采用水热合成法制备了具有CHA骨架结构的SAPO-34和MeAPSO-34(Me=Ni、Zn、Fe、Cu和Ni-Zn)分子筛。以甲醇裂解制取低碳烯烃(MTO)为模型反应,采用固定床反应装置,对所制备的分子筛进行了催化性能评价。结果表明,所制备的MeAPSO-34分子筛具有比SAPO-34分子筛更高的乙烯选择性和乙烯与丙烯总选择性,且Ni-Zn双金属改性比单金属改性更有利于乙烯与丙烯总选择性的提高,但金属离子的添加会导致丙烯选择性的降低。与SAPO-34相比,单金属Ni的加入可使乙烯的选择性增加7.7%(由SAPO-34的40.7%增加至NiAPSO-34的48.4%),乙烯与丙烯总选择性增加2.5%;而双金属Ni-Zn的加入可使乙烯的选择性增加6.5%,乙烯与丙烯总选择性增加3.2%。
SAPO-34 and MeAPSO-34 (Me=Ni,Zn,Fe,Cu or Ni-Zn) zeolites have been synthesized by the hydrothermal method. The catalytic performance of these zeolites was experimentally evaluated taking methanol to olefins (MTO) as a model reaction in a fixed-bed reactor. The results showed that the MeAPSO-34 (Me=Ni,Zn,Fe,or Ni-Zn) zeolites prepared by adding metal ions during the synthesis of SAPO-34 had a higher selectivity for ethylene and higher total selectivity for ethylene and propylene than SAPO-34 zeolite. The total selectivity for ethylene and propylene was higher for Ni-ZnAPSO-34 than for other MeAPSO-34 (Me=Ni,Zn,Fe,Cu) and it was noteworthy that adding metal ions led to a decrease in the propylene selectivity. The NiAPSO-34 gave an increase in ethylene selectivity of 7.7% (from 40.7% over SAPO-34 to 48.4% over NiAPSO-34) and the total selectivity for ethylene and propylene increased by 2.5%; the Ni-ZnAPSO-34 gave an increase of ethylene selectivity of 6.5% and an increase in total selectivity for ethylene and propylene of 3.2%.