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Influence of CO2 and H2O co-feeding in the NOx abatement by SCR over an efficient Cu-CHA catalyst
[Display omitted] •Cu-SAPO-34 with 2 wt% of copper is effective in SCR in quasi-real conditions.•Cu-CHA model catalyst with copper inside the framework is hydrothermal stable.•NH3 oxidation and nitrate decomposition are hindered under H2O + CO2 atmosphere.•Hydrated-carbonated copper species are resp...
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Published in: | Chemical engineering science 2019-06, Vol.201, p.373-381 |
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Main Authors: | , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | [Display omitted]
•Cu-SAPO-34 with 2 wt% of copper is effective in SCR in quasi-real conditions.•Cu-CHA model catalyst with copper inside the framework is hydrothermal stable.•NH3 oxidation and nitrate decomposition are hindered under H2O + CO2 atmosphere.•Hydrated-carbonated copper species are responsible for SCR activity improvement.
Cu-SAPO-34 materials with 2 wt% of copper synthesized in one pot with all the copper inside the framework are hydrothermally stable. Copper oxide species were not detected by XRD after thermal and hydrothermal aging at 750 °C. CO2 and H2O molecules are retained on Cu-SAPO catalyst and are related to CO2 adsorption aided by water involving the Cu-species. Copper species coordination is modified by the reaction atmosphere and the species are directly involved in the SCR-process. A decrease in the ammonia storage capacity in the presence of water has been justified due to the cooperative competition between the ammonia and water adsorption and/or CO2 carbonation over the same sites. Higher coordinated Cu species localized inside of CHA-framework, up to a loading close to 4% with this methodology, are highly efficient in the removal of NOx by reaction with ammonia, in the presence of oxygen, water (1.5%) and CO2 (0.3%) as reaction atmosphere. The SCR mechanism is essentially the same as in dry conditions because the Cu2+/Cu+ ions, in equilibrium with H2O + CO2, are the active species in the SCR-reaction. Hydrated-carbonated Cu(II) and hydrated-carbonated Cu(I) species are associated with the redox-chemistry of NOx abatement as responsible for the improvement in the standard SCR; favoring the hindering of ammonia oxidation and nitrate decomposition. In the SCR temperature range, the conversion values registered for this catalyst are higher than 80% with total selectivity to N2. |
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ISSN: | 0009-2509 1873-4405 |
DOI: | 10.1016/j.ces.2019.02.031 |