Research On Molecular Sieve Structured Molding Technology

With the rapid development of human production and life,the air pollution problem caused by human behavior is becoming more and more serious,and the deterioration of various environments has sounded the alarm to improve our awareness of environmental protection.Molecular sieve catalysts have begun to show more signs in environmental protection fields such as waste gas treatment.Fe-Beta zeolite was used for the catalytic decomposition of N2O,and Mn-ZSM-5 was used for the catalytic decomposition of O3.Powdery catalysts can not meet the industrial application,so it is necessary to form a catalyst with a certain shape and mechanical strength.In this paper,the technological conditions for the preparation of monolithic catalysts by extrusion honeycomb molding and 3D printing of Fe-Beta and Mn-ZSM-5 molecular sieves were mainly explored.Using reaction temperature,volume space velocity,molecular sieve content and pore type as reference factors,the overall catalyst activity obtained by different methods was evaluated.For extrusion molding,the plasticity R can be formed normally between 0.27 and 0.50.Molecular sieve in powder:binder is about 8:2.The ratio of extrusion aids to powder weight was 4.8%,organic binder to powder weight was 3.2%,deionized water to powder weight was 70%,and vegetable oil to powder weight was 2%.At this time,the mechanical strength of the honeycomb monolithic catalyst can reach 65-85 N/cm2,and the decomposition efficiency of N2O is about 90%at appropriate temperature and space velocity,and the decomposition efficiency of O3 is about 100%.For 3D printing molding,the plasticity R can be formed normally between 0.078 and 0.206.Molecular sieve:clay:active clay=65:25:10.The ratio of organic binder to powder weight is 2%,and the ratio of deionized water is 66%.At this time,the mechanical strength of the monolithic catalyst can reach 55-75 N/cm2,which also has good catalytic effect.In the evaluation of catalytic activity,the influence of the overall catalyst pore on the catalytic activity is mainly due to the turbulence of the fluid.In the diesel stack pore,the fluid turbulence is the largest,the external diffusion speed is the fastest,and the catalytic effect is the best.The turbulence caused by straight wall pores is the worst,so the catalytic effect is poor.The catalytic activity of other heterotypic channels is between the straight wall channel and the diesel stack channel.