Heterogeneous Catalysis of Alkene Epoxidation

Linic, Suljo; Barteau, Mark A.

doi:10.1002/9783527610044.hetcat0175

Cited by 46 publications

(76 citation statements)

References 125 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Computational results supported an oxometallocycle (OMC) mechanism, in which a key step is the formation of an OMC surface intermediate: an ethylene molecule adsorbed on an ensemble of surface oxygen atoms and a metal site [21,22]. This OMC can then form ethylene oxide (EO) or acetaldehyde, of which the latter is subsequently fully oxidized over silver [11].…”

Section: à2mentioning

confidence: 82%

Preparation and particle size effects of Ag/α-Al2O3 catalysts for ethylene epoxidation

Reijen

Kanungo

Welling

et al. 2017

Journal of Catalysis

View full text Add to dashboard Cite

a-AluminaCatalyst design Ethylene oxide Particle size effect a b s t r a c t Currently, for the industrial ethylene epoxidation a-alumina supported silver catalysts are the only catalyst of choice. We demonstrate a novel method to produce these catalysts with different silver particle sizes, but without changing other key parameters that may affect the catalytic performance such as support specific surface area or metal precursor. a-Alumina was impregnated with a silver oxalate solution, and was subsequently dried and treated in different gas atmospheres and at different temperatures to tune the silver particle sizes in the range of 20-500 nm. Particles of 20 nm exhibited a lower turnover frequency than particles of 70 nm and larger, which exhibit a constant turnover frequency, in accordance with results in literature. However, the selectivity, when measured at constant conversion, was particle size independent. This is the first time that the effect of the particle size on the selectivity of ethylene epoxidation is reported at constant conversion. This was made possible by a new method of producing supported silver catalysts, which we expect that is also applicable for silver catalysts with other supports and for the preparation of other supported metal catalysts.

show abstract

Section: à2mentioning

confidence: 82%

Preparation and particle size effects of Ag/α-Al2O3 catalysts for ethylene epoxidation

Reijen

Kanungo

Welling

et al. 2017

Journal of Catalysis

View full text Add to dashboard Cite

show abstract

“…Ethylene oxide is the largest volume compound produced by the chemical process industry via selective oxidation, with annual production valued at close to $9 billion USD ([1.4 9 10 10 kg) [2]. Despite over 70 years of industrial practice, the mechanism of the reaction remained obscure until recently [3][4][5][6][7][8][9], and the majority of significant advances in Ag-catalyst development occurred primarily through empirical approaches [10]. Silver, however, remains the cornerstone of commercial catalysts for ethylene oxide production due to its unique ability to selectively epoxidize ethylene with high selectivity.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Ethylene Oxide on Clean and Oxygen-Covered Ag(110) Surfaces

Lukaski

Barteau

2008

Catal Lett

Self Cite

View full text Add to dashboard Cite

Temperature-programmed desorption (TPD) and Density Functional Theory (DFT) were used to investigate the reactions of oxametallacycles derived from ethylene oxide on clean and oxygen-covered Ag (110) surfaces. Ethylene oxide ring-opens following adsorption at 250 K on both clean and O-covered Ag(110) to form a stable oxametallacycle. On the clean Ag(110) surface, the oxametallacycle reacts to reform the parent epoxide at 280 K during TPD, while the aldehyde isomer, acetaldehyde, is observed at higher oxametallacycle coverages. In the presence of coadsorbed oxygen atoms, a portion of the oxametallacycles dissociate to release ethylene. However, of those that react to form oxygen-containing products, the fraction forming ethylene oxide is similar to that on the clean surface. The acetaldehyde product of oxametallacycle reactions combusts via formation of acetate species; the acetates react to form CO 2 at temperatures as low as 360 K on the O-covered surface. No evidence was observed for other combustion channels. This work provides experimental evidence for the connection of oxametallacycles to combustion via acetaldehyde formation as well as to ringclosure to form ethylene oxide.

show abstract

“…The mechanism starts with olefin adsorption on the oxidized silver surface, atomic oxygen being the active species. [22,27,33] Activation of the allylic proton (step A) leads to formation of a radical intermediate that subsequently would generate acrolein and/or CO 2 , depending on the operating reaction conditions. [7,[33][34][35][36][37] Activation of the primary (step C) or secondary (step B) vinylic carbon atoms ends up with formation of a cyclic structure commonly referred as oxametallacycle or OMMP, where M stands for the metal atom inserted and the last letter is the initial letter for the olefin precursor, propylene (P) in this case.…”

Section: Introductionmentioning

confidence: 99%

“…After extensive theoretical and experimental investigations of the ethylene epoxidation process over silver-based catalysts [6,12,[22][23][24][25][26][27][28][29][30][31][32] , a fairly good understanding of the reaction mechanism, [22][23][24][25][26][27][28][29][30] the role of catalyst promoters (such as chlorine and alkali metals) [6,12] and other factors such as catalyst particle size, shape and morphology [31][32] on the catalytic performance has been achieved. Direct ethylene and propylene epoxidation over silver-based catalysts using oxygen as oxidizing agent are generally assumed to follow the same reaction pathway, which is schematically shown in Scheme 1.…”

Section: Introductionmentioning

confidence: 99%

Aerobic epoxidation of propene over silver (111) and (100) facet catalysts

Pulido

Concepción

Boronat

et al. 2012

Journal of Catalysis

View full text Add to dashboard Cite

Academic Press; ElsevierPulido Junquera, MA.; Concepción Heydorn, P.; Boronat Zaragoza, M.; Corma Canós, A. (2012). Aerobic epoxidation of propene over silver (111) and (100) AbstractCatalytic performance of single crystal Ag(100) and Ag(111) catalysts for propene oxidation has been investigated by means of Raman spectroscopy and mass spectrometry, and the energy profile has been obtained at the DFT-D level. It has been theoretically found, and confirmed by Raman spectroscopy, that Ag(100) surface is more reactive towards O 2 dissociation than Ag(111), and that adsorbed oxo-species are more strongly bonded to the Ag(100) facet. The higher selectivity towards propylene oxide (PO) observed for the Ag(100) catalyst can be rationalized from theoretical calculations indicating that the activation barriers for formation of the allylic intermediate -precursor of combustion products-are rather similar on both silver surfaces, whereas energy barriers on the reaction pathways for formation of PO and carbonylic products (acetone and propanal) are systematically smaller on the Ag (100) surface.

show abstract

Heterogeneous Catalysis of Alkene Epoxidation

Cited by 46 publications

References 125 publications

Preparation and particle size effects of Ag/α-Al2O3 catalysts for ethylene epoxidation

Preparation and particle size effects of Ag/α-Al2O3 catalysts for ethylene epoxidation

Investigation of Ethylene Oxide on Clean and Oxygen-Covered Ag(110) Surfaces

Aerobic epoxidation of propene over silver (111) and (100) facet catalysts

Contact Info

Product

Resources

About