rho".
A form of zeolite H-rho containing very low
level6 of re6idual C~ ion can be generated by
treating zeolite H-rho with NaOH ~olution6 followed
by exchanye with NH4+-ion containing solution6 and
calcination. Repetition of the~e 6tep6 provide~ a
form of zeolite H-rho with particularly enhanced
~electivity for dime~ylamine.
Identification of zeolite Na,Cfi-~ho i6
generally made by X-ray powder diff~action. The
integra~ed in~ensitie~ of the ob6erved ~-ray pea~6
can be u~ed a~ a measure of zeolite cry~tall~nity.
High inten6itie~ indicate a highly cry~tallin~
p~oducts while low inten6tie~ indicate a le6~
c y~alline material. However, as cry6tallite size
~alls below about 50 nm, X-~ay dif~ractio~ peak6
broaden (H. P. Klug and ~. E. ~lexander, -Ra~
~:~
12
1 ~
Diffraction Techni~ue~, ~iley-Inter~cience. N.Y.,
1974). When cry~tallite ~ize fall6 below about
2-6 nm, peak~ become ~o broad ~hat they are difficult
to detect by conventional analog recording
~pectrometer~.
However, de6pite a lack sf mea6urable ~-~ay
peak intensity, ~uch ~-ray amorphour~ zeolite
crystallites are capable of ~hape 6elective cataly~
a~ recently reported by Jacob6 et al., J. Chemical
Society, Chem;cal Com~unications, p. 591 (1981). For
such crystallit0~, zeolite crystallinity i6 eYiden~
from infra-red ~pectra, so~ption mea~ure- ment6, and
catalytic 6hape ~electivity. The acidic eho zeolite~
of the p~esen~ invention can be highly cry6talline,
poorly crystalline, or ~-lay amorphous cry6tallite~.
Cation-exchanged forms o zeolite ~ho carl be
prepared from a Na,Cs form of zeolite rho or from
zeolite H-rho by contacting a cry6talline form of the
zeolite with a solution containing the ion to he
exchanged. Reeeated application~ of fresh ~olutions
are nece~sary to obtain a significant degree of
ca~ion exchange. A6 u6ed throughout the
specific2tion, the term "zeolite Ca-rho" or "Ca-rho"
refer~ to a cation-exchan~ed ~orm of zeolite rho
wherein the cation i6 Ca.
It is known (Rob60n, U.S. Patent 3,904,738;
Barrer et al., Proc. 5th Conf. on Zeolites, ~aple~,
1980, pp. 20-29) that ~mall amount6 o~ chabazite and
pollucite impuritie6 are frequently found in r~o
p~eparation6. It i~ believed that the~e impurities
and small quantities of ce6idual gel are not
~elective to dimethylamine, and thus might reduce the
selectivi~y to a ~e~cee dependent upon the quantity
present in indi~idual sa~ple~.
1~ has previou~ly be~n e~tabli~hed ~K~
I'Hydrogen ~eolite Y, U}tra~table Zeolite Y, and
.
6~
14
Aluminum-Deficien~ Zeolite~", in Molecular 5erie~,
Advances in ChemistrY Se~ie& 121:210 (American
Chemical Society 1973)) that WH4-zeolite~ deammoni-
ated by deep-bed calcination techniques e~hibit
propertie6 di~tinct from tho~e of zeolite~ deammoni-
S ated by ~hallow-bed calcination technique6. Deep-bed
calcination refe~ to combinations oiE bed geometry
and calcination condition~, e.g., thick bed~ andJor
~low flow of ga~ over zeolite, which do not re~ult in
rapid removal of gaseous H20 and NH3 from the heated
zeolite. In contra~t, 6hallow-bed cal~ination rQfer6
~o bed geometrie~ and condition~, e.g., ~hallow
bed6 and rapid stripping of ga6e6 from the bed, uhich
maximize removal of ~2 and N~3 f rom zeoli~.
The nature of the dif ference6 between a~id
fo~m6 of zeolite rho a~ prepared by the above-
described technique~ has not been pceci6ely
pinpoin~ed. It ha~ been sugge~ted, however, that
products of deep-bed calcination conditions contain
nonframewor~ Al 6pecie6 which have di6sociated from
the zeolite lattice ducing ~he deammoniation
pcoce~6~ F~eude e~ al., Zeolite6 3:171 ~19~3) have
6hown that, according to temperature and the degree
of deep-bed calcination of zeolite NH4-Y,
n~nframework Al 6pecie~ contaîning octahedcally-
~5 coordinated A1 are progre~6ively condensed.P-e~umably 6uch nonframework ~pecie~ function a6
catalytically active Bite6 OL as modifier6 of o~her
catalytically-active ~ites. Conceivably, such
highly-~onden~ed s~e~ies pre~ent following high-
tempera~ure ~alcination are re6pon6ible fo~ the~ucpri~ingly high propoction of dimethylether
produced over zeolite H-~ho cal~ined at hiqh
temperature~ under deep-bed condi~ion6. AlternatiYe-
ly, the high dimethyle~her yields might be caused by
1~
~6~
othe~ catalytic ~ite6 produced ducing the dealumina-
tion proce~ and the extLa lattice Al pha6e migh~ not
be directly involYed. ~ illustca~ed by the ~xample~
set foLth below, the method of deammoniation
~ignificantly affect~ catalytic activity, and hence,
product di~tribution, when acid fo~m6 of zeoli~e rho
are employed a6 cataly6t~ in the reaction of ~ethanol
and ammonia to produce mono-, di-, and trime~hylamine.
Clearly, a continuous gradation of calcina-
tion condition~ can be azranged between extreme
"deep-bed" conditions and extreme "shallow-bed~'
conditions. Accordingly, def inition~ regarding ~uch
condition6 are by necefiity ~omewhat arbi~rary, and
various equivalent~ to the condition6 for calcination
set forth helow can be a~ranged. However, the
definition6 for calcination condition~ fiet forth Ln
Table I. below, apply throughout the ~pecification.
