Chemical deactivation of commercial vanadium SCR catalysts in diesel emission control application
[Display omitted] •Phosphorous and zinc were the primary chemical contaminants on Field returned vanadium SCR catalysts.•NOx conversion during the NH3-SCR reaction was lowered and altered by chemical contamination.•Chemical deactivation was mainly caused by NH3 storage capability reduction and oxida...
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| Published in: | Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 287; pp. 680 - 690 |
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| Main Authors: | , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Elsevier B.V
01-03-2016
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| Subjects: | |
| Online Access: | Get full text |
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| Summary: | [Display omitted]
•Phosphorous and zinc were the primary chemical contaminants on Field returned vanadium SCR catalysts.•NOx conversion during the NH3-SCR reaction was lowered and altered by chemical contamination.•Chemical deactivation was mainly caused by NH3 storage capability reduction and oxidation activity modification.
Irreversible chemical deactivation of state-of-the-art vanadium selective catalytic reduction (SCR) catalysts was investigated using an aftertreatment system from a heavy-duty diesel vehicle for general haulage application. Elemental analysis revealed that Field returned vanadium SCR catalysts had higher phosphorous and zinc concentrations than those from a fresh catalyst. Phosphorous concentration dropped significantly from catalyst inlet to outlet, while zinc concentration remained almost constant. Broadened infrared intensity from V5+O and W6+O bonds were observed from contaminated vanadium SCR samples. Anatase phases and crystallite size remained unchanged in the presence of chemical contaminants.
Chemical contamination monotonically reduced NH3 storage capability but non-linearly modified acid site distribution and oxidation activity, causing differences in NOx reduction behaviors. Low chemical contamination on vanadium SCR catalyst reduced NOx conversion below 450°C due to the decrease in NH3 storage capacity and oxidation activity. NOx conversion over a sample with high phosphorus concentration was lowered by the weakened NH3 storage capacity below 350°C and the enhanced parasitic NH3 oxidation above 400°C. High levels of phosphorus increased low-temperature NOx conversion compared to low levels of phosphorus due to increase in oxidation capability. |
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| ISSN: | 1385-8947 1873-3212 |
| DOI: | 10.1016/j.cej.2015.11.043 |