Ex-situ catalytic fast pyrolysis of soapstock for aromatic oil over microwave-driven HZSM-5@SiC ceramic foam

Abstract

In view of the poor selectivity of aromatic hydrocarbons in bio-oil from biomass pyrolysis and the high pressure drop and rapid coking and deactivation of catalyst in industrial scale, a microwave-driven HZSM-5@SiC ceramic foam has been constructed, and applied to the ex-situ catalytic fast pyrolysis of soapstock to improve the content of aromatic hydrocarbons in bio-oil. The effects of different catalysts and heating modes and mass ratios of HZSM-5@SiC ceramic foam to soapstock on the distribution of pyrolysis products have been investigated. In addition, combined with the comparison of microwave and electric heating, the deactivation characteristics of HZSM-5@SiC ceramic foam have been studied. Finally, the process of preparing aromatic oil by microwave-driven catalytic pyrolysis of soapstock was discussed. Experimental results indicate that compared with HZSM-5, HZSM-5@SiC ceramic foam has a higher yield of bio-oil and higher aromatization activity. Under microwave heating, the relative content of aromatic hydrocarbons increases from 25.18% to 100% when the mass ratio of HZSM-5@SiC ceramic foam to soapstock increases from 0:1 to 1:1. Compared with electric heating catalysis, HZSM-5@SiC ceramic foam has the lowest yield of coke under microwave heating. After five consecutive uses, it still maintains more than 90% catalytic activity and has higher stability, which provides a scientific basis for the pilot scale experiments of soapstock catalytic pyrolysis.