Selective Hydrogenation Of Crotonaldehyde Research Articles

Selective Hydrogenation of Croton Aldehyde on Pt Nanoparticles Controlled by Tailoring Fraction of Well-Ordered Facets Under Different Pretreatment Conditions

Selective Hydrogenation of Croton Aldehyde on Pt Nanoparticles Controlled by Tailoring Fraction of Well-Ordered Facets Under Different Pretreatment Conditions

Selective Hydrogenation of Crotonaldehyde on SiO2‐Supported Pt Clusters: A DFT Study

AbstractThe selective hydrogenation of crotonaldehyde has gained considerable attention owing to its industrial applications for producing fine chemicals. Understanding the hydrogenation mechanism from density functional theory (DFT) calculations can provide insights for designing catalysts with high selectivities toward the target products. Among contemporary theoretical investigations of the hydrogenation, the calculated selectivities are not in agreement with the experimental results. Herein, a SiO2‐supported Pt nanocluster is developed, and it is used to investigate the selective hydrogenation of crotonaldehyde. The nanocluster model is used to obtain free energy barriers from DFT calculations, and these are used to build a microkinetic model. The theoretical selectivity values for the products are in agreement with the experimental results. According to the density of state analysis, this is directly attributed to the more accurate d‐band width from the Pt cluster. The contribution of each step to the final product is identified and can be used to intensify the process of generating the target product.

Dual Interface Synergistic Catalysis: The Selective Hydrogenation of Crotonaldehyde Over Pt/Co3O4@PDA

Dual Interface Synergistic Catalysis: The Selective Hydrogenation of Crotonaldehyde Over Pt/Co3O4@PDA

Recent Advances in Selective Hydrogenation of Crotonaldehyde over Noble Metal Catalysts

Recent Advances in Selective Hydrogenation of Crotonaldehyde over Noble Metal Catalysts

Synthesis of bimetallic SnPt-nanoparticle catalysts for chemoselective hydrogenation of crotonaldehyde: Relationship between SnxPty alloy phase and catalytic performance

Bimetallic SnPt-nanoparticle (SnPt-NP) catalysts with several types of SnxPty alloy structures were prepared using a polyalcohol reduction process; the catalytic behavior of each SnxPty alloy phase toward the selective hydrogenation of unsaturated aldehydes to the corresponding unsaturated alcohols was elucidated. Atomic absorption spectroscopy (AAS) and transmission electron microscopy (TEM) indicate that SnPt-NP catalysts with various Sn/Pt atomic ratios can be successfully prepared by a polyalcohol reduction process using Pt(acac)2 and Sn(AcO)2 as the metal precursors. X-ray diffraction (XRD) results reveal that the Sn1Pt3, Sn1Pt1, and Sn2Pt1 alloy phases are formed through control of the Sn/Pt atomic ratio of the starting mixture during preparation. The Sn1Pt3 alloy phase enhanced the hydrogenation of both the CC and CO bonds during the selective hydrogenation of crotonaldehyde. When only Sn1Pt1 alloy phases (Sn/Pt = 1.40), accompanying with separated Sn phase, were formed in the SnPt-NP catalysts, the highest unsaturated alcohol (UOL) selectivity (71.5% at 37.6% conversion) was observed. The formation of the Sn2Pt1 alloy phase led to decreased UOL selectivity. We suggest that the Sn1Pt1 alloy phase is an effective bimetallic SnPt hydrogenation catalyst for the selective formation of unsaturated alcohols.

Catalytic hydrogenation of crotonaldehyde and oxidation of benzene over active and recyclable palladium nanoparticles stabilized by polyethylene glycol

Polyethylene glycol (PEG)-stabilized Palladium (Pd) nanoparticles have been successfully synthesized by a simple hydrothermal approach. The as-prepared catalyst was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and N2 adsorption-desorption measurements. Pd nanoparticles show a high degree of dispersion in PEG with a small average particle size distribution in the range of 3–6nm. The Pd/PEG catalyst exhibited a remarkable catalytic activity toward selective hydrogenation of crotonaldehyde and oxidation of benzene in liquid phase under mild conditions. The catalyst could be easily removed from the reaction mixture and its recyclability was possible for ten times for crotonaldehyde and two times for benzene. The catalytic performance was found to depend essentially on the catalyst and target concentrations and reaction time.