T e I: CatalY6t Calcination Condition6
Bed T~pe
Qua6i-
Shallow-Bed Deep-Bed Dee~=@~
Bed
Thickness < 3 ~ 3 ~ 3
(mm)
Gas Flow Rapid or continuou~ Same afi Little or
Condition6 gas flow, vacuum 6hallow- no ga~ flow
ga6 removal, or bed during cal-
fluidi~ed bed con- calcina- cination
ditions maintained tion
du~ing calcination
3~
Te~pera~ure ~00-750 400-800 $00-6~0
(C) ~prefe~red:
~educed DMæ
60a-7so production)
~prefec~ed)
650-800
(grea~er ~ME
production~
~`
...~
~6~
16
In general, zeolite H-cho exhibi~6 greater
~electivity to dimethylamine when ~he NH~-f orm i~
calcined at higher temperatures and/or fcr lo~ger
time6. Increac~ed deammonication temperatures appear
to be more effe~tive than increa6ed calcination
S periods for increasing selectivity ~o dimethylamine.
However, deep-bed calcination6 at high temp~rature6
~>650C) can re~ult in a catalyst with higher level6
of dimethylether (DME) production than tho~e at lower
temperature6. Use of cataly6e6 prepared under
shallow-bed conditions generally result6 in lower
level~ of D~E p~oduction.
Generally. calcination temperature6 ~ust be
6ufficiently high to convert 6ubstantially all NH4~
~ites to H+ 6i~e~ and o~her acid 6ite~, yet no~ high
enough ~o render 6ignificant amount6 of ~he zeolite
amorphou6. The pre6ence o~ NH4~ in a qiven 6ample
can be determined by infrared measurement6.
Exce~6ive cal~ination can lead to ~ollapse of zeolite
cry~talline structure and an a~orphou6 state, which
i~ to be distinguî6hed from the "X-ray amorphous"
zeolitic material~ de~cribed abo~e. The "X-ray
amorphou6~ zeolite~ are obtained by limiting
cry~tallization time6, ~o that very ~all zeoli~e
~rystallites r~6ult. The~e crystallite~ exhibit
charac~eri~tic zeolite 6ele~tivity, but pe~mit rapid
ingce~ of reactant molecule6 and egre6s of product
~olecule~ Bue to their 6mall ~ize.
~ here deep-bed condition6 are employed and
DME production 15 undesi~able, calcination
temperature~ of about 500 to 650C are prefe~red~ If
D~E production can be tolerated, the upper limit for
calcination temperature can be extended to abou~
800~C. Under ~hallo~-be~ ~onditionfi~ calclnation
temperature6 of abou~ 400 to 750C ~an be ~mployed.
Temperature~ of 60Q-750C are p~eferred~
16
17
Proce~s Condition~
As p~eviou61y noted, the proce~ of the
pce6ent invention compri~es reacting methanol and/o~
dimethylether (DME) and ammonia, in ,amounts
~ufficient to provide a carbon/nit~ogen (C/N) ratio
from about 0.2 to about 1.5, at a temperature ~rom
about 250C to about 450C, in the pre6ence of a
catalytic amount of an acidic zeolite rho, of which
zeolite6 ~-rho and Ca-rho are examples. Rea~tion
pressure~ can be varied from 1-1000 p~i (7-7000 kPa)
with a methanol/DMæ ~pace time of 0.~} to 80 hour6.
The re6ulting conversion of me~hanol and/or DME to
methylamine~ i6 generally in exce~6 of 85~ (on a ~ole
ba6i6) and 6electivity (on a ~ole ba~i6~ to
dimethylamine i~ generally greater than 4Q~. In
addition, selectivity to and yield of trimethylamine
i~ ~uppres~ed. Thu6, molar yield6 of dimethylamine
geneeally exceed 40~ and molar yield~ of
trimethylamine generally are les6 than 30% under the
proce6~ conditions of the present in~ention.
The proce~ variable~ to be monitored in
pcacticing the p~oce6~ ~f ~he p~esent inventio~
in~lude C~N ratio, temperature, pres~ure, and
me~hanol/DME ~pa~e ti~e. The latter variable i6
calculated a6 ca~alyst ma~ divided by the ma66 flow
rate of ~ethanol and DME introdu~ed to ~ proce6~
ceactor, (ma~6 cataly6t~ma6~ methanol~DME fed per
hour).
Gen~rally, if proce~ tempe~ature6 ace too
low, ~educed conversion of reactant6 to dimethylamine
will re6ult. On the other hand, if temperatures are
: exce~6ively high, equilibrium con~er~ion~ and
cataly6t deac~ivation ~an oc~ur. P~ef~lably,
temperatures are maintained between about 300C and
about 400C, with lower ~emperature~ withi~ thi6
: 35
:::
~ : ~7
lB
range especially pre~elced in ocder to minimize
cataly6t deactivation. At rela~ively lo~ pre6~e~,
product~ must be refrigerated to conden6e them for
fur~her purification, adding ~o~t to ~he ove~all
~roce~. However, exces6ively high pre~ure6 require
co~tly thick-walled reaction ve~6el~. Prefer~ed
pces~ure range from 10-500 psi [70-3000 kPa~. Short
~ethanol/DMæ 6pace times re~ult in low conver~ion6
and tend to favor the production of monomethylamine.
Long methanol/DME 6pace time~ may re~ult eithe~ in
inefficient use of catalyst or p~oduetion of an
equilibrium di~tribution of ~e~hylamine~ at very high
conversion~. Generally, methanol~DMæ ~pace ~imes of
0.01-80 hourfi are satisfactory, with methanol/D~E
space time6 of 0.10-1.5 hour~ being preferred
(corre~ponding to methanol/D~E ~pace velocitie6 of
O.013-100 g msthanol+VMEtg catalyst/hou~, prefecably
O.67-10 g met~anol~DME/g cat.alyfit/hour).
