Note: Descriptions are shown in the official language in which they were submitted.
2~,03~.4 - -
PROCESS AND CATALYST
FOR HYDROCHLORINATION OF HYDROCARBONS
This invention relate_ to catalytio hydro- ;
chlorination processes. In particular, the invention
relates to the catalytic hydrochlorination of hydro-
carbyl compounds.
: Chlorinated hydrocarbons have various utilities .:- a~ lndustrial chemicals and solvents. For example,
methyl chloride i8 useful aq a catalyst carrier in low
temperature polymerizations; as a fluid for thermometric
and thermo~tatic equipment; as a methylating agent in
organlc synthesis, such as of methylcellulose; in the
preparation of silicone rubberq; and as an extractant
and low temperature solvent.
Method~ for the production of chlorinated
~;: hydrocarbons, such as methyl chloride, are well-known.
In a typical method for the production of methyl chlo-
ride, vaporized methanol and hydrogen chloride are mixed
in approximately equimolar proportions and pa~ed
through a converter packed with a catalyst such as
alumina gel or zinc chloride on activated carbon to form
- methyl chloride. Other known methods involve reactions
: 25 in the liquid phaqe uqing an aqueou~ solution of
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catalyst. For example, U.S. Patent 4,073,816 teaches
that monochloroalkane~ or monochlorocycloalkane~ can be
prepared by reacting an alcohol with hydrogen chloride
in the presence of aqueous zinc chloride. German
Offensive 3332253 teaches that mixtures containing
alcohols and ethers may be converted to alkyl halides by
reactions with hydrogen chloride in the presence of an
aluminum-zinc chloride catalyst. This reference further
teache3 that small amounts of alkali metal chlorides and
larger amounts of cadmium, iron and/or magnesium
chlorides may be added with the zinc ~hloride to
inarease the efficiency of the catalyst.
Such methods do not resolve all the existing
problems. The problems relating to the manufacture of
chlorinated hydrocarbons include excessive production of
by-products; requirements for use of excess hydrochloric
acid and excessive coking of the catalyst. An
additional problem related to the use oP alumina or
alum$na ~upported catalysts is the breakdown of the
alumina to produce bohemite. What is needed is a non-
-alumina càtalyst which results in a high yield of
chlorinated hydrocarbon; which permits the complete
conversion of hydrochloric acid; which does not
experience excessive coke formation; and which reduces
the amount of by-product3 formed.
In one aspect, the preqent invention is such
a hydrochlorination catalyst comprising a Group IA cat-
ion, a Group IIA or IIB cation and a neutralizing number
of counter anions supported on a non-alumina porous
carrier. The molar ratio of the Group IA cation to the
Group IIA or IIB cation is at least about 0.5:1 and no
greater than about 1.5:1.
36,~67-F -2-
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2~31~
In a second aspect, the present invention is
a proce~s for the hydrochlorination of hydrocarbyl com-
pounds to form chlorinated hydrocarbyl compounds wherein
the hydrocarbyl compounds and hydrogen chloride are
contacted in the vapor phase in the presence of the
catalyst described above under reaction conditions suf-
ficient to form the chlorinated hydrocarbyl compounds.
The chlorinated hydrocarbyl compounds produced :~
by the practice have variou~ utilitieq as industrial
chemical~ and ~olvent~. Methyl chloride, for example, - ,
i9 uqeful as a cataly~t carrier in low temperature
polymerizations; aq a fluid for thermometric and ther-
moqtatic equipment; as a methylating agent in organic
qyntheqis, such as of methylcellulo~e; and as an
extractant and low temperature solvent.
It i~ ~urpri~ing that the use of a catalyst
supported on a non-alumina ~upport and comprising the
specified molar ratio of the cations described above
reqùlt~ ln a high yield of chlorinated hydrocarbyl
compound~ with reduced formation of by-products and with
minimal ¢oking of the cataly9t. The u~e of ths
z5 specified non-alumina supported cataly~t eliminates the
problem of bohemite formation while maintaining high -~
yield~.
The catalyst of the present invention is
advantageously a salt of a Group IA metal (alkali
: metal); a Group IIA or IIB, preferably Group IIB, metal;
and a neutralizing number of counter anions supported on
: a non-alumina porou~ carrier material. Preferred Group
i:
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IA metals include sodium, potassium, rubidium, lithium
and cesium, with pota~sium and cesium being more pre-
ferred and potaq~ium being most preferred. The
preferred Group IIB metals include zinc, cadmium and
mercury with zinc being more preferred. While any
counter anion, -~uch as bromide, chloride and fluoride,
is suitable in the catalyst of this invention,
the halide~-are preferred with chloride being most pre-
ferred. Other suitable anions are nitrates, ~ulfate,
phosphate, acetates, oxylate and cyanides.
