Product distribution and interaction of co-pyrolysis of biomass and oil slurry

Biomass is a renewable resource with nearly zero carbon emissions in the whole life cycle. The extraction of light fuels and chemicals from biomass is the ultimate direction to achieve carbon peak and carbon neutrality. Co-conversion of fossil energy and biomass is a feasible way to seek optimal combination of fossil energy and new energy in accordance with basic national conditions. In this paper, the interaction between corn stalk (CS) and fluid catalytic cracking slurry (FCC) during co-pyrolysis and the effect of biomass intrinsic minerals on product distribution and product characteristics were studied.The results show that there was obvious interaction between CS and FCC slurry in different proportions during the co-pyrolysis process, the polymerization reaction played a dominant role in the process,and the yield of semi coke increased. The interaction during co-pyrolysis enhanced the removal of oxygen containing compounds, promoted the generation of hydrocarbons, and finally improved the quality of the tar products. Among them, the content of phenolic substances decreased significantly, the polycyclic aromatic hydrocarbons of 3～4 rings in aromatic hydrocarbon increased, and the hydrocarbon with more than 13 carbon atoms in aliphatic hydrocarbons also increased. For the co-pyrolysis of 30%FCC with 70% CS, the phenolic compounds in the co-pyrolysis oil decreased by about 7% compared with the calculated values, and the contents of aromatic hydrocarbons and aliphatic hydrocarbons increased by about 2% and 9%, respectively. Compared with demineralized CS, the co-pyrolysis of un-demineralized CS and FCC promoted the formation of tar, and inhibited the generation of semi coke and gas. The presence of minerals could enhanced the interaction between CS and FCC, which not only promoted the cracking of oil slurry, strengthened the deoxidation reaction of biomass and produced more hydrocarbons, but also relieved the polymerization of free radicals and improved the condensation degree of polycyclic compounds in the co-pyrolysis system. The content of pyrene in tar was reduced and the amount of aliphatic hydrocarbon increased.Thermogravimetric experiment evaluation showed that the gasification reactivity of the char produced from co-pyrolysis was obviously improved, which was beneficial to the subsequent utilization.