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The interfacial characteristics of platinum (Pt) metal catalysts can be systematically regulated by interacting them with electropositive metals, leading to synergistic interactions for extensive catalytic applications. In this study, an evenly dispersed polyol-synthesized iron (Fe)-promoted Pt bimetallic nanoparticle (BNPs) system was embedded in MIL-101(Cr). The PtFe 2 @MIL-101(Cr) catalyst unveiled remarkable activity (86%) and selectivity (89%) for the superior hydrogenation of the targeted C O bond of cinnamaldehyde (CAL). The exceptional hydrogenation performance can be credited to the interplay of the geometric and electronic properties arising from charge shuttling between Fe and Pt within the homogenously distributed Pt–Fe bimetallic nanoparticle system. The experimental results indicate enhanced valence electrons in the Pt d-band through the mutual synergetic interface between the Pt and Fe BNPs. Consequently, these Fe–Pt sites functioned as interfacial electrophilic and nucleophilic (Lewis acid-base) sites, enhancing H 2 activation and facilitating C O bond conversion to yield unsaturated cinnamal alcohols (COL). Additionally, the narrow pores of MIL-101(Cr) encapsulating the Pt–Fe BNPs induced steric hindrance, allowing only C O bond hydrogenation. Furthermore, the PtFe 2 @MIL-101(Cr) catalyst maintained its optimal hydrogenation performance over five cycles, demonstrating no substantial loss in either CAL conversion or COL yield, thus endorsing the universal practical applicability of the catalyst. [Display omitted] • Polyol-synthesized iron (Fe) promoted Pt bimetallic nanoparticle (BNPs) systems embedded in MIL-101(Cr). • PtFe 2 @MIL-101(Cr) showed remarkable activity in the hydrogenation of cinnamaldehyde. • The exceptional performance can be attributed to the interplay of the geometric and electronic properties arising from the Pt–Fe BNPs. • The PtFe 2 @MIL-101(Cr) catalyst maintained optimal performance over a series of five cycles. [ABSTRACT FROM AUTHOR]

A new hybrid catalyst consisting of cobalt nanoparticles immobilized onto cellulose was developed. The cellulosic matrix is derived from date palm biomass waste, which was oxidized by sodium periodate to yield dialdehyde and was further derivatized by grafting orthoaminophenol as a metal ion complexing agent. The new hybrid catalyst was characterized by FT-IR, solid-state NMR, XRD, SEM, TEM, ICP, and XPS. The catalytic potential of the nanocatalyst was then evaluated in the catalytic hydrogenation of 4-nitrophenol to 4-aminophenol under mild experimental conditions in aqueous medium in the presence of NaBH4 at room temperature. The reaction achieved complete conversion within a short period of 7 min. The rate constant was calculated to be K = 8.7 × 10−3 s−1. The catalyst was recycled for eight cycles. Furthermore, we explored the application of the same catalyst for the hydrogenation of cinnamaldehyde using dihydrogen under different reaction conditions. The results obtained were highly promising, exhibiting both high conversion and excellent selectivity in cinnamyl alcohol. [ABSTRACT FROM AUTHOR]

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 C O 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. [Display omitted] • h-BN-supported bimetallic RuCo catalyst exhibits high activity and selectivity in cinnamaldehyde C O hydrogenation. • Co additive metal plays geometric and electronic modification roles on Ru active site. • Partially oxidized Ruδ+ and decorated CoO x serve as Lewis acid sites for enhancing C O activation. • Hydrogen dissociative activation ability can be promoted by bimetallic RuCo catalyst. • Water as the solvent plays multiple positive roles of polarizing C O bond and hydrogen transfer. [ABSTRACT FROM AUTHOR]

An NiZr/N‐doped TiO2/Ti3C2 catalyst was prepared by KBH4 reduction for cinnamaldehyde hydrogenation. Characterization results showed that the synthesis of N‐doped TiO2 on Ti3C2 and the uniform dispersion of TiO2 on the Ti3C2 surface increased the specific surface area of NiZr/Ti3C2 by 164.4 m2/g. N‐doping at a level of 19.03 % was used to replace O in the TiO2 lattice; the Ti−O−Ti peak in the XPS spectrum of the undoped catalyst was shifted by 0.3 eV in the spectrum of the doped catalyst; as a result, there was a 15.40 % increase in the number of surface oxygen vacancies of the NiZr/Ti3C2 catalyst. The synthesis of N‐doped TiO2 on Ti3C2 converted the moderately acidic sites of NiZr/Ti3C2 to strong Lewis acid sites and increased the total number of acid sites by approximately 0.8‐fold. The active Lewis acid sites on the surface of NiZr/N‐doped TiO2/Ti3C2 adsorbed only C=O bonds and inhibited the adsorption of C=C bonds, resulting in a high cinnamaldehyde conversion of 90.69 % and a cinnamyl alcohol selectivity of 91.87 %. [ABSTRACT FROM AUTHOR]

An NiZr/N‐doped TiO2/Ti3C2 catalyst was prepared by KBH4 reduction for cinnamaldehyde hydrogenation. Characterization results showed that the synthesis of N‐doped TiO2 on Ti3C2 and the uniform dispersion of TiO2 on the Ti3C2 surface increased the specific surface area of NiZr/Ti3C2 by 164.4 m2/g. N‐doping at a level of 19.03 % was used to replace O in the TiO2 lattice; the Ti−O−Ti peak in the XPS spectrum of the undoped catalyst was shifted by 0.3 eV in the spectrum of the doped catalyst; as a result, there was a 15.40 % increase in the number of surface oxygen vacancies of the NiZr/Ti3C2 catalyst. The synthesis of N‐doped TiO2 on Ti3C2 converted the moderately acidic sites of NiZr/Ti3C2 to strong Lewis acid sites and increased the total number of acid sites by approximately 0.8‐fold. The active Lewis acid sites on the surface of NiZr/N‐doped TiO2/Ti3C2 adsorbed only C=O bonds and inhibited the adsorption of C=C bonds, resulting in a high cinnamaldehyde conversion of 90.69 % and a cinnamyl alcohol selectivity of 91.87 %. [ABSTRACT FROM AUTHOR]

