Fast pyrolysis of baked wheat straw catalyzed by Fe-Ni modified composite porous molecular sieves for the preparation of aromatics

Abstract

Wheat straw (WS) baked at 260°C is used as raw material. The HZSM-5 was modified through alkali treatment (NaOH) and metal loading (Ni, Fe), followed by the introduction of MCM-41 layers onto the modified HZSM-5 to synthesize composite pore zeolites. A tubular furnace and Py-GC/MS were used to investigate the effects of different composite pore catalysts on the three-phase products and the distribution of bio-oil components during the catalytic fast pyrolysis(CFP) of WS. The use of 1 %FeAZ@M as a catalyst achieved the highest bio-oil yield (31.31 %). Introducing the micro-meso composite pore zeolite 0.3AZ@M as a catalyst resulted in the highest selectivity of monocyclic aromatic hydrocarbons (MAHs) in the bio-oil from WS CFP (52.12 %), along with a bio-oil yield of 26.50 %. The metal-modified composite pore zeolites exhibit enhanced acidity, which can further enhance the composition distribution in the bio-oil. The use of 1 %NiAZ@M as a catalyst resulted in the highest production of MAHs in the bio-oil from WS of CFP (60.67 %), with a bio-oil yield of 23.27 %. Among the bimetal-modified composite pore zeolites, 1 %Ni1 %FeAZ@M demonstrated the highest selectivity for MAHs, with MAHs in the bio-oil reaching 66.36 %, while the bio-oil yield increased to 28.41 %.