The eeactant ~atio of methanol ~nd~or DME to
ammonia, her2in expre~ed a~ the C~N ratio (g ~toms
C/g atom~ N), i6 c~itical to the process of the
pre~en~ invention. A~ the C/N ratio i~ deccea6ed,
production of monomethyl~mine i6 increa6ed. Az the
C/N ~atio i6 increa~ed, produceion of trimethylamine
increases. Cataly6t deactivation i6 al60 greater at
high C/N ratios. Accordingly, for be6~ result6, C~N
~atio~ ~hould be maintained between 0.2 to 1.5, and
preferably from 0.5 ~o 1.2 in condueting the p~oce
of the p~e~ent invention.
The efficie~cy of the proces6 of the inven-
~ion i6 measured by overall conve~sion of methanoland/~r DMæ to methylamines, and by ~electivity of
dimet~ylamine production. For example, if ~ethanol
i8 u~ed az the 801e reactant, overall conver~ion i6
~e~e~mined by ~omparison of the amoun~ ~in mole~) of
3s
lB
;,
:
19
methanol in the pr~duct mixture, which i6 con6idered
to be unconverted, to ~he amount in tAe leactant feed.
Thus, ove~all conversion, in percent, i~ given by:
100 (1 Mol~s ~eOH i~ produ~t)
Moles ~eOH in ~eed
Conve~ion of methanol to methylamines, in percent,
is given by:
10o /1_Moles ~eOH in product f 2(Moles DME in Product))
~ ~ole6 ~eOH in feed
Conver~ion of methanol to monomethylamine (MMA) in
percent, is given by:
100 ~ MGle6 MMA
~ Mole~ MeOH i~ ~eed J
Similarly, conver6ion of methanol to dimeehylamine
(DMA), in percent, is given by:
lQO ~ 2(~oles DMA~ )
~ Mole~ MeOH in feed
and converfiion of methanol to trimethylamine (TMA),
in percent, is given by:
loo / 3 (Moles T~A~ ~
~Mole~ MeOH in feed
Finally, ~eles~ivity to DMA is calculated by analysi6
of p~oduct compo6ition. Thu6, B*lectivity ~o VMA, in
30 percent, i6 provided by the following expre~6ion:
100 l ~
~ ~MMA~ ~ 2[DMA] + 3[TM~] /
19
, ~
6~
For efficient operation, the cataly~t mu~t
be ~elec~ive at high conve~6ion~ (87-98%) and a CiN
ra~io of 0.5-1.2.
In practicing the proce~ of the invention,
the zeolite cataly~t can be combined wi~h another
mate~îal re~i~tant to the tempe~ature and other
condition~ employed in the p~oce~. Such mat~ix
materials include synthstic or natural ~ub~tan~es
fiuch a~ clay~, silica, and me~al oxides.
Comparion of 6electivitie~ for different
~ample6 ~hould be made at ~imilar conver6ion~, since
~electivity change~ with conver~ion. At low ~onver-
sion~, ~MA production i~ favored; at ve~y high
conver6ion~, the reaction will approach an equilib~ium
di~tribution and thus ~e6ult in inc~ea6ed TM~
p~oduction.
The proces6 of the pre6ent invention can be
furthe~ unde~6tood by refe~ence to the following
Exam~le~, wherein all temperature~ are expre~sed in
degree6 Cel6ius (C) and all percentage~ are by
Zo weight unle6~ othelwi~e indicated. In compo~ition
determination~, it wa~ a66umed that there were 96
oxygen atom~ per unit cell. Analy~i6 determined the
~ela~ive amount~ of the variou~ cation6 pre6ent, and
remaining positively-charged ~pecie6 were a~fiumed to
be hydrogen.
E~MPLE 1
A Ra~ple oS zeolite H-~ho, whieh was
employed a~ catalys~ in this Example and Example 2,
below, wa~ prepared as follow~. A mixture having the
compo6i~ion 2.80 Na20- 0.5 C~20 ~A1203 ~11.1
Si02-120 H20 was formed by adding gO m~ 4 ~
Na2A1020H, 31. 5 ~L 5 . 79 N C60H, and 13 g NaO~ to 355
~L eollsidal ~ilica ~Ludox~ LS-30~ in a polypropylene
~onta~er. ~he re~ulting mixture wa~ allowed ~o
~tand a~ 25 for~ days, and ehe~ h~a~ed
~2~6~
at 100 for 10 day~. The re~ulting product wa~
washed sevecal time6 and then allowed to ~tand in
contact with a 23~ NH4N03 ~olution fo~ about 65 hour~
to p~oduce NH4-rho. Thi~ material wa6 then convected
to ~-cho by calcinaeion at 415~ in aic for about 16
hour~ unde~ deep-bed co~dition~. Analy~ f the
re~ulting zample of zeolite H-rho indicaeed it~
compo~ition to be C~0 7~a0~2Hlo~22Al~ ssi367~4os6
Two g~ams of thi~ p~epa~ation of zeolite
H-rho were placed in a ~tainles~-~telel U-tube reactoc
0.12~ in (0.55 cm) in diameter and about 12 in (30
cm) in length. The reactor ~a~ heatled ~o reaction
temperature in a fluidized ~and bath. Thi6
experiment and that reported in Example 2, below,
were conducted at atmo~pheric pre6~ure (14.7
lS lb6-in 2, 101 kPa). Reactant6 methanol and ammonia
wece fed to a preheater a~ a liquid ~ixture at a
molar ratio of about 1, vaporized, and then pa6sed
th~ouqh the Leacto~ into contact with the cataly6t.
Reaction temperatur~ and reactant flow rate~ are
shown in Table II, below.
The ceactor effluen~ wa~ analyzed by gas
chromatog~aphy for ammonia, dimethylether (DME),
methanol, water, and mono-, di-, and tri~ethylamine.
