Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2002-03-15
2002-12-17
Shippen, Michael L. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S864000, C568S885000
Reexamination Certificate
active
06495730
ABSTRACT:
This application is the national phase under 35 U.S.C. § 371 of PCT International Application No. PCT/JP00/06473 which has an International filing date of Sep. 21, 2000, which designated the United States of America.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a catalyst for hydrogenating a carboxylic acid. More particularly, the present invention is concerned with a catalyst for hydrogenating a carboxylic acid, which comprises a specific activated carbon having carried thereon an active metal species comprising ruthenium and tin. By the use of the catalyst of the present invention, a primary alcohol can be efficiently produced directly from a carboxylic acid or carboxylic anhydride by hydrogenation thereof, not through esterification thereof. Further, the catalyst of the present invention can be applied to the hydrogenation of a wide variety of carboxylic acids. Therefore, the catalyst of the present invention is extremely advantageous from the commercial viewpoint. The present invention is also concerned with a method for producing a primary alcohol, which comprises reacting at least one starting material selected from the group consisting of a carboxylic acid and a carboxylic anhydride with hydrogen gas in the presence of water and the above-mentioned catalyst to thereby effect a catalytic hydrogenation of the starting material.
2. Prior Art
The term “alcohol” is a general term covering organic compounds having a hydroxyl group. An extremely large number of alcohols exist. Many of the alcohols are very important compounds which are widely used in various industrial fields. These many important alcohols are commercially produced in large amounts.
Examples of alcohols having one hydroxyl group (monohydric alcohols) include methanol, ethanol, n-propanol and the like. Many monohydric alcohols are frequently used as a raw material for chemical synthesis or as a solvent. Examples of alcohols having two hydroxyl groups (dihydric alcohols or diols) include ethylene glycol, propylene glycol, 1,4-butanediol and the like. Many dihydric alcohols are useful as a raw material for producing a polyester, a polyurethane and the like.
A large number of methods for producing alcohols are conventionally known. Commercial production of primary alcohols (alcohols having a hydroxymethyl group (—CH
2
OH)) is performed mainly by any of the following two methods: a method in which an olefin is subjected to a hydration reaction and a method in which a carboxylic ester is subjected to a hydrogenation reaction in the presence of a copper-containing catalyst under high temperature and high pressure conditions.
Of these two methods, the method in which an olefin is subjected to a hydration reaction is mainly used for producing ethanol. However, this method cannot be used for producing an alcohol having 3 or more carbon atoms, such as n-propanol, n-butanol or 1,4-butanediol. Therefore, these alcohols must be produced by the method in which a carboxylic ester (hereinafter, simply referred to as an “ester”) is subjected to a hydrogenation reaction. Hereinbelow, an explanation is made with respect to the production of a primary alcohol by this method involving hydrogenation of an ester, wherein, in the explanation, production of 1,4-butanediol is taken as an example.
At present, 1,4-butanediol is produced from n-butane. Although it is not impossible to produce 1,4-butanediol by introducing two hydroxyl groups into n-butane by a one-step reaction, such a reaction is extremely disadvantageous from an economical viewpoint. Therefore, it is virtually impossible to produce 1,4-butanediol on a commercial scale by the above-mentioned one-step reaction. For this reason, at present, 1,4-butanediol is produced from n-butane by a method comprising:
subjecting n-butane to air oxidation to produce succinic acid, maleic acid, succinic anhydride or maleic anhydride, especially maleic acid or maleic anhydride; and
producing 1,4-butanediol from the thus produced acid or acid anhydride.
In general, a carboxylic acid can be easily converted to a primary alcohol by a reduction reaction. In a reduction reaction, generally, an appropriate reducing agent is used. However, usually, a reduction reaction of a carboxylic acid requires the use of a strong reducing agent having extremely high reactivity, such as lithium aluminum hydride. Special care must be taken in the handling and storage of such a strong reducing agent. Therefore, such a strong reducing agent is not suitable for use in the commercial scale production of a primary alcohol.
On the other hand, the so-called hydrogenation reaction, i.e., a reduction reaction performed using hydrogen gas (as a reducing agent) and an appropriate catalyst, is suitable for being practiced on a commercial scale. However, usually, the hydrogenation reaction cannot be applied to the reduction of a carboxylic acid. This is because the conventional catalyst used for hydrogenation is soluble in a carboxylic acid, so that the catalyst activity of the catalyst cannot be maintained in the presence of a carboxylic acid.
Therefore, at present, the production of 1,4-butanediol is performed by a method in which maleic acid or maleic anhydride (obtained by air oxidation of n-butane) is esterified with an appropriate alcohol, and the resultant ester is subjected to a hydrogenation reaction in the presence of a copper-containing catalyst under high temperature and high pressure conditions, to thereby convert the ester to 1,4-butanediol.
The method for producing an alcohol by the hydrogenation of an ester in the presence of a copper-containing catalyst under high temperature and high pressure conditions is described in, for example, Japanese Patent Application prior-to-examination Publication (Kohyo) No. 2000-510837 (corresponding to U.S. Pat. No. 6,100,410), Japanese Patent Application prior-to-examination Pubication (Kohyo) No. 2000-510475 (corresponding to U.S. Pat. No. 6,077,964), Japanese Patent Application prior-to-examination Pubication (Kohyo) No. 2000-506134 (corresponding to U.S. Pat. No. 5,981,769), Unexamined Japanese Patent Application Laid-Open Specification No. 7-196558 (corresponding to U.S. Pat. No. 5,414,159) and U.S. Pat. No. 5,334,779.
However, in this method, three steps (i.e., production of a carboxylic acid, esterification of the produced carboxylic acid, and hydrogenation of the produced ester) are required, so that the process for producing a primary alcohol inevitably becomes complicated. The complicated process poses a problem in that the process needs a number of pieces of equipment, such as the equipment for the esterification of the carboxylic acid and the equipment for separating, recovering and recycling the alcohol which is used in the esterification of the carboxylic acid and by-produced in the hydrogenation of the ester.
Because of this problem, it is apparent that the production of a primary alcohol by the hydrogenation of an ester is disadvantageous from the viewpoint of the production cost and the like. Therefore, various studies have been made with respect to the method for shortening the process for producing a primary alcohol.
As an example of such a method, there can be mentioned a method in which a carboxylic acid (but not an ester thereof) is directly subjected to hydrogenation using a catalyst which can maintain its catalyst activity even in the presence of an acid, to thereby obtain a primary alcohol.
In this method, a primary alcohol can be obtained by a two-step reaction, i.e., a process comprising the production of a carboxylic acid and the hydrogenation of the produced carboxylic acid. In this method, esterification of a carboxylic acid (wherein the esterification is required in the conventional process) is not required, so that equipment for this esterification is not required. Further, since this method does not involve esterification, this method is free from the problem that an alcohol (used in the esterification) is by-produced in the hydrogenation, and therefore this method does not need equipment for recover
Konishi Mitsuo
Ueno Eizaburou
Asahi Kasei Kabushiki Kaisha
Shippen Michael L.
LandOfFree
Catalysts for hydrogenation of carboxylic acid does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Catalysts for hydrogenation of carboxylic acid, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Catalysts for hydrogenation of carboxylic acid will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2980268