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Bifunctional Cu/H-ZSM-5 zeolite with hierarchical porosity for hydrocarbon abatement under cold-start conditions

Paper ID Volume ID Publish Year Pages File Format Full-Text
45050 46395 2014 10 PDF Available
Title
Bifunctional Cu/H-ZSM-5 zeolite with hierarchical porosity for hydrocarbon abatement under cold-start conditions
Abstract

•Hierarchical Cu/H-ZSM-5 superior catalytic trap for hydrocarbon abatement.•Improved hydrocarbon retention achieved following loading with copper.•The presence of mesoporosity favored higher dispersions of CuO nanoparticles.•CuO nanoparticles catalyzed the total oxidation of the trapped hydrocarbons.•This bifunctional solid reduces hydrocarbon emissions under cold-start conditions.

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, N2 sorption, 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.

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Keywords
Cold-start vehicle emissions; Cu/H-ZSM-5; Hierarchical zeolite; Bifunctional catalysis
First Page Preview
Bifunctional Cu/H-ZSM-5 zeolite with hierarchical porosity for hydrocarbon abatement under cold-start conditions
Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volumes 154–155, July–August 2014, Pages 161–170
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis