| Fast pyrolysis of biomass is a efficient technique to obtain crude bio-oil,which is expected to ease the depletion problem of fossil fuels such as coal,oil and natural gas and the environmental problem associated with the usage of fossil fuels.However,such a technology is still not scaled up for industrial use for the inferior quality of crude bio-oil.We carry out researches on the modification and refining of crude bio-oil in order to improve the quality of bio-oil and expand the scope of its application.Some Literatures show that catalysts formed by C,N,P and other atoms penetrating into lattice structure of transition metal element(IVB-VIB family)show good catalytic hydrogenation performance,which are known as noble metal-like catalysts.Based on the above,this paper prepared a series of noble metal-like catalysts and their modified catalysts for on-line catalytic cracking of pine fast pyrolysis vapors expecting to obtaine aromatic hydrocarbons-rich bio-oil.1.On-line catalytic cracking of pine fast pyrolysis vapors over Mo2N/HZSM-5.A series of noble metal-like catalysts prepared by Mo2N,W2N,MoP and WP supported on Hβ,HY and HZSM-5 were used for catalytic conversion of biomass fast pyrolysis vapors.Pyrolysis-gas chromatography/mass spectrometry(Py-GC/MS)experiments were conducted to analyze the pyrolytic product distribution and evaluate the catalyst performance.The results indicated that among the noble metal-like catalysts,Mo2N/HZSM-5 showed the best selectivity for MAHs.Compared with HZSM-5 catalyst,the modification with Mo2N could significantly decrease the formation of polycyclic aromatic hydrocarbons,while slightly increase monocyclic aromatic hydrocarbons;the actual yields of aromatic hydrocarbons reached maximum values from HZSM-5 and Mo2N/HZSM-5 catalysts under optimal conditions of 750 ℃ and catalyst-to-biomass ratio of 5;in addition,catalyst recycling experiments showed that MO2N/HZSM-5 can improve the anti-deactivation property of the catalyst,which meant Mo2N-modification can extend the life of the catalyst.2.On-line catalytic cracking of pine fast pyrolysis vapors over different Mo-loading and modified Mo2N/HZSM-5A series of noble metal-like catalysts prepared by different Mo-loading Mo2N supported on HZSM-5 and Fe-,Cu-,Cr-,La-and Ce-Mo2N/HZSM-5 prepared by modification with different metal additives based on the optimal Mo-loading were used for catalytic conversion of biomass fast pyrolysis vapors.Pyrolysis-gas chromatography/mass spectrometry(Py-GC/MS)experiments were conducted to analyze the pyrolytic product distribution,the effects of Mo loading,different metal additives modification,temperature and ratio of catalyst/biomass were investigated.The results showed that Ce-10%Mo2N/HZSM-5 exhibited excellent catalytic performance,compared with 10%Mo2N/HZSM-5,the former can significantly inhibited the formation of PAHs and promote the formation of MAHs;the actual yields of aromatic hydrocarbons reached maximum values under optimal conditions of 750 ℃ and catalyst-to-biomass ratio of 5;in addition,the catalytic cracking of three components of pine wood by Ce-10%Mo2N/HZSM-5 showed that the three components can be pyrolyzed to produce aromatic hydrocarbon products under the action of the catalyst,and the synergistic interaction between the three components favored the formation of aromatic hydrocarbon products. |
