Zeolite-driven Ag species during redox treatments and catalytic implications for SCO of NH3
| Autor: | Teresa Blasco, Kinga Góra-Marek, Joaquin Martinez-Ortigosa, Christian W. Lopes, Karolina A. Tarach, Eduardo Palomares, Giovanni Agostini, Fernando Rey, Alejandro Vidal Moya |
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| Přispěvatelé: | Ministerio de Economía y Competitividad (España), Ministerio de Ciencia, Innovación y Universidades (España) |
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
In situ
X-ray absorption spectroscopy Renewable Energy Sustainability and the Environment Chemistry Metal-clustersag-109 nmr Nanoparticle General Chemistry Redox INGENIERIA QUIMICA Catalysis Transformation Metal Al203 Ammonia visual_art Selective catalytic oxidation Oxidation visual_art.visual_art_medium General Materials Science Silver nanoparticles Zeolite Stability Consequences Spectroscopy Nuclear chemistry |
| Zdroj: | RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia instname Digital.CSIC. Repositorio Institucional del CSIC |
| Popis: | [EN] Supported silver species are among the most promising catalysts for the depletion of ammonia emission by selective catalytic oxidation (NH3-SCO). Here, an investigation on the influence of small pore CHA and RHO zeolite structures on the silver species formed and their catalytic activity for the NH3-SCO reaction has been conducted. To this end, AgRHO(4) and AgCHA(4) zeolites with similar Si/Al molar ratios (approximate to 4) and silver content (similar to 15 wt%, Ag/Al approximate to 0.6), and AgCHA(2) with Si/Al approximate to 2 and higher silver loading, while maintaining the Ag/Al ratio (similar to 26 wt%, Ag/Al approximate to 0.6), have been submitted to different treatments and characterized by using a large variety of techniques (XRD, UV-Vis, Ag-109 NMR, in situ XAS and operando FT-IR). The reduction of the AgCHA and AgRHO zeolites at low temperature (100-200 degrees C) produces silver clusters, which remain in the AgRHO zeolite when the temperature is increased to 400 degrees C. However, the silver species in the AgCHA zeolites evolve to nanoparticles (NPs) at 400 degrees C under H-2. The catalytic tests show that metal particles are the active sites while silver clusters are inactive for the NH3-SCO reaction. Also, there are important differences in the stability of the reduced Ag species under oxidizing or under reaction conditions at 400 degrees C. Metal NPs are partially redispersed and oxidized to (Ag)(n)(+), while silver clusters are completely oxidized to Ag+. Our results indicate that silver clusters are stabilized in the RHO-type and not in the CHA-type zeolite, and thus they display very different catalytic activities for the NH3-SCO reaction. The authors acknowledge grant RTI2018-101784-B-I00 funded by MCIN/AEI/10.13039/501100011033 and by "ERDF A way of making Europe". Also, the project SEV-2016-0683 funded by MCIN/AEI/10.13039/501100011033 is acknowledged. The project Prometeo/2021/077, Conselleria de Educacion, Cultura y Deporte de la Generalitat Valenciana is also acknowledged. K. G.-M. acknowledges Grant No. 2015/18/E/ST4/00191 from the National Science Centre, Poland. K. T. acknowledges the scholarship within the Bekker Programme (PPN/BEK/2018/1/00406) from the Polish National Agency for Academic Exchange. C. W. Lopes (Science without Frontiers -Process no. 13191/13-6) thanks Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior -Brasil (CAPES - Finance Code 001) for the predoctoral fellowship. J. Martinez-Ortigosa (SEV-20120267-02) acknowledges the Severo Ochoa Program for a predoctoral fellowship. We gratefully acknowledge the ALBA synchrotron for allocating beamtime (proposals 2016021665 and 2017032119), CLAESS beamline staff, and particularly Carlo Marini for their help and technical support during our experiment. |
| Databáze: | OpenAIRE |
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