Catalysts and Processes for Producing p-xylene from Biomass

Abstract

Biomass is converted to a fluid hydrocarbon product comprising p-xylene by reaction over a zeolite catalyst. An iron-modified zeolite catalyst having a siliceous coating and methods of making the catalyst are also described.

What is claimed: 
     
         1 . A process for converting biomass to liquid hydrocarbons, comprising:
 feeding biomass into a reactor;   heating the biomass in the presence of an aluminosilicate zeolite catalyst; and   wherein the aluminosilicate zeolite catalyst further comprises at least 0.2 wt % Fe wherein the Fe is not derived from biomass or reactor walls, or   wherein the aluminosilicate zeolite catalyst has been manufactured to contain at least 0.2 wt % Fe or pretreated to contain at least 0.2 wt % Fe; and   converting the biomass to a gaseous product stream comprising p-xylene.   
     
     
         2 . The process of  claim 1  wherein the aluminosilicate zeolite catalyst further comprises at least 0.5, or at least 1.0, or at least 1.5 wt % Fe, and in some embodiments up to 10 wt % Fe, up to 5 wt % Fe, or up to 3 wt % Fe. 
     
     
         3 . The process of  claim 1  wherein the gaseous product stream comprises at least 10 wt % of aromatic compounds or at least 15 wt % of aromatic compounds and in some embodiments up to 30 wt % aromatics, in some embodiments up to 25 wt %; and/or wherein at least 85% of the xylenes in the gaseous product stream is p-xylene. 
     
     
         4 . The process of  claim 1  wherein the aluminosilicate zeolite catalyst has been pretreated with a siliceous coating, or wherein the aluminosilicate zeolite catalyst has a siliceous coating. 
     
     
         5 . The process of any of  claim 1  further comprising:
 removing the catalyst from the reactor after it has been used to pyrolyze the catalysis, 
 heating the used catalyst in the presence of an oxygen containing gas (preferably O2) to form a regenerated catalyst, and returning the regenerated catalyst to the reactor, and again using the catalyst to catalyze the conversion of the biomass to a gaseous product stream comprising p-xylene. 
 
     
     
         6 . A method of making a catalyst, comprising:
 providing a zeolite catalyst;   treating the catalyst to increase the iron content; and   applying a siliceous coating to the catalyst;   resulting in an Fe-modified, zeolite catalyst having a siliceous coating.   
     
     
         7 . The method of  claim 2 , comprising:
 using the Fe-modified, zeolite catalyst having a siliceous coating to catalyze the pyrolysis of biomass; and   subsequent to the pyrolysis of biomass, regenerating the catalyst by heating in the presence of an oxygen containing gas.   
     
     
         8 . A hydrocarbon mixture, comprising: a biomass-derived (i.e.,  14 C-containing) mixture of hydrocarbons comprising at least 10 mass % of xylenes; wherein the xylenes are made up of 85 to about 91% p-xylene. 
     
     
         9 . The hydrocarbon mixture of  claim 8  made by the process of any of  claims 1  to  5 . 
     
     
         10 . The hydrocarbon mixture of  claim 8  comprising catalyst particles of the type described herein. 
     
     
         11 . A chemical system, comprising:
 a reactor, comprising   an Fe-modified zeolite catalyst;   biomass; and   a hydrocarbon product stream comprising at least 10 mass % xylenes wherein at least 80% of the xylenes are p-xylene.   
     
     
         12 . The chemical system of  claim 11  wherein the Fe-modified zeolite catalyst comprises a siliceous coating. 
     
     
         13 . The chemical system of  claim 11  wherein the zeolite catalyst comprises ZSM-5. 
     
     
         14 . An aluminosilicate zeolite catalyst having a Si/Al molar ratio of 100 or less, comprising:
 at least 0.2 wt % Fe wherein the Fe is not derived from biomass or reactor walls, or   wherein the aluminosilicate zeolite catalyst has been manufactured to contain at least 0.2 wt % Fe or pretreated to contain at least 0.2 wt % Fe; and   a siliceous coating.   
     
     
         15 . The aluminosilicate zeolite catalyst of  claim 14  wherein the catalyst has Fe evenly distributed over the surface as measured by SEM-EDS. 
     
     
         16 . The aluminosilicate zeolite catalyst of  claim 14  wherein the catalyst comprises ZSM-5. 
     
     
         17 . The aluminosilicate zeolite catalyst of  claim 14  wherein the catalyst has a surface ratio of Si/Fe in the ratio of 50:1 to 4:1; preferably 30:1 to 5:1; in some embodiments 20:1 to 7:1. 
     
     
         18 . The aluminosilicate zeolite catalyst of  claim 14  wherein the Fe is concentrated in clusters on the surface of the catalyst. 
     
     
         19 . The aluminosilicate zeolite catalyst of  claim 14  having a Brønsted acidity of greater than 0.01, 0.05 or greater, preferably a Brønsted acidity in the range of 0.01 to 0.2, preferably in the range of 0.04 to 0.15, preferably in the range of 0.05 to 0.1 μmol/mg.