A novel production of aromatic hydrocarbons via dielectric barrier discharge assisted one-stage pyrolysis-catalysis of biomass: Insights into modified HZSM-5 selectivity and stability

Dielectric barrier discharge (DBD) was employed to assist to convert biomass into aromatic hydrocarbons under the vacuum pyrolysis and zeolite catalysis conditions. This study was to investigate the selectivity and stability of HZSM-5 modified by Ti, Ni, and Ni-Ti. The texture and acidity of different modified catalysts varied greatly. Ti modification strengthened the cracking removal of carbon and oxygen, while Ni-modified version improved hydrogen transfer capacity. Bimetallic modification increased the HHV to 36.93 MJ/kg, and obtained a compromised yield of 28.10%. Hydroxyl was difficult to completely remove due to hydrophilicity, carbonyl removal was better, and refined bio-oils had a high aromatic degree, of which, bimetallic modification increased the selectivity of MAHs to 76.61% and the refined bio-oil was more suitable to be used as gasoline additives. Although the aromatization performance of Ti-modified version was weaker than that of Ni-modified version, its anti-coking performance was better. The acidity adjustment of bimetallic modification cooperated with the synergistic effect of metal species and discharge, so that the difficulty of carbon deposition was increased significantly. The high-temperature catalytic coke was not distinguished and the low-temperature thermal coke mainly deposited on the outer surface was further reduced for bimetallic modified catalyst. Therefore, the Ni-Ti/HZSM-5 assisted by DBD exhibited better potential in improving the selectivity of aromatic hydrocarbons and enhancing the stability of zeolite catalyst.