晶化时间及母液循环对SAPO-34分子筛合成的影响

Effect of Crystallization Time and Mother Liquor Recycling on the Synthesis of SAPO-34 Molecular Sieve

以二乙胺为模板剂采用传统水热法制备SAPO-34分子筛,研究了不同晶化时间下分子筛晶体结构与形貌的变化。以X射线衍射仪(XRD)与扫描电镜(SEM)测试结果确定最佳产物并回收所得晶化母液。以此为初始凝胶环境,在不添加有机模板剂的条件下补充原料制备SAPO-34分子筛。确定了最佳晶化时间,并对两种合成方法所得最佳产物进行了傅里叶红外光谱仪(FTIR)与氨气程序升温脱附(NH3-TPD)测试。结果表明,在200℃条件下传统水热法需48 h得到最佳产物,母液循环法仅需36 h,晶化速度更快。两种方法制备所得分子筛具有相似的骨架结构与酸性,证明母液循环在保证产物一致的前提下加快了制备速度,实现了母液的循环回用与分子筛的绿色合成。

The SAPO-34 molecular sieve was prepared by traditional hydrothermal method with diethylamine as the template,and the changes of the molecular sieve crystal structure and morphology under different crystallization time were studied.The X-ray diffractometer(XRD)and scanning electron microscope(SEM)test results were used to determine the best product and recover the crystallization mother liquor.Using mother liquor as the initial gel environment,the SAPO-34 was prepared by supplementing raw materials without adding organic templates,and the optimal crystallization time was determined.Fourier transform infrared spectroscopy(FTIR)and ammonia desorption by programmed temperature(NH3-TPD)were carried out on the both optimal products of the two synthetic methods.The results show that the traditional hydrothermal method takes 48 h to obtain the best product at 200℃,while the mother liquor recycling method only needs 36 h,which has faster crystallization speed.The molecular sieves obtained by the two methods have similar skeleton structures and acidity,which proves that the mother liquor recycling method accelerates the preparation speed while ensuring the consistency of the products,and realizes the mother liquor reuse and green synthesis in the meantime.