Exceptional Activity for NOxReduction at Low Temperatures Using Combinations of Hydrogen and Higher Hydrocarbons on Ag/Al2O3Catalysts

Burch, Robbie; Breen, John; Hill, Christopher J.; Krutzsch, B.; Konrad, B.; Jobson, Edward; Cider, L.; Eränen, Kari; Klingstedt, Fredrik; Lindfors, Lars-Eric

doi:10.1023/b:toca.0000029722.12588.1f

Cited by 116 publications

(90 citation statements)

References 6 publications

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“…13,159,160 In the presence SO 2 , the deteriorated Recently, it was found that the presence of H 2 significantly enhanced the low temperature activity of Ag-based catalysts for NO x reduction by hydrocarbons. 17,40,[209][210][211] Up to now, however, the interpretation of the H 2 promotional effect on HC-SCR has been under debate. To increase the rate of NO x conversion, basically, the hydrogen must accelerate the rate(s) of the slow step(s) in the reaction of HC-SCR, while the slow step(s) are likely to vary depending on the reaction temperature and feed conditions.…”

Section: Reactivity Of Intermediates Originating From Partial Oxidatimentioning

confidence: 99%

Environmentally-benign catalysts for the selective catalytic reduction of NO_xfrom diesel engines: structure–activity relationship and reaction mechanism aspects

2014

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Selective catalytic reduction of NO x using NH 3 or hydrocarbons (NH 3 -SCR or HC-SCR) in oxygen-rich exhaust from diesel engines remains a major challenge in environmental catalysis. The development of highly efficient, stable and environmentally-benign catalysts for SCR processes is very important for practical use. In this feature article, the structure-activity relationship of vanadium-free catalysts in the NH 3 -SCR reaction is discussed in detail, including Fe-, Ce-based oxide catalysts and Fe-, Cu-based zeolite catalysts, which is beneficial for catalyst redesign and activity improvement. Based on our research, a comprehensive mechanism contributing to the performance of Ag/Al 2 O 3 in HC-SCR is provided, giving a clue to the design of a catalytic system with high efficiency.

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Section: Reactivity Of Intermediates Originating From Partial Oxidatimentioning

confidence: 99%

Environmentally-benign catalysts for the selective catalytic reduction of NO_xfrom diesel engines: structure–activity relationship and reaction mechanism aspects

2014

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“…Instead of NO oxidation, Shibata et al [9][10][11] proposed that the positive effect of H 2 addition on the NO x reduction was attributed to the formation of small charged metallic Ag n d+ clusters based on the results of UV-vis spectroscopy. Burch and Breen et al [15,16] postulated that the improvement of added H 2 in the SCR of NO x was due to the formation of C N species, and was not associated with significant structural changes in the Ag/Al 2 O 3 catalyst at low temperatures.…”

Section: Introductionmentioning

confidence: 99%

Effect of hydrogen on reaction intermediates in the selective catalytic reduction of NOx by C3H6

Zhang

2007

Applied Catalysis B: Environmental

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Selective catalytic reduction of NO x by C 3 H 6 in the presence of H 2 over Ag/Al 2 O 3 was investigated using in situ DRIFTS and GC-MS measurements. The addition of H 2 promoted the partial oxidation of C 3 H 6 to enolic species, the formation of -NCO and the reactions of enolic species and -NCO with NO x on Ag/Al 2 O 3 surface at low temperatures. Based on the results, we proposed reaction mechanism to explain the promotional effect of H 2 on the SCR of NO x by C 3 H 6 over Ag/Al 2 O 3 catalyst. #

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“…To achieve the practical use, a SCR catalyst should also have a high level of activity for NO x reduction at lower temperature, considering the typical temperatures of diesel exhausts and cold-start driving cycle. Modification of the reaction atmosphere by adding H 2 to an HC-SCR system could be useful because of the surprising promotional effect on the SCR of NO x over Ag/Al 2 O 3 catalyst [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Review of Ag/Al2O3-Reductant System in the Selective Catalytic Reduction of NO x

Zhang

et al. 2008

Catal Surv Asia

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Ag/Al 2 O 3 is a promising catalyst for the selective catalytic reduction (SCR) by hydrocarbons (HC) of NO x in both laboratory and diesel engine bench tests. New developments of the HC-SCR of NO x over a Ag/ Al 2 O 3 catalyst are reviewed, including the efficiencies and sulfur tolerances of different Ag/Al 2 O 3 -reductant systems for the SCR of NO x ; the low-temperature activity improvement of H 2 -assisted HC-SCR of NO x over Ag/ Al 2 O 3 ; and the application of a Ag/Al 2 O 3 -ethanol SCR system with a heavy-duty diesel engine. The discussions are focused on the reaction mechanisms of different Ag/ Al 2 O 3 -reductant systems and H 2 -assisted HC-SCR of NO x over Ag/Al 2 O 3 . A SO 2 -resistant surface structure in situ synthesized on Ag/Al 2 O 3 by using ethanol as a reductant is proposed based on the study of the sulfate formation. These results provide new insight into the design of a high-efficiency NO x reduction system. The diesel engine bench test results showed that a Ag/Al 2 O 3 -ethanol system is promising for catalytic cleaning of NO x in diesel exhaust.

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Exceptional Activity for NO_xReduction at Low Temperatures Using Combinations of Hydrogen and Higher Hydrocarbons on Ag/Al₂O₃Catalysts

Cited by 116 publications

References 6 publications

Environmentally-benign catalysts for the selective catalytic reduction of NO_xfrom diesel engines: structure–activity relationship and reaction mechanism aspects

Environmentally-benign catalysts for the selective catalytic reduction of NO_xfrom diesel engines: structure–activity relationship and reaction mechanism aspects

Effect of hydrogen on reaction intermediates in the selective catalytic reduction of NOx by C3H6

Review of Ag/Al2O3-Reductant System in the Selective Catalytic Reduction of NO x

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Exceptional Activity for NOxReduction at Low Temperatures Using Combinations of Hydrogen and Higher Hydrocarbons on Ag/Al2O3Catalysts

Cited by 116 publications

References 6 publications

Environmentally-benign catalysts for the selective catalytic reduction of NOxfrom diesel engines: structure–activity relationship and reaction mechanism aspects

Environmentally-benign catalysts for the selective catalytic reduction of NOxfrom diesel engines: structure–activity relationship and reaction mechanism aspects

Effect of hydrogen on reaction intermediates in the selective catalytic reduction of NOx by C3H6

Review of Ag/Al2O3-Reductant System in the Selective Catalytic Reduction of NO x

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Product

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Exceptional Activity for NO_xReduction at Low Temperatures Using Combinations of Hydrogen and Higher Hydrocarbons on Ag/Al₂O₃Catalysts

Environmentally-benign catalysts for the selective catalytic reduction of NO_xfrom diesel engines: structure–activity relationship and reaction mechanism aspects

Environmentally-benign catalysts for the selective catalytic reduction of NO_xfrom diesel engines: structure–activity relationship and reaction mechanism aspects