Study On Application Of Supported Nickel Catalysts In Straw Pyrolysis

The effective use of biomass has always been a scientific issue for researc hers.The main purpose of biomass pyrolysis and gasification is to produce hig h quality gas.However,tar and semi-coke are inevitably generated during the pyrolysis/gasification process.On the other hand,the production of tar has a serious impact on the gasification system and caused serious environmental po llution problems.However,tar contains a part of energy.If it cannot be fully utilized,it includes biomass pyrolysis and gas.Will result in reduced conversio n efficiency.Therefore,it is necessary to use new treatment technology.Bioma ss catalytic pyrolysis has good catalytic effect.Firstly,the biomass straw purchased from farms near Wuhan was used as pyrolysis raw materials（such as soybean,sesame,peanut,corn,rice）.Five kin ds of biomass straws were used as research objects for pyrolysis experiments.The types of raw materials and pyrolysis temperature were discussed,Particle size and gas phase residence time on the composition and yield of pyrolysis gas products.The results showed that the yield of sesame straw was significan tly higher than that of the other four kinds of straw.The main components of pyrolysis were CO,H₂,CH₄ and CO₂.The content of CO and H₂ gas,and t he low calorific value of combustible gas are the highest.In the experiment,different types of nickel-based catalysts（Ni/CNTs,Ni-L a/CNTs,etc.）were prepared by the uniform precipitation method,and a fixed bed pyrolysis tube furnace was used to test different types of catalysts at diffe rent reaction temperatures and active components.Relevant researches have bee n carried out on the effects of loading amount,gas phase residence time,etc.on the characteristics of gas products and the content of gas components,and the number of times the catalyst has been used has also been investigated.Dif ferent characterization methods（BET,XRD,TEM,XRF）were used to analyze the catalyst before and after the catalytic pyrolysis reaction.The experimental results show that the active components are well supported and dispersed unif ormly,and the specific surface area of the 10%Ni/CNTs support is 224.55m²/g.The catalyst contains Ni O and La₂O₃ active components.Because carbon nano tubes are nano-sized,from the SEM image we can see that the Ni/La active c omponents are well dispersed on the support surface.From the BET analysis r esults,we can see that the carbon nanotubes（CNTs）support has a large specif ic surface area and a large pore volume.,Porosity and mechanical strength ar e very large,showing a slender roll shape,therefore,the active components ha ve a good load inside and outside structure.From the XRD spectrum,we can see that the peak intensities of Ni O and La₂O₃ are large,indicating that they h ave a good loading effect.The experimental results show that the two types of catalysts have better catalytic performance,and the Ni/CNTs catalyst has the best catalytic effect.Different types of catalysts（Ni/FA-γAl₂O₃,Ni-Mg/FA-γAl₂O₃,Ni-Mg-Zr/FA-γAl₂O₃,etc.）were prepared and synthesized by the precipitation method.A la boratory fixed bed pyrolysis tube furnace was used to investigate the catalytic reforming performance of different types of catalysts at different pyrolysis temp eratures and catalyst holding times.The experimental results show that the thre e catalysts have better loading effects evenly,and the three catalysts have high specific surface area and spherical structure.From the XRD spectrum,we can see that the supported catalyst has a good catalytic effect.The experimental r esults show that the pyrolysis temperature of the catalyst has a great influence on the pyrolysis of biomass straw,and the conversion rate of combustible gas is very high.