The pe~cen~age conve~ion~ of ~ethanol (overall), of
methanol to methylamine6 (MA), and the percentage
6electivitie~ of conve~6ion to each me~hylamine
specie~ a~e given in Table II, below. That portion
o~ methanol convected eo other than methylamine6 wa6
converted to DM2 in ~hi6 and all other Examples
reported herein.
EX~MPLE_2
A portion o~ ~he zeolite H-rho preparation
de6cribed in Example 1, above, was heated in flowing
N2 at 5Q0~ for 2 hc~ under qua~i-deep-bed
.
~ 21
i~
:. .. . . .
:~f~
calcination conditiong. 2 g of this material were
placed in a reactor and employed in a catalyst
evaluation experiment conducted ~ub61:antially
similarly to that reported in Example l. The re6ult~
of thi~ experiment are set forth in T2ble II, below:
Table IIo U6e of Zeolite H-rho
as Catalyst for Dimeth~lamine Synthesi6
~eOH- Selectivity
Calcination Reactor _ MeOH MA (~)
Ex~ T Time T Feed Flow Conv. Conv.
10 ample (C) (hr) (C~ (mL/hr) tS~ MMA DMA TMA
l ~15 l~ 350 12 85 79 16 3~ 48
2 500 2 300 3 87 84 19 4B 33
E~MPLES 3-ll
The result6 of Exameles 3 through ll, which
are ~et forth in Table III, below, illustrate the
celationshie between selacti~ity to methylamine
products and ~eed flow rate and pres~ure. DMA yield~
in exce~ of 40% at a C/N ratio of l were obtained in
2 each of Examples ~-ll. The zeolite H-rho amployed a6
cataly~t in the6e examples wa~ p~epared by the
following procedur~:
A mixture of 200 mL 4 M Na2AlO2OH, 56 mL 50
C~OH, and 26 g NaOH wa~ added to 720 mL of colloidal
2 silica (Ludox~ LS-30) in a polytetrafluoloethylene
(Teflon~ bottle, and permitted to ~tand at 25~ for 9
days. The re6ulting mixt~re was then heated at l00
for 7 day~, allowed to stand at 25 for a~ additional
3 day6, and then reheated to lOO for 2q hr~. $he
re6ulting product wa6 then washed and contacted
overnight 3 ~ime6 ~ith a 20% NH4NO3 ~olution. The
~e~ulting prepara~ion of zeolite N~4-rho indicated a
formula upon analy~i~
(NH~)9.6C~ 0.3si37 796 q2-9 ~zO-
22
, ~
~2~ 2
23
A po~tion of this material was converted to H-lho by
calcination at 550 in air for 18 h~ under deep-bed
condition~.
The cataly~ evaluation expe~iments of
E~amples 3-11, which are reported in. Table III, were
conducted ~ub~tantially ~imilarly to Example 1,
above. Examples 3-11 demon~t~ate that higher flows
and lower methanol conver~ions increa~e ~electivity
to ~A and decrea~e ~electivity to TMAt In addi~ion,
Example~ 3-11 indicate ~hat increa6ed reactor pre~sure
inc~ea~es ~elec~iYity to DMA a~d decrea~e6 ~electivity
tD TMA when compared at ~imilar methanol conversion6.
Table III: Effect of Feed Flow Rate and
Pre~ure on H-~ho Selectivity for Dimethylamine
MeOH- Selec~ivity
Feed MeOH ~A ~)
Ex- Pres~ure T Flow Conv. Conv.
amPle ~ %C~ (mL/hr) (t~MMA DMA TMA
3 14.7/101 3001& S7 65 31 5713
4 14.7/101 30012 ~O 78 23 ~016
20 5 14.7/101 300 ~ ~6 ~ 21 ~020
6 14.7~1~1 300 6 92 ~0 18 ~022
7 14.7~101 ~OO 4 98 9~ 16 5925
8 120/830 3004B 66 65 29 63 7
9 12~/830 30032 ~6 ~5 lg 6812
2510 120J830 30016 92 91 18 7012
11 120/830 300 8 9~ 97 15 6322
EXAMPLES 12-19
Example~ 12-19 illu6t~ate the effect~ of
high deep-bad calcination te~p~ratures and extended
calcination time~ upon s~lectivity to DMA ~4r H-rho
~: zeolite~. In genelal, in~rea~ing calcinaeion
temperatures and lengthening calcination times
inc~ea e electivity to D~A, but al~o increa6e
conve~ion of methanoI eo dimethyleth~r ~DM~).
23
;
,
12
24
Each sample of zeolite ~-rho evalua~ed in
Examples 12-15 was evaluated for sorp~ion of methanol
and n-propanol. The following procedure wa~ employed:
Each ~ample ~as placed into a preweighed
cell and evacua~ed. The sample wa~ slowly heated to
425 under vacuum and held at 4Z50 for 18 hr6. Af~er
expo6ing the ~ample to 375 mm oz ~or ~0 minutes to
burn off any oryanic ma~erial, the sample was
evacuated at 425 until the pressure ~eached 3.7 ~ -
10 5 mm Hg ~.9 x 10 3 Pa). A~ this point, the
sample was weighed. The sample was then expo~ed to
38 mm methanol vapor for ~0 hr~e and then weighed
again to deter~ine the amount of methanol that had
been sorbed. The methanol ~oebed per 100 g zeolite
could then be calculated. Subtraction of 0.37 g
~eOH/100 g zeolite ab60~bed on the external 6urface
o the zeolite yielded the sorption values indica~ed
in Table IV, below. Quanti~ies of n-propanol sorbed
were determined in a 6i~ilar mannec. Table I~ li8~6
the amount of methanol and n-propanol sorbed for each
of the rho zeolite6 and the GSI calculated from these
measurement~. De~pite the laLge increase in
selectivity to DMA with increa6ing calcination
temperature, GSI values remain low and essentially
constant. ~his higher ~electivity to D~A, at
essentially constant GSI, could ari~e from
non-geometric ~actors induced or enhanced by
calcination at progre6sively higher temperatures, or
from geometric factors present at reaction conditions
but ~ot at the conditions at which GSI measurement6
are made, or from a co~bination of these effects.