Small Pt–Co bimetallic nanoparticles were prepared on ionic liquid-functionalized SBA-15. The prepared 2Pt–2Co/IL@SBA-15 showed high activity and selectivity in cinnamaldehyde hydrogenation to form cinnamyl alcohol under solvent-free conditions. The reaction proceeded efficiently without any addition of solvent with simple product recovery. 2Pt–2Co/IL@SBA-15 exhibited superior activity compared to the monometallic catalysts and Pt–Co on unmodified SBA-15, with 97.1% conversion and 96.2% selectivity to cinnamyl alcohol. The formation of small Pt–Co bimetallic nanoparticles and the presence of an ionic liquid are the keys to its high activity. XAFS analysis and STEM EDS mapping revealed that Pt–Co bimetallic nanoparticles were formed with both Pt and Co exposed on the surface of the nanoparticles. The charge transfer from Co to Pt on the surface of bimetallic nanoparticles results in a high selectivity for cinnamyl alcohol formation. The ionic liquid assisted the formation of small Pt–Co nanoparticles inside the pores of SBA-15 and acted as an "immobilized solvent" allowing the hydrogenation reaction to proceed efficiently without the need for an additional solvent. Moreover, the ionic liquid is strongly bonded to SBA-15, preventing aggregation of bimetallic nanoparticles, resulting in high durability and stability that allows the catalyst to be used six times without significant activity loss. [ABSTRACT FROM AUTHOR]

Selective catalytic hydrogenation of cinnamaldehyde is an important chemical reaction process for the preparation of high-value chemical products. However, the hydrogenation of the C=O group in cinnamaldehyde is not affected by the thermodynamics, which causes the C=O double bond in its molecular structure difficult to be hydrogenated. In this work, Pt-Fe/Fe-NTA materials were prepared by a simple impregnation reduction method, and used as highly efficient catalysts for chemoselective hydrogenation of cinnamaldehyde. Built on a series of characterization technologies including XRD, FT-IR, XPS, SEM, and HRTEM the micro-structure and properties of Pt-Fe/Fe-NTA nanocatalysts were studied in detail. The experimental results suggest that the excellent catalytic performance of Pt-Fe/Fe-NTA catalysts mainly comes from the electron-rich property of the active center Pt and the existence of the surface Fe3+ species, which both contribute to enhance the chemisorption of the C=O double bond in cinnamaldehyde and to improve the selectivity of cinnamyl alcohol. Under optimal reaction conditions, a cinnamaldehyde conversion of 90.8% and a selectivity to cinnamyl alcohol of 90.9%, respectively were achieved, with the turnover frequency up to 1489 h−1. In addition, a possible catalytic reaction mechanism of hydrogenation of cinnamaldehyde on Pt-Fe/Fe-NTA catalysts was proposed. Pt nanocatalyst supported by Fe-NTA nanorods was synthesized. The obtained Pt-Fe/Fe-NTA catalyst exhibits excellent catalytic activity (TOF=1489 h-1) and superior catalytic selectivity to cinnamal alcohols (90.9%) at 40 °C for chemoselective hydrogenation of cinnamaldehyde [ABSTRACT FROM AUTHOR]

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 CO and CC 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 CO bond.

Allylic alcohols typically produced through selective hydrogenation of α,β-unsaturated aldehydes are important intermediates in fine chemical industry, but it is still a challenge to achieve its high selectivity transformation. Herein, we report a series of TiO2-supported CoRe bimetallic catalysts for the selective hydrogenation of cinnamaldehyde (CAL) to cinnamyl alcohol (COL) using formic acid (FA) as a hydrogen donor. The resultant catalyst with the optimized Co/Re ratio of 1:1 can achieve an exceptional COL selectivity of 89% with a CAL conversion of 99% under mild conditions of 140 °C for 4 h, and the catalyst can be reused four times without loss of activity. Meanwhile, the Co1Re1/TiO2/FA system was efficient for the selective hydrogenation of various α,β-unsaturated aldehydes to the corresponding α,β-unsaturated alcohols. The presence of ReOx on the Co1Re1/TiO2 catalyst surface was advantageous to the adsorption of C=O, and the ultrafine Co nanoparticles provided abundant hydrogenation active sites for the selective hydrogenation. Moreover, FA as a hydrogen donor improved the selectivity to α,β-unsaturated alcohols. [ABSTRACT FROM AUTHOR]

A bimetallic Pt8Co1 supported on alkali-treated ZSM-5 zeolite (ZSM-5-AT) was prepared through the impregnation method. The structure and surface properties of the catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2-sorption and X-ray photoelectron spectroscopy (XPS) as well as temperature-programmed desorption of NH3 (NH3-TPD) and temperature-programmed reduction of H2 (H2-TPR). The TEM images present that the bimetallic Pt8Co1 nanoparticles with a mean particle size of 4–6 nm were uniformly dispersed on the alkali-treated ZSM-5 zeolite. The bimetallic Pt8Co1/ZSM-5-AT catalyst exhibited an extraordinary COL selectivity of 65% at a >99% CAL conversion efficiency, which showed a much higher catalytic performance (including the activity and selectivity) than the monometallic Pt/ZSM-5-AT and Co/ZSM-5-AT catalysts in the selective hydrogenation of cinnamaldehyde (CAL) to cinnamyl alcohol (COL) using hydrogen as reducing agent. The high catalytic activity of the bimetallic catalyst was attributed to the higher electron density of Pt species and more acidic sites of the alkali-treated ZSM-5 zeolite support. The recovery test showed no obvious loss of its initial activity of the Pt8Co1/ZSM-5-AT catalyst for five times. [ABSTRACT FROM AUTHOR]

