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Pt/Al2O3@Ce/ZrO2-S bifunctional catalysts prepared by mechanically milling for selective catalytic oxidation of high-concentration ammonia.
- Source :
- Environmental Science & Pollution Research; May2024, Vol. 31 Issue 25, p37746-37756, 11p
- Publication Year :
- 2024
-
Abstract
- The selective catalytic oxidation (SCO) is an effective method for removing slipped high-concentration ammonia from NH<subscript>3</subscript>-fueled engine exhaust gas. Herein a novel bifunctional catalyst was synthesized by mechanically mixing sulfated Ce/ZrO<subscript>2</subscript> (Ce/ZrO<subscript>2</subscript>-S) with a small fraction of Pt/Al<subscript>2</subscript>O<subscript>3</subscript> (Pt 0.1 wt.%) for SCO of NH<subscript>3</subscript>. As expected, the introduction of a small amount of Pt/Al<subscript>2</subscript>O<subscript>3</subscript> significantly improved NH<subscript>3</subscript> conversion ability of Ce/ZrO<subscript>2</subscript>-S catalysts toward low-temperature direction. When the mass ratio of Pt/Al<subscript>2</subscript>O<subscript>3</subscript> to Ce/ZrO<subscript>2</subscript>-S was 7.5% (the corresponding mixed catalyst was denoted as P@CZS-7.5), T<subscript>90</subscript> temperature was 312 °C. More importantly, P@CZS-7.5 catalyst exhibited a much better N<subscript>2</subscript> selectivity (> 96%) in a wide temperature range (320 ~ 450 °C). H<subscript>2</subscript>-TPR results revealed that the addition of a trace amount of Pt/Al<subscript>2</subscript>O<subscript>3</subscript> significantly led to a distinct shift of reduction temperature peak toward low-temperature direction, thereby greatly improved the low-temperature redox performance of mixed catalysts. Furthermore, NH<subscript>3</subscript>-TPD and BET results showed that P@CZS-7.5 catalyst exhibited a similar NH<subscript>3</subscript> adsorption capacity to Ce/ZrO<subscript>2</subscript>-S catalyst, while the former had a relatively higher specific surface area than the latter. It was considered as a crucial factor for P@CZS-7.5 catalyst maintaining superior N<subscript>2</subscript> selectivity in high-concentration NH<subscript>3</subscript> (5000 ppm) removal processes. In situ DRIFTS results indicated that P@CZS-7.5 catalyst followed the internal selective catalytic reduction (i-SCR) mechanism in NH<subscript>3</subscript>-SCO reactions. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 09441344
- Volume :
- 31
- Issue :
- 25
- Database :
- Complementary Index
- Journal :
- Environmental Science & Pollution Research
- Publication Type :
- Academic Journal
- Accession number :
- 178046444
- Full Text :
- https://doi.org/10.1007/s11356-024-33744-6