Tuning the selectivity of a supported gold catalyst in solvent- and radical initiator-free aerobic oxidation of cyclohexene

Abstract

The selectivity of supported gold catalysts in solvent- and radical initiator-free aerobic oxidation of cyclohexene was tuned by either WO3 or MIL-101.

The Low Temperature Solvent-Free Aerobic Oxidation of Cyclohexene to Cyclohexane Diol over Highly Active Au/Graphite and Au/Graphene Catalysts

“…This then limits possible yield to cyclohexane diol, a key intermediate in the formation of adipic acid. An adapted mechanism from the paper by Ovoshchnikov et al is shown in Scheme 3 for the formation of cyclohexane diol with the addition of water [31]. The results in Table 2 demonstrate the importance of water in the formation of cyclohexane diol, and therefore any process that achieves high selectivity to the epoxide would be limited because of the lack of in situ water formed via dehydration of the hydroperoxyl intermediate.…”

“…This large discrepancy between sol immobilisation and impregnation selectivity is likely linked to their activity, as the small Scheme 3. Adapted reaction scheme from Ovoschnikov et al for effect of additional water [31].…”

Toward Control of Gold Cluster Aggregation on TiO2 via Surface Treatments

“…a bulk-like Au signal in XPS) and a distinct surface plasmon resonance band. [25][26] Peaks with intermediate binding energies (84 -84.5 eV) can be attributed to the small aggregates of clusters. It is also important to note that agglomeration of clusters affects the intensity of the Au signal.…”

“…The fundamental study reported herein is therefore intended to act as a foundation for further studies on the applications of these materials. [25][26][27] In the proceeding sections we present X-ray photoelectron spectroscopy (XPS) measurements of the gold core, the triphenylphosphine periphery, and the titanium dioxide support respectively. Following this, we present results of the UV-vis DRS spectroscopy investigations of these (and related) materials, which support the conclusions obtained from XPS data.…”

Selective epoxidation of cyclohexene with molecular oxygen on catalyst of nanoporous Au integrated with MoO3 nanoparticles

“…[31][32][33][34] For example, using silica or manganese oxide supported gold catalysts, selectivity for production of epoxide (i.e., cyclohexene oxide) is generally lower than 10% when molecular oxygen was used. 31,32 In order to improve the selectivity for production of cyclohexene oxide, gold nanoclusters (i.e., Au 9 and Au 101 ) were anchored onto WO 3 nanoparticles 35 ; the selectivity for production of cyclohexene oxide on Au 101 /WO 3 catalyst was improved largely to 35% comparing to 7% of Au 101 /SiO 2 catalyst when molecular oxygen or peroxide is used as the oxidant. 35 This difference suggests the promotion effect of the support, WO 3 on catalytic selectivity of cyclohexene oxide.…”