[Display omitted] The confinement effect known as efficient strategy to enhance the heterocatalytic activity and stability, but a clear view regarding the role of encapsulated overlayers is far from convincing at present, especially, the penetration of substrates with different size. Herein, the experimental evidence about the impacts of BN overlayers on hydrogenation is obtained over Co@BN/BN model catalysts with tuned thinness, in which BN overlayers encapsuled Co particles that dispersed on the defective BN supports, fabricating by the nitridizing of ball-milled BN microplates under NH 3 atmosphere. The thinness and crystallinity of BN shells was simply tuned by controlling the pyrolyzed temperature (600–900 °C). The cinnamaldehyde (CAL) selective hydrogenation is taken as probe reaction due to (1) both larger CAL and small H 2 molecule involved simultaneously, (2) the middle C C and terminal C O bonds all involved. Combined with structural analysis, the results demonstrate that small H 2 molecule can penetrate into the metal-cover interface through the defect sites, then inner Co core dissociate it to atomic H, and the hydrogenation mainly resulting from the spillover of H atoms which occurred on the BN surface. As a result, the thickest BN shells (∼3.4 nm) with ordered-layer-lattice significantly hindered the adsorption and activation of CAL, also the longest H spillover distance led to the lowest activity of Co@BN/BN-900. Instead, Co@BN/BN-600 with merely 2 ∼ 3 overlayers presented the most efficient and highly chemoselective hydrogenation activity. The ultrathin but turbostratic BN overlayers provide more migrating sites also shortened the H spillover distance effectively, and the more favorable C O hydrogenation was also achieved driven by the steric hindrance effect of thinner BN shells. These observations provide new insights towards understanding of confined effect on catalysis process through the accurate regulation of BN shells properties. [ABSTRACT FROM AUTHOR]

Since efficient hydrogenation was valued for manufacture of pharmaceutical intermediates and fragrances in recent years, the development of easily accessible heterogeneous catalysts was preferably made. Here we designed a facile one-pot synthesis of Ni modified COF-derived catalyst for selective catalytic hydrogenation of cinnamaldehyde. The nickel-based COFs catalyst reduced at 600 °C exhibited better catalytic activity for the selective production of hydrocinnamyl with an excellent yield of 98%, and the nickel-based COFs reduced at 500 °C and 700 °C preferred to selectively produce benzenepropanal. Overall, this work proves cost-effective and sustainable access to the wide application of selective hydrogenation reaction.

[Display omitted] Cerium–zirconium mixed oxides with different Ce/Zr ratio were prepared and used as supports for Pt-containing catalysts. The study of the catalysts in the cinnamaldehyde hydrogenation reaction has shown that cinnamaldehyde conversion and cinnamyl alcohol selectivity strongly depend on the CeO 2 content in the support. The highest cinnamyl alcohol yield of 81% was obtained in 105 min at room temperature and atmospheric pressure over the 1%Pt/CeO 2 –ZrO 2 catalyst with Ce : Zr atomic ratio equal to 4 : 1. [ABSTRACT FROM AUTHOR]

Allylic alcohols typically produced through selective hydrogenation of α,β-unsaturated aldehydes are important intermediates in fine chemical industry, but it is still a challenge to achieve its high selectivity transformation. Herein, we report a series of TiO2-supported CoRe bimetallic catalysts for the selective hydrogenation of cinnamaldehyde (CAL) to cinnamyl alcohol (COL) using formic acid (FA) as a hydrogen donor. The resultant catalyst with the optimized Co/Re ratio of 1:1 can achieve an exceptional COL selectivity of 89% with a CAL conversion of 99% under mild conditions of 140 °C for 4 h, and the catalyst can be reused four times without loss of activity. Meanwhile, the Co1Re1/TiO2/FA system was efficient for the selective hydrogenation of various α,β-unsaturated aldehydes to the corresponding α,β-unsaturated alcohols. The presence of ReOx on the Co1Re1/TiO2 catalyst surface was advantageous to the adsorption of C=O, and the ultrafine Co nanoparticles provided abundant hydrogenation active sites for the selective hydrogenation. Moreover, FA as a hydrogen donor improved the selectivity to α,β-unsaturated alcohols.

The conversion of cinnamaldehyde (CALD) to Cinnamyl alcohol (CALC) over a Pt/SiO2 catalyst was investigated. To achieve maximum CALC production, the historical data design of using a response surface methodology (RSM) experimental design was applied to Correlate and optimize the operation process variables (i.e., catalyst amount, 0.1-0.3 g; reaction temperature, 70-110 °C; pressure, 20-40 bar; and reaction time, 30-360 min) for the CALD conversion and selectivity for CALC. The obtained experimental values of the conversion and selectivity were in good agreement with those predicted by a second-order quadratic model, indicating the suitability of the model to estimate the conversion and selectivity. The maximum CALD conversion and selectivity for CALC were 98.905% and 80.295%, respectively, at the following conditions: temperature, 75.96 °C; pressure, 20.11 bar; catalyst amount, 0.19 g; and reaction time, 296.59 min. [ABSTRACT FROM AUTHOR]

[Display omitted] • A hydrophobic and porous Fe-Pdb (CFs) was prepared by a hydrothermal method. • The Fe-Pdb (CFs) was used to fabricate an effective Pt-Fe/Fe-Pdb (CFs) catalyst. • The Pt-Fe/Fe-Pdb (CFs) catalyst showed better catalytic activity and selectivity. • The CAL conversion and COL selectivity were 88.9% and 85.8% at 60℃. The selective hydrogenation of cinnamaldehyde to cinnamyl alcohol has remained a ponding challenge due to competitive hydrogenation reactions between C C and C O groups. In this work, a hydrophobic and porous Fe and 3,3′-(pyridine-3,5-diyl)-dibenzoic acid coordination framework structure (Fe-Pdb (CFs)) was employed to support Pt-Fe nanoparticles and synthesize a high-performance Pt-Fe/Fe-Pdb (CFs) heterogeneous catalyst. The reactivity activity could be greatly improved by introducing electrophilic sites and enhancing the enrichment effect of Fe-Pdb (CFs) material. Thus, the optimal cinnamaldehyde conversion reached approximately 88.9%, with a better selectivity of 85.8% towards cinnamyl alcohol at 60°C. [ABSTRACT FROM AUTHOR]

