Propylene epoxidation with in situ generated H2O2 in supercritical conditions

Prieto, Alejandro; Palomino, Miguel; Díaz, Urbano; Corma, Avelino

doi:10.1016/j.cattod.2013.10.004

Cited by 18 publications

(14 citation statements)

References 44 publications

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“…Therefore, several attempts have been made to utilize hydrogen peroxide produced in-situ from a mixture of H 2 and O 2 gas for a liquid-phase epoxidation process [5,14,25,[27][28][29][30][31][32][33][34][35][36]. For this purpose, the TS-1 catalyst modified by the impregnation of precious metals such as palladium, platinum and gold has been used to generate hydrogen peroxide and oxidize propene at the same time.…”

Section: Introductionmentioning

confidence: 99%

The effects of impregnation of precious metals on the catalytic activity of titanium silicate (TS-1) in epoxidation of propene using hydrogen peroxide

Shin

Lee

Chadwick

2016

Journal of Molecular Catalysis A: Chemical

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Propene oxide is an important chemical intermediate and titanium silicalite (TS-1) has been widely investigated as a promising catalyst for the direct epoxidation of propene with ex-situ or in-situ produced hydrogen peroxide as an oxidant. In order to clarify the effects of the kind of precious metal and treatment process in the catalyst preparation on the propene epoxidation and the hydrogen peroxide decomposition, TS-1 was impregnated with gold and palladium via drying, calcination and reduction and the experiments to check its catalytic performance were conducted in a gas aspirating autoclave reactor in the absence of mass transfer limitations. The presence of precious metals vigorously catalyzed the side reactions and hydrogen peroxide decomposition. Some of the precious metal containing TS-1 catalysts showed high initial rates but there was no catalyst with a propene oxide yield after 5 h reaction time comparable to TS-1 alone because of the enhancement of side reactions by precious metals. The significant decline in the selectivity to propene oxide over the dried precious metal containing TS-1 catalysts was attributed to the leaching of precious metals into the reaction medium. Palladium containing TS-1 showed exceptionally high decomposition of hydrogen peroxide. Reduction and calcination increased the decomposition by forming metallic gold and palladium. Homogeneous dispersion of gold nanoparticles was achieved by a sol immobilization method which led to a decrease of propene oxide selectivity and an increase of hydrogen peroxide decomposition.

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Section: Introductionmentioning

confidence: 99%

The effects of impregnation of precious metals on the catalytic activity of titanium silicate (TS-1) in epoxidation of propene using hydrogen peroxide

Shin

Lee

Chadwick

2016

Journal of Molecular Catalysis A: Chemical

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“…SiO 2 did not present any absorption and in the raw Ti-SiO 2 a small fraction of octahedral Ti(IV) was observed at 300 nm but the main absorption of the support was displayed in the 200 nm range corresponding to tetrahedral Ti(IV) dispersed in the SiO 2 framework. 25,26 After…”

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confidence: 99%

Enhanced ammonia-borane decomposition by synergistic catalysis using CoPd nanoparticles supported on titano-silicates

et al. 2016

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The decomposition of small molecules (such as formic acid or ammonia-borane (AB)) is one of the most promising alternatives for the in-situ H 2 generation towards a H 2 scenario implementation. 1-3 AB is claimed as one of the inorganic compounds with the highest hydrogen content (19.6 H 2 wt. %). This, added to its high reactivity with noble metals (such as Ru, Pd or Pt) makes it one of the best candidates for its use as H 2 feed in a PEMFC. [3][4][5][6][7][8] The total decomposition of this compound in liquid phase using water as solvent produces 3 mol of H 2 per mol of AB according to the following reaction equation.Ammonia borane is a liquid-phase chemical hydrogen storage material with great current interest. Its decomposition on a wide range of catalysts has been extensively reported in the literature. Among these, noble metals such as Rh, Ir, Ru, and Pt, have shown interesting catalytic activities, 10 but they are unsuitable for widespread practical applications due to their availability and price. Previous studies have demonstrated that bimetallic nanoparticles combining a noble metal and a firstrow transition metal forming an alloy structure could be promising candidates for the design of catalysts for the hydrolysis of ammonia borane. 11In order to assess the beneficial effect of these noble metal/first-row transition metal combinations for this application, we have used Pd due to its moderate activity among noble metals 12 and Co because it shows the highest activity among non-noble metal catalysts. 11,13,14The enhancement of the catalytic activity of the supported noble metal can be attained by different routes; i) increasing the metal dispersion on the support by the synthesis of very small NPs, 15 ii) alloying the noble metal with a transition metal, (which is also attractive due to the cost reduction of the catalysts) 11,16,17 and iii) supporting the NPs on an UV-Vis active support to upgrade the electron-transfer from the support to the NPs. 1,18 In the present study, the synthesis of Pd and Co-PdNPs by the reduction-by-solvent methodology has been applied with successful results in the production of H 2 by AB decomposition. The synthesis conditions allow a perfect control over size and morphology of the NPs (both mono-and bimetallic). Pure or alloyed cobalt (as oxide or reduced form) has been addressed in the recent literature as a promising metal in the AB decomposition reaction due to its low cost (compared with noble metals) and its high activity in relevant reactions. 12,16,[19][20][21] Due to their different reduction potential (compared with Pd), when M-Pd (i. e. Cu or Co) are wellalloyed there is a charge transfer from the M to Pd increasing the electron density on the Pd atom and its activity in the AB decomposition is enhanced. 1,18 On the other hand, the use of an active support (under UV-Vis conditions), such as titania or a titano-silicate (Ti-SiO 2 ), is an available strategy to enhance the catalytic activity of the final catalytic system. 22,23In the present work, Pd and Co x Pd 1-x...

