Improvement of Alkali Metal Resistance for NH3-SCR Catalyst Cu/SSZ-13: Tune the Crystal Size

Zexiang Chen,Jianqiang Wang,Jun Wang,Meiqing Shen,Chen Wang,Gurong Shen

doi:10.3390/catal11080979

Abstract

To improve the alkali metal resistance of commercial catalyst Cu/SSZ-13 for ammonia selective catalytic reduction (NH3-SCR) reaction, a simple method to synthesize Cu/SSZ-13 with a core–shell like structure was developed. Compared with smaller-sized counterparts, Cu/SSZ-13 with a crystal size of 2.3 μm exhibited excellent resistance to Na poisoning. To reveal the influence of the crystal size on Cu/SSZ-13, physical structure characterization (XRD, BET, SEM, NMR) and chemical acidic distribution (H2-TPR, UV-Vis, Diethylamine-TPD, pyridine-DRIFTs, EDS) were investigated. It was found that the larger the crystal size of the molecular sieve, the more Cu is distributed in the crystal core, and the less likely it was to be replaced by Na to generate CuO. Therefore, a 2.3 μm sized Cu/SSZ-13 well-controlled the reactivity of the side reaction NH3 oxidation and the generation of N2O. The result was helpful to guide the extension of the service life of Cu/SSZ-13.

Highlights

For health and environmental considerations, the current community strongly demands to improve air quality
Through a series of trials, we found that the crystal size of SSZ-13 is most sensitive to the amount of seed crystal added
The results show that the crystal sizes of the synthesized SSZ-13 are 0.4, 0.8, and 2.3 μm

Summary

Introduction

For health and environmental considerations, the current community strongly demands to improve air quality. Numerical theoretical and experimental studies have revealed the pore structure, NH3 -SCR catalytic active sites, high-temperature hydrothermal stability, sulfur poisoning mechanism and alkali metal poisoning mechanism of Cu/SSZ-13 [7,8,9,10,11,12,13,14,15,16,17,18,19,20] Alkali metals, such as sodium (Na) and potassium (K) are present in conventional diesel fuel and biodiesel fuel, and have been implicated in internal injector deposits [21,22]

Methods

Results

Conclusion