The amalgamation of an appropriate cocatalyst is a proficient technique to expand the efficacy of precious Pt-based catalytic materials. In this study, Mo 2 N–TiO 2 with regularly distributed Mo 2 N particles were simply prepared for the deposition of precious Pt nanoparticles (NPs). Numerous techniques were implemented to thoroughly explore, how synthesis method influence the bulk structural, interfacial and cata1ytic features of the as-prepared 3 wt%Pt/TiO 2 and 3 wt%Pt/Mo 2 N–TiO 2 catalytic materials. The catalytic results obviously show that the 3 wt%Pt/Mo 2 N–TiO 2 catalyst has exceptional hydrogenation performance when compared to 3 wt%Pt/TiO 2 catalyst. The 3 wt%Pt/Mo 2 N–TiO 2 catalyst displayed high conversion (72.4 %) of cinnamaldehyde (CAL) with a maximum selectivity (82.1 %) towards C O bond. The excellent hydrogenation performance is attributed to the synergistic interaction taking place between Pt NPs and Mo 2 N entities of 3 wt%Pt/Mo 2 N–TiO 2. Also, the enhanced standardized dispersal of Pt NPs on the Mo 2 N–TiO 2 surface causes more exposed Pt0 sites on the 3 wt%Pt/Mo 2 N–TiO 2 surface, which is productive for the improved activation and conversion of C O bond of CAL to yield COL. In addition, the 3 wt%Pt/Mo 2 N–TiO 2 catalyst retained its higher catalytic activity for consecutive five successive rounds without substantial loss in either conversion or selectivity. [Display omitted] • Mo 2 N–TiO 2 were synthesized through one pot synthetic procedure. • Pt NPs was uniformly dispersed over Mo 2 N–TiO 2 by a simple polyol method. • The Pt/Mo 2 N–TiO 2 catalyst exhibits good catalytic activity for CAL hydrogenation. • Pt has synergistic effect with Mo 2 N for the selective hydrogenation of CAL. [ABSTRACT FROM AUTHOR]

[Display omitted] • Core-shell structured NPs that consisted of Pt cores and Sn shells were prepared. • The partial coverage of Pt by Sn facilitated their adsorption of C O bonds. • The strong Pt-Sn interaction is responsible for the enhanced performance. The selective hydrogenation of cinnamaldehyde (CAL) to prepare cinnamyl alcohol (COL) is challenging as the unwanted hydrogenation of C C bond in CAL is thermodynamically more favorable than the hydrogenation of C O bond. We herein designed core–shell structured nanoparticles (NPs) that consisted of Pt cores and Sn shells to catalyze the CAL to COL conversion. By simply changing the amount of Sn precursor, we generated Pt@Sn NPs with different Sn shell thickness and catalytic performance. Among the samples, Pt@Sn/SiO 2 with Pt/Sn of 1/1 achieved the highest CAL conversion (87.2 %) as well as the COL selectivity (95.4 %), which were 5-fold and 6-fold, respectively, higher than those of Pt/SiO 2. This catalyst was also applicable to the hydrogenation of other α, β-unsaturated aldehyde and unsaturated carbonyl compounds. Both experiments and theoretical calculations indicated that the strong Pt-Sn interaction and the partial coverage of Pt by Sn facilitated their adsorption of C O bonds, thus enhancing the conversion of CAL and the selectivity towards COL. [ABSTRACT FROM AUTHOR]

• Co-based catalysts are prepared via calcination and reduction of Co-Al-contained hydrotalcites. • Reduction condition of Co 2 Al catalyst was optimized for good selectivity of C=O hydrogenation. • Co2+ species as Lewis acid site prefers to activate and hydrogenate the C=O bond. • Small-size metallic Co site promotes the hydrogen activation and dissociation. • Water as the solvent or additive facilitates the production of cinnamyl alcohol. Non-noble metal-catalyzed selective C O hydrogenation of α,β-unsaturated aldehydes to corresponding alcohols is chemically atom economic and practically feasible. This work reports hydrotalcite-derived Co-based catalysts for catalyzing aqueous phase selective hydrogenation reaction of cinnamaldehyde to cinnamyl alcohol. The structure characterizations demonstrate the phase transition from hydrotalcite to co-existed CoO x and metallic Co0 in the optimal Co 2 Al-H 2 -400 catalyst. It exhibits superior catalytic activity and selectivity relative to other as-obtained Co catalysts, because of the synergy effect of Co2+ sites to promote the adsorptive activation of C O group and small-size Co0 sites to facilitate the activating dissociation of hydrogen. Furthermore, the catalytic role of water has also been explored. Adopting water as pure solvent and partially adding water into organic solvent can both effectively enhance the activity and selectivity. Such reaction environment may induce creation of more intermolecular hydrogen bonds for promoting the hydrogen transfer and thus boosting the hydrogenation reaction. [Display omitted] [ABSTRACT FROM AUTHOR]

A bimetallic Pt8Co1 supported on alkali-treated ZSM-5 zeolite (ZSM-5-AT) was prepared through the impregnation method. The structure and surface properties of the catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2-sorption and X-ray photoelectron spectroscopy (XPS) as well as temperature-programmed desorption of NH3 (NH3-TPD) and temperature-programmed reduction of H2 (H2-TPR). The TEM images present that the bimetallic Pt8Co1 nanoparticles with a mean particle size of 4–6 nm were uniformly dispersed on the alkali-treated ZSM-5 zeolite. The bimetallic Pt8Co1/ZSM-5-AT catalyst exhibited an extraordinary COL selectivity of 65% at a >99% CAL conversion efficiency, which showed a much higher catalytic performance (including the activity and selectivity) than the monometallic Pt/ZSM-5-AT and Co/ZSM-5-AT catalysts in the selective hydrogenation of cinnamaldehyde (CAL) to cinnamyl alcohol (COL) using hydrogen as reducing agent. The high catalytic activity of the bimetallic catalyst was attributed to the higher electron density of Pt species and more acidic sites of the alkali-treated ZSM-5 zeolite support. The recovery test showed no obvious loss of its initial activity of the Pt8Co1/ZSM-5-AT catalyst for five times.

