Synthesis And Characterization Of Mesoporous Zeolite And Study On Its Performance Of Hydrogenation Dechlorination Reaction

Mesoporous zeolite is a kind of rich mesoporous crystalline zeolite, which is different from a simple mechanical mixture of mesoporous molecular sieve and microporous zeolite. It not only has the high hydrothermal stability, excellent selectivity and activity of microporous zeolites, but also improves the molecular adsorption and diffusion properties due to the introduction of mesopores. Therefore, mesoporous zeolite has gradually become one of the hotspots in research field of porous catalytic materials. In this study, mesoporous Y zeolites with different pore sizes were synthesized from low cost silicon, aluminum sources and polymer template by a hydrothermal method. Furthermore, various mesoporous zeolites supported Ni2P catalysts were prepared by an impregnation method, and their catalytic activities were examined in trichloroethylene hydrogenation dechlorination. The main conclusions are as follows:Synthesis of mesoporous Y zeolite:Water glass was regared as silicon source, together with sodium aluminate and aluminum sulfate as aluminum source. Mesoporous Y zeolite was successfully synthesized through a hydrothermal method with two different length connected groups of the polymer as template agent. It was also found that mesoporous Y zeolites with different pore sizes and high crystallinity can be prepared by changing the length of the connecting groups of the polymer.Hydrogenation dechlorination of trichloroethylene:Compared with microporous ZSM-5 and other mesoporous zeolites, mesoporous ZSM-5 (MZSM-5) zeolite supported metal nickel phosphide catalyst gave the highest trichloroethylene hydrogenation dechlorination activity. It was because the MZSM-5 zeolite possessed larger mesoporous surface area and pore volume, which was conducive to the diffusion and mass transfer of trichloroethylene (TCE). In addition, it was shown that with the increase of the loading of Ni2P, catalyst reduction temperature, hydrogenation to remove chlorine reaction temperature, and hydrogen flow rate, the performance of TCE dechloridation increased at first and then decreased. After the reduction under 500℃ and 50ml/min hydrogen flow, the 15wt% Ni2P/MZSM-5 catalyst showed the highest dechlorination rate of TCE, i.e.,63.3%, when hydrogenation dechlorination reaction was conducted under the condition of 75ml/min hydrogen flow and 450℃.