Process for organosolv pulping and use of a gamma lactone in a solvent for organosolv pulping

Abstract

The invention provides a process for organosolv pulping, wherein solid lignocellulosic feed material is heated at a temperature in the range of from 50 to 210° C. in a solvent to obtain a solid cellulosic fraction comprising at least 50 wt % of the cellulose present in the feed material and a liquid fraction, wherein the solvent comprises at least 10 wt % of a compound according to general molecular formula wherein R<SUB>1 </SUB>to R<SUB>6 </SUB>each represent, independently, a hydrogen atom or an organic group connected with a carbon atom to the lactone group. The invention further provides the use of a compound according to general molecular formula (1) in a solvent for organosolv pulping.

1 . A process for organosolv pulping, wherein solid lignocellulosic feed material is heated at a temperature in the range of from 50 to 210° C. in a solvent to obtain a solid cellulosic fraction comprising at least 50 wt % of the cellulose present in the feed material and a liquid fraction, wherein the solvent comprises at least 10 wt % of a compound according to general molecular formula  
       
         
           
           
               
               
           
         
       
       wherein R 1  to R 6  each represent, independently, a hydrogen atom or an organic group connected with a carbon atom to the lactone group.  
     
     
         2 . A process according to  claim 1 , wherein the solid cellulosic fraction comprises at least 60 wt % of the cellulose present in the feed material.  
     
     
         3 . A process according to  claim 1 , wherein the cellulose in the solid cellulosic fraction obtained has an average degree of polymerisation of at least 300.  
     
     
         4 . A process according to  claim 1 , wherein the feed material is heated at a temperature in the range of from 100 to 200° C.  
     
     
         5 . A process according to  claim 1 , wherein the solvent comprises at least 20 wt % of the compound according to general molecular formula (1).  
     
     
         6 . A process according to  claim 1 , wherein the solvent comprises an acid catalyst.  
     
     
         7 . A process according to  claim 6 , wherein the acid catalyst is a strong mineral acid having a pKa below 2.5.  
     
     
         8 . A process according to  claim 6 , wherein the acid catalyst is a strong organic acid having a pKa below 2.5.  
     
     
         9 . A process according to  claim 6 , wherein the acid catalyst is present in a concentration of at most 5% by weight of the solvent.  
     
     
         10 . A process according to  claim 1 , wherein the feed material is heated at a temperature in the range of from 100 to 210° C. in a solvent that is free of mineral acid.  
     
     
         11 . A process according to  claim 1 , wherein the feed material is heated in the solvent at a pressure in the range of from 1 to 10 bar (absolute).  
     
     
         12 . A process according to  claim 1 , wherein R 1 , R 2 , R 3  and R 4  each are a hydrogen atom.  
     
     
         13 . A process according to  claim 12 , wherein R 5  is a methyl group.  
     
     
         14 . A process according to  claim 13 , wherein the compound according to general molecular formula (1) is gamma valerolactone (R 6  is a hydrogen atom), 2-methyl-5-oxotetrahydrofuran-2-carboxylic acid (R 6  is a carboxyl group), a compound having a molecular structure according to any one of molecular formulas (2) to (5):  
       
         
           
           
               
               
           
         
       
       or an ester of a compound having a molecular structure according to molecular formula (2) or (3).  
     
     
         15 . A process according to  claim 1 , wherein the compound having a gamma lactone group has a molecular structure according to molecular formula (6) or (7):  
       
         
           
           
               
               
           
         
       
       or is an ester of a compound having a molecular structure according to molecular formula (6) or (7).  
     
     
         16 . Use of a compound according to general molecular formula (1) in a solvent for organosolv pulping.  
     
     
         17 . A process according to  claim 1 , wherein the solid cellulosic fraction comprises at least 80 wt % of the cellulose present in the feed material.  
     
     
         18 . A process according to  claim 2 , wherein the cellulose in the solid cellulosic fraction obtained has an average degree of polymerisation of at least 300.  
     
     
         19 . A process according to  claim 2 , wherein the feed material is heated at a temperature in the range of from 100 to 200° C.  
     
     
         20 . A process according to  claim 3 , wherein the feed material is heated at a temperature in the range of from 100 to 200° C.