Hydrogenation Of Cinnamaldehyde Research Articles

Screening support effect of Pt/MOx for selective hydrogenation of cinnamaldehyde

In supported metal catalysts, solid support material is of great importance for immobilizing and dispersing metal species, which can affect the catalytic performance of supported metal catalysts in terms of selectivity. Rational design of supported metal catalysts with tailored performance, in particular with controlled catalytic performance, is highly desired yet poses challenges in chemoselective hydrogenation reactions. Here, platinum nanoparticles (Pt NPs) supported on a series of commercial oxides were synthesized by a facile wet impregnation and thermal treatment under the air. The catalytic performance of as-prepared catalysts was evaluated in chemoselective hydrogenation of cinnamaldehyde. The varied product distribution demonstrates that supports affect markedly on selectivity. Fourier transform infrared spectra (FTIR) spectroscopy reveals that the high selectivity towards cinnamyl alcohol could be attributed to the preferential adsorption of aldehyde group. Meanwhile, the existence of Ptδ+ could enhance activity markedly by facilitating the spillover of activated H species.

Constructing a Highly Active Pd Atomically Dispersed Catalyst for Cinnamaldehyde Hydrogenation: Synergistic Catalysis between Pd–N3 Single Atoms and Fully Exposed Pd Clusters

Constructing a Highly Active Pd Atomically Dispersed Catalyst for Cinnamaldehyde Hydrogenation: Synergistic Catalysis between Pd–N₃ Single Atoms and Fully Exposed Pd Clusters

Hydrogenation of Cinnamaldehyde Using Carbon Dots Reduced Palladium Nanoparticles

Carbon dots (CDs) with a size range of 0.2 to 2 nm were prepared using a hydrothermal treatment of sucrose and oleic acid. The as-synthesized CDs were used to reduce H2PdCl4 to metallic Pd nanoparticles with dPd = 9.3 ± 3.7 nm, as confirmed by PXRD and HRTEM data. Pd particles were made to be larger than the CDs, to observe any inverse support effects, however, TEM data revealed that the CDs were transformed to carbon sheets in the reduction reaction at 100 °C. The synthesized Pd-CDs catalysts (0.81 wt. % loading) and CDs were both tested for the liquid phase hydrogenation of cinnamaldehyde. The influence of mass, temperature, and hydrogen flow rate on the activity and selectivity of the CDs and Pd-CDs catalyst on the hydrogenation of cinnamaldehyde was investigated. The CDs gave a cinnamaldehyde conversion (40%, 4 h) with selectivity towards the reduction of the C = O bond (cinnamyl alcohol) while the Pd-carbon catalyst was only selective to the reduction of the C = C bond (conversion 78%) indicating the dominance of Pd in the reaction. Post analysis of the deactivated catalysts indicated formation of carbon sheets and sintering of the Pd nanoparticles. It is thus shown that the presence of Pd induces the CDs to carbon sheet formation and thus indicates the limited use of CDs as a support for the olefin hydrogenation reaction with the CDs produced carbon support. This finding has implications for other studies using CDs as supports.Graphical abstract

Solvent effect in selective hydrogenation of cinnamaldehyde over Pd–Ni nanoclusters encapsulated within siliceous zeolite

Selective hydrogenation of unsaturated-organic compounds derived from biomass sources is a key step for producing chemicals and fuels, but it faces challenges in enhancing product selectivity and energy efficiency. Metal nanoparticles (NPs) encapsulated in zeolite crystals (metal@zeolite) are desirable and robust materials that can control catalytic activity and selectivity by tuning their structure. However, the solvent effect on selective hydrogenation over metal@zeolite has been unexplored, which plays a significant role in the reaction process. Here, the solvent effect on the selective hydrogenation of cinnamaldehyde (CAL), a representative substrate, over Pd–Ni bimetallic clusters encapsulated inside S-1 zeolite (Pd0.6Ni@S-1) was first reported. The results showed that Pd0.6Ni@S-1 effectively converted CAL into hydrocinnamaldehyde (HCAL) under mild conditions and that the product distribution was solvent-dependent by correlating the selectivity with solvent properties. The polarity of polar solvents affected the solvent-CAL interaction and thus the hydrogenation pathway. Our study reveals the importance of solvent engineering for selective hydrogenation over metal@zeolite catalysts and provides insights for designing efficient and robust materials for biomass conversion.