~5
24
.:~
~able IV: Effect of Calcination ~empera~ure
Upon Geome~ic Selectivity Indices ~GSI~
of Selected Sample~ of Zeoli~e H-Rho
al~ination Sorption
Temp. Timefq/100 q zeolite)
Exam~le(C) (hr) MeOH n-PrOH GSI
12 450 65 24.7 ~0.6 1.2
13 5~0 1~ 20.2 13.~ 1.5
14 625 2 18.6 15.4 1.2
725 2 20.Z 16.6 l.Z
~E~CAMPI,E 12
For this exampleO ~eolite H-rho ~as prepaced
by a modifi~ation of ~he general procedure de~cribed
in aobson, U.S. Patent 3,904~738. Three sepa~ate
~ample~ of Na,Cs-rho were prepa~ed by combining 100
mL 4 M Na2AlO2OH. 16 g ~aOH, and 27.7 mL S0~ C~OH
with 357 mL colloidal SiO2 (Ludox~ L5-30) in a 500 mL
polypropylene bottle. The re~ul~ing mixture wa6
permi~ted to 6tand at 25 fo~ 6 day6, and then heated
on a 6team b~th ~or 3 days at ~2-93. The cesulting
produc~ we~e then filtered, d~ied, and contacted
with 23~ NH4NO3 at 90 for 65 hour~. An ~-ray
difraction paStecn disclo ed the presence of zeolite
NH4-rho and a trace of a chabazite-li~e impurity.
Each of the 6a~ple~ wa6 heated under deep-bed
condition6 at 400 in air for 2 day~. ~wo of the
three ~ample~ were combined and con~acted with 20%
NH~NO3 at 100 for 2 day~,. After filtering, ~a~hing,
and drying, the sample wa6 calcined again unde~
deep-bed condition~ at 450 for 65 hr6, coo].ed. and
the resulting zeol~te H-rho ~valuated afi a cataly~t
6ub~tantially accordinq to the procedure de~cribed in
Example 1, above. The re~ult6 are set for~h in
~ ~able ~, below.
: : :
2S
,:
::~2~6~
~6
EXAMPLE 13
A mix~ure of 200 mL ~ M Na2A1020~, 56 mL 50%
C~OH, and 26 g ~aOH was added to 720 mL of colloidal
6ilica (Ludo~ LS-30~ in a poly~et~afluoro- ethylene
(Teflon~) bo~tle. The re~ulting preparation was
4 5 allowed to stand for 7 day~ at 25 and ~hen for 1
days at 90. A ~o~tion of the re~ulting zeolîte
~aOC~-rho was cvntacted ~wice for 16 hr~ with a 20%
NH4N03 ~olu~ion at 80 ~o produce zeolite NH4-rho.
Zeolite H-rho wa~ prepared by heating the zeolite
NH4-rho under deep-bed ~ondition6 in air at 250 for
1 hr and then at 500 foc 16 hr6. 2 g of the
re~ulting ~ataly~t ~a~ evaluated sub~tantially
according ~o the procedure o~ Example 1. The re6ul~8
of thi6 experiment are set forth in Table V.
EX~MPLES 14 and 15
200 mL 4 ~ Na2A1020H, 56 mL 50% C60H, and Z6
g NaOH were added to 720 mL colloidal silica (Ludox~
LS-30) in a polytetrafluoroethylene bottle, and
permitted ~o ~tand for 12 day~ at 25. The re6ulting
mixture was then heated for 7 day6 at gO, ~hen
contacted twice with 20~ NH4N03 at 80, for about lB
h~6 each ~ime, to pcoduce zeolite NH4-rho. ~hi~
material was then calcined under deep-bed condition~
in air at 465 for 16 hr6, follo~ed by 30 minu~e~ at
600~. The re~ul~ing preparation wa~ divided into ~wo
~ample6. A first sample, employed in Example 14, wa~
heated for an additional t~o hour~ at 625. The
other ~ample. evaluated in Example 15, wa~ heated for
two hour6 at 725. In 6eparate experiments, 2 g of
each 6ampIe were evaluated in a research reactor
~ubstantially as de6cribed in Example 1. The re6ult~
of Example~ 14 and 1~ are ~et for~h in Table V, below.
~: 35 ~
i
~24~
E~AMPLE 16
Zeolite Na,C~-rho was prepared according to
the following procedure. A mixture of 800 mL of 4
Na2A10zOH, 224 mL of 50~ C~OH, and 104 g NaO~ wa~
added to 2B80 mL of colloidal SiO2 (Ludox LS-30~) in
a Teflon~ bottle and allowed to ~tand at 25C ~or 11
days. The mixture was heated at 100C for 9 day6.
The product ~Na,C~-rho) wag washed and dried at
110C. Thi~ Na,Cs-rho, after washing and filtering,
wag contacted four time~ with a 20% NH4N03 ~olution
at ~90C with filte~ing between each exchange~ to
produce NH4-rho.
Zeolite H-rho wa~ prepared by heating 5 g of
N~4-rho for 1 hr undar deep-bed condi~ions in air at
800. After cooling, the sample ~as pre6sed in~o a
wafer. cru6hed, granulated and 6craened.
In an experiment sub~tantially ~imilar to
that described in Example 1, methanol and ammonia
were pa~6ed over a cataly6t consi6ting of Z g of thi~
preparation of ~eolite ~-rho, in the form of ~ 20-40
me6h powde~. The condition~ employed and result6
obtained are ~hown in ~able V.
