The Study On Modified H-Beta Zeolite And Its Catalysis

Zeolite-beta is modified by dealumination with leaching in HCl solution and realumination with NaAlO2 solution. The effects of concentration of HCl on framework dealumination and surface acidity, and the effects of concentration of NaAlO2 and PH value on realumination result are studied. The results show that the non-framework aluminum and transitional aluminum can be removed by light solution, and the framework aluminum can be also removed by thick solution. The surface acidity of modified samples decreases with the concentration of HCl increased. It is investigated that the aluminum returns to framework by realumination. The best result of realumination can be obtained when concentration of NaAlO2 is 0.5mmol/g.cat, PH=8. If the concentration of NaAlO2 and PH value are increased, the crystal will be changed from zeolite beta to zeolite ANA. The results of the catalytic activities of modified beta samples used as catalyst of o-xylene isomerisation reaction show that there is a maximum value with increasing the concentration of HCl, the corresponding concentration of HCl is 0.04mol/l. The catalytic activities used as catalysts of iso-propylbenzene cracking and n-hexadecane cracking are very high. The results of the catalytic activities of pyridine adsorption and desorption show that the n-hexadecane cracking is catalyzed with B acid.