Bifunctional Cu/H-ZSM-5 zeolite with hierarchical porosity for hydrocarbon abatement under cold-start conditions
Bifunctional Cu/H-ZSM-5 zeolite with hierarchical porosity for hydrocarbon abatement under cold-start conditions
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DOI：
10.1016/j.apcatb.2014.02.013
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发表时间：
2014-07
影响因子：
22.1
通讯作者：
B. Puértolas;L. García-Andújar;T. García;M. Navarro;S. Mitchell;J. Pérez–Ramírez
中科院分区：
文献类型：
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作者：
B. Puértolas;L. García-Andújar;T. García;M. Navarro;S. Mitchell;J. Pérez–Ramírez
降低汽车尾气中碳氢化合物排放的一个关键目标是改善冷启动条件下的减排。在这里，我们展示了一个层次的Cu/H-ZSM-5沸石为基础的系统作为催化陷阱的特殊性能。大大增加的外表面积加上在常规ZSM-5沸石的碱处理和随后的酸洗后可获得的保留的固有性质，使得铜物质在分级对应物中的分散得到改善。通过XRD、N2吸附、FTIR、NH3-TPD、TEM、SEM和HAADF-STEM清楚地揭示了合成后改性对含铜ZSM-5制备的影响。通过提供更强的吸附位点，铜物质的引入改善了丙烯和甲苯相对于质子沸石的保留，并且使得它们能够进一步转化为二氧化碳和水，而不是它们在废气中的排放。分级Cu/H-ZSM-5催化剂相对维斯其常规对应物表现出的相等的吸附容量和改进的氧化活性以及对失活的较低敏感性产生了能够在实际操作条件下达到完全烃转化的上级双功能催化剂。
A key target to reduce current hydrocarbon emissions from vehicular exhaust is to improve their abatement under cold-start conditions. Here, we demonstrate the exceptional properties of a hierarchical Cu/H-ZSM-5 zeolite-based system as a catalytic trap. The largely increased external surface area coupled with the preserved intrinsic properties attainable upon alkaline treatment and subsequent acid washing of a conventional ZSM-5 zeolite enable an improved dispersion of copper species in the hierarchical counterpart. The impact of post-synthetic modification on the preparation of copper-containing ZSM-5 is clearly revealed by XRD, N2sorption, FTIR, NH3-TPD, TEM, SEM, and HAADF-STEM. By providing stronger adsorption sites, the introduction of copper species improves the retention of propene and toluene with respect to the protonic zeolites, and enables their further conversion to carbon dioxide and water rather than their emission in the exhaust. The equivalent adsorption capacity and improved oxidation activity and lower susceptibility to deactivation exhibited by the hierarchical Cu/H-ZSM-5 catalyst vis-a-vis its conventional counterpart yield a superior bifunctional catalyst able of reach full hydrocarbon conversion under realistic operating conditions.