金属掺杂改性Cu-ZSM-5催化剂催化脱硝性能研究

发布时间：2018-06-22 00:26

本文选题：Cu-ZSM-5 + 合成　；参考：《中国石油大学(华东)》2015年硕士论文

【摘要】：氮氧化物(NOx)是产生光化学烟雾、酸雨及破坏臭氧层的主要大气污染物之一,对人体健康、工农业生产和生态环境造成巨大的危害。目前氮氧化物的主要处理技术包括燃烧前控制技术、选择性催化还原技术、选择性非催化还原技术和直接催化分解技术等。其中,直接催化分解技术因不需要添加还原剂且不产生二次污染的特点备受关注。本文以硅溶胶为硅源、铝酸钠为铝源,采用水热合成法直接合成杂原子Cu-ZSM-5催化剂,通过改变合成条件和掺杂碱金属及碱土金属对其进行改性,采用模拟烟气考察直接催化分解NO的活性,同时对所制备的催化剂进行了表征。研究结果表明:制备催化剂的最佳条件是硅铝比为60,硅铜比为17,混凝胶的pH为10~12,晶化温度为165°C,晶化时间24h,空速和O2浓度对催化剂的活性影响较大;掺杂碱金属及碱土金属对Cu-ZSM-5的影响依次是K+Mg2+Ca2+,K离子的掺杂可以显著提高活性,与贵金属掺杂的Zr-Cu-ZSM-5相比,K-Cu-ZSM-5的催化效果更好。表征结果表明:高结晶度无杂相的分子筛结构是催化剂具有活性的基本条件,载体具有合适大小、表面洁净的晶粒有利于提高催化剂的活性;催化剂表面的活性物质分布均匀及较大的有效比表面积和有效孔容,有利于提高催化剂活性,同时发现Cu+和弱酸性位更利于提高催化剂的活性。
[Abstract]:Nitrogen oxides (NOx) are one of the main atmospheric pollutants which produce photochemical smog acid rain and destroy the ozone layer and cause great harm to human health industrial and agricultural production and ecological environment. At present, the main treatment technologies of nitrogen oxides include pre-combustion control, selective catalytic reduction, selective non-catalytic reduction and direct catalytic decomposition. Among them, direct catalytic decomposition technology has attracted much attention because it does not need reducing agent and does not produce secondary pollution. Using silica sol as silicon source and sodium aluminate as aluminum source, Cu-ZSM-5 catalyst was synthesized directly by hydrothermal synthesis method. The catalyst was modified by changing the synthesis conditions and doping alkali metal and alkaline earth metal. The catalytic activity of direct catalytic decomposition of no was investigated by simulated flue gas, and the prepared catalyst was characterized. The results showed that the optimum conditions for the preparation of the catalyst were as follows: Si-Al ratio of 60, Si-Cu ratio of 17, pH value of mixed gel at 10 掳12, crystallization temperature of 165 掳C, crystallization time of 24 h, space velocity and O2 concentration, which had a great influence on the activity of the catalyst. The effect of doping alkali metal and alkali earth metal on Cu-ZSM-5 is that the doping of K mg 2 Ca 2 + K ion can significantly improve the activity, and the catalytic effect of K mg 2 Ca 2 + K ion is better than that of Zr-Cu-ZSM-5 doped with noble metal. The results show that the molecular sieve structure with high crystallinity and no impurity phase is the basic condition for the catalyst to have activity, the support has the appropriate size, and the clean grain on the surface is advantageous to improve the activity of the catalyst. The uniform distribution of active substances and large effective specific surface area and effective pore volume on the surface of the catalyst are beneficial to increase the activity of the catalyst. At the same time, it is found that Cu and weak acidic sites are more conducive to the improvement of the activity of the catalyst.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X701

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