Effects of Reduction Temperature on Selective Hydrogenation of Crotonalde-hyde over Ir/ZrO<SUB>2</SUB> Catalyst

Effects of Reduction Temperature on Selective Hydrogenation of Crotonalde-hyde over Ir/ZrO<SUB>2</SUB> Catalyst

Selective hydrogenation of crotonaldehyde on Au supported on mesoporous titania

We report here on how gold supported on mesoporous anatase work as a catalyst for the highly-selective hydrogenation of crotonaldehyde into crotyl alcohol. The gold was supported by deposition–precipitation method onto mesoporous titania prepared using hexadecylamine as the structure directing agent. This mesoporous titania provides a narrow pore size distribution and an amorphous framework, which can be converted to another pore size distribution and anatase framework by heating at 673K. Gold was more highly dispersed on mesoporous anatase prepared by heating at 673K than on anatase sample heated at 473–573K or on commercially-available anatase. The structure of these catalysts was analysed by XRD, N2-adsorption/desorption, TEM and XPS. In the hydrogenation of crotonaldehyde at ambient pressure, the selectivity for crotyl alcohol reached 82% on gold supported on mesoporous anatase, while 49% selectivity was obtained for gold supported on commercially-available anatase under the same reaction conditions. In addition, the rate of hydrogenation is also four times greater on Au/mesoporous anatase than on Au/anatase. The selectivity for crotyl aldehyde on gold on mesoporous amorphous titania was 68% under the same reaction conditions.

Selective Hydrogenation of Crotonaldehyde over Pt/Ce<SUB>0.8</SUB>La<SUB>0.2</SUB>O<SUB>1.9</SUB> Catalysts

Selective Hydrogenation of Crotonaldehyde over Pt/Ce<SUB>0.8</SUB>La<SUB>0.2</SUB>O<SUB>1.9</SUB> Catalysts

Role of Pt Oxidation State on the Activity and Selectivity for Crotonaldehyde Hydrogenation Over Pt–Sn/Al2O3–La and Pt–Pb/Al2O3–La Catalysts

Pt–Sn/ALa10 and Pt–Pb/ALa10 catalysts (10 wt% La2O3) were studied in the selective hydrogenation of crotonaldehyde. Oxidized Pt2+ and reduced Pt0 species were identified by XPS on the bimetallic catalysts. High selectivity to crotylalcohol was obtained on the Pt–Pb/ALa10 catalyst where an electron transfer effect from Pb to Pt was proposed. For the Pt–Sn/ALa10 catalyst the formation of Pt–SnO x –La2O3 complexes showing low activity and low selectivity was inferred.

Selective Hydrogenation of Crotonaldehyde over ZrO<sub>2</sub>-Supported Pt Catalysts

Selective Hydrogenation of Crotonaldehyde over ZrO<sub>2</sub>-Supported Pt Catalysts

Liquid-Phase Hydrogenation of Crotonaldehyde over Platinum- and Palladium-Based Catalysts

The selective hydrogenation of crotonaldehyde in liquid phase, at a temperature of 353 K and a H2 pressure of 400 kPa, is studied over different palladium- and platinum-based catalysts (Pd−Pb/α-Al2O3, Pd−Zn/α-Al2O3, Pd/ZnO, and two Pt/ZnO samples, prepared from Pt(NH3)4(NO3)2 and H2PtCl6, respectively). The intrinsic selectivity of palladium cannot be modified by alloying or following a promotion with a second metal, and the selectivity to crotyl alcohol measured over palladium-based samples is nil or extremely low. The selectivity corresponding to the Pt/ZnO catalysts increases with the time-on-stream reaching high levels. The formation of a Pt−Zn alloy is the origin of the enhanced selectivity toward crotyl alcohol; this effect is more pronounced for the sample that has been prepared from H2PtCl6.

Hydrogenation of α, β unsaturated aldehydes over polycrystalline, (111) and (100) preferentially oriented Pt nanoparticles supported on carbon

The influence of the shape/surface structure of Pt nanoparticles on the selective hydrogenation of crotonaldehyde and cinnamaldehyde has been studied. (111) and (100) preferentially oriented Pt nanoparticles (10 nm) as well as polyoriented Pt nanoparticles (3 nm) were synthesized, characterized (by TEM, cyclic voltammetry and adsorption microcalorimetry) and their catalytic properties evaluated. TEM analysis provided information about the size and shape of the Pt nanoparticles, whereas cyclic voltammetry allowed gaining qualitative and quantitative information about their surface structure. Thus, small Pt nanoparticles ( ≈ 3 nm ) were revealed to have a polyoriented surface, containing high ratio of corner and edges atoms to terrace atoms, whereas large Pt nanoparticles ( ≈ 10 nm ) were shown to have larger Pt domains with (100) and (111) surface structures. Microcalorimetric results for CO adsorption showed higher values of initial heat for polyoriented Pt/C compared to preferentially oriented samples, thus accounting for a higher amount of highly unsaturated surface platinum atoms for Pt/C, in agreement with cyclic voltammetry. The catalytic performances of the samples showed a strong structure-sensitive character for both reactions, with TOF values following the trend Pt(100)/C > Pt(111)/C > Pt/C. Moreover, Pt(111)/C showed higher selectivities to unsaturated alcohol than Pt(100)/C and Pt/C samples.

