Catalytic Hydrogenation Of Cinnamaldehyde Research Articles

Fabrication of SBA-15-supported nanoscale Co3O4 and its use in the catalytic hydrogenation of cinnamaldehyde

Fabrication of SBA-15-supported nanoscale Co3O4 and its use in the catalytic hydrogenation of cinnamaldehyde

Cu–Ga2O3nanoparticles supported on ordered mesoporous silica for the catalytic hydrogenation of cinnamaldehyde

Cu–Ga<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow/><mml:mn>2</mml:mn></mml:msub></mml:math>O<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow/><mml:mn>3</mml:mn></mml:msub></mml:math>nanoparticles supported on ordered mesoporous silica for the catalytic hydrogenation of cinnamaldehyde

Redundancy-Free Models for Mathematical Descriptions of Three-Phase Catalytic Hydrogenation of Cinnamaldehyde

A new approach on how to formulate redundancy-free models for mathematical descriptions of three-phase catalytic hydrogenation of cinnamaldehyde is presented. An automatically created redundant (generalized) model is formulated according to the complete reaction network. Models based on formal kinetics and kinetics concerning the Langmuir-Hinshelwood theory for three-phase catalytic hydrogenation of cinnamaldehyde were investigated. Redundancy-free models were obtained as a result of a step-by-step elimination of model parameters using sensitivity and interval analysis. Starting with 24 parameters in the redundant model, the redundancy-free model based on the Langmuir-Hinshelwood mechanism contains 6 parameters, while the model based on formal kinetics includes only 4 parameters. Due to less degrees of freedom of molecular rotation in the adsorbed state, the probability of a direct conversion of cinnamaldehyde to 3-phenylpropanol according to the redundancy-free model based on Langmuir-Hinshelwood approach is practically negligible compared to the model based on formal kinetics.

Atomic Layer Deposition (ALD) as a Way to Prepare New Mixed-Oxide Catalyst Supports: The Case of Alumina Addition to Silica-Supported Platinum for the Selective Hydrogenation of Cinnamaldehyde

The case is made here for the power of using atomic layer deposition (ALD) as a way to induce changes in the nature of the oxides used as supports in many catalytic processes. ALD provides a route to grow thin films in a conformal way and with submonolayer thickness control, affording the creation of unique mixed-oxide structures with new reaction sites. This approach is exemplified here for the case of the hydrogenation of unsaturated aldehydes with platinum-based catalysts. Silica-supported catalysts were modified with thin alumina films, grown by ALD using trimethylaluminum(III) (TMA) and water, and their performance contrasted with pure Pt/SiO2 and Pt/Al2O3 samples as well as with catalysts previously reported by us made by silica ALD on Pt/Al2O3. The quality of the alumina films grown on Pt/SiO2 was first evaluated by using N2 adsorption–desorption isotherms in conjunction with SBA-15 as the support, a mesoporous material with well-defined 1D cylindrical pores. An initial deposition of approximately 1.5 A of the alumina film per ALD cycle was estimated from those measurements, with retention of the narrow distribution of pore diameters indicative of homogeneous coverage throughout the length of the pores. The catalytic hydrogenation of cinnamaldehyde was then determined to be slower but more selective with silica supports compared to alumina. Addition of a half of a monolayer of alumina to Pt/SiO2 reduces the total activity, but only marginally. In exchange, the new mixed-oxide catalysts exhibit a higher selectivity toward the production of the desirable unsaturated alcohol at high conversions, and a lower activity for its subsequent hydrogenation to the saturated alcohol. These trends were associated with the formation of new Bronsted and Lewis acidic sites, possibly based on mixed Si–O–Al surface structures.

Precious metal nanoparticles supported on KOH pretreated activated carbon under microwave radiation as a catalyst for selective hydrogenation of cinnamaldehyde

A series of precious metals (Pd, Pt, Ru, Rh, and Au) supported on commercial activated carbon (AC) catalysts were prepared and their catalytic performance in the selective hydrogenation of cinnamaldehyde (CAL) were evaluated. Among these catalysts, Pt supported on AC pretreated by 10 % KOH under microwave radiation has the highest catalytic activity and selectivity in the selective hydrogenation of CAL, which provided a selectivity to cinnamyl alcohol of 73.4 % with a conversion of CAL of 62.8 %. The structure and morphology of the AC and the precious metal supported catalysts were characterized by BET, FT‐IR, XPS, XRD, and TEM. The catalytic performances of various precious metals as active components were compared. The effects of reaction temperature, hydrogen pressure, and reaction time on the catalytic hydrogenation of CAL were investigated. The by‐products were analyzed by GC‐MS and their formation mechanism was proposed. This work provides an efficient method of using commercial AC as the support for preparing promising catalysts in the selective hydrogenation of CAL.

In situ Growing PtCo Bimetallic Catalyst on Plant Tannin-grafted Collagen Fiber for Catalytic Hydrogenation of Cinnamaldehyde with Desirable Performance

PtCo x bimetallic nanoparticles(NPs) supported on tannin-grafted collagen fiber(CF-BT) have been pre-pared via a novel synthetic strategy, and applied for catalytic hydrogenation of cinnamaldehyde(CAL), a typic unsa-turated aldehyde. The catalysts were systematically and specifically characterized by means of XRD, XPS, TEM-EDX and SEM to clarify the structure-property correlation. It was found that the PtCo x /CF-BT catalysts exhi-bited significantly enhanced catalytic activity and desirable stability in catalytic hydrogenation of CAL, which is ascribed to the synergistic interaction between bimetallic components, the effective dispersion, the anchoring role of CF-BT matrix on bimetallic NPs, as well as the lower mass transfer resistance of the matrix.

