Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Boron or compound containing same
Reexamination Certificate
2000-04-20
2002-07-16
Killos, Paul J. (Department: 1623)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Boron or compound containing same
C502S105000, C502S151000, C502S152000, C502S159000, C502S200000, C502S313000, C562S518000, C562S517000, C562S497000, C562S606000, C562S607000, C562S890000, C562S891000, C562S519000
Reexamination Certificate
active
06420304
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a polymer-supported carbonylation catalyst and its use in a process for preparing organic carboxylic acids or anhydrides having n +1 carbon atoms.
The invention relates also to a process for preparing organic carboxylic acids or anhydrides having n +1 carbon atoms by reacting, in the presence of the above-mentioned carbonylation catalyst, an alcohol having n carbon atoms, an ether having 2n carbon atoms or an ester formed from said alcohol and acid with carbon monoxide. In particular, the invention relates to a process for preparing acetic acid by reacting methanol with carbon monoxide in the presence of said carbonylation catalyst.
The most commonly known process for preparing acetic acid up to date has been the process described by Paulik et al. in U.S. Pat. Nos. 3,769,329 and 4,690,912. That process comprised synthesizing acetic acid through a carbonylation reaction of carbon monoxide and methanol in the presence of a rhodium catalyst at a temperature of 180° C., and a carbon monoxide pressure of 35-70kg/cm
2
as well as using methyl iodide as promoter. These patents disclosed that the most effective solvent for the production reaction of acetic acid was the product, acetic acid, itself. Its main advantages were that the catalyst had very high conversion and selectivity (>95%), had a relatively long service life, and could be recycled almost completely to the reactor. However, water content in those reaction system should be maintained at least higher than 14-15wt. % in order to prevent the rhodium catalyst from precipitation and keep a relatively high reaction rate. Such high water content would increase the cost of equipment used in the purification process and consume considerable energy that it becomes so-called a “high water content” carbonylation process.
Thereafter, there have been a number of patents proposing improved methods with respect to this acetic acid process. The main objective of those patents was aimed at increasing the stability of the rhodium catalyst under low water content (<14 wt. %) in order to alleviate the corrosion problem of moisture reaction to the equipment and also reduce largely the energy consumption during isolation and purification of the product. Namely, they were developed toward a “low water content” carbonylation process. Their main approaches comprised of (1) incorporating inorganic or organic salts as additives in the reaction medium, (2) using supported catalyst by combing the rhodium catalyst with a polymer, active carbon or ion exchange resin, and (3) using both of (1) and (2).
U.S. Pat. No. 4,733,006 disclosed the use of an inorganic salt XOAc (X=Li
+
,Na
+
,K
+
) as additives. However, it did not teach the effect of these inorganic salts on the reaction rate throughout the entire disclosure. EP 55618 disclosed a technique to reduce the precipitation of the rhodium catalyst due to low water content during the carbonylation of methanol by adding an organic catalyst stabilizer in the reaction solution. Stabilizers used in that patent comprised several types of organic compounds containing, concurrently or individually, one or more nitrogen or phosphorus atom, or carboxyl group (COOH):
1. N,N,N
1
,N
1
-btetramethyl-o-phenylenediamine and 2,3
1
-dipyridyl
2. HOOC-Y
1
-COOH and
where: Y
1
=(CX
1
X
2
)
m
,m=2-10 Y
2
,Y
3
,Y
4
,Y
5
=(CX
1
X
2
)
n
n=2-10
Where:
R
1
,R
2
,R
4
, and R
5
is an alkyl or an aralkyl having 1-20 carbon atoms;
R
1
,R
2
,R
4
,
5
is an alkyl or an alkaryl having 6-20 carbon atoms
R
3
is a polymethylene group having 1-3 carbon atoms.
