The conversion of wood lignin to char materials in a fluidized bed of AlCuCr oxide catalysts

Abstract

The process of powdered lignin pyrolysis was studied in a pilot installation with a fluidized bed of AlCuCr oxide catalyst under different operating conditions. The advantages of the studied thermocatalytic process are the high productivity, the increased yield of char and the low level of harmful compounds in the gaseous products of lignin pyrolysis. The porosity of the chars varied from 1.58 to 2.15 cm 3/g with an increase of gas flow-rate from 100 to 154 m 3/h. Increasing the O 2/lignin ratio in the reaction mixture resulted in formation of char products with higher sorption ability. Char samples obtained under different operating conditions of lignin pyrolysis showed different reactions to water-steam activation. The application of a manufacturing scheme, including the stages of catalytic pyrolysis, steam activation and ash removal by water treatment, would allow production of good-quality carbon sorbents (porosity up to 2.9 cm 3/g, surface area 750–800 m 2/g) in a yield of 15–19% relative to dry lignin.