Nickel–Silicon Intermetallics with Enhanced Selectivity in Hydrogenation Reactions of Cinnamaldehyde and Phenylacetylene

Nickel–silicon intermetallics have been prepared by a direct silicification method using SiH4 as the silicon source. The prepared nickel–silicon intermetallics were characterized by X-ray diffraction, transmission electron microscopy, temperature-programmed reduction, temperature-programmed desorption, X-ray photoelectron spectroscopy, and CO chemisorption measurements. The catalytic hydrogenation of cinnamaldehyde and phenylacetylene over the nickel–silicon intermetallics was investigated. Nickel–silicon intermetallics presented much higher selectivity to the intermediate product (hydrocinnamaldehyde) than monometallic nickel catalyst, which may be attributed to the repulsive force between the electronegative silicon atoms in the nickel–silicon intermetallics and oxygen atoms in the C═O bond of cinnamaldehyde. In addition, nickel–silicon intermetallics showed excellent selectivity for the hydrogenation of phenylacetylene to styrene (ca. 93%) due to the strong modification of the electronic structure deri...

Effects of Promoters on Properties of Cu-Zn-Al Catalyst for Selective Hydrogenation of Cinnamaldehyde to Cinnamyl Alcohol

Cu-Zn-Al catalyst was modified by the additives such as Ni and Mn, and the prepared catalyst was employed in the selective catalytic hydrogenation of cinnamaldehyde. The results showed that the addition of Ni could improve catalytic activity significantly, moreover, the improving effect was highest when Zn was replaced by Ni, simultaneously leading to excessive hydrogenation. The Cu-(5%)Mn-Zn-Al catalyst exhibited a higher selectivity of 93.6% for C = O bond to cinnamyl alcohol and hydrogenation activity of 33.0% conversion at 130°C under 1.0 MPa of H2 pressure with the reaction time of 1 h. TPR and XRD characterization showed that Mn promoter was favorable for the growth of Cu0 fine grains on the surface of catalyst, which not only led to steric effect which improved the selectivity for cinnamyl alcohol, but also reduced the numbers of active centers, consequently decreased the reaction rate.

The role of macroligands in regioselective hydrogenation of cinnamaldehyde

Attention has been paid to the role of a macroligand in the regioselective catalytic hydrogenation of cinnamaldehyde. The macroligands tested were of ordered, regular structures and also served as catalytic supports (natural graphite, plankton based silica, latex templated titania). The active part - ruthenium - was, besides the macroligands, supported also on active charcoal and high surface area sol-gel prepared silica and titania.

On the catalytic properties of mixed oxides obtained from the Cu-Mg-Al LDH precursors in the process of hydrogenation of the cinnamaldehyde

Catalytic hydrogenation of cinnamaldehyde (CNA) was investigated over oxidic materials obtained by the calcination of Cu-Mg-Al layered double hydroxide (LDH) precursors. A series of precursors with different Cu/Mg ratios (with a constant M 2+/Al 3+ ratio) were prepared by coprecipitation (under low supersaturation) and heated under reductive atmosphere until 623 K in order to avoid the formation of Cu-based spinels and to reduce the copper cations. The presence of Mg noticeably enhanced the selectivity of Cu-based catalysts with respect to the hydrogenation of the carbonyl group relative to the favoured hydrogenation of the CC bond. Moreover, the self-condensation of hydrocinnamaldehyde (HCNA) and the cross-condensation of hydrocinnamaldehyde with cinnamaldehyde were also observed especially when the basic sites of LDH structures are preponderant over hydrogenation species. Finally, all that reaction from CNA are of great interest for getting information about: (i) basic sites involved in condensation of CNA and HCNA; and (ii) active species for selective hydrogenation of CNA to cinnamyl alcohol (CNOL) which seem in strong interaction with the first ones.

XPS and XAFS Pt L2,3-Edge Studies of Dispersed Metallic Pt and PtSn Clusters on SiO2 Obtained by Organometallic Synthesis: Structural and Electronic Characteristics

In this work, well-defined silica-supported Pt and PtSn catalysts were prepared by surface organometallic reactions and were characterized by EXAFS-XANES at the Pt L2,3 edge and XPS of the Pt 4f and Sn 3d levels. These catalysts were tested in the catalytic hydrogenation of cinnamaldehyde in the liquid phase. XPS results showed that in PtSn−OM* (not having butyl groups anchored on the surface), tin was present as Sn(0) adatoms “decorating” the metallic surface, isolating Pt atoms; in the PtSn−OM catalyst (Bu groups remain grafted on the surface), tin was found in the form of Sn(0) and Sn(II, IV) in similar proportions. EXAFS experiments do not provide evidence of the existence of PtSn alloys in any of these systems. In the bimetallic PtSn−BM systems, it was possible to observe by XPS that tin was found in the form of Sn(0) and Sn(II, IV). EXAFS experiments, in this case, allowed us to demonstrate the existence of a PtSn alloy diluting metallic Pt atoms. In tin-modified systems, when a fraction of ionic tin is present, the activation of the CO group of the cinnamaldehyde is favored, increasing the selectivity to UOL. An increase in the number of Pt 5d holes measured by Pt-L2,3 XANES could be indicating as a d → s, p rehybridization process in the PtSn 3D small nanoclusters present in PtSn−BM catalysts.