Effect of Catalyst, Fluidized Gases and Operating Conditions upon Light Aromatic Hydrocarbon Yield for Catalytic Pyrolysis of Woody-Chip by Powder Particle Fluidized Bed

Abstract

In a process of catalytic pyrolysis of woody chip by a powder-particle fluidized bed (PPFB), the effects of catalyst fluidized gases, pyrolysis temperature and catalyst static height on the yields of the pyrolysis products were investigated at ambient pressure. The optimum operating condition was found for obtaining a high yield of light aromatic hydrocarbon, such as benzene, toluene, xylene and naphthalene (BTXN). Under the optimum conditions of CoMo-B catalyst static height of 0.08 m and pyrolysis temperature of 863 K, BTXN yield was 6.3 wt%, (daf base). In the case of 50 vol% of highly active CoMo-A catalyst mixed with 50 vol% of low active alumina catalyst, the yield of BTXN was about 3.5 times larger than that in the case of activated alumina catalyst. As activity of NiMo-A catalyst is so high for the secondary reaction of the primary pyrolysis products, even at 723 K, most products of the pyrolysis were methane and the yield of methane was more than 45 wt%, dry base. If hydrogen content in the fluidized gas was higher than 50 vol%, the yield of BTXN was not affected by the hydrogen content. There is a possibility for using the pyrolysis-recovery gas or coke-oven gas as the fluidized gas for woody pyrolysis.