Co–Fe catalyst supported on acidified bentonite for selective hydrogenation of cinnamaldehyde

Acidified bentonite supported Co and Fe catalyst (Co–Fe/ACBT) with abundant strong Lewis acid sites was used for cinnamaldehyde selective hydrogenation, which showed a great catalytic activity with 90.5% CAL conversion and 86.8% COL selectivity.

Construction of intimate Lewis acid and basic sites on an Al2O3–NC composite catalyst with enhanced performance in transfer hydrogenation of cinnamaldehyde

The concerted function of acidic and basic sites leads to enhanced catalytic performance in transfer hydrogenation of cinnamaldehyde.

The nature of crystal facet effect of TiO2-supported Pd/Pt catalysts on selective hydrogenation of cinnamaldehyde: electron transfer process promoted by interfacial oxygen species.

Supported noble metal nanocatalysts typically exhibit strong crystal plane dependent catalytic behavior, but their working mechanism is still unclear. Herein, using anatase TiO2 with well-exposed crystal facets of {101}, {100} and {001} as a prototype support, Pd- and Pt-based supported TiO2 nanocatalysts (TiO2-Pd and TiO2-Pt) were prepared by chemical reduction with NaBH4 as reducer, and they showed a distinct metal-dependent crystal facet effect in the selective hydrogenation of cinamaldehyde (CAL). For Pd-based nanocatalysts, most Pd species on the {100} plane of TiO2 are present in the oxidized form with positive charges and unexpectedly show higher reactivity than the Pd species in the zero-valence state on the {101} and {001} planes. On the contrary, Pt species on all three crystal planes of TiO2 show zero-valence state, with relatively low conversion, but much better selectivity for hydrogenation of a CO bond than Pd-based catalysts. Well-designed experiments manipulating the stability and type of surface oxygen species confirmed that the essence of the crystal facet effect of the catalyst support actually creates a unique nanoconfined interface at the molecular level to construct a surface p-band intermediate state (PBIS), which provides a new alternative channel for surface electron transfer and consequently accelerates the reaction kinetics.

Selective Hydrogenation of Cinnamaldehyde, Furanic, and Aromatic Aldehydes over a Z-Scheme Heterojunction Photocatalyst Constituted of Pd NPs Supported on g-C3N4/ZnO Nanocomposite

Selective Hydrogenation of Cinnamaldehyde, Furanic, and Aromatic Aldehydes over a Z-Scheme Heterojunction Photocatalyst Constituted of Pd NPs Supported on g-C₃N₄/ZnO Nanocomposite

Enhanced Selective Hydrogenation of Cinnamaldehyde to Cinnamyl Alcohol over Silica-Coated Pt-CoxOy Hybrid Nanoparticles.

Selective hydrogenation of cinnamaldehyde (CAL) to cinnamyl alcohol (COL) is difficult due to the intrinsic difficulty with thermodynamically easier hydrogenation of C═C bonds. In this work, Pt-CoxOy hybrid nanoparticles encapsulated in mesoporous silica nanospheres (Pt-CoxOy@mSiO2) were synthesized by a sol-gel method, which showed greatly improved COL selectivity for hydrogenation of CAL. At 80 °C and 1.0 MPa of H2, Pt-CoxOy@mSiO2 achieved a CAL conversion of 98.7% with a COL selectivity of 93.5%. In contrast, Pt@mSiO2 yields 3-phenylpropanol (HCOL) as the major product with HCOL selectivity of 67.2%, while PtCo@mSiO2 yields 3-phenylpropionaldehyde with selectivity of 51.8% under the same conditions. The enhanced catalytic performance of Pt-CoxOy@mSiO2 for hydrogenation of CAL to COL is ascribed to the Pt surface electron deficiency induced by metal-oxide interaction, and the protection of active NPs by silica shells results in good catalytic stability.

