Preparation Of Multi-pore ZSM-5 Molecular Sieve And Catalytic Pyrolysis Of Biomass Tar Model Toluene

Biomass energy has a very good prospect as an effective alternative to alleviating the global fossil energy crisis.Pyrolysis gasification is widely studied as one of the commonly used means of biomass energy utilization.The tar produced by pyrolysis gasification can cause problems such as blockage of pipes,damage to equipment,and deterioration of biomass pyrolysis gas quality.Catalytic cracking is one of the more efficient and feasible methods for removing biomass tar.The ZSM-5 molecular sieve biomass pyrolysis tar catalyst can remove tar efficiently and improve the gas production quality;On the other hand,it can produce some chemical products by catalytic pyrolysis,and improve the economic benefits of by-products.In addition,it is a synthetic catalyst with high controllability,so exploring the influence of its physicochemical properties on catalytic performance is of great guiding significance for industrial production.In this paper,the effects of crystallization temperature and crystallization time on the preparation of ZSM-5 molecular sieves prepared by static hydrothermal method and dynamic hydrothermal method were investigated.The effect of loading amount on the catalytic activity of ZSM-5 molecular sieves was investigated by using the active metal Ni,prepared by dynamic hydrothermal method.It was characterized by X-ray diffraction,scanning electron microscopy,Fourier transform infrared spectroscopy and other methods.The catalytic cracking test was carried out on a thermal cracker with a tar model compound compound.The characterization results of the molecular sieve catalyst were analyzed and combined with the results of the biomass tar catalytic cracking test to draw conclusions.It was found that the ZSM-5 zeolite catalysts prepared in this experiment all reached the micron level,presented in the form of molecular sieve microsphere,and the microspheres were stacked with a hexagonal cube with the core as the center of the nano-sized hexagonal cube.Both crystallization time and crystallization temperature play an important role in the synthesis of ZSM-5 molecular sieve.Under the condition of 72 h,the molecular sieves showed the best catalytic activity and physicochemical properties,and the toluene removal rate reached 40%.Under the condition of 175℃,the molecular sieve showed the best catalytic activity and physicochemical properties,and the removal rate of toluene reached 49%.The ZSM-5 molecular sieves synthesized by dynamic hydrothermal method are better than ZSM-5molecular sieves synthesized by static hydrothermal method in the aspects of particle size,uniformity,pore structure and so on.In the experiment of loading active metal Ni,it is found that the removal efficiency of toluene can be greatly improved by 0.5 wt% of loading,whichis up to 90%.The experimental results show that compared with static hydrothermal method,dynamic hydrothermal method can provide a better crystallization environment for the synthesis of ZSM-5 molecular sieves and improve the physical and chemical properties of the products.The crystallization time and crystallization temperature affect the catalytic performance of ZSM-5 catalyst.Supported active metal Ni can improve its catalytic cracking performance for aromatics in tar.Therefore,through strict regulation and exploration,it will have far-reaching significance to solve the tar problem of biomass pyrolysis and industrialization in the future.