Direct oxidative esterification of methacrolein with methanol is a more environmentally benign route for producing methyl methacrylate in comparison with the traditional acetone cyanohydrin method [1]. Since the early work of Haruta et al., in which, Au showed remarkable activity and selectivity when it was highly dispersed in the form of nanoparticles (&lt;5 nm diam.), it has been studied for many other reactions with high selectivity towards the desired products [2]. Nanoporous Au has been examined in the gas phase and UHV studies for the methacrolein – methanol coupling, and an excess of methanol (&gt;90%) was found necessary for the effective cross-coupling [3]. In addition, Au nanoparticles deposited on basic supports has also been tested for the liquid phase coupling reaction, but the reaction mechanism has not been investigated in detail [4].<br/><br/>In the present work, we study Au and NiAu alloy catalysts where Au is either supported in nanoparticle form on silica or unsupported in nanoporous form for the oxidative coupling of methacrolein with methanol. Catalytic performance tests show that these catalysts show almost 100% selectivity towards methyl methacrylate and remarkable stability. Addition of Ni atoms on Au surface greatly improves its activity (conversion increases from 5% on Au to 25% on NiAu) while selectivity is maintained at the same levels as pure Au. Formation of highly dilute Ni-Au alloys is followed by CO-DRIFTS. The promoting effect of Ni is also investigated by operando ATR-IR under reaction conditions. ATR-IR also provides an insight into the reaction mechanism through identification of reaction intermediates-adsorbates on the catalytic surface. Catalysts were also characterized by ICP, XRD, HRTEM, and XANES-EXAFS.<br/>

NiAu single atom alloys for the oxidative coupling of methacrolein with methanol

256th National Meeting (2018)

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