ZSM-5分子筛负载高分散Pd催化剂低温捕集净化CO/C_(3)H_(6)的性能与机理研究  

Performance and mechanism of highly dispersed Pd catalysts supported on ZSM-5 zeolite for low-temperature trap and abatement of CO/C_(3)H_(6)

作　　者：李颖 陈冬冬 王昕煜 徐鑫 叶代启 陈培榕 LI Ying;CHEN Dongdong;WANG Xinyu;XU Xin;YE Daiqi;CHEN Peirong(School of Environment and Energy,South China University of Technology,Guangzhou 510006;National Engineering Laboratory for VOCs Pollution Control Technology and Equipment,Guangzhou 510006;Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control(SCUT),Guangzhou 510006)

机构地区：[1]华南理工大学环境与能源学院,广州510006 [2]挥发性有机物污染治理技术与装备国家工程实验室,广州510006 [3]广东省大气环境与污染控制重点实验室,广州510006

出　　处：《环境科学学报》2023年第11期258-269,共12页Acta Scientiae Circumstantiae

基　　金：国家重点研发计划(No.2022YFB4101503-3);广东省自然科学基金(No.2023A1515011682);中央高校基本科研业务费项目(No.2022ZYGXZR018)。

摘　　要：冷启动工况下尾气CO和碳氢化合物的高效消除是实现柴油车近零排放的关键.采用氨蒸发法制备同时包含高分散PdO_(x)纳米颗粒和Pd^(2+)的Pd-ZSM-5催化剂AE-PdH,并应用于模拟冷启动工况下CO和C_(3)H_(6)的低温捕集净化.结果表明,AE-PdH能在低温下同时吸附CO和C_(3)H_(6),且CO可显著促进AE-PdH的C_(3)H_(6)捕集净化性能;与传统浸渍法制备的Pd-ZSM-5相比,AE-PdH具有更高的CO/C_(3)H_(6)协同氧化活性,因此在升温脱附过程中C_(3)H_(6)逃逸更少.结合原位漫反射红外光谱和原位紫外拉曼光谱表征的机理研究揭示:AE-PdH含有强吸附CO和C_(3)H_(6)的离子态Pd活性位点;CO通过在低温下将AE-PdH中的高分散PdO_(x)还原为金属Pd,促进升温过程中AE-PdH对C_(3)H_(6)的吸附和催化氧化,从而减少了C_(3)H_(6)逃逸.Efficient abatement of CO and hydrocarbons during the cold-start period is essential for achieving near-zero emissions in exhausts from diesel vehicles.In this paper,Pd-ZSM-5 catalyst prepared by an ammonia evaporation method(namely AE-PdH),which contains both highly dispersed PdO_(x) nanoparticles and Pd^(2+)ions,was applied in low-temperature trap and abatement of CO/C_(3)H_(6) under simulated cold-start conditions.While CO and C_(3)H_(6) could be simultaneously adsorbed on AE-PdH at low temperatures,CO demonstrated a significant promoting effect on the trap and abatement of C_(3)H_(6).Compared to the Pd-ZSM-5 prepared by a conventional wet impregnation method,AE-PdH was more active in simultaneous CO/C_(3)H_(6) oxidation,thus decreasing C_(3)H_(6) slip during temperature ramping.A combination of in situ diffuse reflectance infrared Fourier transform spectroscopy and in situ UV Raman spectroscopy revealed that cationic Pd sites are responsible for a strong adsorption of CO and C_(3)H_(6) over AE-PdH.Furthermore,the highly dispersed PdO_(x) species in AE-PdH were easily reduced to metallic Pd by CO at low temperatures,thus facilitating C_(3)H_(6) adsorption and oxidation and,eventually,reducing C_(3)H_(6) slip during temperature ramping.

关 键 词：氨蒸发 Pd-ZSM-5 C_(3)H_(6)捕集 CO/C_(3)H_(6)协同净化 冷启动减排 

分 类 号：X511[环境科学与工程—环境工程]