Aqueous phase selective C[dbnd]O hydrogenation of cinnamaldehyde over bimetallic RuCo catalysts with electronic and geometric modification

Aqueous phase selective hydrogenation of cinnamaldehyde (CALD), as a representative α,β-unsaturated aldehyde, into cinnamyl alcohol (CALA) has been investigated over monometallic Ru and bimetallic RuCo catalysts on pristine h-BN support. Using water as the solvent, the optimal 0.5%Ru-1.1%Co/h-BN catalyst exhibits 510 h−1 specific reaction rate and 78.9 % CALA selectivity as well as good recycling stability at 100 °C. Based on the structure characterizations of catalysts, metal nanoparticles consisting of metallic Ru0 and partially oxidized Ruδ+ sites are uniformly dispersed on h-BN thin sheets. In comparison to monometallic catalysts, additive Co metals in bimetallic RuCo/h-BN catalysts play significant geometric and electronic modification roles on Ru active sites depending on the Ru/Co ratio, and therefore remarkably enhances the preferential activation of CALD CO bond and selectivity of CALA product as well as accelerates the catalytic reaction. Furthermore, the hydrogen dissociative activation ability of various Ru and RuCo catalysts was evaluated, while the superior catalytic performance in water than other commonly used solvents was also clarified and discussed.

Hexagonal boron nitride sheet-anchored palladium‑nickel nanoparticles for highly selective hydrogenation of cinnamaldehyde under mild conditions

Selective hydrogenation of cinnamaldehyde toward hydrocinnamaldehyde is an extremely important and challenging reaction. Herein, ultrafine PdNi bimetallic nanoparticles with different Pd to Ni ratios were uniformly anchored on hexagonal boron nitride nanosheet (BNNS) by a coprecipitation-reduction method. The resulting Pd4Ni0.6/BNNS (4 wt% Pd and 0.6 wt% Ni with respect to BNNS) catalyst displayed the excellent catalytic performance and gave the hydrocinnamaldehyde selectivity of 94 % with quantitative conversion of cinnamaldehyde under atmospheric pressure at 60 °C. Moreover, Pd4Ni0.6/BNNS had excellent reusability with a conversion of 92 % and a hydrocinnamaldehyde selectivity of 85 % after three recycle process. The high catalytic performance of BNNS-anchored PdNi nanoparticles was likely due to the synergy of PdNi and the alteration of electronic and surface properties of Pd by reasonable interactions between bimetallic nanoparticles and BNNS support.

Carbon-Coated Ni-Fe Nanocatalysts: Bridging the Gap in Cinnamaldehyde Hydrogenation Performance and Durability

This study focuses on the synthesis and evaluation of carbon−coated Ni−Fe alloy catalysts (NiFex@C, x = 0, 0.3, 0.7, 1.1) for the hydrogenation of cinnamaldehyde. The catalysts were characterized using Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Raman spectroscopy, and X-ray Photoelectron Spectroscopy (XPS). The introduction of Fe was found to increase the average particle size of the bimetallic catalysts compared to the monometallic Ni@C. Ni existed in both metallic and oxide states, while Fe exhibited multiple oxidation states in the bimetallic catalysts. The carbon layer, approximately 2–3 nm thick, was confirmed to envelop the alloy particles. The catalytic performance of carbon−coated Ni−Fe alloy catalysts indicated that the addition of Fe to Ni@C enhanced the selectivity towards hydrocinnamaldehyde (HCAL), with NiFe0.7@C showing the highest selectivity (~88.6%) but at a reduced conversion rate. The carbon layer played a pivotal role in the stability and reusability of the catalysts. NiFe0.7@C maintained consistent performance over multiple reaction cycles, while NiFe0.7 NPs (without a carbon layer) exhibited significant deactivation. Both catalysts displayed strong magnetism, facilitating easy separation from the reaction mixture. This study sheds light on the significance of the carbon layer in bimetallic catalysts and provides valuable insights for designing efficient catalysts for hydrogenation processes.