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. [Display omitted] • Pd0.6Ni@S-1 showed high activity and selectivity for the selective hydrogenation of CAL to HCAL under mild conditions. • The hydrogenation of the C O bond of HCAL was difficult, and the main by-product HCOL was derived from COL. • Conversion and selectivity were controlled by steric effect and polarity of solvent. • Solvent engineering was a key factor in optimizing the performance of metal@zeolite catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • ZIF-8 decorated Au/Al 2 O 3 hybrid material Au@ZA was successfully prepared. • Au@ZA provided higher selectivity and prevented the loss or aggregation of Au particle. • The conversion and selectivity did not decrease significantly after 8 times cycles over Au@ZA. • Au@ZA exhibited significant differences in electronic interactions between CAL and COL. 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/Al 2 O 3 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/Al 2 O 3 hybrid material Au@ZA (Z refers to ZIF-8, A refers to Al 2 O 3) 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. [ABSTRACT FROM AUTHOR]

Selective hydrogenation of cinnamaldehyde toward hydrocinnamaldehyde is an extremely important and challenging reaction. Herein, ultrafine Pd Ni bimetallic nanoparticles with different Pd to Ni ratios were uniformly anchored on hexagonal boron nitride nanosheet (BNNS) by a coprecipitation-reduction method. The resulting Pd 4 Ni 0.6 /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, Pd 4 Ni 0.6 /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 Pd Ni nanoparticles was likely due to the synergy of Pd Ni and the alteration of electronic and surface properties of Pd by reasonable interactions between bimetallic nanoparticles and BNNS support. [Display omitted] • Ultrafine Pd Ni nanoparticles were anchored on hexagonal boron nitride sheets by a coprecipitation-reduction method. • Pd 4 Ni 0.6 /BNNS achieved the hydrocinnamaldehyde selectivity of 94 % with quantitative conversion of cinnamaldehyde under mild conditions. • The alteration of electronic and surface properties of Pd and the synergy of Pd Ni contributed to the exceptional catalytic activity. [ABSTRACT FROM AUTHOR]

• Ni x Fe 1- x Al 2 O 4+ δ composite oxides are suitable for loading Pt nanoparticles. • Selectivity switch can be realized by adjusting the Ni/Fe molar ratios. • Pt/Ni x Fe 1- x Al 2 O 4+ δ is efficient for selective hydrogenation of cinnamaldehyde. • Up to 92.2% selectivity to cinnamyl alcohol was furnished with Pt/FeAl 2 O 4+ δ. • Above 80% selectivity to hydrocinnamaldehyde was obtained with Pt/NiAl 2 O 4+ δ. Due to coexistence of two conjugated unsaturated functional groups in cinnamaldehyde (CAL), exploring efficient catalysts with desirable selectivity to highly value-added products is still challengeable for the selective hydrogenation of CAL. Herein, Ni x Fe 1- x Al 2 O 4+ δ spinel composite metal oxides (SCMOs) supported Pt catalysts were developed and proved to be active and selective for the selective hydrogenation of CAL. Moreover, the selectivity switch can be realized just by changing the Ni/(Fe + Ni) molar ratios in Ni x Fe 1- x Al 2 O 4+ δ SCMOs. As a result, the excellent cinnamyl alcohol (COL) selectivity (~92.2%) and hydrocinnamaldehyde (HCAL) selectivity (~80.7%) were achieved on Pt/FeAl 2 O 4+ δ and Pt/NiAl 2 O 4+ δ , respectively. Based on the kinetic investigation of further hydrogenation of semi-hydrogenated product, the reason for the selectivity switch with Pt/Ni x Fe 1- x Al 2 O 4+ δ was revealed. In combination with detailed characterization, the excellent COL selectivity on Pt/FeAl 2 O 4+ δ can be attributed to more Pt(1 1 1) facets and FeO x species which can facilitate the preferential activation of C O bonds; while the high HCAL selectivity on Pt/NiAl 2 O 4+ δ is owing to the fact that there are more low coordinated active sites and two neighbouring Pt sites. [ABSTRACT FROM AUTHOR]

Selective hydrogenation of C=O against the conjugated C=C in cinnamaldehyde (CAL) is indispensable to produce cinnamyl alcohol (COL). Nonetheless, it is challenged by the low selectivity and the need to use organic solvents. Herein, for the first time, we report the use of Fe‐Co alloy nanoparticles (NPs) on N‐doped carbon support as a selective hydrogenation catalyst to efficiently convert CAL to COL. The resultant catalyst with the optimized Fe/Co ratio of 0.5 can achieve an exceptional COL selectivity of 91.7 % at a CAL conversion of 95.1 % in pure water medium under mild reaction conditions, ranking it the best performed catalyst reported to date. The experimental results confirm that the COL selectivity and CAL conversion efficiency are, respectively promoted by the presence of Fe and Co, while the synergism of the alloyed Fe‐Co is the key to concurrently achieve high COL selectivity and CAL conversion efficiency. [ABSTRACT FROM AUTHOR]

The selective hydrogenation of α,β-unsaturated aldehydes plays a crucial role in industrial production, and an efficient non-noble metal catalyst for it has been pursued to reduce the cost. Herein, we report an amorphous nickel phosphide for the selective hydrogenation of cinnamaldehyde. Compared to crystalline nickel phosphide, amorphous nickel phosphide showed both high activity and high selectivity to target products. Its catalytic performance was also better than that of commercial Pd/C catalyst. In addition, initial P/Ni ratio was found to be an important factor to affect the activity of amorphous nickel phosphide. High initial P/Ni ratio led to high activity owing to small particles, high surface area and strong metallicity of as-synthesized catalyst. Moreover, excellent catalytic performances of amorphous nickel phosphide were observed in the selective hydrogenation of different α,β-unsaturated aldehydes and ketones. [ABSTRACT FROM AUTHOR]

