Study On The Catalytic Pyrolysis Characteristic Of Biomass Based On Modified HZSM-5 And Nanosheet Lamellar Zeolite

As the only resource that can replace fossil energy,biomass can be converted into gaseous,liquid,solid fuel and other chemical raw materials,receiving more and more attention.Bio-oil obtained from biomass pyrolysis can be refined by catalytic pyrolysis,making the bio-oil more valuable and better in quality.HZSM-5 is widely used in pyrolysis of biomass to produce aromatic hydrocarbons because of its unique pore structure and a large number of acid sites,but its microporous properties limit the transmission of pyrolysis gas and may even cause the deactivation of HZSM-5.In this paper,HZSM-5 handled by steam combined with metals loading were characterized then applied in pyrolysis of camellia nut shell firstly.Then,the product distribution and pyrolysis characteristics of catalytic co-pyrolysis of camellia nut shell and take-out solid waste were investigated.Lastly,a kind of nanosheet lamellar zeolite N-ZSM-5 was synthesized and the effects of pyrolysis temperature,dosage of catalyst and placement methods of catalysts on the catalytic pyrolysis of camellia nut shells by nanosheet lamellar zeolite were investigated.The MFI structure of HZSM-5 still be retained after combined modification of steam and metals loading.The specific surface area of combined modified HZSM-5 decrease to below300 m~2/g from 360.11 m~2/g and some mesoporous were introduced into HZSM-5 after steam treatment.The number of acidic sites decreased significantly when HZSM-5 were modified.There were no aromatic hydrocarbons in the pyrolysis products when steam treatment zeolite HH-700 as catalyst in the catalytic pyrolysis of camellia nut shell,meaning steam treatment reduced performance of HZSM-5 seriously.Monocyclic aromatic hydrocarbons and considerable olefins were detected in the pyrolysis products of catalytic pyrolysis of camellia nut shell when steam and metals loading combined modified HZSM-5 as catalysts.HH5%Mg behaved best in the pyrolysis of camellia nut shell with the relative yield of 13.75%of monocyclic aromatic hydrocarbons,15.62%of olefins and 1.96%of acids.The lowest Eave values were 165.33 k J/mol(by OFW)and 163.14 k J/mol(by KAS)which occurred in the mixing ratio of camellia nut shell and take-out solid waste was 3:7.The results of the orthogonal experiment analysis show that the biggest factor of yield of aliphatic hydrocarbon was mixing ratios and more take-out solid waste in the materials more aliphatic hydrocarbon can be obtained;the biggest factor of yield of monocyclic aromatic hydrocarbons was catalysts types and HZSM-5 promoted the formation of monocyclic aromatic hydrocarbons and the biggest factor of yield of acids was pyrolysis temperature and the higher temperature the less acids formed.The optimal mixing ratio,pyrolysis temperature and catalyst type were identified for catalytic co-pyrolysis of camellia nut shell and take-out solid waste which were 3:7,700℃and HZSM-5 combined with Ca O,respectively.Nanosheet lamellar zeolite N-ZSM-5 had typical MFI structure and had much more specific surface area than HZSM-5 which was 472.39m~2/g.N-ZSM-5 had large amount of mesoporous and lower acids amount than HZSM-5.N-ZSM-5 promote the formation of monocyclic aromatic hydrocarbons and reduce the yield of polycyclic aromatic hydrocarbons and acids in the catalytic pyrolysis of camellia nut shell.Higher pyrolysis temperature inhibited the formation of monocyclic aromatic hydrocarbons and the highest yield was31.89%,occurred when the temperature was 500℃.More monocyclic aromatic hydrocarbons and polycyclic aromatic hydrocarbons and less olefins obtained when the addition of N-ZSM-5 became lager.The largest yield of 50.6%of monocyclic aromatic hydrocarbons occurred when the ratio of N-ZSM-5 and camellia nut shell was 3:1.In-situ catalytic pyrolysis and ex-situ catalytic pyrolysis make a little difference on the product distribution of pyrolysis of camellia nut shell.Ex-situ catalytic pyrolysis produced less monocyclic aromatic hydrocarbons in pyrolysis of camellia nut shell than in-situ catalytic pyrolysis did.