The molar ratio of Group IA metal to Group ~IA
or IIB metal in the salt is preferably at least about
0.5:1 and no greater than about 1.5:1. It i~ more pre-
ferred that the molar ratio is at least about 0.9:1 andno greater than about 1.1:1 and most preferred that
approximately equimolar portions of the two metals are
used. The amount of counter anion u~ed is that which is
suffl¢ient to neutralize the cations of the salt.
Any non-alumina support which will withstand
the hydro¢hlorinat~on ¢onditions de~cribed herein can be
used ln the pro¢e8~ of the present invention. Examples
of appropriate supports include the well-known carbon
supports su¢h as activated ¢arbon, carbon black, chars
and ¢oke. Other suitable supports that may be used to
support the catalyst include pumice, silica gel,
a~bestos, diatomaceous earth, fullers earth, titania,
zirconia, magnesia, magnesium silicate, silicon carbide,
~ilicalite, and silica. A preferred ~upport is silica.
A silica having a surface area between 100 m2/g and 300
m2/g and a pore volume in the range of 0.75 cc/g to 1.4
cc/g is particularly active in the process of this
invention.
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The salt is suitably supported on the carrier ~-;
material by any standard impregnation technique such as
that disclosed in ExperimentalMethods~nCatalyticResearch,
Vol. II, edited by R. B. Anderson and P. T. Dawson,
Academic Press, New York, 1978. A solution o~ both the
Group IA and Group IIA or IIB metal cations and the
a~qociated anions may be employed to impregnate the
support material or the metal salts may be impregnated
from separate solutions. The resulting cataly~t com-
prising the catalytically active salt and the supportpreferably comprises from 1 to 50 weight percent of the
Group IIA or IIB metal salt, e.g., ZnCl2, and from 0.5
to 30 weight percent of the Group IA metal Qalt, e.g.,
KCl, based on the percentage by weight of the total
salts to the support. It i~ preferred to use at least
about 20 and no greater than about 30 weight percent of
the Group IIA or IIB metal salt and at least about 10
and no greater than about 20 weight percent of the Group
IA metal salt and more preferred to use about 20 weight
percent of the Group IIA or IIB metal ~alt and about 10
weight percent of the Group IA metal salt. Preferred
weight percents of the two salts are selected so as to
result in approximately equimolar proportions of the
Group IA and Group IIA or IIB salt being used.
The proceqs of the present invention comprise~
contacting a hydrocarbon and hydrogen chloride in the
presence of the aforementioned cataly~t under reaction
condition~ sufficient to produce the corresponding chlo-
rinated hydrocarbon. Example~ of hydrocarbons u~eful in
the practice of this invention include compounds
corresponding to the formula
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.. . .. . .
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ROH
wherein ~ is alkyl, aryl, arylalkyl and alkylaryl. It
i~ preferred that R i9 alkyl and more preferred that R
iq lower alkyl having from 1 to 5 carbon atom~. It i~
most preferred that R i_ alkyl having from 1 to 3 carbon
atom3. Example~ of preferred hydrocarbyl compounds thus
include methanol, ethanol and propanol with methanol
being more preferred.
Molar ratio~ of hydrocarbon to hydrogen
chloride useful in the practice of thi~ invention are -~
generally at least about 1:10 and no greater than about
10:1. When hydrogen chloride i~ used in exces~, it iq
15 preferred that the amount of exces~ hydrogen chloride i_
no more than about 30 molar percent. It i~ preferred
that the hydro¢arbon be uqed in exceq~. When the
hydrocarbon i3 used in excesq, the molar ratio of
hydro¢arbon to hydrogen chloride i9 preferably no
greater than about 2:1, more preferably no greater than
about 1.5:1 and most preferably about 1.1:1.
The temperature range u~eful in the pra¢tice of
25 this invention ~g any at which the hydrochlorination
reaction will pro¢eed. Preferably, the reactian is
conducted at a temperature o~ at least about 25C and no
greater than about 475C with at lea~qt 175C to no
greater than 300C being more preferred. The most
30 preferred temperature range~ from at lea_t 250C to no
greater than 275C. Preqqureq typically employed in the
proces~ of the pre~ent invention are at lea~t about 14
p~ig (97 kPa gauge) and no greater than about 500 pqig
~(3450 kPa gauge). Preferred pressure~ are at lea~t
,' ~
; 36,467-F -6-
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about 35 psig (240 kPa gauge) and no greater than about
150 psig (1035 kPa gauge).
Gas hourly space velocities are suitably at
least about 100 and no greater than about 10,000
hours~1, preferably at least about 300 and no greater
than about 3000 hr~1.
The process may be operated in a batch mode
or ¢ontinuously, although continuous operation is pre-
~erred. In a preferred embodiment, vaporized methanol
and hydrogen chloride are added in approximately equi-
molar proportions to a fixed bed reactor containing a
KZnCl3 catalyst supported on silica. The resultant
products are separated by distillation.
