Co-pyrolysis of soybean soapstock with iron slag/aluminum scrap, and characterization and analysis of their products

Abstract

Soybean soapstock (SS) is one of the main solid wastes produced in the refinery of edible oil processing. In this study, the co-pyrolysis of SS with iron slag (IS) and aluminum scrap (AS) was carried out in a tubular furnace. The gas, liquid and solid products were characterized and the char yield decreased with increasing IS/AS ratio. IS and AS can improve the gas yield, and when the ratio of SS/IS was 1:0.25, the total pyrolysis gas and hydrogen contents were significantly increased. The content of oxygen compounds in pyrolysis oil decreased during co-pyrolysis, while AS promoted the content of polycyclic aromatic hydrocarbons in pyrolysis oil. The co-pyrolysis reaction can be divided into four stages, the weight loss rate reaches the maximum at the third stage (390℃-575℃). The molar ratio of H/C was lower for pyrolysis, indicating good stability of pyrolysis char owing to the high degree of carbonization and aromaticity. The possible co-pyrolysis reaction mechanism was explored.