Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Reexamination Certificate
2000-06-19
2001-09-04
Gitomer, Ralph (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
Reexamination Certificate
active
06284917
ABSTRACT:
The present invention relates to a process for hydrogenating benzenepolycarboxylic acids or derivatives thereof, such as esters and/or anhydrides, by bringing one or more benzenepolycarboxylic acids or one or more derivatives thereof into contact with a hydrogen-containing gas in the presence of a catalyst containing macropores.
Furthermore, the present invention also relates to selected products as obtained by the hydrogenation according to the invention as such, i.e. the corresponding cyclohexane compounds, in particular of cyclohexanedicarboxylic esters and cyclohexanetricarboxylic esters, in particular the cyclohexanedicarboxylic esters and cyclohexanetricarboxylic esters. Furthermore, the invention also relates to the use of the obtained cyclohexanedicarboxylic esters as plasticizers in plastics.
In U.S. Pat. No. 5,286,898 and U.S. Pat. No. 5,319,129, dimethyl terephthalate is hydrogenated at ≧140° C. and a pressure of from 50 to 170 bar over supported Pd catalysts which are treated with Ni, Pt and/or Ru to give the corresponding dimethyl hexahydroterephthalate. In DE-A 28 23 165, aromatic carboxylic esters are hydrogenated at from 70 to 250° C. and from 30 to 200 bar over supported Ni, Ru, Rh and/or Pd catalysts to give the corresponding cycloaliphatic carboxylic esters. U.S. Pat. No. 3,027,398 describes the hydrogenation of dimethyl terephthalate over supported Ru catalysts at from 110 to 140° C. and from 35 to 105 bar.
EP-A 0 603 825 relates to a process for the preparation of 1,4-cycylohexanedicarboxylic acid by hydrogenating terephthalic acid by using a supported palladium catalyst, wherein as support alumina, silica or active charcoal is used. The process described therein is particularly characterized in that the solution comprising an 1,4-cyclohexanedicarboxylic acid as obtained in a first step is brought into contact with steam, thereby leading to an extraction of the impurities as obtained in said solution. This process is, however, only applicable to acids, since when using it for derivatives, such as e.g. esters, anhydrides, etc. there exists the risk of hydrolysis. The use of a support comprising macropores is not mentioned in this application.
Up to now, predominantly phthalic acid esters, such as dibutyl, dioctyl or isononyl esters of phthalic acid have been used as plasticizers in plastics, such as PVC, as may be deduced from e.g. FR-A 2,397,131. However, since recently these compounds are regarded as being detrimental under health aspects and thus their use in plastics for producing e.g. tools for children is under an increasing criticism, in some countries their use is even forbidden.
The use of several cyclohexane-1,2-dicarboxylic acid esters as plasticizer is known from the prior art. Described is the use of cyclohexanedicarboxylic acid dimethyl or diethyl esters (DE-A 28 23 165), cyclohexane-1,2-dicarboxylic acid di(isononyl)ester (EP-A 07-011074) and cyclohexane-1,2-dicarboxylic acid di(2-ethylhexyl)ester (DE-A 12 63 296) as plasticizers in plastic.
It is an object of the present invention to provide a process for hydrogenating benzenepolycarboxylic acids or derivatives, in particular benzenedicarboxylic esters, using specific catalysts, by means of which the corresponding ring-hydrogenated derivatives, in particular cyclohexanedicarboxylic esters, can be obtained with a very high selectivity and in a very high space-time yield without significant secondary reactions.
A further object of the present invention lies in providing new products which are obtainable by the hydrogenation of benzenepolycarboxylic acid (derivatives) according to the invention, which should be preferably useable as plasticizers in plastics.
The present invention accordingly provides a process for hydrogenating a benzenepolycarboxylic acid or a derivative thereof or a mixture of two or more thereof by bringing the benzenepolycarboxylic acid or the derivative thereof or the mixture of two or more thereof into contact with a hydrogen-containing gas in the presence of a catalyst which comprises as active metal at least one metal of transition group VIII of the Periodic Table alone or together with at least one metal of transition group I or VIII of the periodic table applied to a support which contains macropores with the proviso that
if dimethyl terephthalate is hydrogenated, the hydrogenation using a catalyst which comprises as active metal ruthenium either alone or together with at least one metal of transition group I, VII or VIII of the Periodic Table applied to a support, where the support has a mean pore diameter of at least 50 nm and a BET surface area of at most 30 m
2
/g and the amount of the active metal is from 0.01 to 30% by weight, based on the total weight of the catalyst, and the ratio of the surface areas of the active metal and the catalyst support is less than 0.05, or
a catalyst which comprises as active metal ruthenium either alone or together with at least one metal of transition group I, VII or VIII of the Periodic Table in an amount of from 0.01 to 30% by weight, based on the total weight of the catalyst, applied to a support, where from 10 to 50% of the pore volume of the support is formed by macropores having a pore diameter in the range from 50 nm to 10,000 nm and from 50 to 90% of the pore volume of the support is formed by mesopores having a pore diameter in the range from 2 to 50 nm, where the sum of the pore volumes adds up to 100%, is excluded.
In a preferred embodiment, the present invention provides a process for hydrogenating a benzenepolycarboxylic acid or a derivative thereof or a mixture of two or more thereof, wherein the catalyst comprises as active metal at least one metal of transition group VIII of the Periodic Table either alone or together with at least one metal of transition group I or VII of the Periodic Table applied to a support, where the support has a mean pore diameter of at least 50 nm and a BET surface area of at most 30 m
2
/g and the amount of the active metal is from 0.01 to 30% by weight, based on the total weight of the catalyst (catalyst 1).
Furthermore, the present invention provides a process of this type in which the catalyst comprises as active metal at least one metal of transition group VIII of the Periodic Table either alone or together with at least one metal of transition group I or VII of the Periodic Table in an amount of from 0.01 to 30% by weight, based on the total weight of the catalyst, applied to a support, where from 10 to 50% of the pore volume of the support is formed by macropores having a pore diameter in the range from 50 nm to 10,000 nm and from 50 to 90% of the pore volume of the support is formed by mesopores having a pore diameter in the range from 2 to 50 nm, where the sum of the pore volumes adds up to 100% (catalyst 2).
In a further preferred embodiment, the present invention provides a process as defined above in which the catalyst (catalyst 3) comprises as active metal at least one metal of transition group VIII of the Periodic Table either alone or together with at least one metal of transition group I or VII of the Periodic Table in an amount of from 0.01 to 30% by weight, based on the total weight of the catalyst, applied to a support, where the support has a mean pore diameter of at least 0.1 {grave over (l)}m and a BET surface area of at most 15 m
2
/g. Supports used can in principle be all supports which contain macropores, i.e. supports which contain only macropores as well as those which contain mesopores and/or micropores in addition to macropores.
Active metals which can be used are in principle all metals of transition group VIII of the Periodic Table. Preference is given to using platinum, rhodium, palladium, cobalt, nickel or ruthenium or a mixture of two or more thereof as active metal; particular preference is given to using ruthenium as active metal. Among the metals of transition group I or VII or else transition groups I and VII of the Periodic Table which are likewise all usable in principle, preference is given to using copper and/or rhenium.
For the purposes of the
Bottcher Arnd
Breitscheidel Boris
Brunner Melanie
Halbritter Klaus
Henkelmann Jochem
BASF - Aktiengesellschaft
Gitomer Ralph
Keil Herbert B.
Khare Devesh
LandOfFree
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