Component analysis of pyrolysis bio-oil from three major components of biomass and Pinus yunnanensis by ZSM-5 catalytic

Abstract: In order to study the catalytic pyrolysis process of the three components （Cellulose, hemicellulose and lignin） with participation of mesoporous ZSM-5, Firstly the pyrolysis of three major components in biomass and wood powder of Pinus yunnanensis were conducted. Then catalytic pyrolysis of the three major components (microcrystalline cellulose, xylan and alkali lignin) and wood powder of Pinus yunnanensis were carried out with the mesoporous ZSM-5 as catalyst. Compositions of the derived bio-oil were identified by gas chromatograph-mass spectrometer (GC-MS). By comparing the product distribution in bio-oil between pyrolysis and catalytic pyrolysis of three major components and wood powder, the catalytic pyrolysis mechanism of biomass was studied. What is more, ZSM-5 was analyzed by N2 adsorption-desorption and XRD diffraction, and ultimate analysis of bio-oil obtained were also identified. The results indicated that during catalytic pyrolysis of three major components and Pinus yunnanensis, mesoporous ZSM-5 showed different performance. The results of XRD diffraction pattern and N2 absorption/desorption demonstrated ZSM-5 used had abundant mesopores with mean pore size of 6.23nm. Through pyrolysis cellulose was mainly converted into β-D-allose (20.39%), furfural, 2,6-di-tert-butyl-4-methylphenol, 3-propyl glutaric acid, and 2,4-Pentadienoic acid. In the process of catalytic pyrolysis, ZSM-5 transformed β-D-allose (20.39%), furfural, 3-Propyl glutaric acid, and 2,4-Pentadienoic acid into 1-methylnaphthalene and 2,6-dimethylnaphthalene. ZSM-5 performed the supreme catalytic activity for cellulose among 4 feedstocks, and the relative content of total aromatics in bio-oil obtained from catalytic pyrolysis of cellulose was 63.89%. The raw bio-oil from hemicellulose pyrolysis mainly contained furfural (67.78%) and 2,6-di-tert-butyl-4-methylphenol. But in the course of catalytic pyrolysis, the relative content of furfural reduced drastically to 2.66% while the relative content of aromatics increased to 36.81%, especially, naphthalene and 2-methylnaphthalene. The primary composition in bio-oil from lignin pyrolysis was 2,6-di-tert-butyl-4-methylphenol (82.33%), which was converted into 1,7-Dimethylnaphthalene and 1,8-dimethylnaphthalene by ZSM-5 through catalytic pyrolysis. The content of 2,6-di-tert-butyl-4-methylphenol decreased to 77.97% while the relative content of total aromatics increased to 14.14%. The bio-oil obtained from Pinus yunnanensis pyrolysis contained 2,6-di-tert-butyl-4-methylphenol (9.73%), 2-methoxy-4 methyl phenol, (Z)-isoeugenol, and 4-hydroxy-3-tert- butylanisole. Through catalytic pyrolysis 2-methoxy-4 methyl phenol and (Z)-isoeugenol were obviously converted into 1-methylnaphthalene, 1-methylene-1 hydrogen-indene, and 2,6-dimethylnaphthalene, and the total aromatics in bio-oil reached at 53.99%. When the Pinus yunnanensis was used as feedstock, the reusability and regeneration of mesoporous ZSM-5 were studied by comparing the chemical components and ultimate analysis of bio-oil. With the use time of ZSM-5 increasing from 1 to 3, in bio-oil the amount of oxygen compounds augmented while aromatics content reduced from 53.99% to 43.32%, and the ultimate analysis showed O content increased with the decreased C content. However, the full catalytic performance of regenerated mesoporous ZSM-5 restored almost. After regeneration ZSM-5 yielded bio-oil with aromatics content of 52.14% and O content of 26.89%.