Reduced amorphous TiO2 (A‐TiO2), with high coverage of electrons and protons on its surface, supplies a steady‐state condition for selective hydrogenation reaction. Generally, there are some complex hydrogenation reaction products ascribed to the presence of multiple adsorption modes of cinnamaldehyde (CAL). In our work, the saturated aldehyde (∼48%) and unsaturated alcohol (52%) coexist in the products with a ratio of near 1 : 1, while the saturated alcohol is not produced in the reaction. Furthermore, the presence of H2O could suppress the adsorption of the C=O group while the C=C group could be strongly adsorbed on the surface of A‐TiO2, which results in the high selectivity of HCAL (∼84%). We explain these results by proposing a reaction mechanism with several adsorption modes of CAL affected by the solvents. This discovery also puts forward a new method for promoting the selectivity of COL by removing the H2O in the reaction system. [ABSTRACT FROM AUTHOR]

• HPZSM-5 was obtained by partial desilication of commercial ZSM-5. • PtFe/HPZSM-5 are more efficient than Pt/ZSM-5 and Pt/HPZSM-5. • Fe-doped Pt/HPZSM-5 catalyst greatly enhanced the catalytic performance. • PtFe/HPZSM-5 furnished the initial activity of 3.41 s−1. • PtFe/HPZSM-5 afforded a 87.6% selectivity toward cinnamyl alcohol. HPZSM-5 with hierarchical porous structure obtained via partial desilication of commercial ZSM-5 was proved to be a suitable support for Pt nanoparticles towards the liquid-phase selective hydrogenation of cinnamaldehyde (CAL) to yield cinnamyl alcohol (COL). Compared with Pt/ZSM-5, Pt/HPZSM-5 showed improved catalytic performance although the improvement seems to be very limited. After doping Fe to Pt/HPZSM-5 with a Fe/Pt molar ratio of 0.25, the PtFe/HPZSM-5 catalyst gave much further enhanced CAL conversion. Under the optimized conditions, a 97.9% CAL conversion with 87.6% selectivity to COL was achieved with the PtFe/HPZSM-5 catalyst. The initial activity (in terms of TOF value, defined as molecules of CAL converted per surface atom of Pt per second) reached about 3.41 s−1 with the PtFe/HPZSM-5 catalyst, one of the highest values up to now to our best knowledge. Moreover, the PtFe/HPZSM-5 catalyst can be recycled for at least 9 times without obvious loss in activity or selectivity to COL. The effect of partial desilication and Fe doping on the catalytic performance of PtFe/HPZSM-5 was discussed based on the characterization results using a series of techniques. [ABSTRACT FROM AUTHOR]

• Co x Fe 1- x Al 2 O 4+ δ oxides were prepared via a sol-gel method with glucose as template. • Pt/Co 0.5 Fe 0.5 Al 2 O 4+ δ furnished the initial activity of 4.1 s−1. • Pt/Co 0.5 Fe 0.5 Al 2 O 4+ δ afforded a 95.0% selectivity toward cinnamyl alcohol. • Pt/Co x Fe 1- x Al 2 O 4+ δ are recyclable for the selective hydrogenation of cinnamaldehyde. • Pt/Co x Fe 1- x Al 2 O 4+ δ are superior to most of the known supported Pt catalysts up to now. Co x Fe 1- x Al 2 O 4+ δ composite oxides were prepared using a sol-gel method with glucose as hard template. Pt nanoparticles supported on Co x Fe 1- x Al 2 O 4+ δ were employed for the liquid-phase selective hydrogenation of cinnamaldehyde (CAL) to yield the desired cinnamyl alcohol (COL). The activity increased with the x value; while the selectivity to COL almost kept above 90% despite of different x values. Upon investigation of kinetic behaviour with Pt/Co 0.5 Fe 0.5 Al 2 O 4+ δ as a model catalyst, the initial activity (in terms of TOF, defined as the converted CAL molecules per surface Pt atoms per second) of 4.1 s−1 was furnished. As for the selectivity to COL, it almost kept around 95% at whatever CAL conversions despite of the reaction temperatures. Pt/Co 0.5 Fe 0.5 Al 2 O 4+ δ catalyst can also be recycled for at least 10 times without obvious loss in activity or selectivity toward COL. This suggests that the active sites on the Pt/Co 0.5 Fe 0.5 Al 2 O 4+ δ catalyst preferentially adsorb and activate CAL via the terminal carbonyl groups. XPS analyses, H 2 -TPR, and CO-IR studies reveal that the intimate contact of Pt nanoparticles with FeO x or CoO x plays an important role in determining the catalytic performance of the Pt/Co x Fe 1- x Al 2 O 4+ δ catalysts. The Pt δ+/Pt0 ratio increased with the x value so that the Pt/CoAl 2 O 4 was the most active among the Pt/Co x Fe 1- x Al 2 O 4+ δ catalysts. [ABSTRACT FROM AUTHOR]

Since hydrogenation of C=C bond in the cinnamaldehyde is thermodynamically favored, the selective hydrogenation of C=O group is challenging. Developing effective catalysts for this transformation has been hindered by the intrinsic disadvantages of traditional materials for decades. Hereby, we report the synthesis of the low dimensional Co based nanorods (NRs) as the effective platform for C=O groups hydrogenation in the conjugated compounds. The Pt/Co-NRs catalyst is simply fabricated by loading the Pt nano-particles (NPs) on the Co-NRs and the stability of the Co-NRs support is improved by coordination between the Pt NPs and the pyridinic N ring. Resorting to XRD, FT-IR, XPS, HRTEM, DTG-TG characterization methods, the catalytic mechanism for C=O bond hydrogenation has been proposed. The synergistic effects of K+ and OH− enhance the polarization of C=O group, leading to more adsorption of C=O groups on the Co-NRs so as to promote its hydrogenation performance. In the absence of spatial micropores in low dimensional Co based nanorods, the Pt/Co-NRs catalyst is more advantageous for mass transfer. Under optimal conditions, the conversion of cinnamaldehyde is 97.9% with 92.7% selectivity of cinnamyl alcohol within 3 h. In addition, the selectivity of cinnamyl alcohol changes slightly (only 2.4% fluctuations) after five recycle tests. [ABSTRACT FROM AUTHOR]

