Non-oxidative dehydrogenation of isobutane over supported vanadium oxide: nature of the active sites and coke formation

Rodriguez‐Gomez, Alberto; Chowdhury, Abhishek Dutta; Çağlayan, Mustafa; Bau, Jeremy A.; Abou-Hamad, Edy; Gascón, Jorge

doi:10.1039/d0cy01174f

Cited by 12 publications

(5 citation statements)

References 114 publications

(177 reference statements)

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“…The coordination structures of the VO x species include isolated tetrahedral VO 4 , oligomeric tetrahedral VO x , polymerized octahedral VO x, and V 2 O 5 microcrystals. [37][38][39] Figure 5 and Table 2 present the deconvoluted UV-Vis DR spectra of dehydrated x VÀ SiO 2 and the estimation of the percentage of different V species in the dehydrated samples. Four absorption bands are observed for the x VÀ SiO 2 catalyst, as shown in Figure 5.…”

Section: Uv-vis Drs Resultsmentioning

confidence: 99%

“…The position of the O→V electron transition varies for different vanadium species, providing a means to assess the state of vanadium species on the catalyst. The coordination structures of the VO x species include isolated tetrahedral VO 4 , oligomeric tetrahedral VO x , polymerized octahedral VO x , and V 2 O 5 microcrystals [37–39] . Figure 5 and Table 2 present the deconvoluted UV‐Vis DR spectra of dehydrated x V−SiO 2 and the estimation of the percentage of different V species in the dehydrated samples.…”

Section: Resultsmentioning

confidence: 99%

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One‐pot synthesis of V doped mesoporous SiO₂ catalysts for selective oxidation of ethane and propane

Song

Fan

et al. 2023

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A series of vanadium‐doped mesoporous SiO2 catalysts were prepared using a one‐pot emulsion method. The effects of VOx species with different structures on C−H bond activation and product selectivity in ethane and propane selective oxidation were investigated using X‐ray diffraction (XRD), N2 adsorption‐desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman, ultraviolet‐visible diffuse reflectance spectroscopy (UV‐Vis DRS), hydrogen temperature programmed reduction (H2‐TPR), and ammonia temperature programmed desorption (NH3‐TPD) characterizations. The results revealed that the highly dispersed isolated tetrahedral VOx species on the catalyst gradually polymerized into highly dispersed oligomeric VOx species with the increased V loading. The former is beneficial for the formation of olefins and total aldehydes during the selective oxidation of propane. Oligomeric VOx species are conducive to improving the selectivity of ethylene and acetaldehyde in the selective oxidation of ethane. The highest catalytic performances for selective oxidation of ethane and propane were obtained at a temperature of 650 °C. The conversion of ethane was 41.6 %, with a corresponding yield of ethylene and acetaldehyde of 23.6 % over a 0.5 V−SiO2 catalyst. In contrast, the propane conversion was 61.5 %, with a corresponding total yield of olefins and aldehydes of 41.3 % over a 1.0 V−SiO2 catalyst.

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Section: Uv-vis Drs Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

One‐pot synthesis of V doped mesoporous SiO₂ catalysts for selective oxidation of ethane and propane

Song

Fan

et al. 2023

ChemistrySelect

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“…In this spirit, high-severity fluid catalytic cracking (FCC) processes that maximize short olefin productivity along with other on-purpose processes have been developed. − One outstanding example of the latter is the production of butylenes, where nonoxidative dehydrogenation of isobutane is currently used to cover the demand for isobutylene, which is employed as a precursor of high-octane oxygenates (MTBE and ETBE) and in the production of butyl rubber . As for the oxidative route with di-oxygen, despite favorable from a thermodynamic and kinetic point of view, has disadvantages such as the low selectivities obtained so far or the high exothermicity and risk of formation of explosive atmospheres. , Commercial catalysts, based on platinum or chromium, usually promoted with tin and alkali metals, respectively, have shown the best catalytic performance. , However, the high cost of platinum and the toxicity of chromium (Cr 6+ species) have encouraged the search for alternatives such as vanadium − and, to a lesser extent, molybdenum, , zirconium, , gallium, , indium, and iron oxides, − which have all shown some promise as potential active phases. Among them, Fe is especially interesting because of its natural abundance, low cost, and low toxicity.…”

