Kinetic study of the selective oxidation of propene with O2 over Au–Ti catalysts in the presence of water

Ferrández, D.M. Pérez; Fernández, Israel; Teley, M.P.G.; Croon, de M.H.J.M.; Schouten, J.C.; Nijhuis, T.A.

doi:10.1016/j.jcat.2015.07.024

Cited by 30 publications

(20 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Because water is regenerated in steps 4 and 5, its role is that of a co-catalyst and not of a stoichiometric reactant. In agreement with our study, Nijhuis and coworkers [58] showed that even though water was not consumed, its presence is critical for the formation of the active hydroperoxy species. Steps 5 and 6 are the rate-determining-steps of the proposed mechanism.…”

Section: H 2 O* + O 2 * Hoo* + Ho* K 3eqsupporting

confidence: 93%

Water-assisted oxygen activation during gold-catalyzed formic acid decomposition under SCR-relevant conditions

Sridhar

Ferri

Bokhoven

et al. 2017

Journal of Catalysis

View full text Add to dashboard Cite

Owing to the problems associated with the usage of urea as the ammonia precursor compound in the selective catalytic reduction (SCR) process in automobiles, alternative compounds such as ammonium formate, methanamide and guanidinium formate have been suggested as more efficient and cleaner candidates. For the application of such formate-based ammonia precursors, a fundamental understanding of catalytic formic acid decomposition in the presence of the diesel exhaust components water and oxygen is required. Oxygen activation is a reaction step common to many catalytic processes. We observed that oxygen activation over titania and base-modified titania-supported gold catalysts is greatly enhanced in the presence of water, resulting in a significant increase in carbon dioxide production from the decomposition of formic acid. Unlike the supports, gold catalyzed the selective production of carbon dioxide. Monodentate and bidentate formates are the kinetically relevant surface species for carbon monoxide and carbon dioxide production, respectively. The support acts as a reservoir, storing bidentate formates that do not react in the steady state when formic acid and oxygen (and water) are co-fed. However, during transient experiments, when the feed is switched from formic acid to oxygen (and water), they are reactivated upon reverse spillover to the active site associated with gold, where they decompose to carbon dioxide. In the presence of oxygen and water, carbon monoxide oxidation and the water gas shift reaction do not produce carbon dioxide. Instead, a direct oxidative-dehydrogenationtype (ODH) pathway proceeds, which strongly differs from stoichiometric formic acid decomposition. A kinetically consistent mechanism is proposed in which the hydroperoxy species facilitate the C-H bond cleavage of formates to release carbon dioxide and water in the rate-determining step.

show abstract

Section: H 2 O* + O 2 * Hoo* + Ho* K 3eqsupporting

confidence: 93%

Water-assisted oxygen activation during gold-catalyzed formic acid decomposition under SCR-relevant conditions

Sridhar

Ferri

Bokhoven

et al. 2017

Journal of Catalysis

View full text Add to dashboard Cite

show abstract

“…In the case of TS-1 as support a correlation between the variation in the UV/Vis band characteristic for Ti-OOH and the production of PO is consistent with Ti-OOH as the active oxygen intermediate [51]. The same conclusion was reached in a kinetic study by Perez Fernandez et al [25 ]. Both groups agree that Au-O species are responsible for the formation of the undesired products CO 2 and acrolein.…”

Section: Propylene Epoxidationsupporting

confidence: 70%

Water-assisted oxygen activation during selective oxidation reactions

Tran

Doan

Chandler

et al. 2016

Current Opinion in Chemical Engineering

View full text Add to dashboard Cite

“…Using oxygen or air as an oxidizing agent instead of toxic chlorine or costly and explosive peroxides is a long‐term goal for PO production. Recently, scientists have proposed a new approach for PO synthesis using an O 2 –H 2 O mixture as an oxidant and supported Au as a catalyst . In this process, O 2 or H 2 O alone cannot achieve the selective transformation of C 3 H 6 to PO.…”

Section: Experimental Observationsmentioning

confidence: 99%

The promotional role of water in heterogeneous catalysis: mechanism insights from computational modeling

Chang

Huang

2016

WIREs Comput Mol Sci

View full text Add to dashboard Cite

Water is the key to life in our planet. As one of the most abundant resources on the earth, water may play important roles in chemical reactions in addition to being a reaction medium. In this review, we highlight recent advances in experimental observations and mechanistic understanding of the promotional role of water in chemical reactions, with an emphasis on the essential effects of water in heterogeneous catalysis. As water may exist in molecular state or dissociate to hydroxyl (OH) and hydrogen (H) species on catalyst surfaces, we have outlined the roles of water from three aspects: (1) the promotional role of molecular water including the solvation-like effect and water-mediated H-transfer, (2) the promotional role of OH/OH − and H/H + species, and (3) some miscellaneous effects of water, such as water-assisted carbon removal, surface reconstruction, and active sites blocking. The results discussed here provide a fundamental understanding of the promotional role of water in heterogeneous reactions and may inspire the theoretical studies of water effects on other fields of chemistry and atmospheric science as well.

show abstract

Kinetic study of the selective oxidation of propene with O2 over Au–Ti catalysts in the presence of water

Cited by 30 publications

References 39 publications

Water-assisted oxygen activation during gold-catalyzed formic acid decomposition under SCR-relevant conditions

Water-assisted oxygen activation during gold-catalyzed formic acid decomposition under SCR-relevant conditions

Water-assisted oxygen activation during selective oxidation reactions

The promotional role of water in heterogeneous catalysis: mechanism insights from computational modeling

Contact Info

Product

Resources

About