The process of this invention is ef~ective in
redu¢ing the amount of by-products ~ormed. In a pre-
', ~erred embodiment wherein methanol and hydrogen chloride
react to Porm methyl chloride, the production of by-
-products ~uch as dimethyl ether i 9 decreased. The
praoess o~ the present inventlon also results in a long-
-llv~d catalyst. The catalyst of the present invention
i~ ~table and the absence o~ alumina eliminate~ the
problem of bohemite formation.
The following examples are provided to illus-
trate the invention and ~hould not be interpreted as
limiting it in any way. Unle~s ~tated otherwise, all
parts and percentages are by weight.
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Exam~le 1 - Catalyst Preparation
A silica qample waq sieved between three
screenq and the fraction_ retained by 4 mesh, 5 mesh and
8 me3h, (4.75 mm, 4.00 mm, 2.36 mm, Tyler Sieve)
respectively, are collected. The 8 meqh (2.36 mm, Tyler
Sieve) fraction waq used in the preparation of 200 g
~amples of about 500 cubic centimeter~ each. A 200 g
sample waq placed in a 2 liter di~h and dried 48 hour~
at 150C. The sample wa~ transferred to a 1 liter
flutsd flacik, placed on a rotovap and cooled to 70C
under vacuum. The silica was then impregnated with a
solution of 60 g of ZnCl2 and 32.81 g of KCl in a total
volume of 278 cubic centimeters of water. The
impregnated cataly~t wa~ returned to the 2 liter dish
and air dried for 24 hour~ and then dried for an
additional 25 hours at 150C.
xamDle 2
.,
A three-liter portion of cataly~t, prepared a~
de~¢ribed above, waq placed into an Inconel reactor that
is 20 ~eet (6 meters) long and 1.25 in¢hes (32 mm) in
diameter. The reactor waCi then purged with nitrogen for
48 hours at 220C. The cataly~t wa~ then conditioned
with HCl mixed with nitrogen prior to reaction with
methanol. The proportion~ of methanol to hydrcgen
chloride and the reaction temperature were varied a~
~hown in Table I below. The reactor effluent wa~
3 an~lyzed by ga~ chromatography to determine the con- i
ver~ion obtained and the amount of dimethyl ether pro-
duced relative to the amount of methyl chloride pro-
duced. The reqult~ obtained are ~hown in Table I below.
~-
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; 36,467-F -8-
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TABLE I
Run i~g~h~l ~Cl, in Temp version~ D~ t~C~
1 8.00 (3.6)10.00 (4.5) 220 96.6 11726
2 8.00 (3.6) 10.00 (4.5) 2~5 96.4 11545
3 3.92 (1.8) 5.5~ ~2.5) 220 99.0 6981
0 4 3.92 (1.8) 4.91 (2.2) 220 98.2 8957
S 7.46 (3.4) 10.57 (4.8) 220 98.4 7713
6 5.83 (2.6) 7.78 (3.5) 220 98.4 8161
7 8.00 (3.6) 10.00 (4.5) 220 93.1 13780
8 4.14 (1.9) 4.95 (2.2) 220 94.3 13441
9 8.00 (3.6) 10.00 (4.5) 220 93.4 14065
4.24 (1.9) 4.84 (2.2) 220 91.3 16209
11 9.81 (4.4) 10.34 (4.7) 220 93.6 13900
~ Conversion Oe methanol to methyl chloride
~art# o~ dimethyl ether producod per million parts of
methyl ~hloride
:
The data abovs illu~Qtrate that the uQe of the
catalytic proceQs o~ this invention re~ultq in a high
rate of conversion of methanol. RunQ 1 and 2 demon-
strate that an increaQe in the reaction temperature from
220C to 235C has little effe¢t on conver_ion or
dimethyl ether production. Run_ 3 and 4 demonqtrats ths
effect of varying the ratio of msthanol to hydrogen
chloride. Run 3 representQ a 25 percent molar exceqq of
hydrogen chloride whils Run 4 shows a 10 psrcent molar
exce~s. At the 10 percent exce_s level, the conversion
decrea-qes and the dimethyl ether production increaseQ
36~467-F -9_
.. . . . .
Z~iO31~
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although in either case the conversion is high and the
dimethyl ether production iq low. Runs 8, 10 and 11
show the effect of decreasing the molar proportion of
HCl until methanol is used in excess. The ratios of
methanol to HCl change from 1:1.05 in Run 8 to 1:1 in
~un 10 and to 1.13:1 and follow the trend shown in Run~
3 and 4. These trends indicate that high conversion and
acceptably low dimethyl ether production may be obtained
when methanol is used in excess. Run~ 1, 7 and 9 are
all identical and demonstrate that after a breaking in
period, the catalyst is stable within the time frame of
the experiment.
:
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36,467-F -10-
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