ZIF-8 decorated Au/Al2O3 hybrid material for highly selective hydrogenation of cinnamaldehyde

Recycling of supported Au catalysts is challenging because of aggregation or loss of Au. Here, we report a strategy for introducing ZIF-8 into traditional Au/Al2O3 surface. The introduction of ZIF-8 can not only provide higher selectivity for the reaction products, but also prevent the loss or aggregation of the Au catalyst. From a series of characterizations, it can be seen that the ZIF-8 decorated Au/Al2O3 hybrid material Au@ZA (Z refers to ZIF-8, A refers to Al2O3) was successfully prepared. Au nanoparticles have better dispersion on the composite carrier, and the particle size is smaller. In the hydrogenation reaction of cinnamaldehyde (CAL), the Au@ZA composite catalyst has both the high chemical stability and the high selectivity of cinnamyl alcohol (COL) due to the micropore size effect of ZIF-8. The Au@ZA catalyst has ∼ 85 % COL selectivity when the CAL conversion is close to 100 %. And after 8 times of repeated use, the conversion of CAL and the selectivity of COL did not decrease significantly. It should be noted that just when a small amount of ZIF-8 is present, the synergistic catalytic effect mentioned above can be produced.

Controlled Surface Modification of Cobalt Phosphide with Sulfur Tunes Hydrogenation Catalysis.

Transition metal phosphides have shown promise as catalysts for water splitting and hydrotreating, especially when a small amount of sulfur is incorporated into the phosphides. However, the effect of sulfur on catalysis is not well understood. In part, this is because conventional preparation methods of sulfur-doped transition metal phosphides lead to sulfur both inside and at the surface of the material. Here, we present an alternative method of modifying cobalt phosphide (CoP) with sulfur using molecular S-transfer reagents, namely, phosphine sulfides (SPR3). SPR3 added sulfur to the surface of CoP and using a series of SPR3 reagents having different P═S bond strengths enabled control over the amount and type of sulfur transferred. Our results show that there is a distribution of different sulfur sites possible on the CoP surface with S-binding strengths in the range of 69 to 84 kcal/mol. This provides fundamental information on how sulfur binds to an amorphous CoP surface and provides a basis to assess how number and type of sulfur on CoP influences catalysis. For the catalytic hydrogenation of cinnamaldehyde, intermediate amounts of sulfur with intermediate binding strengths at the surface of CoP were optimal. With some but not too much sulfur, CoP exhibited a higher hydrogenation productivity and a decreased formation of secondary reaction products. Our work provides important insight into the S-effect on the catalysis by transition metal phosphides and opens new avenues for catalyst design.

Efficient C = O bond hydrogenation of cinnamaldehyde over PtCu alloy frame: Insight into the morphology and Pt species state

Highly selective hydrogenation of cinnamaldehyde (CAL) to cinnamic alcohol (COL) remains the great challenge due to the co-existence of C = C and C = O bond in CAL. Herein, Al2O3 supported a series of wheel-like PtCux nanoframes (NFs) with varied Pt/Cu ratios were successfully fabricated, featuring unique electronic and geometric structure. Theoretical calculations and characterizations demonstrate that Cu can effectively optimize the d-band center, improve the distribution and utilization of Pt significantly. Compared with pure Pt crystal, PtCu1.21 NFs display the superior catalytic performance with high selectivity towards COL at a CAL conversion of over 99 %. The in-situ Fourier transform infrared (FTIR) spectroscopy reveals that the highly distribution and optimized d-band center of Pt could effectively weaken C = C bond interaction and strengthen the interaction of C = O bond on catalysts surface, boosting C = O bond hydrogenation to COL.

