低温甘氨酸法制备小尺寸SAPO-34及其催化性能

Preparation of small sized SAPO-34 by low temperature glycine method and its catalytic performance

为了得到适宜MTO反应的酸性可调控的小尺寸SAPO-34分子筛,本文研究了降低水热温度、掺入不同比例甘氨酸对SAPO-34分子筛酸性和催化MTO反应性能的影响。在160℃采用水热法,改变甘氨酸的掺入量,分别以吗啉和四乙基氢氧化铵作为模板剂,合成了SP-M和SP-T系列分子筛。对所得到的催化剂进行了XRD、SEM和NH_3-TPD等测试。XRD图谱表明,初始凝胶中的甘氨酸可以通过煅烧成功除去,并不会对分子筛的结构造成破坏。SEM照片表明,甘氨酸的加入对SAPO-34分子筛的形貌及晶体尺寸大小几乎不造成影响。NH_3-TPD分析表明,甘氨酸的引入可以有效调节SAPO-34分子筛的酸性。合成的小尺寸SAPO-34在甲醇制烯烃反应中表现出的催化性能有明显差异。SP-T4催化MTO反应具有较长的使用寿命(501 min)和较高的低碳烯烃选择性(81.0%)。

In order to obtain the controllable acidity small sized SAPO-34 zeolite suitable for MTO reaction,the reducing hydrothermal temperature,the adding of different glycine amount and their effect on acidity and catalytic MTO reaction of SAPO-34 zeolites were investigated.SP-M and SP-T series zeolites were obtained at 160℃using the hydrothermal method with the changing amount of glycine added,in which morpholine and tetra-ethylammoniumhydroxide were used as templates,respectively.The obtained catalysts were tested by XRD,SEM and NH3-TPD.The XRD pattern shows that glycine in the initial gel can be successfully removed by calcination,and it does not damage the structure of the SAPO-34.The SEM images show that the addition of glycine has almost no effect on the morphology and crystal size of SAPO-34 molecular sieve.NH3-TPD analysis shows that the introduction of glycine can effectively adjust the acidity of SAPO-34 molecular sieve.The results show that the synthesized small sized SAPO-34 exhibits significant differences in catalytic performance in the methanol-to-olefin reaction.The SP-T4 catalyzed MTO reaction has a long service life(501 min)and a high selectivity for light olefins(81.0%).