Nano‐Au Anchored in Organic Base Group‐Grafted Silica Aerogel: A Durable and Robust Catalysts for Green Oxidative Esterification of Furfural

Abstract

Inorganic metal (hydro)oxide supports with appropriate basicity or acid-base properties can promote oxidative esterification of furfural over Au-based catalysts, however, they suffer the problems of easy inactivation induced by the leaching of the components in this water-producing reaction and the shield of catalytic sites by product adsorption. In this work, we report efficient and stable oxidative esterification of furfural over Au nanoparticles anchored in aminopropyl-grafted silica aerogel. The support is insoluble and possesses no strong Lewis acid sites to adsorb oxygen-containing products or intermediates, reducing the probability of catalyst deactivation induced by adsorption. In 7 cycles of reactions, the catalyst maintained the initial activity without any treatments, the yields of alkyl furoate kept above 98 %, and no agglomeration and leaching of Au occurred. Moreover, the roles of Au, alkyl chain, À NH 2 group and Au-activated O species in reactions were clarified, and accordingly, a possible catalytic mechanism involving oxidative dehydrogenation was given.

Additive- and base-free tandem aerobic oxidative cleavage of olefins to esters using bifunctional mesoporous copper-incorporated Al-SBA-15

“…Mesoporous functionalized silica shows promising results in the oxidative esterification of alcohols to esters. 22,23 Transition metal-supported silica materials show promising results in the oxidation reaction due to their large surface area and uniform immobilization of active sites within their pores. 24,25 However, the silica-supported metal catalyst was not effective for the one-pot conversion of olefins to esters.…”

Influence of Oxide Coating Layers on the Stability of Gold Catalysts for Furfural Oxidative Esterification to Methyl Furoate

“…as well as transition metal catalysts (i.e., Co [27,28], etc.) have shown great potential in the oxidative esterification process due to their capability of converting O 2 molecules into highly active atomic O or other reactive oxygen species [29]. This capability allows for the use of O 2 and air as green oxidants, avoiding the environmental damage and high cost associated with stoichiometric oxidants with toxicity.…”

Effect of Support on Oxidative Esterification of 2,5-Furandiformaldehyde to Dimethyl Furan-2,5-dicarboxylate

“…Therefore, alkaline supports are often used as a potential alternative to alkaline additives. Song et al [12] used an organic base group-grafted silica aerogel-supported Au to catalyze oxidative esterification of furfural, and the yield of methyl furoate was above 98%. Ferraz [13] used an Au/MgO catalyst in the oxidative esterification of furfural, achieving a methyl furoate yield of 95%.…”