Construction of modularized catalytic system for transfer hydrogenation: Promotion effect of hydrogen bonds

The construction of enzyme-mimicking catalysts is a crucial route for achieving green chemical transformations; however, integrating multiple sites into one catalyst is challenging. Herein, a facile method is reported to combine different active sites by constructing a modularized catalytic system. A modularized catalytic system composed of covalent organic frameworks (COFs) and Cu2Cr2O5 exhibits remarkable efficiency in the transfer hydrogenation of cinnamaldehyde, with a selectivity of over 99% towards cinnamyl alcohol, surpassing the reaction rate of Cu2Cr2O5 by more than fourfold. The results of the mechanistic study and density functional theory calculations suggest that the enhanced activity of the modularized catalytic system is derived from the hydrogen bonds between the COFs and isopropyl alcohol, which promote isopropyl alcohol dehydrogenation and hydride transfer. In addition, the modularized catalytic system is efficient for various saturated and unsaturated aldehydes and could be replaced by different submodules. This study demonstrates the efficiency of a modularized catalytic system for mimicking the functions of enzymes in catalysis.

Continuous Hydrogenation of Cinnamaldehyde: Gas–Liquid–Liquid–Solid Helical Coil Reactor

Continuous Hydrogenation of Cinnamaldehyde: Gas–Liquid–Liquid–Solid Helical Coil Reactor

Unusual size effect of spinel Co0.5Fe0.5Al2O4 supported Pt catalysts on the selective hydrogenation of cinnamaldehyde

Pt/Co0.5Fe0.5Al2O4 catalysts with the average Pt particle size of 1.6–3.4 nm were prepared and applied to the selective hydrogenation of cinnamaldehyde (CAL). Not only the TOF was promoted from 0.19 to 2.70 s−1, but also the selectivity to cinnamyl alcohol (COL) was improved from 68% to 94%, with the increase of Pt particle size. Stronger interaction occurred between Co0.5Fe0.5Al2O4 and smaller-sized Pt particles, resulting in electron-deficient Pt particles, so that CO and CC bond could be activated simultaneously. However, electron-rich Pt species existed on Pt/Co0.5Fe0.5Al2O4 with larger Pt size, which is beneficial for the preferential activation of CO bond.

PtCo/MWCNTs Prepared by a Microwave‐assisted Polyol Method for Selective Cinnamaldehyde Hydrogenation

AbstractUsing microwave irradiation, PtCo alloy nanoparticles were deposited within a few minutes on COOH‐functionalized MWCNT supports. The obtained catalysts were used for selective hydrogenation of cinnamaldehyde, a reaction whose products are widely used in various fields. In the selective cinnamaldehyde hydrogenation to cinnamyl alcohol, microwave‐prepared catalysts (generically, PtxCoy‐MW) outperformed a catalyst prepared by the conventional method (Pt1Co2‐con). The highest selective hydrogenation to cinnamyl alcohol, 89%, was obtained using Pt1Co2‐MW, while Pt1Co2‐con showed a selectivity of 76%. Characterization results confirmed that the microwave prepared samples had a stronger interaction between Pt and Co than that in the Pt1Co2‐con sample. The alloyed Co altered the electronic structure of Pt, leading to favorable adsorption of the C=O bond by the lone‐pair electrons of its oxygen atom. Moreover, the Pt1Co2‐MW sample showed neglectable change in catalytic performance (e. g., cinnamaldehyde conversion and selective hydrogenation to cinnamyl alcohol) during recycling experiments.

Boosting the selectivity of Pt catalysts for cinnamaldehyde hydrogenation to cinnamylalcohol by surface oxidation of SiC support

The selective hydrogenation of cinnamaldehyde (CAL) is very important, but still remains challenging due to the coexistence of easily hydrogenated CC and CO bonds in CAL molecule. In this work, we report that employing partially oxidized SiC (SiC–O) as the support of Pt can evidently enhance the catalytic selectivity for the selective hydrogenation of CO in CAL. Further investigations show that the partially oxidized SiC surface can change the adsorption mode of CAL and facilitate the selective adsorption of CO in CAL. During the catalytic process, H2 was dissociated on Pt particles while CAL was mainly adsorbed and activated on the surface of support. The active H species generated on the Pt surface then spilled over to the support surface and reacted with the CO bond activated by the support surface to selectively form cinnamylalcohol. The present work revealed an important cooperative catalysis of metal and SiC, which would be helpful to design and application of more SiC-based catalysts.