Production of hydrocarbon-rich bio-oil from soapstock via fast microwave-assisted catalytic pyrolysis

•It is the first time that soapstock was used for fast microwave-assisted catalytic pyrolysis.•An improved fast microwave-assisted catalytic pyrolysis system was proposed.•Hydrocarbon-rich bio-oil with abundant aromatics, alkanes, and olefins was obtained.•Catalyst, pyrolysis temperature and catalyst ratio have great effects on pyrolysis product fractional yields and chemical composition.

Fast microwave-assisted catalytic pyrolysis (fMACP) of soapstock for hydrocarbon-rich bio-oil using different catalysts was investigated in this study. Effects of catalyst, pyrolysis temperature and catalyst to feed ratio on product fractional yields and chemical composition were studied. Experimental results indicated that the use of catalyst increased the relative content of hydrocarbons and selectivity of aromatics. Moreover, HZSM-5 catalyst enhanced the bio-oil yield. When HZSM-5 zeolite was used as a catalyst, 600 °C was the optimal pyrolysis temperature, which provides the maximum bio-oil yield and high content of hydrocarbons. At the cost of the decrease of bio-oil yield, the increase of catalyst to feed ratio increased the relative content of hydrocarbons from 65.41% to 88.59% and selectivity of aromatics from 5.99% to 29.46%. In addition, the analytical results of bio-char show that bio-char with micropore structure and high contents of the essential plant nutrients and micronutrients can be used as a soil amendment to improve soil productivity.