• Pt/BN exhibited a high performance for the selective C O hydrogenation at room temperature. • BN with an inert surface and few acid-base sites favors a simple adsorption mode of cinnamaldehyde. • Large Pt particles with few low coordinated Pt sites favors a higher selectivity to cinnamyl alcohol. BN-supported Pt catalysts were prepared by an impregnation method using Pt(NH 3) 4 (NO 3) 2 as metal precursors and tested in the liquid-phase selective hydrogenation of cinnamaldehyde. It was found that the Pt/BN catalyst exhibited a high performance for the selective C O hydrogenation at room temperature. A selectivity of over 85% towards cinnamyl alcohol at a cinnamaldehyde conversion of over 95% could be obtained. The effects of supports and Pt particle sizes were explored by N 2 physisorption, XRD, TEM, HRTEM, HAADF-STEM, TPD, H 2 -TPR, XPS, CO-DRIFTS, etc. The influences of solvents and operation conditions were investigated, and a simplified kinetics test was also carried out. The comparison of different supports suggested that BN with an inert surface and few acid-base sites possibly favors a simple adsorption mode of cinnamaldehyde dependent only on the supported Pt particles, resulting in a high selectivity to cinnamyl alcohol. While the abundant acid-base surface sites on the Pt/Al 2 O 3 or Pt/SiO 2 , possibly associated with the multiple adsorption modes of cinnamaldehyde, had an adverse effect on the selective C O hydrogenation. The investigation of Pt size effect showed that large Pt particles with few low coordinated Pt sites displayed a higher selectivity to cinnamyl alcohol than small Pt particles with more low coordinated Pt sites on the Pt/BN catalysts. It was also revealed that water is a suitable solvent, and the presence of water in a mixture solvent is crucial for achieving a high activity of the Pt/BN in cinnamaldehyde hydrogenation. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Thermosensitive Pd catalyst supported on poly(N -isopropylacrylamide) grafted carbon nanotube (CNT-PNIPAM) was constructed. • As-prepared Pd/CNT-PNIPAM was applied for selective hydrogenation of cinnamaldehyde. • The hydrophilic surface of CNT-PNIPAM at 25 °C improved the dispersion of Pd nanoparticles on it in catalyst preparation. • Pd/CNT-PNIPAM exhibited the hydrophobic surface at 80 °C, improving adsorption properties for reactants in the reaction. • High Pd dispersion on catalyst as well as its good adsorption properties resulted in an improved catalytic performance. Abstract A wettability-controllable surface on carbon nanotubes (CNTs) was successfully constructed through directly grafting poly(N -isopropylacrylamide) (PNIPAM) from CNT surface (i.e. CNT-PNIPAM) via a facile method. The hybrid was employed as the support to prepare Pd catalyst (i.e. Pd/CNT-PNIPAM) for selective hydrogenation of cinnamaldehyde (CAL). The effects of thermoresponsive surface chemistry on catalytic performance were studied. Results showed that CNT-PNIPAM had the lower critical solution temperature (LCST) at about 37 °C. The hydrophilic surface of CNT-PNIPAM at 25 °C (< LCST) improved the dispersion of Pd nanoparticles on it in catalyst preparation. As-prepared Pd/CNT-PNIPAM then automatically switched its hydrophilic surface to the hydrophobic one at 80 °C (>LCST), which exhibited the good adsorption properties for reactants in the reaction. The high Pd dispersion on Pd/CNT-PNIPAM as well as its good adsorption properties for CAL jointly resulted in an enhanced catalytic activity, meanwhile maintaining the selectivity to cinnamyl alcohol (COL) unchanged in comparison to CNT supported Pd catalyst (Pd/CNT). [ABSTRACT FROM AUTHOR]

Hydrocinnamaldehyde (HCAL) is a crucial intermediate in the manufacture of perfumes and pharmaceuticals, but highly selective hydrogenation of cinnamaldehyde (CALD) to hydrocinnamaldehyde with a good conversion rate is a challenging. We report that the incorporation of Ag into Pd-based catalysts promotes their catalytic activity and HCAL selectivity (HCAL selectivity of 98.6% with >99.9% CALD conversion for Pd-0.3Ag/MCM-41) for CALD hydrogenation compared to those of catalysts with no Ag, e.g., HCAL selectivity of 84.5% for Pd/MCM-41and 77.3% for Pd/AC (activated carbon). The Pd-0.3Ag/MCM-41 catalyst shows an outstanding stability during five cycles of use. The excellent performance of the Pd-0.3Ag/MCM-41 catalyst in CALD hydrogenation is due to the ultra-small size of the Pd nanoparticles (Pd-Ag alloy, a geometric and electronic modification of Pd). [ABSTRACT FROM AUTHOR]

Pt/Co 0.5 Fe 0.5 Al 2 O 4 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 Co 0.5 Fe 0.5 Al 2 O 4 and smaller-sized Pt particles, resulting in electron-deficient Pt particles, so that C O and C C bond could be activated simultaneously. However, electron-rich Pt species existed on Pt/Co 0.5 Fe 0.5 Al 2 O 4 with larger Pt size, which is beneficial for the preferential activation of C O bond. [Display omitted] • Size dependence was observed on Pt/Co 0.5 Fe 0.5 Al 2 O 4 catalysts with various Pt sizes. • Pt particle size varies within 1.6–3.4 nm by changing Pt loading from 0.3 to 5 wt%. • Larger Pt nanoparticles favors higher selectivity to cinnamyl alcohol. • Pt particles with various sizes have various interaction with spinel Co 0.5 Fe 0.5 Al 2 O 4. • The electronic states of Pt sites affect the adsorption mode of cinnamaldehyde. [ABSTRACT FROM AUTHOR]

ZnO-Fe2O3 mixed oxides and supported gold nanocatalysts were prepared by using coprecipitation and deposition-precipitation methods, respectively. Cinnamaldehyde hydrogenation over various ZnO-Fe2O3 mixed oxides supported gold nanocatalysts have been investigated at 140 °C and a hydrogen pressure of 1.0 MPa. The molar ratio of Fe to Zn was found to greatly affect the selective hydrogenation catalytic activity of ZnO-Fe2O3 mixed oxide supported gold nanocatalysts. Among these supported gold nanocatalysts in this work, Au/Zn0.7Fe0.3Ox (Au loading of 1.74 wt %) exhibited the highest conversion of cinnamaldehyde and high selectivity to cinnamal alcohol. The excellent catalytic activity of Au/Zn0.7Fe0.3Ox was tightly associated with a large surface area, small gold nanoparticles, and good H2 dissociation ability at low temperature. [ABSTRACT FROM AUTHOR]

