Separated Active Site and Reaction Space for Multi-Pollutant Elimination Significantly Enhancing Low Toxic Product Selectivity

It is possible to remove volatile organic compounds containing chlorine (CVOCs, such as chlorobenzene) in a single device designed for selective catalytic reduction of NOx with NH3 for the industries containing CVOCs and NOx. Breaking the efficiency-selectivity trade-off in chlorobenzene oxidation remains a major challenge due to the conjugation of halogen atoms with the benzene ring and the reducing nature of NH3. A stepwise synthesis strategy is demontrated to disperse dual Ru/Cu Lewis acid sites outside and inside the zeolite channel. Under the confinement of zeolite, the Ru4+ Lewis acid site on the external surface of the zeolite promotes chlorobenzene oxidation by weakening the p-& pi; conjugate structure of Cl and benzene ring, while the Cu2+ Lewis acid site within the internal channel converts NOx and NH3 to N-2. The mutual interference between catalytic oxidation and reduction is successfully avoided. Therefore, the low toxic CO2 and HCl selectivity experience a considerable increase from 21% to 86%, and from 51% to 94% with 91% conversion of chlorobenzene, while maintaining excellent elimination performance for NO (with N-2 selectivity exceeding 90%). The incorporation of separated active sites and reaction spaces into the design may offer potentials for other energy and environmental applications.

Automated summary

A stepwise synthesis strategy is employed to disperse dual Ru/Cu Lewis acid sites inside and outside the zeolite channel for efficient selective catalytic oxidation of chlorobenzene and reduction of NOx. The mutual interference between the two reactions is successfully avoided, leading to high selectivity and conversion rates.