کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
48837 46522 2007 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Conditioning of Rh/α-Al2O3 catalysts for H2 production via CH4 partial oxidation at high space velocity
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی کاتالیزور
پیش نمایش صفحه اول مقاله
Conditioning of Rh/α-Al2O3 catalysts for H2 production via CH4 partial oxidation at high space velocity
چکیده انگلیسی

Experimental evidence and literature indications suggest that the process of methane partial oxidation over Rh catalysts is structure sensitive. Crystal phases and Rh cluster size are thus expected to affect the final catalytic performance. In this work, it is observed that outstanding performances are obtained when the as-prepared catalysts are conditioned through repeated runs at increasing temperature and O2/CH4 = 0.56. Catalysts slowly activate, that is CH4 conversion and synthesis gas selectivity progressively grow with time on stream. On the basis of TPO and CH4 decomposition measurements, this phenomenon is herein explained as the result of a surface reconstruction driven by the repeated exposition to the reaction at high temperature; it is thought that such reconstruction tends to eliminate defect sites and disfavors C-deposition reactions (extremely fast over steps and kinks). Conditioning with O2-enriched feed streams makes conditioning faster, since the accumulation of surface C-species is suppressed; however, the catalyst is eventually less active than a catalyst conditioned with standard feed mixtures. As an alternative, accumulation of carbon can be suppressed and surface reconstruction proceeds faster if the catalyst is directly exposed to the reaction at high temperature for several hours.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Applied Catalysis B: Environmental - Volume 70, Issues 1–4, 31 January 2007, Pages 515–524
نویسندگان
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