In situ Synthesis of Gold Nanoparticles inside the Pores of MCM‐48 in Supercritical Carbon Dioxide and its Catalytic Application

AbstractGold nanoparticles are deposited into the channels of MCM‐48 through a simple H2‐assisted reduction of HAuCl4 (aqueous solution) in supercritical carbon dioxide medium at 70 °C within 2–4 h. The nanoparticles were characterized by powder X‐ray diffraction (PXRD), N2 adsorption‐desorption, transmission electron microscopy (TEM), and UV‐Vis spectroscopy. The particle size of the synthesized material is tunable with the pressure (density) of the supercritical carbon dioxide medium. At the fixed temperature (70 °C) and hydrogen pressure [P(H2)=2 MPa], the Au particle size varies from ca. 25 nm to ca. 2 nm with the change in CO2 pressure from 7 MPa to 17 MPa. At the low solvent density conditions, larger particles of ∼25 nm were obtained. On the contrary, a high solvent density of CO2 slows down particle aggregation, resulting in the small particle size within the range of 2–5 nm. This change in particle size with CO2 pressure and the interaction of the particles with the silica support were correlated well with long‐range van der Waals interactions and consequently the Hamaker constant for the gold nanoparticle‐CO2 (A131) and silica‐gold core‐CO2 (A132), respectively. Supercritical carbon dioxide alone can provide a unique environment for stabilizing gold nanoparticles in the channels of the cubic mesoporous MCM‐48 support and exquisite control of the particle size without perturbing the support structure. The synthesized material is highly stable, recyclable and no metal nanoparticle leaching was observed. The selective hydrogenation of crotonaldehyde with the synthesized material provides convincing evidence that the particles are inside the pores and available to the reactant molecules.

Selective hydrogenation of crotonaldehyde on Au/HSA-CeO 2 catalysts

The gas-phase hydrogenation of crotonaldehyde was carried out over Au supported on high-surface area (HSA) CeO 2, previously reduced at 120 °C. The products analyzed during the initial, nonequilibrium stage showed the formation of large amounts of ethanol, which rapidly decreased with time on stream and were replaced by a combination of condensation products (mainly 2,4,6-octatrienal) under equilibrium conditions. The production of crotyl alcohol largely exceeded that of butanal at any time on stream. Under steady-state conditions, the crotyl alcohol-to-butanal ratio was equal to 1.7. When the catalyst was recalcined in air at 300 °C, just before the reduction treatment, the formation of ethanol in the initial stage and that of condensation products under steady state decreased. Besides, notable increase in the production of crotyl alcohol was observed, whereas butanal formation was unaffected. Finally, Au/HSA-CeO 2 is a highly selective catalyst for C O bond hydrogenation when crotyl alcohol/butanal ratio is equal to 3 under a steady-state regime. These results were compared to those obtained for Au/TiO 2 [R. Zanella, C. Louis, S. Gorgio, R. Touroude, J. Catal. 223 (2004) 328]. The role of acid–base sites, as well as that of the redox centers of HSA-CeO 2, is evaluated. Even though ceria sites are engaged in the reaction, the catalytic properties of Au/HSA-CeO 2 are attributed mainly to the gold nanoparticles.

Effect of the support composition on the vapor-phase hydrogenation of crotonaldehyde over Pt/Ce xZr 1− xO 2 catalysts

Vapor-phase hydrogenation of toluene and selective hydrogenation of crotonaldehyde (2-butenal) have been performed at 333 K over Cl-free Pt/ZrO 2 and Pt/Ce x Zr 1− x O 2 catalysts ( 0.2 ⩽ x ⩽ 0.8 ) after reduction under H 2 at low (473 K) and high (773 K) temperatures. The catalysts were characterized by X-ray diffraction, Raman spectroscopy, temperature-programmed reduction, and X-ray photoelectron spectroscopy after each reduction treatment. An important effect of the support composition on the catalytic activity was observed for both reactions. The catalytic behavior of Pt in the two test reactions studied was strongly dependent on the support composition and on the reduction temperature. For toluene hydrogenation, after reduction at 473 K, catalytic activity was higher for catalysts with no or low ceria content. Furthermore, whereas the increase in the reduction temperature hardly modified the activity of Pt/ZrO 2, it strongly deactivated the catalysts with high cerium content in the support. For crotonaldehyde hydrogenation, on the other hand, increased reduction temperature produced a general increase in activity (except for the catalyst with the highest cerium content), along with an increase in selectivity toward the hydrogenation of the carbonyl bond to yield crotyl alcohol. The results are explained on the basis of the effect of partial reduction of Ce(IV) in the support.

