In-situ catalytic pyrolysis of biomass with nickel salts: Effect of nickel salt type

Aiming to investigate the role of anions in the process of biomass pyrolysis catalyzed by nickel salts, four types of nickel salts (Ni(NO3)2, NiSO4, (CH3COO)2Ni, NiCl2) were impregnated on reed to investigate their effects on biomass pyrolysis. The results showed that nickel salts inhibited the release of volatiles from biomass and increased the yield of bio-char, with NiCl2 being the most effective. NiSO4 dramatically increased the specific surface area and graphitization of bio-char, and improved the selectivity of phenolic compounds in bio-oil (62.27 area%) as well as the concentration of CO in pyrolysis gas (37.78 vol%). The addition of NiCl2 enhanced the selectivity of ketone-rich oil (26.95 area%) and hydrogen-rich gas (56.39 vol%). Ni(NO3)2 is weaker than other nickel salts in catalyzing the cleavage of macromolecular compounds. This research offers a prospective approach to control the distribution and quality of pyrolysis products by using suitable catalyst precursors.