Kinetics study of C 2+ oxygenates synthesis from syngas over Rh–MnO x /SiO 2 catalysts

Mao, Wei; Su, Junjie; Zhang, Zhengpai; Xu, Xiaoyun; Dai, Weiwei; Fu, Donglong; Xu, Jing; Zhou, Xinggui; Han, Yi‐Fan

doi:10.1016/j.ces.2015.02.035

Cited by 35 publications

(36 citation statements)

References 67 publications

(77 reference statements)

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“…Compared to the monometallic Rh/SiO 2 catalyst 8 (X CO =4.8 %, S EtOH =6.5 %; Table S2), all Mn‐promoted catalysts show a substantially higher activity and ethanol selectivity. The enhancement of the catalytic performance due to the close proximity between Rh and MnO x was also observed for other reported RhMnO x catalysts ,. The catalytic results show a lower CO conversion of the SSP‐originated catalysts 3–5 compared to the ‘traditionally’ prepared catalyst 6 .…”

Section: Resultssupporting

confidence: 75%

“…According to a recent review by Luk et al ., the most performant Mn‐promoted Rh catalysts in the conversion of StE showed an ethanol selectivity of 17.7 % and an overall C 2+ oxygenate selectivity of 42.0 % at a CO conversion of 17.0 %. These catalysts were prepared by incipient wetness impregnation of the respective metal nitrates and subsequent calcination …”

Section: Introductionmentioning

confidence: 99%

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From a Molecular Single‐Source Precursor to a Selective High‐Performance RhMnO_x Catalyst for the Conversion of Syngas to Ethanol

et al. 2019

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The first molecular carbonyl RhMn cluster Na2[Rh3Mn3(CO)18] 2 with highly labile CO ligands and predefined Rh‐Mn bonds could be realized and successfully used for the preparation of the silica (davisil)‐supported RhMnOx catalysts for the conversion of syngas (CO, H2) to ethanol (StE); it has been synthesized through the salt metathesis reaction of RhCl3 with Na[Mn(CO)5] 1 and isolated in 49 % yields. The dianionic Rh3Mn3 cluster core of 2 acts as a molecular single‐source precursor (SSP) for the low‐temperature preparation of selective high‐performance RhMnOx catalysts. Impregnation of 2 on silica (davisil) led to three different silica‐supported RhMnOx catalysts with dispersed Rh nanoparticles tightly surrounded by a MnOx matrix. By using this molecular SSP approach, Rh and MnOx are located in close proximity on the oxide support. Therefore, the number of tilted CO adsorption sites at the RhMnOx interface increased leading to a significant enhancement in selectivity and performance. Investigations on the spent catalysts after several hours time‐on‐stream revealed the influence of rhodium carbide RhCx formation on the long‐term stability.

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Section: Resultssupporting

confidence: 75%

Section: Introductionmentioning

confidence: 99%

From a Molecular Single‐Source Precursor to a Selective High‐Performance RhMnO_x Catalyst for the Conversion of Syngas to Ethanol

et al. 2019

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“…1, le middle). 23,37,49 The peak shi suggests that Mn is in close contact with Rh, which apparently impedes the reduction of Rh oxide species. The second peak located at 500 K is increased in intensity compared to the unpromoted catalyst indicating that Mn has an impact on the nanostructure of the calcined precursor.…”

Section: Resultsmentioning

confidence: 99%

“…19 Furthermore, Mn oxide has been suggested to facilitate CO dissociation through the formation of a tilted CO species adsorbed in di-hapto conguration at the Rh-MnO x interface and to stabilize acyl species, known as the precursors for oxygenates. 12,20,24 On the other hand, the modication of metallic Rh with MnO x was interpreted in terms of a stabilization of non-dissociatively adsorbed CO on the Rh surface, which enhanced the CO insertion to form CH x CO intermediates. 23,24 Recently, model catalysts have been prepared by using atomic layer deposition.…”

Section: 34mentioning

confidence: 99%

“…12,20,24 On the other hand, the modication of metallic Rh with MnO x was interpreted in terms of a stabilization of non-dissociatively adsorbed CO on the Rh surface, which enhanced the CO insertion to form CH x CO intermediates. 23,24 Recently, model catalysts have been prepared by using atomic layer deposition. 25 The results suggest that MnO x over-layers on Rh appear to suffer from poor stability upon CO adsorption and are less effective than a thin MnO x sandwich layer in between the silica support and the Rh particle in enhancing the Rh-MnO x interface that facilitates CO dissociation and stabilizes the transition state of C 2+ oxygenate formation.…”

