The Study Of Catalytic Fast Pyrolysis Of Biomass Using Microwave Heating By Three Transition Metal Oxides

Compared with traditional fossil fuels, biomass has become a global research hotspot because of its large reserves of resources, renewability and little environment damage. Pyrolysis of biomass is considered as one of the most promising way for using biomass.In this paper, biomass was used for fast catalytic pyrolysis in a microwa-ve reactor, and optimal experimental conditions were investigated.Under the optimal experimental conditions,three typical biomass samples, pine and ashtree and corncob were pyrolyzed.The yields and components of pyrolytic products were studied. The results showed that we can get the highest liquid yield un-der the optimal experimental conditions,microwave power800W, microwave h-eating time12min,the flow of carry gas0.3L/min. The liquid yields of pine a nd ashtree are higher than the one of corncob.Ashtree have the highest yields of liquid (44.57%).Corncob have the highest yields of acid (36.83%) and fur-fural (7.48%) in pyrolysis liquid products. Pine has the highest yields of aro-matics which can reach26.40%.Three transition metal oxide catalysts MOx/HZSM-5(MOxstand for Fe2O3, Co3O4and NiO) were prepared using HZSM-5as carrier with coprecipitatio-n method.Then, the catalytic effect of three transition metal oxide catalysts were investigated by catalytic pyrolysis on ashtree in the microwave reactor. The result showed that three transition metal oxide catalysts can increase liqu-id yields,Co3O4/HZSM-5had the highest liquid yield which reached as high as51.8%.All chosen catalysts were highly actived in deoxygenation for all bi-omass samples, and they all can reduce the contents of acids and ketones in liquid products significantly. Each catalyst can improve the yield of aromatics considerably. Especially Co3O4/HZSM-5has the most significant effect whose highest yield was up to49.61%. And all these transition metal oxides catalyst s can promote the G-type phenols and S-type phenols to transform to H-type phenols which were more stable,the role of NiO/HZSM-5is particularly evi-dent. Fe2O3/HZSM-5and NiO/HZSM-5can also promote the direct pyrolysis of biomass, and they had an evident effect on the improvement of the yield of furfural (10.86%) and phenol (14.60%).Deactivation reason of Fe2O3/HZSM-5was studied.It was regenerated by air charcoal method and then was used as catalysis.The results showed that the life of Fe2O3/HZSM-5was70min,and its deactivation was caused by carb-on distribution. Regenerated Fe2O3/HZSM-5had a significant improvement of liquid yiled and bio-oil quality with good stability.