Nanostructured copper, chromium, and tin oxide multicomponent materials as catalysts for methanol decomposition: ¹¹C-radiolabeling study

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• 作者：Tanya Tsoncheva^a ; ^{tsoncheva@orgchm.bas.bg} ; Eva Sarkadi-Priboczki^b ; Momtchil Dimitrov^a ; Izabela Genova^a
• 关键词：11C-labeling study ; Methanol conversion ; Copper and chromium modified SnO2 ; Mesoporous nanostructured SnO2
• 刊名：Journal of Colloid and Interface Science
• 出版年：2013
• 出版时间：1 January, 2013
• 年：2013
• 卷：389
• 期：1
• 页码：244-251
• 全文大小：535 K

文摘

Copper and chromium modified tin oxide nanocomposites were obtained via incipient wetness impregnation of high surface area nanosized SnO₂ with the corresponding metal acetylacetonates and their further decomposition in air. Powder X-ray diffraction (XRD), Nitrogen physisorption, UV-Vis, and Temperature-programmed reduction (TPR) with hydrogen were applied for the samples characterization. The catalytic activity of the obtained materials was tested in methanol conversion. A new approach based on the selective coverage of the surface with ¹¹C-methanol was used for the characterization of the catalytic sites. It was demonstrated that the products distribution could be controlled by the surface coverage with methanol and the role of different active sites was discussed. The modification of SnO₂ with copper oxide increased the activity in methanol decomposition to CO₂ via dioxymethylene intermediates, but the catalyst suffered considerable loss of activity due to the reduction transformations by the reaction medium and formation of an inactive intermetallic alloy. The modification with chromium changed the acid-basic properties of SnO₂ by the formation of Cr₂O₃ nanoparticles as well as anchored to the support chromate species. The former particles facilitated the formation of dimethyl ether (DME), while the latter species converted methanol predominantly to hydrocarbons. The fraction of chromate species increased in Cu-Cr-Sn oxide multicomponent nanocomposites and promoted the formation of hydrocarbons over DME at low temperatures, while at higher temperatures, the activity of the copper species leading to CO₂ formation was more pronounced.