Selective preparation of tetrahydrofuran by hydrogenation of maleic anhydride

Abstract

A catalyst for the hydrogenation of C 4 -dicarboxylic acids and/or derivatives thereof, preferably maleic anhydride, in the gas phase comprises a) 20-94% by weight of copper oxide (CuO), preferably 40-92% by weight of CuO, in particular 60-90% by weight of CuO, and b) 0.005-5% by weight, preferably 0.01-3% by weight, in particular 0.05-2% by weight, palladium and/or a palladium compound (calculated as metallic palladium) and c) 2-79.995% by weight, preferably 5-59.99% by weight, in particular 8-39.95% by weight, of an oxidic support selected from the group consisting of the oxides of Al, Si, Zn, La, Ce, the elements of groups IIIA to VIIIA and of groups IA and IIA of the Periodic Table of the Elements.

1 - 4 . (canceled) 
     
     
         5 . A process for the hydrogenation of C 4 -dicarboxylic acids and/or derivatives thereof, in the gas phase in the presence of a catalyst, wherein said catalyst comprises 40-92% by weight of copper oxide 0.005-5% by) weight of palladium and/or of a material having acid sites, which support material is selected from the group consisting of: oxides of Al, Si, Zn, La, Ce, elements of groups IIIA to VIIIA and elements of groups IA and IIA. 
     
     
         6 . A process as claimed in  claim 5 , wherein the GHSV is from 10 to 50 000 h −1 . 
     
     
         7 . A process as claimed in claim, wherein the reaction temperature is from 150 to 400° C., and the pressure during the reaction is from 0.5 to 50 bar. 
     
     
         8 . A process as claimed in  claim 5 , wherein the concentration of C 4 -dicarboxylic acid or the derivative thereof is from 0.5 to 5% by volume. 
     
     
         9 . (canceled) 
     
     
         10 . The process for the hydrogenation of C 4 -dicarboxylic acids and/or derivatives thereof as claimed in  claim 5  for the hydrogenation of maleic anhydride. 
     
     
         11 . The process of  claim 5 , wherein the catalyst comprises palladium oxide and/or palladium nitrate. 
     
     
         12 . The process of  claim 5 , wherein the support material is selected from the group consisting of aluminum oxide, silicon oxide, titanium oxide, zinc oxide, zirconium oxide and cerium oxide. 
     
     
         13 . The process of  claim 5 , wherein the catalyst consists of copper oxide, palladium and/or a palladium compound and aluminum oxide. 
     
     
         14 . The process of  claim 5 , wherein the GHSV is from 100 to 10 000 h −1 . 
     
     
         15 . The process of  claim 7 , wherein the reaction temperature is from 200 to 300° C. 
     
     
         16 . The process of  claim 7 , wherein the pressure during the reaction is from 1 to 20 bar. 
     
     
         17 . The process of  claim 8 , wherein the concentration of C 4 -di-carboxylic acid or the derivative thereof is from 0.2 to 2% by volume.