کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
66196 48419 2012 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
The effect of palladium clusters (Pdn, n = 2–8) on mechanisms of acetylene hydrogenation: A DFT study
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی کاتالیزور
پیش نمایش صفحه اول مقاله
The effect of palladium clusters (Pdn, n = 2–8) on mechanisms of acetylene hydrogenation: A DFT study
چکیده انگلیسی

The mechanisms of acetylene hydrogenation on palladium clusters (Pdn, n = 2–8) are researched by using the B3PW91/GENECP method of density functional theory. The calculation results indicate that there are two possible pathways for the hydrogenation reaction on Pdn cluster from the reactant acetylene to the product ethane. One of the pathways undergoes through two intermediates, the vinyl (Pdn(H)⋯CHCH2) and ethene (Pdn⋯CH2CH2) to form the ethane, and the other goes along vinylidene (Pdn(2H)⋯CCH2), ethylidyne Pdn(2H)⋯CCH3) and ethylidene (Pdn(2H)⋯CHCH3) to ethane. Those intermediates in the two pathways can convert into each other which make the reaction profile complicated. The value of n in Pdn cluster can directly affect the reaction pathway: when n ≤ 4, the acetylene hydrogenation reaction will proceed via the pathway of Pdn(2H)⋯CHCH → Pdn(H)⋯CHCH2 → Pdn⋯CH2CH2 → Pdn(2H)⋯CH2CH2 to form ethane. However, when n > 4, the reaction choose the following pathway: Pdn(2H)⋯CHCH → Pdn(H)⋯CHCH2 → Pdn⋯CHCH3 → Pdn(2H)⋯CHCH3. In addition, the value of their turnover frequency (TOF) for the ethylene formation catalyzed by Pdn cluster is larger than that for ethane, which indicates that the catalytic cycles in the formation of ethylene is efficient.

When the value of n in Pdn is equal or lesser than 4 (n ≤ 4), the acetylene hydrogenation reaction will proceed via the pathway of Pdn(2H)⋯CHCH → Pdn(H)⋯CHCH2 → Pdn⋯CH2CH2 → Pdn(2H)⋯CH2CH2 to form ethane. However, when n > 4, the reaction choose the following pathway: Pdn(2H)⋯CHCH → Pdn(H)⋯CHCH2 → Pdn⋯CHCH3 → Pdn(2H)⋯CHCH3.Figure optionsDownload high-quality image (180 K)Download as PowerPoint slideHighlights
► Two feasible pathways of the acetylene hydrogenation on Pdn clusters.
► One of the pathways goes along the vinyl and ethene intermediates to form the ethane.
► The other way proceeds via vinylidene, ethylidyne and ethylidene to form ethane.
► The intermediates of the two pathways can convert each other.
► The catalytic cycles in ethylene forming are efficient than that for ethane.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Molecular Catalysis A: Chemical - Volume 359, July 2012, Pages 14–20
نویسندگان
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