EX~MPLE 17
Zeolite H-rho was prepared by heating 4 g of
the powdered zeolite NH4-rho pcepared in Example 16
for two weekg undeL deep-bed condition6 in air at
550. The weight lo~ during thi~ thermal treatment
wag 19.5~. The~product was zeolite H-rho.
I~ a pro~edure 6ub6tantially the same a6
that described in ~xample 1, methanol and ammonia
ware pa~ed over a ca~aly6t consi~ting of 2 g of the
zeolite ~-rho. The condition6 employed and re6ults
obtainad are shown in Table V.
3 5
2'7
.:,,
,
2~
EXAMPLE lB
Zeolite H-rho wa~ prepared as follow~. A
mixture of 200 mL 4 M Na2~1O2OH, 32 q NaOH, and 56 mL
50% CsOH ~a6 added to 720 mL of colloidal ~ilica
(Ludox~ LS-30) and allowed to ztand at room
5 temperature for 6 days. Thi~ mixture wa~ heated to
100~ for 6 days. The re~ulting product (Na,Cs-rho)
wa~ filtered. wa6hed ~ith distilled water, and
dried. This procedure wa~ repeated and the dried
products of both batche6 combined. A 50 g ~ample of
the combined Na,C~-rho product wa~ contacted witb 50
mL of a 10~ NH4NO3 ~olution th~ee times at 90 for 1
hr ea~h. After thorough washing with di6tilled
water, the ~ample (WH4-rho) wa~ dried at 110.
por~ion of the dried NH4-rho wa~ then calcined under
deep-bed condition6 by rai~ing ~he temperature 50~
per hr to 550 and then heating the fiample at 550
~or 10 hr~ to give H-rho. The result~ of the
evaluation of thi6 material, which wa6 conducted
sub6~antially a~ de6cribed in Example 1, are ~et
forth in Table V.
EXAMPL~: 1 9
Zeolite NH4-rho was p~epaced ~ub~tantially
a6 desccibed in Example 16.
Zeolite H-rho wa6 prepared by slowly heating
250 g of the zeolite NH4-rho under deep-bed
: conditions, in a slow ~ream of air. flom room
temperature to 550 in 30 minute~. ~he tempecature
wa~ then held at 550 for 3 hrs. The ~ample was then
allowed to cool to 100, tcan~fe~red to a tared jar,
~ealed, allowed to cool to room temperature, and then
weighed. The weight of the calcined sample wa~
223 g~ cocre6ponAing ~o a weighS lo~ o~ abouC 9~O
Chemical analy~i6 ~howed that the sample contained,
~y weight, 3.3% CB, 9~ ~1, and 160 ppm Na~ The
- 3S prod~cS wa~ zeoli:te H-~ho.
.:
: : .,
29
~ H4-~ho was prepared by contacting ~50 g of
the re~ulting produc~ H-rho with 1500 mL of a 10~
NH4N03 ~olution at 90 ~hre~ time6 for 1 hour each.
After thorough wa~hing with di~tilled water, the
~ample wa6 dried at 110. The re~ulting NH4-rho ~a~
calcined by raising the temperature 50 per hr ~o a
final temperature of 700 and ~eating th~ 6ample at
700 for 10 hrs to give H-rho. ~hi6 material wa~
evaluated ~ubstantially as de~cribed in Example 1,
and the re~ult6 are se~ forth in Table V, below.
EXAMPLES 20-23
The re~ult~ of Example6 20-Z3 demon6t.rate
~ha~ ~hallow-bed calcination technique6 provide ~-rho
zeolite catalysts ~i~h exceptionally high
6electivities to DMA.
Por~ion6 of the 6ample of N~14-rho prepared
in Example~ 3-11 were converted to H-rho by a
6hallow-bed calcination technique. A ~ample
con6i6ting of 5.0 g of UH4-eho wa6 6pread out in an
A1203 boat, pa66ed into the hot zone of a belt
furnace at 0.64 cm/mlnute, and held at 400 for 27
hr6 under a N2 f low of 20 L~in. An infra-red
spectrum indicated, from the ab6ence of an ab~orption
band at 1400 cm 1, that sub6tantially all NH4~ ions
had decompo~ed, giving H-~ho containing e6sentially
no NH4 . A 6eries of ~ample6 were prepared by this
6hallow-bed calcination te~hnique at different
temperatures under the condieions indicated i~
Table VI. Each 6ample was evaluated 6ub6tantially
30 according to the proceduce of Example 1. ae6ult6 are
6et forth in ~able Vl, below.
:
~5
29
Table V: Eff ect of Deep-Bed Calcination~ Upon
Selectivity of Zeolite H-rho for Methylamine~
Calcina- Reaction ~eOH- MeOH- Selec~ivi~y
tion Feed MA DM~ (t)
~x- T Time T Flow Conv. Conv.
amPle (CL (hr) (~C) (mL/h~ %) UMA DMA TMA
12 45065 300 4 95 l l9 31 50
13 500l~ 300 8 88 l 20 ~9 41
14 625 2 300 8 ~8 l Z~ 47 31
15 725 2 300 R 90 2 24 5Z 24
16 800 l 300 4 64 25 17 73 l~
17 550 356 300 8 91 3 17 54 28
l~ 550 lO 300 ~ 87.4 2.6 13 50 37
19 770 lO 300 6 74 ll 21 6~ 16
Table VI: Effect of Shallow-Bed Calcinations Upo
lS Selectivit~ of Zeolite H-rho for MethYlamine~
Calcina- ~Reaction MeOH- MeOH- Selectivity
tion Feed M~ DME . (~) _
Ex- T Time r Flow Con~. Conv.
amPle (C~ (hr) (C) (mL~hr~ S%~ ~MA DMA TMA
40027 328 3 88.3 4.7 14 5432
21 50016 325 3 84.7 4.3 16 ~024
2~ 600 4 300 2 ~3 7 16 7~8
23 700 4 325 Z 87.3 6.7 15 7~ll
EX~MPL~S 24-27
Example~ 24-27 illu~trate the enhancement of
dimethylamine ~electivity provided when zeolite H-rho
i~ trea~ed with NaOH, further exchanged with NH4N03
~olution, and then calc;ned.
