Reactivity and stability investigation of supported molybdenum oxide catalysts for the hydrodeoxygenation (HDO) of m-cresol

Shetty, Manish; Murugappan, Karthick; Prasomsri, Teerawit; Green, William; Román‐Leshkov, Yuriy

doi:10.1016/j.jcat.2015.07.034

Cited by 213 publications

(192 citation statements)

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“…[36,37] Molybdenumc arbide-am aterialf eaturing redox sites and tunable Brønsted acidity [38][39][40] -has been shown to be ah ighly active HDO catalyst, but with low selectivity for alkylation (< 1%), [41,42] whereas nickel phosphides have shown improved selectivity for alkylation approaching 15 %. [46] Ceria-zirconia catalysts also show high activity for the demethoxylation of guaiacol to phenol 80-90 %withmoderate yields of cresols 6-10 %. [46] Ceria-zirconia catalysts also show high activity for the demethoxylation of guaiacol to phenol 80-90 %withmoderate yields of cresols 6-10 %.…”

Section: Introductionmentioning

confidence: 99%

Bifunctional Molybdenum Polyoxometalates for the Combined Hydrodeoxygenation and Alkylation of Lignin‐Derived Model Phenolics

et al. 2017

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Reductive catalytic fractionation of biomass has recently emerged as a powerful lignin extraction and depolymerization method to produce monomeric aromatic oxygenates in high yields. Here, bifunctional molybdenum-based polyoxometalates supported on titania (POM/TiO ) are shown to promote tandem hydrodeoxygenation (HDO) and alkylation reactions, converting lignin-derived oxygenated aromatics into alkylated benzenes and alkylated phenols in high yields. In particular, anisole and 4-propylguaiacol were used as model compounds for this gas-phase study using a packed-bed flow reactor. For anisole, 30 % selectivity for alkylated aromatic compounds (54 % C-alkylation of the methoxy groups by methyl balance) with an overall 72 % selectivity for HDO at 82 % anisole conversion was observed over H PMo O /TiO at 7 h on stream. Under similar conditions, 4-propylguaiacol was mainly converted into 4-propylphenol and alkylated 4-propylphenols with a selectivity to alkylated 4-propylphenols of 42 % (77 % C-alkylation) with a total HDO selectivity to 4-propylbenzene and alkylated 4-propylbenzenes of 4 % at 92 % conversion (7 h on stream). Higher catalyst loadings pushed the 4-propylguaiacol conversion to 100 % and resulted in a higher selectivity to propylbenzene of 41 %, alkylated aromatics of 21 % and alkylated phenols of 17 % (51 % C-alkylation). The reactivity studies coupled with catalyst characterization revealed that Lewis acid sites act synergistically with neighboring Brønsted acid sites to simultaneously promote alkylation and hydrodeoxygenation activity. A reaction mechanism is proposed involving activation of the ether bond on a Lewis acid site, followed by methyl transfer and C-alkylation. Mo-based POMs represent a versatile catalytic platform to simultaneously upgrade lignin-derived oxygenated aromatics into alkylated arenes.

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Section: Introductionmentioning

confidence: 99%

Bifunctional Molybdenum Polyoxometalates for the Combined Hydrodeoxygenation and Alkylation of Lignin‐Derived Model Phenolics

et al. 2017

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“…Their acid-based properties strongly affect PyA selectivity. TiO 2 , ZrO 2 , and SnO 2 typically result in higher selectivity to pyruvates compared to conventional oxidation catalysts such as MoO 3 , [14][15][16][17] 29 The high catalytic performance of these catalysts in selective oxidation of organic molecules has been linked to highly reactive sites at the interface between the two oxides. 30,31 Accordingly, it has been proposed that the catalytic performance of such materials crucially depends on the dispersion of the MoO 3 phase on TiO 2 .…”

Section: Introductionmentioning

confidence: 99%

MoO₃–TiO₂ synergy in oxidative dehydrogenation of lactic acid to pyruvic acid

et al. 2017

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An efficient catalytic process for the oxidative dehydrogenation of biomass-derived lactic acid by earthabundant MoO 3 /TiO 2 mixed oxide catalysts is presented. A series of MoO 3 /TiO 2 materials with varied MoO 3 loadings were prepared and their performance in the aerobic and anaerobic conversion of lactic acid was evaluated. A strong synergistic effect between MoO 3 and TiO 2 components of the mixed oxide catalyst was observed. Optimum catalysts in terms of activity and pyruvic acid selectivity can be obtained by ensuring a high dispersion of MoO x species on the titania surface. Mo-oxide aggregates catalyze undesired side-reactions. XPS measurements indicate that the redox processes involving supported Mo ions are crucial for the catalytic cycle. A mechanism is proposed, in which lactic acid adsorbs onto basic sites of the titania surface and is dehydrogenated over the MovO acid-base pair of a vicinal tetrahedral Mo site. The catalytic cycle closes by hydrolysis of surface pyruvate and water desorption accompanied by the reduction of the Mo center, which is finally oxidized by O 2 to regenerate the initial active site. Under anaerobic conditions, a less efficient catalytic cycle is established involving a bimolecular hydrogen transfer mechanism, selectively yielding propionic and pyruvic acids as the major products. The optimum catalyst is 2 wt% MoO 3 /TiO 2 predominantly containing tetrahedral Mo species. With this catalyst the oxidative conversion of lactic acid at 200°C proceeds with a selectivity of ca. 80% to pyruvic acid. The pyruvic acid productivity is 0.56 g g −1 h −1 .

