Study On The Characteristics Of Catalytic Cracking Of Tar With Biomass Primary Structure-derived Semi-coke Catalyst

The massive use of fossil energy brought about by economic development has caused global energy shortages and environmental pollution problems.The development of renewable,clean and low-polluting new energy has become the focus of countries around the world.As a renewable resource with huge reserves and a wide range of sources,biomass plays an increasingly important role in replacing some traditional fossil fuels and reducing environmental pollution.Through pyrolysis and gasification,biomass can be converted into high-quality syngas,which is an important way to develop biomass energy.Tar is an inevitable product process of pyrolysis and gasification,and it is one of the important problems restricting the development of biomass pyrolysis gasification technology.Catalytic cracking is regarded as the most effective technology for tar removal.Research on catalysts with high activity and high stability is the key to achieve efficient catalytic cracking of tar.Based on this,in this thesis,a typical forest biomass pine wood was used as raw material,and the natural biological structure formed during its growth was used to synthesize the primary structure catalysts with high catalytic performance,and its catalytic cracking of biomass tar and its typical mold compounds was studied.（1）Using whole pine wood block as raw material,Ni Cl₂ as activator and imparting metal substance,through simple impregnation and carbonization,catalysts with its primary structure of nickel metal nanoparticles was prepared,and its effect on the catalytic cracking of biomass tar was explored.It was found that regular flow channels（20-50μm）was realized in the axial direction of the catalyst,and there were irregular pores in the lateral direction.During the process of biomass carbonization,high-density and well-dispersed Ni⁰ nanoparticles are formed through in-situ reaction and encapsulated on the channel wall.The existence of the channels ensures the rapid passage of airflow,which can effectively reduce the coke deposition problems during the reaction process.Based on its unique structure,the catalyst exhibits high activity and good stability for the decomposition of biomass tar.When the pyrolysis temperature is 600°C and the reforming temperature is 800°C,the tar conversion rate reaches92.11%,and the gas production rate reaches 411.6m L/g.The tar conversion rate remains stable in the five-cycle experiment,indicating the qualitative catalytic properties at high temperatures.（2）Catlysts with Co-Ni bimetallic nanoparticles were prepared by introducing the components of Co Cl₂ and Ni Cl₂ by using the whole pine wood blocks as the raw material,and the strengthening characterisitics of the catalyst for the catalytic cracking of biomass tar and toluene were studied.The results show that there is a strong interaction between cobalt and nickel,which polymerizes to form cobalt-nickel alloy nanoparticles.The presence of cobalt-nickel alloys greatly improved the stability of the catalyst.At a reforming temperature of 700^oC,the toluene conversion rate was maintained at more than 90%within 6 hours,and the conversion rate of biomass tar reached 93.64%and remained stable during the five-cycle experiments.Under the effect of cobalt,the yield of synthesis gas,especially hydrogen,has been greatly improved,reaching 495.4 m L/g and 174.38 m L/g,respectively.（3）Using monolithic pine blocks as raw materials,based on the synergistic effect of cobalt and nickel,a hydrothermal method was introduced to prepare catalysts with decorative pores of graphitic carbon structure.The results showed that the internal structure of the catalysts was further enriched and the activity and stability of the catalyst were improved under the combined effect of hydrothermal and carbonization treatment.At a reforming temperature of 700^oC,the catalytic stability of toluene was extended to 9h,and maintained above 90%after use,indicating its catalytic activity and excellent stability.