EXA~PLES 24 and 25
: Zeolite H-rho wa~ prepared by heating a
por~ion of the NH4-Lho prepared in Example~ 3-ll at
: 545 in air ~or 6 hr6. Analy~i~ indica~ed that ehe
p oduct zeolite H-cho had the compo~ition
: : 35
. ~ .
31
Hl0.0C80.8Allo 8Si37.296'54 H2O- A portion of thi~
material wa~ ~e6erved for evaluation a~ Example 24.
Another portion of the zeolite H-rho was
~lurried at 25 for 14 hour~ wi~h 500 mL of lN NaOH
~olution ~o prepare Na-rho. Thi~ ~lurry w~s
filtered, wa~hed thoroughly, and exchanged twice with
500 mL of a 20~ NH4NO3 ~olution. Aftar fllt~ation,
washing and drying, ~he re~ulting mat:erial wa~
calcined for 6 houL~ in air a~ 550. Thi~ two tage
proce~s (61urcying with lN NaOH. recovery and
~esluerying twice with 20~ N~4NO3) wafi then
repeated. After a final calcination at ~50~ for 6
hou~, the product wa~ analyzed, indicating the
following composition:
Hg,02CS0.04(NH4)0,0l 9.08 38.92 96 Z
In a procedure ~ubs~antially the sa~e as
that de~cribed in Example 1. methanol and ammonia
we~e pas~ed ovec a cataly~t con~i~ting of 2 g of the
zeolite H-~ho of Example 24 and 2 g of the zeolite
H-~ho of Example 25. The condi~ion6 employed and
re~ult~ obtained are 6hown i~ Table VII.
E~MPLES 26 and 27
Zeolite E~-rho wa6 prepared as follow~. A
~ixture of 400 mL 4 M NazAlO2OH, llZ mL 50~ C~OH, and
6~ g ~aOH wa~ added to 1440 mL of colloidal ~ilica
(Ludox~ LS-30) ~n a polytetrafluoroethylene
container, and allowed to stand 6 day~ at 25. The
re~ulting material was then hea~ed at 100 until
crystalline, a~ dete~mined by powde~ X-ray
dif~raction. The re~ultin~ product wa~ filta~ed,
wa~hed and dried at 110. The foregoing procedure
wa~ 6ubstantially repeated fo~ a ~econd ba~ch, which
wa6 combined ~ith the product o~ the fir6t batch.
750 g o the combined product~ were contacted three
31
"
i6~
~ 2
times, for one hour each time, wi~h 7500 mL of a 10
NH~N03 601ution at 90 to produce zeolite NH4-rho.
Zeolite ~I-rho wa6 pLepared by calcining thi~ m~telial
unde~ deep-bed ~onditions~ in ai~, by raising the
calcination temperatu~e 60 per hour to 550, and
then holding the sample at 5500 for 10 hours.
~ample of this material wa~ re6erved for evaluation
a~ Example 26.
300 g of the zeolite H-rho prepared above
were sti~ed in 750 mL 1 N NaOH for 24 hour~. ~he
treated zeolite was then filtered, wa~hed with
di~tilled water and methanol~ ~nd then d~ied a~
110. The dried zeolite wa~ then 61urried in 10~
NH4N03 three time~, f Ol one hour each ~ime. at 90.
After thorough wa~hing again with water and ~ethanol,
the ~ample was again dried at 110. The ee~ulting
~aterial wa~ then calcined in air by rai6ing the
temperature 60 per hour ~o a final temperature of
550 and heating the matec~al at 550 or 10 hour6.
The entice proceduce de~cri~ed above was then
ZO repeated. The re~ulting ~aterial wa5 given the
de~ignation "NaOH-treated H-rh~'`.
U6ing a procedure ~ubstantially similar to
that de~cribed in ~xample 1, methanol and ammonia
were con~acted with 2 g of ~he H-rho prepa~ed a~
Example 26 and 2 g of the MaOH-treated H-rho prepared
a~ Example 27. The ce~ult~ are 6et forth in Table
VII, below.
The lower DMA 6electivitie6 of Example~ 26
and 27 are believed to result rom the pre~ence of
amorphous contaminant~.
` 3Z
6~
33
Table VII: ~:ffect of NaOH Peecalcination Treatment
Upon Dimethylamine Selectivit~ of Zeolite H-Rho
MeO~-
Reaction _ MeOH ~ Selecti~ity
Temp. Flow Conv. Conv. _ ~%)
Exa~Ple ~C) ~mL/hr) (%2 ~ ~A D~A TUA
24 30012 87 86 21 S722
30~6 ~9 ~ 20 73 7
26 3004 9~ 91 11 3~53
27 3004 ~4 91 15 55~9
E~AMPLES ?8 and ~9
Example6 28 and 29 demonst~ate the
~ele~tivity to dimethylamine of zeolite H-rho and
zeolite Ca-~ho.
To prepare cation-exchanged sample6 of
zeolite H-rho, a mixture of 270 mL 4 M Na2A1020H,
74.B ~L 50% CsOH, and 43.2 g NaOH wa~ added to 9fi4 mL
colloidal si}ica (Ludox~ L~-30) in a polytetrafllloro-
ethylene bottle and allowed to stand for 6 day~ at
25o followed by 3 day6 a~ 100. The re6ulting
20 Na,C~-rho wa~ then exchanged ~wice (48 hour~ and 95
hou~s) with 20~ NH4N03 a~ 90 to produce NH~-rho.
Zeolite H-rho wa~ prepared from ~e re~ulting NH4-~ho
by heating in air at 450 fol 16 hour~ Some of Shi~
~_rho wa~ evaluated as Example 2~.
