Catalyst For Tetrahydrofuran Synthesis

Abstract

Provided are catalysts suitable for the production of tetrahydrofuran from 1,4-butanediol. Also provided are methods of use of these catalyst, as well as catalyst systems. The catalysts described herein contain only Lewis acidity, but not Brønsted acidity, which results in decreased production of ether byproducts.

1 . A catalyst composition for the synthesis of tetrahydrofuran, the catalyst composition comprising about 3 to about 50 wt % copper oxide on a gamma-alumina support, wherein the catalyst composition comprises less than about 1.5 wt % silica and the catalyst composition has Lewis acidity and no Brønsted acidity. 
     
     
         2 . The catalyst composition of  claim 1 , wherein the catalyst composition comprises less than about 1 wt % silica. 
     
     
         3 . The catalyst composition of  claim 2 , wherein the catalyst composition comprises substantially no silica. 
     
     
         4 . The catalyst composition of  claim 1 , wherein the catalyst composition has substantially only Lewis acidity determinable from IR absorption spectra of pyridine adsorbed on the catalyst. 
     
     
         5 . The catalyst composition of  claim 1 , wherein the catalyst composition contains from about 3 to about 30 wt % copper oxide. 
     
     
         6 . The catalyst composition of  claim 1 , wherein the gamma-alumina contains substantially no stabilizers. 
     
     
         7 . A method of synthesizing tetrahydrofuran, the method comprising:
 contacting a stream comprising 1,4-butanediol with a catalyst composition comprising about 3 to about 50 wt % copper oxide on a gamma-alumina support, wherein the catalyst composition comprises less than about 1.5 wt % silica, and with the proviso that the catalyst composition has Lewis acidity and no Brønsted acidity, thereby converting at least a portion of the 1,4-butanediol into tetrahydrofuran.   
     
     
         8 . The method of  claim 7 , wherein the catalyst composition comprises less than about 1 wt % silica. 
     
     
         9 . The method of  claim 8 , wherein the catalyst composition comprises less than about 0.5 wt % silica. 
     
     
         10 . The method of  claim 9 , wherein the catalyst composition comprises substantially no silica. 
     
     
         11 . The method of  claim 7 , wherein the catalyst composition has substantially only Lewis acidity determinable from IR absorption spectra of pyridine adsorbed on the catalyst. 
     
     
         12 . The method of  claim 7 , wherein the catalyst composition contains from about 5 to about 20 wt % copper oxide. 
     
     
         13 . The method of  claim 7 , wherein the gamma-alumina contains substantially no stabilizers. 
     
     
         14 . The method of  claim 7 , further comprising reducing the CuO to copper metal prior to contacting the catalyst composition with a stream comprising 1,4-butanediol. 
     
     
         15 . A catalyst system for the synthesis of tetrahydrofuran from maleic anhydride, the system comprising:
 a first catalyst composition effective to convert dimethyl maleate and dimethyl succinate to1,4-butanediol and methanol; and   a second catalyst composition comprising about 3 to about 50 wt % copper oxide on a gamma-alumina support, wherein the catalyst composition comprises less than about 1.5 wt % silica, and the catalyst composition has Lewis acidity and no Brønsted acidity.   
     
     
         16 . The catalyst system of  claim 15 , wherein the first and second catalyst compositions are in pellet form in a fixed bed reactor. 
     
     
         17 . The catalyst system of  claim 16 , wherein the fixed bed reactor contains a layer of the first catalyst composition over a layer of the second catalyst composition. 
     
     
         18 . The catalyst system of  claim 17 , further comprising a protective layer over the layer of the first catalyst composition. 
     
     
         19 . The catalyst system of  claim 15 , wherein the first and second catalyst compositions are in pellet form in separate reactors. 
     
     
         20 . The catalyst system of  claim 19 , further comprising a protective layer over the first catalyst composition. 
     
     
         21 . The catalyst system of  claim 17 , wherein the gamma-alumina contains substantially no stabilizers.