Characteristics of co pyrolysis of biomass and heavy oil and the evolution behavior of produced gases

Biomass is an energy source that is abundant,clean and renewable,and the development and utilization of biomass can effectively solve the environmental pollution and energy problems.However,there are a series of problems such as the low calorific value of produced gas and oil inhibited its exploration.Co-processing of biomass and heavy oil is believed as a good way for which could reduce the difficulty of heavy oil processing and solve the problems of the low calorific value of the gas and oil produced from biomass.In this paper,the pyrolysis and co-pyrolysis characteristics of corn stalk and a petroleum residue obtained from fluid catalytic cracking process (FCC) at different blending ratios were studied via thermogravimetry coupled with mass spectrometry.The intrinsic thermal reactions of the co-processing of corn stalk and FCC were investigated by comparing the experimental and calculated values.The results show that the main reaction temperature regions of corn stalk and FCC are close,and both of them have severe weight loss at 200-400 ℃,while the intrinsic reactions are different.Corn stalk’s pyrolysis mainly occurs as thermal cracking reactions,which is accompanied by the emission of small molecules such as H2,CH4,CO,CO2,H2O(g),etc.However,the thermal conversion of FCC is more likely to undergo volatilization or pyrolysis reactions,with only severe cracking reactions occur at a temperature above 400 ℃,accompanied by the emission of CH4.The experimental curve of co-pyrolysis is basically consistent with theoretical curve,and no mutation is observed.The positive synergistic effect exists in the main reaction temperature regions of pyrolysis (400 ℃.Combined with online mass spectrometry data,the amount of gas emission increases regularly with the increase of corn stalk addition,indicating that the change caused by the interaction of biomass and FCC is mild during co-pyrolysis.The co-pyrolysis of corn stalk ash and FCC shows that the corn stalk ash promotes the pyrolysis of FCC,while the FCC almost has no catalytic effect on the co-pyrolysis of FCC with de-ashed corn stalk.