To p~epare Ca-~ho for evaluation a6 Example
29, a portion of the H-rho p~epared above wa~
slu~ried with 0.6 g of Ca(OH)2 in 200 mL H20 at Z5
fo~ 6 day~. The re~ulting pLoduct, de~ignated
Ca-~ho, exhibited a Ca/Al ratio of 1.23. A
30 non-zeoli~e Ca-~on~aining phase ~ay also have been
pce~ent.
~ ach of the ~ample~ prepared above W26
evaluaeed for dimethyla~ine ~electivity and catalytic
: 33
, .
34
performance 6ubstantially according to the procedure
of Example 1. ~he lesult~ and condition~ of Example~
2B and 29 are ~et forth in Table VIII, below.
Table VIII: Effect6 of Cation Exchange Upon
_ Selectivity of Zeolite H-rho
~eOH-
Feed HeOH H~ Selectivity
Zeolite Temp. Flow Conv. Conv. ~%2
Exam~le Catalyst (C) (mL/~r~ (%~ ~%~ MMA DMA ~MA
28 H-rho 300 5 91 89 12 45 43
29 Ca-rho ~50 2 94 89 16 51 33
COMPARA~IVE E~PERIME~TS A -_E
Comparative Experi~ent6 A - E demon6tra~e
that certain zeolite~ having pOlt6 bounded by 8
aluminosili~ate tetrahedra, for examp}e~ erionite,
and zeolites having port6 bounded by }O or ~2
alumino~ilicAte tetralledra, fo~ example, ferrierite,
silicalite, and zeolite Y, displ~y little or no
selectivity to dimethy~amine when compared to the
20 value~ attained at equilibrium for the uncatalyzed
reaction of methanol and ammonia. Similar re~ults
are ob~aihed when a~ alumina-6ilica ca~aly~ (91
Alz03, 6.5% SiO2) is employed. Compari~on of the
re6ult6 of Comparati~e Experiment~ A, B, C and E witb
~5 example~ of ~he invention conducted at si~ilar flow
rate~ ~ugge~ that comparable conver6ion~ can be
obtained wi~h acidic zeolite rhQ at tempera~ure~ 100
belo~ tho~e employed in the Comparative Experiments.
COM2ARATIVE E~PERI~ENT A
~eolite H-ferrierite wa6 prepared ~y heating
a 6ample of ~errierite t2eolon~ 700, Norton Co~pany)
to 500 in flowing ~2 o~ ~0 hour6 and the~
contacti~g ~he resulting sample three time~, ~or one
: hour each time, with a 10~ NH~03 solutio~ at
::
: 34
. ~
~ 5
~0~. The re~ul~ing material w~6 dried and heated by
increa~ing the temperature 50 per hou~ ~o 500O and
then ~eld at 500 for ten houE60 The ~esulting
sample of H-fe~rierite wa~ ~hen cooled and evalu~ed
for dimethyla~ine ~electivi~y by ~ procedure
6ubstan~ially similar to t~a~ de~cribed in
Example 1. The condi~ion~ employed and ~he resul~
obtained are ~et forth in Table I~, belGw.
COMPARATIVE EXPERIMENT B
Zeolite H-erionite wa~ prepared ~rom a
sampl~ o zeolite N~4-erionite ~Linde* E~10) by a
procedure sub~tantially 6imilar to that de~cribed fol
prepara~ion of H-fe~rieri~e in Comparative Experiment
A. The re~ul~ing material wa~ evaluated for
dimethylamine selectivity ~ub~tantially according to
15 the procedure of Example 1. The re~ult~ obta~ned are
6et forth i.n Table 1~, below.
COMPARATIVE EXPERIME~T C
Methanol and ammonia were pas~ed ove~ a
cataly6t con~ifiting of 2 g of zeolite ~I-silical:ite
(S-ll~. Union Carbide Corporation~ substantially as
de~cribed in Example 1. The condition~ and re6ult6
are di~played in Ta~le I~. Thi8 material 60rbed 12.5
g methanol and 12 . 5 g n-propanol per 100 g ~ataly6t,
proYiding a GSI of 1.
Z5 COMP~RATIVE E~PERIMENT D
100 g of zeolite NH4-Y (Linde LZY-82) wa~
calcined in air by heating in 50 6tepwise increment~
to 545, and ~hen held at 5~0 or about 10 hour6.
The ~esulting product, zeolite H-Y, wa~ evaluated for
30 dimethylamine ~ele~tivity by a procedure ~ubstantially
6imilar ~o ~ha~ de~cribed in Example 1. The
condition~ and re6ultfi are ~et f~rth i~ Table I~.
* denotes trade mark
3S
' ,~
12~G61Z
J
36
COMPARATIVE E~PERIMENT E
In a procedure ~ub6tantially ~imi1ar to that
deEcribed in Example 1, methanol and ammonia were
ea~sed over a cataly~t consisting of 2 g of
~ilica-alumina (~1~ A12O3, 6.5% SiO2: Har~haw
Chemical Co., Al-1602T). The conditions and result~
are di~played in Table IX, below.
Table IX: ~ethylamine Selectivitie6 of E~ionite,
10- and 12-Rin~ ~eolites, and Silica-Alumina Catalvst~
~eOH-
Feed ~eOH MA Selectivity
Compara~ive T Flow Conv. Conv. (%~
~xPeriment Catalyst (~ ~mL/hr~ L~ MMA DMA TMA
A H-fercie~ite 400 0.5 94 90 13 Z~ 59
B H-erionite ~00 2 98 ~8 1831 51
15 C H-6ilicalite 400 4 97 929 22 69
D H-Y LZY-82 300 4 94 70 14 95
E Har6haw 400 6 92 80 1114 75
Al 1602
Equilibrium 400 10 22 68
~0
: 25
~:
,
: 35
~:
: 36
.~
, ~ ,,
