钛交换对Cu-SSZ-13分子筛柴油车尾气脱硝性能的影响

发布时间：2018-03-26 10:13

  本文选题：Cu-SSZ-13　切入点：钛交换　出处：《太原理工大学》2017年硕士论文

【摘要】：汽车尾气是城市大气污染的主要来源之一,其中氮氧化物(NOx)是形成光化学烟雾和酸雨重要因素。NH_3-SCR技术被认为是目前最有前景的机动车尾气脱硝技术之一,其核心是高效稳定催化剂的研发。分子筛是目前国内外学者研究的重点,其中Cu-SSZ-13催化剂由于其优异的脱硝活性、N_2选择性和水热稳定性而受到广泛关注。在Cu-SSZ-13分子筛中引入杂原子,可以丰富分子筛的骨架结构,调节活性金属铜的分布和状态,进而提高其脱硝反应活性、选择性和水热稳定性。Ti是一种常被用来改性分子筛的元素。本课题通过离子交换的方式在原位制备的Cu-SSZ-13分子筛催化剂和传统水热合成法制备的SSZ-13分子筛催化剂中引入钛原子,考察TiCl_4浓度、离子交换时间、温度以及Ti和Cu交换顺序对Cu-SSZ-13分子筛催化剂脱硝活性、选择性、水热稳定性及其物理化学性质的影响。实验得到主要结论如下:(1)利用离子交换法对原位水热合成法制备的Cu-SSZ-13催化剂进行改性,通过NH_3-SCR脱硝实验评价,优化出TiCl_4的最佳浓度为0.075 mol/L,最佳交换温度为35 ℃,最佳交换时间为6 h。在此条件下,样品具有相对较好的脱硝活性和水热稳定性。老化后样品的比表面积增大,低温活性与新鲜样品相差不大。(2)在传统水热合成法制备SSZ-13分在筛的基础上,考察Cu和Ti交换顺序对脱硝性能的影响。钛交换是用0.075 mol/L的TiCl_4溶液,在35 ℃水浴条件下与样品交换6 h。铜交换是用0.025 mol/L的硫酸铜溶液在80 ℃条件下水浴交换1 h。结果表明:钛原子的引入提高了SSZ-13催化剂的高温活性;先交换钛再交换铜的样品具有相对较好的水热稳定性。
[Abstract]:Automobile exhaust is one of the main sources of urban air pollution, among which no _ x (no _ x) is an important factor in photochemical smog and acid rain. NH _ S _ 3-SCR technology is considered to be one of the most promising denitrification technologies. Its core is the research and development of high efficient and stable catalyst. Molecular sieve is the focus of domestic and foreign scholars. Among them, Cu-SSZ-13 catalyst has attracted wide attention due to its excellent denitrification activity, N _ 2 selectivity and hydrothermal stability. Introducing hetero-atoms into Cu-SSZ-13 molecular sieve can enrich the skeleton structure of molecular sieve and regulate the distribution and state of active copper. Then the denitrification reaction activity was improved. Selectivity and hydrothermal stability. Ti is an element commonly used to modify molecular sieves. Titanium atoms are introduced into Cu-SSZ-13 molecular sieve catalysts prepared in situ and SSZ-13 molecular sieve catalysts prepared by traditional hydrothermal synthesis by ion exchange. The activity and selectivity of TiCl_4 concentration, ion exchange time, temperature and Ti and Cu exchange sequence for denitrification of Cu-SSZ-13 molecular sieve catalyst were investigated. The main conclusions are as follows: (1) the Cu-SSZ-13 catalyst prepared by in situ hydrothermal synthesis was modified by ion exchange method and evaluated by NH_3-SCR denitrification experiment. The optimum concentration of TiCl_4 is 0.075 mol / L, the best exchange temperature is 35 鈩，

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