Dramatic Effects of Gallium Promotion on Methanol Steam Reforming Cu鈥揨nO Catalyst for Hydrogen Production: Formation of 5 脜 Copper Clusters from Cu鈥揨nGaOx

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• 作者：Weiyi Tong ; Adam West ; Kevin Cheung ; Kai-Man Yu ; Shik Chi Edman Tsang
• 刊名：ACS Catalysis
• 出版年：2013
• 出版时间：June 7, 2013
• 年：2013
• 卷：3
• 期：6
• 页码：1231-1244
• 全文大小：700K
• 年卷期：v.3,no.6(June 7, 2013)
• ISSN：2155-5435

文摘

A new class of copper, zinc, and gallium mixed oxides (CuZnGaO_x) with different chemical compositions obtained by a coprecipitation technique is identified as a highly active catalyst for the low-temperature, direct steam reforming of methanol to supply hydrogen gas to portable fuel cell devices. Their catalytic activity and selectivity are found to be critically dependent on the copper surface area, catalyst structure, and metal鈥搒upport interaction, etc. As a result, temperature-programmed reduction has been used to investigate the copper ion reducibility and resulting copper speciation; N₂O chemisorption and advanced microscopies to determine specific copper surface area, dispersion, and particle size; XRD to investigate the catalyst structure; EPR spectroscopy to probe the environment of Cu²⁺ species; and AC impedance spectroscopy to probe the mobility of trapped ions in solids. It is proposed that Ga incorporation into Cu鈥揨n oxide leads to the formation of a nonstoichiometric cubic spinel phase containing interstitial Cu⁺ ions, which can produce in situ a high population of extremely small 5 脜 copper clusters at high dispersion on a defective ZnGa₂O₄ surface for effective catalysis.

Keywords:

H₂ production; fuel cells; methanol steam reforming; catalyst; particle size; gallium; copper clusters