Selective Catalytic Reduction Of Nitrogen Oxides On Metal Modified Zeolites Molecular Simulation

Molecular sieve was widely used in chemical separation and other related fields because of its regular pore structure and high specific surface area.The characteristics of the structure make it have a larger adsorption capacity.And because the molecular sieve has the characteristics of selective catalysis,the adsorbed guest molecules can be initially screened through the pores of the molecular sieve.There are differences in the molecular size of the nitrogen containing exhaust gases in the air.The size of the toxic gas molecules is much larger than that of the nitrogen molecules which are harmless to the environment.Based on this,this paper uses molecular simulation technology to simulate the adsorption calculation and diffusion of nitrogen containing waste gas on different molecular sieves.According to the calculation results,the direction and methods of molecular sieve modification are deduced,and the theoretical basis for designing molecular sieves with better separation performance is made.Firstly,the effects of adsorbate on the adsorption of molecular sieves were investigated from the two aspects of the type of atomic charge and the adsorbed gas fraction(single component and two components).After that,the effects of adsorbents on the adsorption of molecular sieves were investigated from the simulation results of molecular sieves and metal loaded molecular sieves.The results showed that there is a competitive behavior between the adsorbed gas molecules,and the molecular sieve modification can have a more obvious effect on the adsorption behavior.With the reduction of the ratio of silicon and aluminum to molecular sieve,the saturated adsorption of the adsorbed gas is increasing.Secondly,the influence of gas molecular load,mixed component and single component gas and the ratio of silicon and aluminum on molecular sieve is studied.The results showed that the increase of load will make the diffusion of gas molecules disadvantageous,and the mixed components may be interrelated when they are diffused.Finally,on the basis of the simulation results of the adsorption and diffusion,the topological structure CHA molecular sieves of the highly promising SSZ-13 molecular sieves have been selected as the research object to further understand the mechanism of the influence on metal modified molecular sieves on the adsorption and diffusion.The results show that the location of modified metal in the molecular sieve chamber determines the adsorption stability and diffusion rate of gas molecules.