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Heterogeneously catalyzed deoxydehydration (DODH) ordinarily occurs over relatively costly oxide supported ReO x sites and is an effective process for the removal of vicinal OH groups that are common in biomass-derived chemicals. Here, through first-principles calculations, we investigate the DODH of 1,4-anhydroerythritol over anatase TiO 2 (101)-supported ReO x and MoO x . The atomistic structures of ReO x and MoO x under typical reaction conditions were identified with constrained thermodynamics calculations as ReO 2 (2O)/6H–TiO 2 and MoO(2O)/3H–TiO 2 , respectively. The calculated energy profile and developed microkinetic reaction model suggest that both ReO 2 (2O)/6H–TiO 2 and MoO(2O)/3H–TiO 2 exhibit a relatively low DODH activity at 413 K. However, at higher temperatures such as 473 K, MoO(2O)/TiO 2 (101) was found to exhibit a reasonably high catalytic activity similar to ReO 2 (2O)/6H–TiO 2 , consistent with a recent experimental study. Mechanistically, the first O–H bond cleavage of 1,4-anhydroerythritol and the dihydrofuran extrusion were found to be the rate-controlling steps for the reaction over ReO 2 (2O)/6H–TiO 2 and MoO(2O)/3H–TiO 2 , respectively. Thus, this study clarifies the mechanism of the DODH over oxide-supported catalysts and provides meaningful insight into the design of low-cost DODH catalysts.
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Highly efficient deoxydehydration and hydrodeoxygenation on MoS2-supported transition metal atoms through a C-H activation mechanism
Deoxydehydration (DODH) is an efficient process for the removal of vicinal OH groups of a diol or polyol. Conventional DODH reactions usually take place at a single-site MOx (M=Re, Mo, V etc.) active center, which proceed through a diol condensation step, an alkene extrusion step and a catalyst regeneration (or reduction) step. Here, we suggest that MoS2-supported transition metal atoms allow for the DODH reaction to occur through an alternative mechanism, whereby the C-H bond of a diol is activated first, which facilitates the C-OH bond cleavage on a neighboring carbon. The removal of the second OH group is also facile over the proposed catalysts. Our kinetic studies suggest that the DODH of ethylene glycol on Ru2/MoS2, Ir2/MoS2 and Ru3/MoS2 are highly active with predicted turnover frequencies of over 1/s. Thus, our study suggests a possible approach for the design of highly active DODH catalysts. Apart from being a DODH catalyst, the proposed MoS2-supported catalysts are also highly active as hydrodeoxygenation catalyst for the removal of alcohol OH groups.
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- Award ID(s):
- 1632824
- PAR ID:
- 10182076
- Date Published:
- Journal Name:
- ACS Catalysis
- ISSN:
- 2155-5435
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1021/acscatal.0c02669
