Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Patent
1994-03-09
1995-02-28
Prescott, Arthur C.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
502313, 502326, 502402, 502406, C07C 5308, C07C 5116, B01J 3116, B01J 2026
Patent
active
053939190
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a catalyst which is useful in the production of acetic acid and/or methyl acetate from methanol, and a process for producing acetic acid and/or methyl acetate by using methanol as a starting material through a one-stage reaction in a gas phase.
RELATED ART
Acetic acid has been industrially produced in a large amount by the methanol carbonylation method, i.e., so-called Monsanto's method. In this method, methanol is reacted with carbon monoxide in a liquid phase in the presence of a catalytic system containing a rhodium catalyst and an iodide.
However, it is necessary in these methods to use rhodium, which is highly expensive. Further, the conditions of location of the factory are restricted because it is necessary to obtain carbon monoxide of a high purity. Furthermore, there is a problem that methyl iodide, which is used as an iodide, corrodes the apparatus. In addition, since the above-mentioned reaction is usually effected in a liquid phase system containing water, the recovery of the acetic acid thus formed requires a lot of energy.
Meanwhile, there has been proposed the use of a Ru--Sn heteronuclear cluster (a polynuclear compound) containing an anion comprising [Ru(SnCl.sub.3).sub.5 L].sup.3- (wherein L represents a ligand) as a catalyst for producing acetic acid and methyl acetate from methanol through a one-stage reaction in a liquid phase by Sumio Shinoda and Tetsu Yamakawa, "One-step Formation of Methyl Acetate with Methanol used as the Sole Source and Catalysis by Ru.sup.II --Sn.sup.II Cluster Complexes", J. Chem. Soc., Chem. Commun., p.p. 1511-1512 (1990).
However, the above-mentioned heteronuclear cluster has a solubility in methanol as small as about 0.05 mM. In addition, since the above heteronuclear cluster is an anionic complex, the solubility of the above heteronuclear cluster is smaller not only in the acetic acid formed but also in common organic solvents. Thus, it is impossible to elevate the concentration of the catalyst, and therefore, the reaction rate also can not be enhanced. Furthermore, it is sometimes observed that formaldehyde is formed by the dehydrogenation of methanol and the metal contained in the catalyst is reduced and precipitated by the formaldehyde, which causes the deactivation of the catalyst within a short period of time. In particular, the catalyst is liable to be deactivated when reacted at a high temperature.
Accordingly, it is an object of the present invention to provide a novel catalyst which has a high catalytic activity and is useful for producing acetic acid and/or methyl acetate from methanol.
It is another object of the present invention to provide a process for producing acetic acid and/or methyl acetate from methanol through a one-stage reaction in a gas phase wherein the catalytic activity can be maintained at a high level throughout the reaction time.
It is another object of the present invention to provide a process for producing acetic acid and/or methyl acetate in the presence of a highly active catalyst at a high reaction rate.
DISCLOSURE OF THE INVENTION
The present inventor has extensively studied for achieving the above-mentioned objects. As a result, he has found that these objects can be achieved by reacting methanol in a gas phase with the use of a solid catalyst and that a specific catalyst with the use of an anion exchanger exhibits a high catalytic activity in a gas phase reaction where methanol is used as a starting material. The present inventor has further found that methylal or methyl formate can be produced by a gas phase reaction wherein methanol is used as a starting material and a solid catalyst is employed. Thus, the present invention has been completed based on these findings.
Thus, the present invention provides a catalyst prepared by exchanging an anion of an anion exchanger with an anion of an Ru--Sn hetero-polynuclear compound represented by the following general formula (1): aryl group, an aralkyl group or an alkoxyl group; Y represents a ligand; m is an intege
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patent: 4537674 (1985-08-01), Ovshinsky et al.
patent: 4626334 (1986-12-01), Ohe et al.
patent: 5214184 (1993-05-01), Matuzaki et al.
Daicel Chemical Industries Ltd.
Prescott Arthur C.
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