Basic Study On Catalytic Pyrolysis And Catalytic Reforming Of Bamboo Biomass

Biomass catalytic reforming to produce high-grade bio-oil is one of the research hotspots of current biomass energy utilization.Microporous molecular sieve ZSM-5 has excellent aromatic selectivity,but its small pore size leads to carbon deposition easily.Mesoporous molecular sieves MCM-41 and SBA-15 have good pore conditions.However,their low acidity leads to low reactivity.Metals or metal oxides have strong deoxidation capacity but they are not selective for aromatics.Two mesoporous-microporous composite molecular sieves HZSM-5/SBA-15 and HZSM-5/MCM-41 were prepared.Bamboo wood is used as raw material for biomass,The synergy between mesoporous and microporous molecular sieves in the catalytic reforming process was investigated by Py-GC/MS test and fluidized bed experiment.The two-stage catalytic deoxidation was carried out by using metal or metal oxide-assisted composite molecular sieves as well.The transformation mechanism of the main products in the pyrolysis and reforming process was analyzed simultaneously.Py-GC/MS experiments on bamboo wood using different composite molecular sieves showed that the optimum Py pyrolysis temperature of bamboo is 600?,and the organic matter yield reaches the maximum at this temperature.HZSM-5 has higher hydrocarbonselectivity.The hydrocarbon yield is 48.41%.MCM-41 catalyzed pyrolysis promotes the formation of furan and alcohols.SBA-15 increases the relative content of long-chain olefins,but the acid increases at the same time.The two mesoporous-microporous composite molecular sieves show good synergy in catalytic pyrolysis and both of them can significantly improve the hydrocarbon yield.In the catalytic reforming of HZSM-5/SBA-15,the hydrocarbons increase with the proportion of microporous molecular sieve.The yield was first increased and then decreased,and the maximum yield was 57.1% at a compound ratio of 1.25 : 1.Unfortunately,the acid yield was also increased.HZSM-5/MCM-41 has a hydrocarbon yield of 58.91% when the microporous mesoporous ratio is 1:1,which mainly composed of monocyclic aromatic hydrocarbons.It also has obvious synergistic effect on the removal of furans and ketones.It can be seen that HZSM-5/MCM-41 has better catalytic effect than HZSM-5/SBA-15.Py-GC/MS experiments on bamboo wood using different metals or metal oxides show that metal or metal oxides have high deoxidation efficiency,and the relative yield of CO2 reaches 35~40%.Among them,metal elemental iron and zinc have better deoxidation efficiency than other metal oxides.The catalytic properties of metals or metal oxides are mild,which can promote the secondary cracking of pyrolysis products.The relative content of phenols,especially light phenols,is significantly increased,and the acid is also reduced in different extents.The addition of HZSM-5/MCM-41 to metal and metal oxides can greatly improve the hydrocarbon yield.The relative yield of hydrocarbons is the highest in the two-stage catalysis ofiron and zinc with composite molecular sieves,reaching 60.7% and 66.11% respectively.The polycyclic aromatic hydrocarbons were secondarily cracked into monocyclic aromatic hydrocarbons.Metal oxides are less synergistic with composite molecular sieves,and the catalytic performance of tin dioxide and stannous oxide is superior to other metal oxides.Experimental study on the mechanism of two-stage catalytic pyrolysis of metallic iron and zinc with composite molecular sieves show that phenol mainly decomposes into hydrocarbons and a small amount of acid and ethers after catalysis.The addition of zinc can increase the yield of monocyclic aromatic hydrocarbons,which composed by 67.3% of benzene and toluene.Iron and zinc can promote the decomposition of more acetone.The main decomposition products are hydrocarbons,ethylene oxide,oxetane and a small amount of alcohols.However,the hydrocarbon selectivity of the composite molecular sieve is lowered,and there is no synergistic effect between metal and composite molecular sieves.After two-stage catalysis,acetic acid is converted into hydrocarbons,malonic acid,acetone and acetic anhydride.Iron can promote carboxyl ketonization,while zinc has poor decarboxylation ability.Fluidized bed experiments on bamboo wood using different metals or metal oxides show that the optimal fluidized bed pyrolysis temperature of bamboo wood is 550?.Metals or metal oxides inhibit the yield of acid and increase the yield of phenol.When metal or metal oxides and HZSM-5/MCM-41 are used for two-stage catalysis of bamboo,the hydrocarbon yield is greatly increased.The content of carbonyl and carboxyl compounds is significantly reduced as well.In wood and iron mass ratio 5: 4,the yield of hydrocarbon reached to 41.25% and the total yield of ketone-aldehyde acid dropped to 0.8%.The thermal stability of the value of the bio-oil are greatly improved.