Process for converting biomass to coal-like material using hydrothermal carbonisation

Abstract

The present invention relates to a hydro thermal carbonization process for the preparation of coal-like material using biomass. The process comprises a step (i) of heating a reaction mixture comprising water and biomass to obtain a reaction mixture comprising activated biomass; and a step (ii) of adding a polymerization initiator to the reaction mixture obtained in step (i) to polymerize the activated biomass and to obtain a reaction mixture comprising coal-like material. The process is beneficial in terms of product control, and process engineering.

1 . A hydrothermal carbonization process for the preparation of coal-like material from biomass, characterized by comprising at least the following steps:
 heating a reaction mixture comprising water and biomass to obtain a reaction mixture comprising activated biomass; and   (ii) adding a polymerization initiator to the reaction mixture obtained in step (i) to polymerize the activated biomass and to obtain a reaction mixture comprising coal-like material.   
     
     
         2 . The process of  claim 1 , wherein the polymerization initiator is selected from oxygen, peroxides, azo compounds and redox initiators. 
     
     
         3 . The process of  claim 1 , wherein the amount of the polymerization initiator is 0.01 to 2 wt %, in terms of the reaction mixture. 
     
     
         4 . The process of  claim 1 , wherein the reaction mixture is heated to a temperature in the range of 210 to 250° C. during step (i). 
     
     
         5 . The process of  claim 1 , wherein the reaction mixture has a pH in the range of 3 to 7, preferably 5 to 7, in step (i). 
     
     
         6 . The process of  claim 1 , wherein an acid is further added to the reaction mixture prior to or during step (i). 
     
     
         7 . The process according to  claim 1 , wherein step (ii) is carried out at a temperature in the range of 140 to 220° C. 
     
     
         8 . The process according to  claim 7 , wherein the temperature in step (i) is above the temperature in step (ii). 
     
     
         9 . The process according to  claim 1 , wherein the coal-like material is the product of the polymerization in step (ii). 
     
     
         10 . The process according to  claim 1 , wherein the coal-like material has, in terms of the dry mass thereof, at least one of the following features (a) and/or (b):
 (a) a carbon content of >50 wt %;   (b) a calorific value of >23 MJ/kg, preferably >24 MJ/kg.   
     
     
         11 . The process according to  claim 1 , further comprising the step of separating the reaction mixture obtained in step (ii) into a solid phase of the coal-like material, and a liquid phase. 
     
     
         12 . The process according to  claim 11 , wherein the liquid phase obtained in the separation step is oxidized to obtain an oxidized liquid phase. 
     
     
         13 . The process according to  claim 12 , wherein the oxidation is carried out by contacting the liquid phase with an oxygen-containing gas. 
     
     
         14 . The process of  claim 13 , wherein the oxygen-containing gas is air. 
     
     
         15 . The process according to  claim 12 , wherein the, optionally oxidized, liquid phase is recycled to step (i) and/or (ii). 
     
     
         16 . A coal-like material obtainable by a hydrothermal carbonization process according to  claim 1 . 
     
     
         17 . The coal-like material of  claim 16 , which has in terms of the dry mass thereof, a carbon contact of >50 wt % and a calorific value of >23 MJ/kg. 
     
     
         18 . The process of  claim 3 , wherein the amount of polymerization initiator is 0.05 to 0.2 wt %, in terms of the reaction mixture. 
     
     
         19 . The process of  claim 5 , wherein the reaction mixture has a pH in the range of 5 to 7, in step (i). 
     
     
         20 . The process according to  claim 7 , wherein step (ii) is carried out at a temperature in the range of 170 to 210° C.