Synergistic catalysis of MCM-41 and HZSM-5 on rape straw pyrolysis

The rape straw was taken as raw materials, and the HZSM-5 and MCM-41 catalysts were used and loaded into bed in two layers with different ways (HZSM-5/MCM-41 and MCM-41/HZSM-5) to explore the synergistic catalytic mechanism on the basis of bio-oil quality and catalyst durability. The physical and chemical characteristics of organic phase in purified bio-oil were analyzed, the compositions were analyzed by FT-IR and GC-MS, and the durability of catalysts was analyzed by TG. The results show that compared with the singular catalytic reaction, the liquid yield from synergistic catalytic reaction lowers somewhat and the gas yield increases. The physciochemical properties of organic phase in purified bio-oil increase and the organic phase obtained from MCM-41/HZSM-5 synergistic catalytic reaction has a relatively higher calorific value, 34.31 MJ/kg. The organic phase in refined bio-oil contains a variety of aromatic substances and a small amount of carbonyl substances, the synergistic catalytic reaction can produce more hydrocarbons and less oxygen-contained aromatic substances. The MCM-41/HZSM-5 synergistic catalytic reaction can produce higher levels of hydrocarbons in organic phase of refined bio-oil, which are mainly in single ring aromatics. There are two weight loss peaks for deactivated HZSM-5 molecular sieve and only one weight loss peak for deactivated MCM-41 molecular sieve in the range of 300-800℃, which show that the coke deposited on the MCM-41 catalyst has a single composition and is easy to remove and the synergistic catalytic reaction forms less coke.