Synthesis Of Hierarchical Nano-Beta Zeolite And Its Catalytic Performance

In order to improve the diffusion properties and catalytic activity of traditional microporous Beta zeolite, nano-Beta and hierarchical nano-Beta were synthesis through hydrothermal method. The samples were characterizated by XRD, XRF, SEM, TEM, N2 physical adsorption and NH3-TPD. The catalytic performance of samples in bulky molecules reaction were evaluated by using synthesis of 2-Ethylanthraquinone (2-EAQ) as a probe reaction. This paper mainly has the following experiments:A series of different Si/Al ratio nano-Beta zeolites with good dispersity were synthesized by optimizing the geling temperature, stirring time, crystallization time, aluminum source and system alkaline, which minimum particle has an uniform size about 20?40 nm and revealed excellent catalytic performance in the reaction of synthesising 2-EAQ.Adding NH4NO3 solution into mother liquid containing nano-Beta zeolites, which acted as a flocculating agent, can improving yields of nano-Beta into nearly 100%. It has advantages of shortening operating time, improving the utilization efficiency of raw materials, and lowering the cost. Meanwhile the dispersion and catalytic performance of samples were almost impregnable.Ordered mesoporous can be introduced into microporous Beta zeolite through synthesizing Beta/MCM-41 composite molecular sieves. Inspected the effect of precursor, solution pH, modulation order, CTAB concentration, secondary crystallization time and crystallization methods to the synthesis of Beta/MCM-41. The introduction of mesoporous can effectively reduce the bulky molecules reaction diffusion limitation, which showed great catalytic activity in the 2-EAQ synthesis reactions, and the degree of ordered mesoporous with no direct relationship between the catalytic activity.Based on the study above, we simplified the procedure, adding different proportions of CTAB into initial gel directly, one-step synthesised hierarchical nano-Beta zeolite. Interestingly, mesoporous pore size distribution can be modified by adjusting mole ratio of CTAB/SiO2, which showed the best catalytic activity in the 2-EAQ synthesis reactions:BE acid conversion rate and selectivity of 2-EAQ can reached about 94%.