Selective hydrogenation of crotonaldehyde on Pt/ZnCl 2/SiO 2 catalysts

5 wt% Pt deposited on two different supports made of 3 and 1/6 equivalent monolayers of ZnCl 2 deposited on silica (termed Pt30 and Pt2) were prepared and tested in the selective hydrogenation of crotonaldehyde. Pt-based catalysts were prepared starting from tetraammine platinum nitrate as a metallic salt precursor. These catalysts showed very different catalytic behaviors in terms of the activity and the selectivity during time on stream. Pt2 was more active than Pt30 but less selective toward the formation of crotyl alcohol. On the Pt30 catalyst, the selectivity to the formation of crotyl alcohol increased with the reduction temperature, whereas the activity did not change significantly. When the catalyst was reduced at 400 °C, the selectivity to crotyl alcohol was >80%. It behaved similarly to Pt/ZnO catalysts prepared from hexachloroplatinic acid precursor [F. Ammari, J. Lamotte, R. Touroude, J. Catal. 221 (2004) 32]. In contrast, the Pt2 sample showed a decrease in the selectivity to crotyl alcohol and an increase in the activity with increasing reduction temperature. The catalysts were extensively characterized by BET, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and Fourier transform infrared pyridine adsorption. The higher selectivity of Pt30 is explained by a synergetic effect of Zn and chlorine. The greater amount of chlorine present on the catalyst surface led to an increase in the Lewis acidity of the support; moreover, the formation of PtZn alloy was observed. In agreement with our previous findings, we propose that modification of the electronic properties of platinum both from alloying to Zn and from the Lewis acidity of the support changes the adsorption mode of crotonaldehyde by favoring the binding of terminal oxygen of the molecule to the electronically modified platinum atoms.

Influence of Zn on the characteristics and catalytic behavior of TiO 2-supported Pt catalysts

Vapor-phase hydrogenation of toluene and selective hydrogenation of crotonaldehyde have been performed over Pt/TiO 2 and PtZn/TiO 2 after low (473 K) and high (773 K) temperature reduction. The catalysts were characterized by H 2 chemisorption, X-ray photoelectron spectroscopy (XPS), and Auger spectroscopy (AES) after each reduction treatment. Infrared spectra of CO alone and followed by the introduction of crotonaldehyde have been recorded for both catalysts after reduction at 473, 673, and 773 K. The presence of zinc and an increase in the reduction temperature strongly decreased the catalytic activity for toluene hydrogenation, but a different effect was observed for crotonaldehyde hydrogenation. After reduction at low temperature, the bimetallic catalyst was somewhat less active than the monometallic catalyst, but the initial activity of the former was greatly increased after reduction at 773 K, whereas the Pt/TiO 2 catalyst reduced at this high temperature was almost inactive. The selectivity toward the hydrogenation of the carbonyl bond exhibited a strong dependence on the presence of zinc and on the reduction temperature. Monometallic Pt/TiO 2 reduced at low temperature showed the maximum selectivity (up to 75%), although with a continuous decrease with time on stream. The bimetallic PtZn/TiO 2 catalyst, reduced at 773 K, showed a more stable selectivity to crotyl alcohol, centered at about 30%.

Catalytic hydrogenation of crotonaldehyde in the liquid phase using Pt and Ru/SnO2 catalysts

Effects of the precursor of active metal and of the reduction temperature upon activity and selectivity in selective hydrogenation of crotonaldehyde by Pt/SnO2 and Ru/SnO2 catalysts were studied. Experiments were performed in the liquid phase with a group of solvents tested: propan-2-ol, toluene, hexane and tetrahydrofuran. The best results were achieved with catalysts from ex-nitrate precursors/Pt(NH3)4(NO3)2 and Ru(NO)(NO3)2/reduced at 150° C. Propan-2-ol was evaluated as the most appropriate solvent to gain high yields of crotylalcohol in this study. A new hydrogenation product, 2-methylprop-2-en-1-ol (methallylalcohol), was observed.

Selective hydrogenation of crotonaldehyde over raney cobalt catalysts modified with heteropolyacid salts

RCo-based catalysts were modified with Keggin type heteropolyacid salts, including alkali, alkaline earth and transition metal salts. The selective hydrogenation of crotonaldehyde was investigated over these catalysts. The selectivities to crotyl alcohol can be improved on all modified catalysts. Among them, the catalyst modified with copper salts of 12-molybdophosphates shows the best performance in improving the selectivity.