缺陷晶种导向的多级孔SAPO-34分子筛的制备及其在甲醇制烯烃中的应用  

Preparation of hierarchical SAPO-34 molecular sieve directed by defect crystal and its application in methanol to olefin

作　　者：丁佳佳 申学峰 刘红星 DING Jiajia;SHEN Xuefeng;LIU Hongxing(State Key Laboratory of Green Chemical Engineering and Industrial Catalysis,SINOPEC Shanghai Research Institute of Petrochemical Technology Co.,Ltd.,Shanghai 201208,China)

机构地区：[1]中石化(上海)石油化工研究院有限公司绿色化工与工业催化全国重点实验室,上海201208

出　　处：《低碳化学与化工》2024年第5期1-7,共7页Low-Carbon Chemistry and Chemical Engineering

基　　金：上海市青年科技英才扬帆计划(21YF1459600)。

摘　　要：为了制备具有更高性能的甲醇制烯烃(MTO)催化剂,实现甲醇向低碳烯烃的高效转化,首先通过对常规SAPO-34分子筛进行后处理制备了具有缺陷位的晶种,并在水热合成体系中,成功制备了具有多级孔结构的SAPO-34分子筛。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、N2吸/脱附、压汞法以及NH3程序升温脱附(NH3-TPD)等表征手段分析了制备的SAPO-34分子筛的晶体结构、形貌、孔道和酸性特征等。将制备的SAPO-34分子筛在固定床反应器上进行了MTO反应的催化性能评价(反应温度为460℃,反应压力为常压,甲醇质量空速为3.0 h-1,原料为纯甲醇)。结果表明,该多级孔结构SAPO-34分子筛具有大孔、介孔和微孔三级孔道结构。介/大孔的存在:一方面可以使目标产物快速从孔道中扩散出去,减少二次反应发生的机率;另一方面可以使重烃分子更容易扩散至活性位上进行进一步的反应。因此,在MTO反应中,多级孔结构SAPO-34分子筛具有最高的乙烯和丙烯选择性(85.3%)和较低的C4和C5+(碳数为4和碳数大于等于5的烃类)选择性,并可在135 min内保持性能稳定,同时经多次反应再生后,仍然能保持良好的催化性能。In order to prepare methanol to olefin(MTO)catalysts with higher performance and achieve efficient conversion of methanol to low-carbon olefins,crystal with defect sites was prepared by post-treatment of conventional SAPO-34 molecular sieve.And then hierarchical SAPO-34 molecular sieve was successfully prepared in the hydrothermal synthesis system.The crystal structures,morphologies,pores and acidities of the prepared SAPO-34 molecular sieve were characterized by X-ray diffraction(XRD),scanning electron microscope(SEM),N2 adsorption/desorption,mercury intrusion porosimetry and NH3 temperature programmed desorption(NH3-TPD).The catalytic activity of the prepared SAPO-34 molecular sieve for MTO reaction was carried out in a fixed bed reactor(reaction temperature of 460℃,atmospheric pressure,mass space velocity of methanol of 3.0 h-1 and raw material of pure methanol).The results indicate that the hierarchical SAPO-34 molecular sieve has a three-level pore structure of macropore,mesopore and micropore.The presence of macro/mesopores can,on the one hand,make the target products diffuse from the pore quickly,reducing the probability of secondary reactions,and on the other hand,make it easier for heavy hydrocarbon molecules to diffuse to the active sites for further reactions.Therefore,in the MTO reaction,the hierarchical SAPO-34 molecular sieve shows the highest selectivity of ethylene and propylene,which is 85.3%,and lower selectivity of C4 and C5+(hydrocarbons with carbon numbers of four and carbon numbers greater than or equal to five)and can maintain stable performance within 135 min.At the same time,after multiple reactions and regeneration,the catalyst can still maintain excellent catalytic performance.

关 键 词：缺陷晶种 分子筛 多级孔SAPO-34 甲醇制烯烃 

分 类 号：TQ426.6[化学工程]