کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
6453304 1418509 2017 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Feature ArticleInvestigation of structures and metallic environment of the Ni/Nb2O5 by different in situ treatments - Effect on the partial oxidation of methane
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی کاتالیزور
پیش نمایش صفحه اول مقاله
Feature ArticleInvestigation of structures and metallic environment of the Ni/Nb2O5 by different in situ treatments - Effect on the partial oxidation of methane
چکیده انگلیسی


- We studied the structure and the metallic environment of 2% Ni/Nb2O5 under different in situ treatment.
- Model catalyst with higher Ni loading presented different structures under reaction conditions compared to those observed in reduction environment.
- XRD, CO-chemisorption, HRTEM and UV-vis DRS evidenced the SMSI effect.
- Under POM reaction we identified NiNbO4 (Ni3+) and NiNb2O6 (Ni2+) phases.
- The surface Nb2O5/Niδ+ interface site appears to be selective to C2 compounds.

We investigated the structure and interface of the Ni/Nb2O5 under different treatment conditions and its effect on the partial oxidation of methane. In situ investigation of the catalyst reduced in H2 at different temperatures (300, 400 and 500 °C) indicated the occurrence of SMSI effect for the sample reduced at the higher temperature, caused by either decoration and/or electronic factors, evaluated by CO chemisorption, X-ray diffraction, HRTEM and UV-vis diffuse reflectance spectroscopy. Under reaction conditions (CH4/O2/N2/Ar = 2/1/1/6, GHSV = 250 mL g−1 h−1), the catalysts reduced at 300 and 400 °C showed two nickel sites: NiNbO4 and NiNb2O6, which were active for syngas production (H2 + CO). On the other hand, the catalyst reduced at 500 °C showed, besides NiNbO4 and NiNb2O6, the Nb2O5/Niδ+ site (where δ = 2 or 3) obtained from the reoxidation of NbOx species priorly generated by SMSI effect. We attribute the activity for methane coupling reactions to this Nb2O5/Niδ+ site (where δ = 2 or 3).

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ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Applied Catalysis A: General - Volume 537, 5 May 2017, Pages 100-110
نویسندگان
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