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“…For the particular properties of gold nanoparticles in generating hydrogen peroxide through H 2 and O 2 , a new horizon that synthesizing hydrogen peroxide in situ and then propylene epoxidation in gas phase has attracted the attention of researchers . Mingming Du et al synthesized multiple Au/TS‐1 catalyst with different size of gold nanoparticles (NPs) and conducted that much small NPs were the dominant active sites with propylene conversion of 11.5 %, PO selectivity of 74.5 % and hydrogen efficiency of 34.6 %.…”

Section: Introductionmentioning

confidence: 99%

“…epoxidation in gas phase has attracted the attention of researchers. [9][10][11][12][13][14] Mingming Du et al [15] synthesized multiple Au/TS-1 catalyst with different size of gold nanoparticles (NPs) and conducted that much small NPs were the dominant active sites with propylene conversion of 11.5 %, PO selectivity of 74.5 % and hydrogen efficiency of 34.6 %. Hikazudani et al [16] used mono-atomically dispersed Pd on TiO 2 as catalyst in the epoxidation of light olefins.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Propylene Epoxidation via O₂ with Co‐Oxidation of Aldehydes by Metalloporphyrins

Wang

Wei

et al. 2018

Eur J Org Chem

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Propylene epoxidation by O2 plus acrolein in the presence of metalloporphyrins were investigated. According to the difference in initiation time and the reaction rate, a hypothesis metalloporphyrins or its center ion played a principal role in the initiation of reaction (redox reaction) rather than in the catalysis of PO generation reaction have been proposed, which was verified by the cyclic voltammogram of metalloporphyrins and UV/Vis spectra of samples in the time course study. Furthermore, the propylene epoxidation experiments using aldehydes easier to be initiated and corresponding blank control without metalloporphyrins were also investigated, and the results showed the same conclusion. On the other hand, the mechanism that the active species are peroxyacyl radical and peroxy acid was proposed through density function theory calculations, and in peroxyacyl radical path the intermediate generation process was the free radical addition of propylene by peroxyacyl radical. Moreover, optimum reaction paths were also carried out by computational calculations, the results showed that peroxyacyl radical was with higher activity than peroxy acid. As for peroxyacyl radical, the main addition site was the C1 of propylene, which was proved by the condensed Fukui function.

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Propylene epoxidation with in situ generated H2O2 in supercritical conditions

Cited by 18 publications

References 44 publications

The effects of impregnation of precious metals on the catalytic activity of titanium silicate (TS-1) in epoxidation of propene using hydrogen peroxide

The effects of impregnation of precious metals on the catalytic activity of titanium silicate (TS-1) in epoxidation of propene using hydrogen peroxide

Enhanced ammonia-borane decomposition by synergistic catalysis using CoPd nanoparticles supported on titano-silicates

Mechanism of Propylene Epoxidation via O₂ with Co‐Oxidation of Aldehydes by Metalloporphyrins

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Propylene epoxidation with in situ generated H2O2 in supercritical conditions

Cited by 18 publications

References 44 publications

The effects of impregnation of precious metals on the catalytic activity of titanium silicate (TS-1) in epoxidation of propene using hydrogen peroxide

The effects of impregnation of precious metals on the catalytic activity of titanium silicate (TS-1) in epoxidation of propene using hydrogen peroxide

Enhanced ammonia-borane decomposition by synergistic catalysis using CoPd nanoparticles supported on titano-silicates

Mechanism of Propylene Epoxidation via O2 with Co‐Oxidation of Aldehydes by Metalloporphyrins

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Mechanism of Propylene Epoxidation via O₂ with Co‐Oxidation of Aldehydes by Metalloporphyrins