Section: 34mentioning

confidence: 99%

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Insights into structure and dynamics of (Mn,Fe)O_x-promoted Rh nanoparticles

et al. 2018

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The mutual interaction between Rh nanoparticles and manganese/iron oxide promoters in silica-supported Rh catalysts for the hydrogenation of CO to higher alcohols was analyzed by applying a combination of integral techniques including temperature-programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS) and Fourier transform infrared (FTIR) spectroscopy with local analysis by using high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) in combination with energy dispersive X-ray spectroscopy (EDX). The promoted catalysts show reduced CO adsorption capacity as evidenced through FTIR spectroscopy, which is attributed to a perforated core-shell structure of the Rh nano-particles in accordance with the microstructural analysis from electron microscopy. Iron and manganese occur in low formal oxidation states between 2+ and zero in the reduced catalysts as shown by using TPR and XAS. Infrared spectroscopy measured in diffuse reflectance at reaction temperature and pressure indicates that partial coverage of the Rh particles is maintained at reaction temperature under operation and that the remaining accessible metal adsorption sites might be catalytically less relevant because the hydrogenation of adsorbed carbonyl species at 523 K and 30 bar hydrogen essentially failed. It is concluded that Rh 0 is poisoned due to the adsorption of CO under the reaction conditions of CO hydrogenation. The active sites

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MnO_x promotional effects on olefins synthesis directly from syngas over bimetallic Fe‐MnO_x/SiO₂ catalysts

Zhang

Dai

et al. 2017

AIChE Journal

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The direct synthesis of lower olefins via the Fischer‐Tropsch reaction (FTO) has been performed over a series of Fe‐MnOx/SiO2 catalysts. The addition of MnOx could improve the dispersion of iron species, and promote the reduction of iron oxide during the activation and subsequent carburization. Moreover, the results of characterization demonstrated that MnOx could enhance the surface basicity of the catalysts due to electronic effects and promote the formation of iron carbides. For the first time, the intrinsic power‐law kinetics for FTO was obtained for both Fe20/SiO2 and Fe20‐Mn1/SiO2 catalysts. Kinetic parameters and structure characterizations indicated that MnOx could facilitate the CO dissociation on the catalyst surface, thus enhancing the adsorption strength and capacity of surface carbonaceous intermediates. The weak hydrogenation of carbonaceous species would boost the selectivities toward lower olefins. Finally, a plausible mechanism for FTO, involving the promotional effects of MnOx on Fe, has been proposed. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4451–4464, 2017

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Kinetics study of C 2+ oxygenates synthesis from syngas over Rh–MnO x /SiO 2 catalysts

Cited by 35 publications

References 67 publications

From a Molecular Single‐Source Precursor to a Selective High‐Performance RhMnO_x Catalyst for the Conversion of Syngas to Ethanol

From a Molecular Single‐Source Precursor to a Selective High‐Performance RhMnO_x Catalyst for the Conversion of Syngas to Ethanol

Insights into structure and dynamics of (Mn,Fe)O_x-promoted Rh nanoparticles

MnO_x promotional effects on olefins synthesis directly from syngas over bimetallic Fe‐MnO_x/SiO₂ catalysts

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Kinetics study of C 2+ oxygenates synthesis from syngas over Rh–MnO x /SiO 2 catalysts

Cited by 35 publications

References 67 publications

From a Molecular Single‐Source Precursor to a Selective High‐Performance RhMnOx Catalyst for the Conversion of Syngas to Ethanol

From a Molecular Single‐Source Precursor to a Selective High‐Performance RhMnOx Catalyst for the Conversion of Syngas to Ethanol

Insights into structure and dynamics of (Mn,Fe)Ox-promoted Rh nanoparticles

MnOx promotional effects on olefins synthesis directly from syngas over bimetallic Fe‐MnOx/SiO2 catalysts

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From a Molecular Single‐Source Precursor to a Selective High‐Performance RhMnO_x Catalyst for the Conversion of Syngas to Ethanol

From a Molecular Single‐Source Precursor to a Selective High‐Performance RhMnO_x Catalyst for the Conversion of Syngas to Ethanol

Insights into structure and dynamics of (Mn,Fe)O_x-promoted Rh nanoparticles

MnO_x promotional effects on olefins synthesis directly from syngas over bimetallic Fe‐MnO_x/SiO₂ catalysts