天然沸石定向合成A型分子筛及其脱氮性能

针对污水厂尾水深度脱氨问题，以河南巩义的天然沸石为起始原料，采用常压水热合成方法，选用4种不同的工艺方案合成A型分子筛，并对合成产物的吸附氨氮性能及其纯度、晶体结构、形貌特征、孔隙率等材料结构特征进行分析与表征，探讨天然沸石制备高效脱氨分子筛的合成方法.结果表明：与直接碱溶法制备硅源相比，碱熔融活化法对沸石原料硅的利用率较高，硅源纯化合成方案产物的氨氮吸附性能显著得到改善，平衡吸附量达20mg/g以上；其晶体形貌规整有序、杂质含量低、孔道通畅，有利于吸附扩散与传质过程.综合考虑硅源制备能耗、物耗及合成产物吸附性能，天然沸石合成A型分子筛适宜的工艺方案为碱溶纯化合成法.

Targeted synthesis of type-A molecular sieve based on natural zeolite and its denitrification performance

In order to address the denitrification problems of sewage plant effluent, type-A molecular sieve was synthesized by hydrothermal method with four different process schemes, using natural zeolite as a raw material that was collected from Gongyi, Henan Province. The synthesized product was examined for its adsorption performance on ammonia nitrogen, purity, crystal structure, morphology, porosity and other structural characteristics. The suitable process scheme for synthesizing high efficiency molecular sieve from natural zeolite was then explored. The alkali melting activation process was more effective than the direct alkali dissolution process in terms of the silicon source utilization from the raw material, while the product from silicon source purification synthesis scheme had a significantly improved ammonia nitrogen adsorption performance, with an equilibrium adsorption capacity of more than 20mg/g. It was associated with orderly crystal morphology, low impurity contents, and unobstructed pore channels, all of which were conducive to adsorption, diffusion and other mass transfer processes. By comprehensively considering the energy and materials consumption for synthesis and the adsorption properties of the synthesized product, the process scheme of alkali dissolution and silicon source purification was deemed as the suitable process plan to type A molecular sieve using natural zeolite.