NaOH预处理对高岭土表面原位合成SAPO-34催化剂性能的影响

以高温煅烧高岭土微球(CKM)为载体,采用原位合成法制备了负载型SAPO-34催化剂(SCKM)。以质量分数2%～10%的NaOH水溶液对高岭土微球进行了预处理。采用XRD、XPS、SEM、N2吸附-脱附对NaOH处理的高岭土微球及原位合成的SAPO-34进行了表征,并在MTO固定床上对合成催化剂的活性进行了评价。结果表明,NaOH水溶液预处理对高岭土微球表面的化学组成、形貌结构以及原位合成SAPO-34负载型催化剂的性能均有显著影响。质量分数4%的NaOH水溶液处理高岭土微球表面合成的SAPO-34催化剂(4-SCKM)在MTO催化反应中的活性最佳,甲醇转化率达到100%,低碳烯烃选择性89.8%,单程寿命964 min,优于非原位合成的SAPO-34催化剂。

Effect of NaOH pretreatment on the property of SAPO-34 catalyst synthesized by in situ hydrothermal method on the kaolin microspheres

SAPO-34/kaolin microspheres catalysts (SCKMs) were in-situ hydrothermally synthesized onto the NaOH-pretreated calcined kaolin microspheres (CKMs). The effect of the NaOH concentration within 2%~10% on the physicochemical properties of CKMs and the ensuing synthesized SCKMs were characterized by means of XRD, XPS, SEM, low-temperature N2 adsorption. The results showed that, NaOH solution had obvious effects on the chemical composition and the morphologies of the CKMs, and then the properties of the in-situ synthesized SAPO-34 catalysts. In comparison, the optimal NaOH concentration was 4%. For the MTO reaction catalyzed by the prepared 4-SCKM catalyst, 100% methanol conversion, 89.8% light olefins selectivity, 964 min lifetime have been obtained, which are better than that of the SAPO-34 catalysts not synthesized by in-situ method.