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“…Its activity is directly related to the support employed, being highly selective to the direct deoxygenation route (DDO) [22]. These authors concluded that the most reactive materials were those supported on ZrO 2 and TiO 2 that favor the formation of Mo(V) or Mo(III) species.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, some authors obtained high HDO activity and selectivity towards non-oxygenated biomass products [23,24]. Román-Leshkov et al [22] found that MoO 3 is active and selective in HDO with hydrogen pressures of 1 bar and temperatures at 300 • C. The MoO 3 catalyst showed a high tolerance to coke formation and was also regenerated by calcination without loss of activity. They further found that the catalyst was gradually deactivated due to the formation of inactive Mo(IV) upon reduction.…”

Section: Introductionmentioning

confidence: 99%

“…Considering the material support, a great variety of supports have been evaluated such as TiO 2 , ZrO 2 , SiO 2 or ZSM-5 [8,15,16,22,27,28]. More recently, the layered double hydroxides (LDH) and their derived metal oxides (DMO) were used as catalytic supports and have proved to be very interesting materials due to their low cost and high possibilities of modification [29].…”

Section: Introductionmentioning

confidence: 99%

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Zirconium Phosphate Heterostructures as Catalyst Support in Hydrodeoxygenation Reactions

et al. 2017

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Abstract:A porous phosphate heterostructure (PPHs) formed by a layered zirconium(IV) phosphate expanded with silica galleries was prepared presenting a P/Zr molar ratio equal to 2 and a (Si + Zr)/P ratio equal to 3. This pillared zirconium phosphate heterostructure was used as a catalyst support for bi-functional catalysts based on noble metals (Pt or Pd) and molybdenum oxide containing a total metallic loading of 2 wt % and Pt(Pd)/Mo molar ratio equal to 1. The catalysts prepared were characterized by different experimental techniques and evaluated in the hydrodeoxygenation (HDO) reaction of dibenzofuran (DBF) as a model compound present in biomass derived bio-oil, at different reaction pressures. The catalyst characterization evidenced that a high dispersion of the active phase can be achieved by using these materials, as observed from transmission electron microscopy (TEM) characterization, where the presence of small particles in the nanometric scale is noticeable. Moreover, the textural and acidic properties of the phosphate heterostructure are barely affected by the incorporation of metals into its structure. Characterization results evidenced that the presented material is a good candidate to be used as a material support. In both cases, high conversions and high selectivities to deoxygenated compounds were achieved and the active phase played an important role. Thus, Pt/Mo presented a better hydrogenolysis capability, being more selective to O-free products; whereas, Pd/Mo showed a greater hydrogenation ability being more affected by changes in pressure conditions.

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Reactivity and stability investigation of supported molybdenum oxide catalysts for the hydrodeoxygenation (HDO) of m-cresol

Cited by 213 publications

References 93 publications

Bifunctional Molybdenum Polyoxometalates for the Combined Hydrodeoxygenation and Alkylation of Lignin‐Derived Model Phenolics

Bifunctional Molybdenum Polyoxometalates for the Combined Hydrodeoxygenation and Alkylation of Lignin‐Derived Model Phenolics

MoO₃–TiO₂ synergy in oxidative dehydrogenation of lactic acid to pyruvic acid

Zirconium Phosphate Heterostructures as Catalyst Support in Hydrodeoxygenation Reactions

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Reactivity and stability investigation of supported molybdenum oxide catalysts for the hydrodeoxygenation (HDO) of m-cresol

Cited by 213 publications

References 93 publications

Bifunctional Molybdenum Polyoxometalates for the Combined Hydrodeoxygenation and Alkylation of Lignin‐Derived Model Phenolics

Bifunctional Molybdenum Polyoxometalates for the Combined Hydrodeoxygenation and Alkylation of Lignin‐Derived Model Phenolics

MoO3–TiO2 synergy in oxidative dehydrogenation of lactic acid to pyruvic acid

Zirconium Phosphate Heterostructures as Catalyst Support in Hydrodeoxygenation Reactions

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MoO₃–TiO₂ synergy in oxidative dehydrogenation of lactic acid to pyruvic acid