用于吸附-低温等离子体催化降解VOCs的锰掺杂核壳结构复合分子筛双功能材料的构建及性能

Sequential adsorption-plasma catalysis is a promising technology for waste gas treatment containing low concentration of VOCs，the bi-functional adsorbent-catalyst is one of the key factors influencing successful implementation of this technology. In this project, the core-shell structured Y zeolite@MCM-41 mesoporous silica composite was prepared by growing MCM-41 shell on Y zeolite core via a facile sol-gel coating strategy; then MCM-41 shell was modified using manganese ion and was further tailored by silylation to increase the hydrophobicity degree. The adsorption and non-thermal plasma (NTP) catalytic performance and mechanism of bi-functional material for VOCs were investigated. The quantitative structure-activity relationship between core-shell structured zeolite composite and its adsorption and NTP catalytic performance was discussed. In addition, carbon deposition inside the pores of bi-functional material and synergetic mechanism of NTP and catalyst were investigated during the NTP catalysis of VOCs. The study should be helpful to construct the bi-functional core-shell structured zeolite composite as adsorbent and catalyst for treating low concentration of VOCs.

序批式吸附-低温等离子体催化再生技术被认为是大风量、低浓度有机废气高效、低能耗处理方法之一，其中具有吸附-催化双功能材料是该技术实现的关键。本项目以Y型微孔分子筛为内核、MCM-41介孔分子筛为外壳，采用溶胶-凝胶法合成核-壳结构微孔/介孔复合分子筛（Y@MCM-41），通过对外壳硅烷化及锰掺杂处理，制备具有吸附-催化双功能的锰掺杂核-壳结构复合分子筛材料（Mn-Y@MCM-41）；开展核-壳结构复合分子筛材料吸附、NTP催化降解VOCs的特性研究，阐明其核-壳结构与吸附、NTP催化性能之间的构效关系，揭示NTP和催化剂的协同作用以及催化剂表面的炭沉积机制，为构建锰掺杂核-壳结构复合分子筛材料用于低浓度、大风量VOCs序批式吸附-低温等离子体催化再生处理提供理论指导。

大风量、低浓度VOCs气体治理已成为大气污染控制中一个急需解决的问题，也是国内外废气治理领域的研究热点和难点。低温等离子体催化技术（non-thermal plasma，NTP）被认为是处理低浓度VOCs的有效方法之一。本项目以Y型微孔分子筛为内核制备了不同壳层厚度、具有显著“多级孔道”特征的核-壳结构分子筛（Y@MCM-41）。采用反相气相色谱法研究了典型VOCs在不同外壳厚度Y@MCM-41上的吸附平衡和动力学特性，揭示了疏水性介孔外壳减弱了水分对VOCs吸附的影响、加快了VOCs扩散；阐明了复合分子筛对于烃类VOCs的吸附，色散力在吸附过程中占主导作用；而对于醇、酯、腈类强极性VOCs，特定性相互作用对吸附过程贡献最多。探究了外壳MCM-41孔径、硅铝比、催化剂负载方法（一步合成法和浸渍法）等对活性组分MnOx微观结构及低温等离子体（NTP）催化降解甲苯的影响机制，研究了Y@MCM-41负载MnOx序批式吸附-NTP催化降解再生甲苯特性，阐述了外壳厚度、MnOx负载位置及负载量的影响，MnOx负载于内核Y上可增强甲苯的降解效率。以CO为探针分子，探究了NTP与催化剂的协同效应，NTP可促进催化剂晶格氧的流动，并产生除L-H途径外新的氧化途径；阐明了水分在等离子体催化过程中影响机制，高湿条件下NTP可以有效地促进氧迁移和加强了表面碳酸盐的分解，水分对催化活性的抑制作用是可逆的。本项目研究成果可为构建用于低浓度VOCs序批式吸附-NTP催化再生处理的核-壳结构复合分子筛材料提供重要支撑。