Fine cubic Cu2O nanocrystals as highly selective catalyst for propylene epoxidation with molecular oxygen

Abstract

Propylene epoxidation with O2 to propylene oxide is a very valuable reaction but remains as a long-standing challenge due to unavailable efficient catalysts with high selectivity. Herein, we successfully explore 27 nm-sized cubic Cu2O nanocrystals enclosed with {100} faces and {110} edges as a highly selective catalyst for propylene epoxidation with O2, which acquires propylene oxide selectivity of more than 80% at 90–110 °C. Propylene epoxidation with weakly-adsorbed O2 species at the {110} edge sites exhibits a low barrier and is the dominant reaction occurring at low reaction temperatures, leading to the high propylene oxide selectivity. Such a weakly-adsorbed O2 species is not stable at high reaction temperatures, and the surface lattice oxygen species becomes the active oxygen species to participate in propylene epoxidation to propylene oxide and propylene partial oxidation to acrolein at the {110} edge sites and propylene combustion to CO2 at the {100} face sites, which all exhibit high barriers and result in decreased propylene oxide selectivity.

A novel environmental nano-catalyst of zeolite amended with carbon nanotube/silver nanoparticles decorated carbon paste electrode for electro-oxidation of propylene glycol

“…The electrocatalytic oxidations of different small organic molecules on various edited electrodes have been examined for application in fuel cells 7 – 13 . Most of recent reports, polyalcohol such as ethylene glycol, propylene glycol and glycerol, are a good choice in fuel cells due to its high reactivity in electro-oxidation, inflammability, lower toxicity and high boiling point that allows tranquil handling and storage 14 , 15 . Polyalcohol fuels are valuable due to they can be produced from renewable sources 16 , 17 .…”

Accelerating photo-thermal CO2 reduction to CO, CH4 or methanol over metal/oxide semiconductor catalysts

“…Plasmonic nanoparticles (Cu and Ag) can also restructure and grow from illumination-induced localized heating ( Kumari et al., 2021 ), ( Molotskii, 2009 ). This can change the distribution of exposed crystal facets and ratio between terrace, kink, and edge sites, affecting selectivity ( Van Hardeveld and Hartog, 1969 ), ( Xiong et al., 2021 ). Also, the distribution and activation of specific reaction intermediates can be influenced by light through selective electronic injection into vacant adsorbate antibonding orbitals, leading to accelerated reaction rates or altered product distribution ( Figure 1 C) ( Tan et al., 2020 ).…”

Ag supported on alumina for the epoxidation of 1-hexene with molecular oxygen: the effect of Ag+/Ag0

“…The detailed calculation equations followed the method proposed by Huang et al and are shown in the ESI †. 3…”

“…20 Recently, Huang et al explored ultrafine cubic Cu 2 O as a nanocatalyst, which showed propylene epoxidation selectivity of over 80% but conversion of 0.2% at 90–110 °C. 3 Xie et al further demonstrated that Cl-doped rhombic dodecahedral Cu 2 O exhibited enhanced PO selectivity of 63% and conversion of 1% at 200 °C. 21 Hutchings et al showed that 1-hexen-3-one (selectivity ∼38%) and 1-hexen-3-ol (∼25%) were the major products, with 18% 1,2-epoxyhexane, using graphite-supported Au at 50 °C (0.1 Mpa O 2 ) in the solvent-free oxidation of 1-hexene.…”

“…Linear terminal olefin epoxidation is an important oxidation reaction that provides valuable chemical intermediates in the production of commodity chemicals, pharmaceuticals and drug intermediates. 1–3 The traditional epoxidation of olefins using organic peracids and chlorohydrin-based protocols always reaches satisfactory conversion/selectivity. As the demand for epoxides continues to grow, it is important to develop green and sustainable reaction system and the progressive replacement of hazardous oxidants by greener tert -butyl hydroperoxide (TBHP), hydrogen peroxide (H 2 O 2 ) and molecular oxygen (O 2 ) has been executed over several decades.…”