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Abstract

Methanol Synthesis over Cu/ZnO Catalysts Prepared by Ball MillingHuang, L.; Kramer, G.J.; Wieldraaijer, W.; Brands, D.S.; Poels, E.K.; Castricum, H.L.; Bakker, H. General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Cu/ZnO catalysts (with a Cu/Zn atomic ratio of 30/70) have been prepared by high intensity mechanical mixing of copper and zinc oxide powder in air and under vacuum. During milling in vacuum gradual amorphisation of the constituents occurs, as evidenced by broadening of the Cu 0 and ZnO diffraction peaks in XRD, but the two original phases remain. The result of such treatment is a catalyst with low BET area and low Cu metal surface area. Consequently, the activity of the vacuum milled samples in batch methanol production from synthesis gas (CO/CO 2 /H 2 20/5/75) at 50 bar and 250 C is low. Milling in air leads to oxidation of the copper metal phase and much higher BET surface area and, after reduction, Cu metal surface area. Prolonged milling times in air result in more than 90% Cu 2 formation as evidenced by TPR. Activity in methanol synthesis for the air milled samples is comparable to a conventional Cu/ZnO catalyst prepared by coprecipitation. It is concluded that high intensity ball milling at ambient conditions is a promising method to prepare mixed oxide catalysts or catalyst precursors.

Oxidation and reduction in copper/zinc oxides by mechanical milling

“…A Cu/ZnO sample milled in vacuum had been investigated previously [11], showing both low Cu metal area and low BET surface area. The Cu 0 specific surface areas of all milled samples discussed here are increased by more than one order of magnitude compared to their unmilled precursors.…”

“…In order to achieve high activity a good intimate mixture of Cu and ZnO must be obtained [9,10]. The ultimate structure and activity of the mechanochemically prepared catalyst show a strong dependency on the milling atmosphere [11]. A mixture of Cu and ZnO milled in vacuum was hardly active, whereas this mixture milled in ambient air was as active as a coprecipitated catalyst.…”

Stabilizer‐Free Metal Nanoparticles and Metal–Metal Oxide Nanocomposites with Long‐Term Stability Prepared by Physical Vapor Deposition into Ionic Liquids

“…[34] Several methods have been developed for the synthesis of Cu/ZnO nanocomposites involving organometallic [35] or mechanochemical routes. [36] Recently, the synthesis of Cu@ZnO core-shell nanocomposites by solvated metal atom dispersion (SMAD) has been reported. [37] The technique, originally developed by Klabunde and co-workers, [38] consists of cocondensation of substrate vapors together with a cosolvent or stabilizing agent, in this case 2-butanone, under high vacuum onto a target that is maintained at liquid nitrogen temperature.…”

Waste-free Soft Reactive Grinding Synthesis of High-Surface-Area Copper–Manganese Spinel Oxide Catalysts Highly Effective for Methanol Steam Reforming

“…Over the past decades, grinding-assisted catalyst synthesis has attracted tremendous attention by providing a much simpler, waste-free, easily scalable and energyefficient technique for fabrication of new catalytic materials with improved and/or novel physical and chemical properties as compared to conventional methods [19][20][21][22][23][24][25]. Very recently, we have shown that highly effective Cu/ZnO materials with favorable surface and structural properties for methanol steam reforming can be prepared via a simple yet versatile technique based on soft reactive grinding (SRG), removing the need of vast amount of water and the formation of large amount of wastes [26].…”