Catalytic epoxidation and degradation of propylene by dioxygen over silver

Portela, M.F.; Henriques, Carlos; Pires, Maria João; Ferreira, Luciana S.; Baerns, M.

doi:10.1016/0920-5861(87)80031-7

Cited by 14 publications

(4 citation statements)

References 7 publications

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“…The partial pressure of oxygen strongly increases propylene conversion but simultaneously decreases PO selectivity. 16,25,26 The same trend in catalytic performance is generally observed also with reaction temperature. Carbonio et al 102 demonstrated, using transient in situ XPS analysis, that diatomic oxygen is present at very low O coverages (<0.04 ML) on a Ag (110) surface, at low temperature.…”

Section: Discussionsupporting

confidence: 69%

“…The partial pressure of oxygen strongly increases propylene conversion but simultaneously decreases PO selectivity. ,, The same trend in catalytic performance is generally observed also with reaction temperature. Carbonio et al .…”

Section: Discussionsupporting

confidence: 61%

“…Farinha Portela et al tested bulk Cr-doped Ag catalysts and proposed that propylene adsorbs on diatomic oxygen and either desorbs as epoxide or stays bound in an open-chain form. Since total combustion and epoxidation proceed through the same oxametallacycle (OMC) intermediate, the selectivity is independent of the temperature.…”

Section: Experimental Propylene Epoxidation On Silver-based Catalystsmentioning

confidence: 99%

“…The authors concluded that NaCl addition triggers the formation of a nanocrystalline AgCl phase, where the chloride changes the electronic properties of the silver catalyst, thus inducing the adsorbed oxygen species to become electrophilic, which is effective for propylene epoxidation. Farinha Portela et al 25 tested bulk Cr-doped Ag catalysts and proposed that propylene adsorbs on diatomic oxygen and either desorbs as epoxide or stays bound in an open-chain form. Since total combustion and epoxidation proceed through the same oxametallacycle (OMC) intermediate, the selectivity is independent of the temperature.…”

Section: Experimental Propylene Epoxidation Onmentioning

confidence: 99%

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Propylene Epoxidation using Molecular Oxygen over Copper- and Silver-Based Catalysts: A Review

et al. 2020

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Propylene oxide (PO) is a versatile chemical, mainly used in the synthesis of polyurethane plastics. Propylene epoxidation using molecular oxygen could replace the tedious current synthesis protocols, which use expensive H 2 O 2 or organic peroxides as oxidants. This review focuses on the propylene epoxidation reaction using molecular oxygen in the gas phase over copper-and silver-based catalysts. Silver is a proven and industrially used ethylene epoxidation catalyst. However, it initiates allylic hydrogen stripping (AHS) in propylene epoxidation, shifting the selectivity toward unwanted acrolein and total oxidation. Nevertheless, silver has been extensively studied to determine if AHS could be mitigated by targeted active site design and various doping strategies. Copper-based catalysts have been less extensively studied but have been experimentally proved as well as theoretically confirmed that their PO selectivity is on par with that of silver. In this review, different catalyst modification strategies have been analyzed and the achieved improvements discussed. Theoretical approaches aimed at understanding the mechanism and predicting catalytic performance on the basis of electronic states (density functional theory calculations) are also reviewed. We conclude with a future outlook on how the current state of the art knowledge of active site modification and reaction engineering approaches could leverage the PO selectivity toward industrial requirements, thus enabling a breakthrough in gas-phase propylene epoxidation using O 2 .

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