ZSM-35分子筛离子交换过程改进降低氨氮污染研究

Improvement of Ion Exchange Process for Reducing Ammonia Nitrogen Pollution on ZSM-35 Molecular Sieve

采用稀盐酸代替氯化铵溶液在一定条件下对高硅铝比镁碱沸石分子筛进行离子交换得到H型ZSM-35,火焰光度计测定显示两种方法离子交换的催化剂中Na^+离子含量相近,X-射线衍射表征两种方法均未改变催化剂的晶型结构。在固定床反应器上评价催化剂的正丁烯骨架异构性能。结果表明,稀盐酸与氯化铵溶液离子交换的ZSM-35分子筛催化性能相近,前者略高,在工业生产上可替代后者从而降低氨氮污染。最佳交换条件为,质量浓度4%稀盐酸,交换温度80℃,交换时间1 h。

The H type of ZSM-35 molecular sieve was obtained by using dilute hydrochloric acid instead of ammonium chloride solution to replace Na+ion in the Na+type of ZSM which had high silica alumina ratio. The content of Na+ion in the catalysts treated with two methods showed similar by using the flame photometry. It can be seen that the crystal structure were not changed through XRD treated by the two methods. And then the isomeric properties of the n-butene skeleton isomerization of the two genre catalysts were evaluated on the fixed bed reactor,which showed that the catalytic performance of that two ZSM-35 were almost the same,and the former one was even better than the latter catalyst. Therefore,in the ion exchange process of industrial manufacture of high silica alumina ratio,it can be achieved to reduce ammonia nitrogen pollution by this method. The optimum ion exchange condition was as follows: utilized 4% concentration of diluted hydrochloric acid in the water bath set temperature 80 ℃,and under magnetic stirring lasted nearly 1 h.