3D Printing Integral SAPO-34 Molecular Sieve MTO Catalytic Performance Of Catalysts

SAPO molecular sieves,especially SAPO-34 molecular sieves,showed excellent catalytic performance in the MTO reaction due to its good medium-strong acidity,hydrothermal stability,special pore structure and small grain size.However,SAPO-34 catalyst produced carbon accumulation reaction due to its unique pore structure during the catalytic process.There will be "deactivation" phenomenon,greatly reducing the catalytic efficiency of the catalyst.Therefore,starting from the macroscopic perspective of the catalyst,the catalyst was prepared into an integral part by using 3D printing technology,aiming to design a multistage pore structure,increase the specific surface area of the catalyst,enhance the mass and heat transfer efficiency,improve the porosity,enhance the methanol conversion rate and catalytic life.In this paper,the 3D printing technology was applied to the preparation of integrated molecular sieve catalyst with multistage pore structure,and its advantages in control and shape control laid the experimental foundation for the preparation of catalyst.The main research content of this paper is as follows:(1)In this paper,triethylamine(TEA)was used as template,pseudo-bauxite,phosphoric acid and attapulgite were used as raw materials to prepare nano SAPO-34 grains.The effects of two different teraplate agents were systematiaffly investigated.The experimental results showed that SAPO-34 nanoparticles of 100-200nm could be successfully prepared by using tetraethylammonium hydroxide as template.The results of MTO catalysis show that the SAPO-34 nanocrit has the best catalytic effect at 400℃,the selectivity of low carbon olefin can reach 88%,and the catalytic life can reach 4.5h.(2)Using 3D printing technology,SAPO-34 molecular sieve catalyst with three-dimensional structure was successfully prepared by adding inorganic binder and organic binder with nano SAPO-34 grain under optimal conditions as the catalyst.The effects of mass space velocity,pore structure and sintering temperature on phase and catalytic performance were systematically investigated.The catalytic results showed that,The selectivity of SAPO-34 catalyst can reach 90%for olefin and 50%for ethylene when the reaction space speed is 1 h-1.(3)The monolithic SPAO-34 zeolite catalyst modified with zinc was prepared in one step by 3D printing technology.The characterization results confirmed that the addition of zinc nitrate was beneficial to increase the porosity of the monolithic catalyst.The results of MTO catalysis show that the 2wt%Zn-modified SAPO-34 catalyst has a low olefins selectivity of 90%and a ethylene/propylene ratio of about 2.5.