Section: Introductionmentioning

confidence: 99%

Fe-MOF Materials as Precursors for the Catalytic Dehydrogenation of Isobutane

et al. 2022

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We investigate the use of a series of iron-based metal−organic frameworks as precursors for the manufacturing of isobutane dehydrogenation catalysts. Both the as-prepared and spent catalysts were characterized by PXRD, XPS, PDF, ICP-OES, and CHNS+O to determine the physicochemical properties of the materials and the active phases responsible for the catalytic activity. In contrast to the previous literature, our results indicate that (i) the formation of metallic Fe under reaction conditions results in secondary cracking and coke formation; (ii) the formation of iron carbide only contributes to coke formation; and (iii) the stabilization of the Fe 2+ species is paramount to achieve stable and selective catalysts. In this sense, promotion with potassium and incorporation of titanium improve the catalytic performance. While potassium is well known to improve the selectivity in iron-catalyzed dehydrogenation reactions, the unprecedented effect of titanium in the stabilization of a nanometric titanomaghemite phase, even under reductive reaction conditions, results in a moderately active and highly selective catalyst for several hours on stream with a remarkable resistance to coke formation.

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“…However, the highly expensive Pt-based or toxic CrO x -based catalysts in current commercial applications restrict its further developments [2,6]. Instead, supported VO xbased catalysts provide a new solution compared with Pt-based and CrO x -based catalysts owing to the competitive performance, low cost and low toxicity [2,[9][10][11][12][13][14][15][16][17][18][19][20]. Nevertheless, due to the complex structures and properties of supported VO x species, the catalytic behaviors of active sites on PDH still remain elusive.…”

Section: Introductionmentioning

confidence: 99%

Roles of V−O sites for non-oxidative propane dehydrogenation over supported vanadium oxides

et al. 2022

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Supported vanadium oxides (VO x ) are alternative candidates for non-oxidative propane dehydrogenation (PDH) owing to their competitive performance. This paper describes the roles of V-O sites on PDH over monomeric VO x species supported on ZrO 2 , Al 2 O 3 and SiO 2 . With the control of pre-reduction, stable structures of V-O sites are obtained for PDH, including V-O-support (V-O-S), V-OH and V=O sites. By tuning the V densities over individual support, the propylene formation rate shows a linear correlation with the number of the V-O-S site, which indicates the V-O-S site plays a decisive role in PDH rather than V-OH and V=O sites. Moreover, the specific activity per V-O-S site over ZrO 2 (8.2 × 10 −3 s −1 ) is higher than those over Al 2 O 3 (6.7 × 10 −3 s −1 ) and SiO 2 (2.8 × 10 −3 s −1 ), due to the discrepant Lewis acidity of various V-O-S sites. This research provides a fundamental insight into the intrinsic nature of V-O sites for non-oxidative propane dehydrogenation.

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Non-oxidative dehydrogenation of isobutane over supported vanadium oxide: nature of the active sites and coke formation

Abstract:
We combine Raman spectroscopy, electron paramagnetic resonance (EPR), x-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), x-ray diffraction (XRD), high-field 51V-solid-state magic angle spinning NMR spectroscopy (ssNMR), transmission electron microscopy (TEM)...

Cited by 12 publications

References 114 publications

One‐pot synthesis of V doped mesoporous SiO₂ catalysts for selective oxidation of ethane and propane

One‐pot synthesis of V doped mesoporous SiO₂ catalysts for selective oxidation of ethane and propane

Fe-MOF Materials as Precursors for the Catalytic Dehydrogenation of Isobutane

Roles of V−O sites for non-oxidative propane dehydrogenation over supported vanadium oxides

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Non-oxidative dehydrogenation of isobutane over supported vanadium oxide: nature of the active sites and coke formation

Cited by 12 publications

References 114 publications

One‐pot synthesis of V doped mesoporous SiO2 catalysts for selective oxidation of ethane and propane

One‐pot synthesis of V doped mesoporous SiO2 catalysts for selective oxidation of ethane and propane

Fe-MOF Materials as Precursors for the Catalytic Dehydrogenation of Isobutane

Roles of V−O sites for non-oxidative propane dehydrogenation over supported vanadium oxides

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One‐pot synthesis of V doped mesoporous SiO₂ catalysts for selective oxidation of ethane and propane

One‐pot synthesis of V doped mesoporous SiO₂ catalysts for selective oxidation of ethane and propane