The Research On Synthesis Of Zeolite With RHO Topology And Performance Of Catalyst Cracking Of Butene

Zeolite RHO has a eight number-ring channel structure. It is formed by alpha cage connected with double eight-number ring. It belongs to the cubic crystal system. It’s main channel is consists of double eight-number ring. The orifice size is 0.36 nm×0.36 nm and it has a large cage. In this paper, we successfully synthesized high crystallinity silicon aluminum RHO and phosphorus RHO molecular sieve in the hydrothermal condition and respectively characterized the characterization of two molecular sieve by using the methods XRD and SEM. The synthesized SiAl-RHO molecular sieve, modified SiAl-RHO and different Si content of SAPO-RHO were used in butylene catalytic cracking reaction respectively, and systematically examined the influence of reaction conditions(reaction time,reaction temperature, and 1-butylene airspeed) and the the modified quantity to the butene cracking reaction.In this paper, the method of dipping was used to modify the RHO molecular sieve with the ions P and La. The two kinds of ions impregnated the same amount when the propene yield reached optimal value. The acid of SAPO-RHO molecular sieve is lower than the RHO with the means of NH3-TPD detection and its catalytic performance is better. The content of Si has a significant impact on the acid and catalytic effect of the SAPO-RHO. By changing the Si content can directly adjust the acid of SAPO-RHO. With the increasing of Si content,molecular sieve acid increased, and the hydrogen transfer reaction faster, propylene yield less in the butene cracking reaction. When Si content is 0.31g(Si/Al ratio 0.52), the propylene yield is highest. When silica alumina ratio is 0.5(Si content 0.33g), the crystallinity of the molecular sieve the was the highest.1%P-SiAl-RHO, 1%La-SiAl-RHO and SAPO-RHO molecular sieves were used in catalytic butene cracking, and we systematically studied the reaction temperature, butene space velocity and reaction time on the properties of butene catalyst cracking before and after modification. After three times of regeneration to SAPO-RHO, butene conversion,propylene yield and propylene selectivity had different degree of decline, but still had a certain catalytic performance.The best reaction conditions was atmospheric pressure, temperature 600℃ and the incoming quality space velocity 7h-1 to the RHO modified with P and La ions.The best reaction conditions was atmospheric pressure, temperature 550℃ and feed space velocity3.5h-1 to the SAPO-RHO molecular sieve.