U.S. Pat. No. 5,001,259 described the use of inorganic iodides LiI as the stabilizer for the rhodium catalyst in the carbonylation of methanol to improve the precipitation of the rhodium catalyst under low water content, and obtained a reaction rate almost equal to that under high water content (14 wt. %). The same patent used also a quaternary ammonium salt, N-methyl-picolinium iodide, under low water content to increase the reaction rate of carbonylation. However, according to the result of the experiment, the N-methyl-picolinium iodide tended to form a hardly soluble complex with Rh that precipitated from the reaction solution. The nitrogen-containing compound, N-methylimidazole, mentioned in EP 1538341 tended also to form a hardly soluble complex with Rh that precipitated from the reaction solution of carbonylation of methanol.
In U.S. Pat. No. 5,442,107, six types of heterocyclic nitrogen compounds were employed as the catalyst stabilizer for the carbonylation of methanol under low water content:
1. 2-ethyl-4-methylimidazole
2. 4-methylimidazole
3. 4-tert-butylpyridine
4. 2-hydroxypyridine
5. 3-hydroxypynidine
6. 4-hydroxypyridine.
However, this patent did not disclose the effect of the additive used on the reaction rate under low water content. No alkyl pyridine was mentioned in that patent. Further, those catalyst stabilizers used in that patent were similar to those organic compounds mentioned in the prior art, i.e., picoline and N-methylimidazole, in that they tended to form a hardly soluble complex with Rh which precipitated from the reaction solution of carbonylation of methanol under low water content. These suggest that, if OH and tert-butyl were present on pyridine, there would be a significant effect of reducing the precipitation of the rhodium catalyst from the reaction solution of carbonylation of methanol under low water content. On the other hand, if no substituent was on pyridine or the substituent was a methyl group, such effect would be insignificant. Furthermore, the prior art has not mentioned or indicated that other pyridine derivatives having substituents other than OH or alkyl had the effect of reducing precipitation of the rhodium catalyst during the carbonylation of methanol under low water content.
Moreover, techniques that used complexes having a supported structure formed by coordinating an organic polymer with rhodium to prevent its precipitation in the reaction system under low water content and to increase further the concentration of the rhodium catalyst and hence the reaction rate were proposed. For example, Webber et al. described in Journal of Molecular Catalyst, 3 (1977/78) 1-9, that a polymer with two functional group was used in a carbonylation reaction. In the practical application of such polymer, however, there were still some problems such as lost of rhodium as well as their stability in the industrial application.
A rhodium complex formed by supporting rhodium with a 2,4-divinylpyridine was used in EP 277824 to perform a heterogeneous carbonylation reaction. In such a system, however, not only the activity of the catalyst was decreased significantly, but also the pyrolysis of the polymer itself or the reaction medium-mediated chemical decomposition of the polymer would resulted in the stripping of the rhodium off the polymer and the complicating of the purification system. Accordingly, such system has not been used in any industrial process.
As described in Journal of Catalyst, 40,255-267 (1975), a copolymer of a styrene having a diphenylphosphinyl group and a divinylbenzene was used as the support of rhodium in liquid and gas phase carbonylation reactions. ROC Patent Nos. 080618 and 094905 described the use of a series of phosphorus-containing liquid such as PPh
3
and Ph
3
PCH
2
CH
2
P(O)Ph
2
. However, in such a reaction system, dissociation of the polymer from the rhodium atom might cause the precipitation of the rhodium. Further, during the reaction, addition of excess of triphenylphosphine was necessary in order to keep so-claimed high catalytic activity.
Inorganic Chemistry, 20,641-644(1981) described reacting ion exchange resin such as Bio Rex 9 Dowex 1-X8 and the like or a copolymer of styrene and 4-vinylpyridine alkylated with methyl iodide with tetracarbonyl dichloro dirhodium or rhodium trichloride hydrate to form a heterogeneous catalyst. Although the author claimed that it could have a reaction effect c
Liu Yao-Lung
Tsai Chia-Jung
Tsai Hsi-Chin
Bacon & Thomas
China Petrochemical Development Corporation
Deemie Robert W.
Killos Paul J.
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