A series of hydrotalcite-like compounds was synthesized by varying Mg/Al molar ratio with values of 2, 3, and 4. After thermal treatment at 823 K, the corresponding mixed oxides were obtained and used as catalytic supports. The incorporation of a Pd metallic phase (0.5 g/g loading), was carried out by two methods: 1) in situ vapour phase thermal decomposition, and 2) impregnation by organic method. Fresh and calcined samples were characterized by XRD and N2 sorption experiments. The basic and metal functions were analyzed by CO2-TPD and H2-TPR. The Pd-support interaction was studied by FTIR spectroscopy using CO as a probe molecule while the morphology of Pd nanoparticles on the catalysts was studied by SEM, HRTEM, and theoretical simulation using the Fast Fourier Transform (FFT) method. Finally, the catalytic activity results showed a higher conversion towards hydrocinnamaldehyde in the cinnamaldehyde hydrogenation reaction for the catalysts prepared by vapour phase thermal decomposition, compared with those prepared by organic method, showing the significant dependence on the catalytic activity and the Pd incorporation method. [ABSTRACT FROM AUTHOR]

Selective hydrogenation of cinnamaldehyde (CAL) to cinnamyl alcohol (COL) was conducted over a series of FeO x -doped Pt catalysts supported on a 15 wt% Al 2 O 3 @SBA-15 composite (15AS). It was found that the addition of FeO x to the catalyst greatly improved its performance. With an optimal Fe/Pt molar ratio of 0.25, the PtFe 0.25 /15AS catalyst reached a maximum reaction rate (defined as moles of converted CAL per gram of Pt per hour) of 13.93 mol g Pt −1 h −1 with 76.9% selectivity to COL. Additionally, the PtFe 0.25 /15AS catalyst afforded the highest TOF value (defined as moles of converted CAL per mole of Pt active sites per second) of 1.54 s −1 . X-ray photoelectron spectroscopy analyses and H 2 temperature-programmed reduction and CO diffuse-reflectance infrared Fourier-transformation spectroscopy studies reveal that there is strong interaction between Pt nanoparticles and Al 2 O 3 @SBA-15 composites and also between Pt and FeO x , resulting in Pt species with a positive charge being dominant in PtFe 0.25 /15AS catalysts. Therefore, Pt species with positive charges, together with FeO x species, are beneficial for preferential adsorption and activation of carbonyl bonds of CAL, so that the activity and selectivity to COL were improved by PtFe x /15AS catalysts ( x represents the Fe/Pt molar ratio). [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni-Pt NPs (0.051–0.126 wt% Pt) were first prepared in RPB without surfactant. • Synergistic effect between Pt and Ni and homogeneous dispersion of Pt were found. • CAL conversion of 97.2% and HCAL selectivity of 88.4% were achieved by Ni-Pt NPs. • Reaction rate obtained by Ni-Pt NPs is 2.94 times larger than that by Ni NPs. • The effect of parameters on CAL hydrogenation and kinetic model were studied. Catalytic hydrogenation of α,β-unsaturated aldehydes is an efficient way to provide chemical feedstocks. Herein, Ni-Pt nanoparticles (NPs) (0.051–0.126 wt% Pt) were first synthesized by liquid reduction without surfactant in a rotating packed bed to catalyze the hydrogenation of cinnamaldehyde (CAL). Catalyst characterizations show that despite the thin amount of Pt, the regional Ni-Pt alloy and uniform distribution of Pt on Ni NPs as well as the unambiguous defect sites were found on the prepared Ni-Pt NPs. These explain the good catalytic performance of CAL hydrogenation where CAL conversion of 97.1% with hydrocinnamaldehyde (HCAL) selectivity of 88.4% was obtained. The reaction rate obtained by Ni-Pt NPs (0.0768 mol⋅g−1⋅h−1) is 2.94 times larger than that by Ni NPs (0.0261 mol⋅g−1⋅h−1) while the selectivity is not affected. Additionally, we investigated different parameters on the effect of CAL hydrogenation. Further, the kinetic study on the hydrogenation of CAL was exposed. The pre-exponential factor and activation energy are 3.22 × 1011 and 90.99 kJ/mol, respectively. [ABSTRACT FROM AUTHOR]

Since efficient hydrogenation was valued for manufacture of pharmaceutical intermediates and fragrances in recent years, the development of easily accessible heterogeneous catalysts was preferably made. Here we designed a facile one-pot synthesis of Ni modified COF-derived catalyst for selective catalytic hydrogenation of cinnamaldehyde. The nickel-based COFs catalyst reduced at 600 °C exhibited better catalytic activity for the selective production of hydrocinnamyl with an excellent yield of 98%, and the nickel-based COFs reduced at 500 °C and 700 °C preferred to selectively produce benzenepropanal. Overall, this work proves cost-effective and sustainable access to the wide application of selective hydrogenation reaction. [Display omitted] • This work provides a nickel encapsulated COF-derived catalysts for hydrogenation of cinnamaldehyde. • The Ni/COF-600 catalyst was active in catalytic hydrogenation of cinnamaldehyde towards hydrocinnamyl with approaching 98% yield, while the Ni/COF-700 COF catalyst was effective for the selective production of benzenepropanal with 90% yield. • These - nickel encapsulated COF-derived catalysts are cheap and highly active non-noble candidates for advanced green chemistry catalysis applications. [ABSTRACT FROM AUTHOR]

Uniform Au particles with a mean size of 1.9 nm were initially synthesized with polyvinyl alcohol (PVA) as protecting agent, and then deposited on MgO, AlO, TiO, FeO, CoO, ZnO and InO. After calcinations at 300 °C in air to remove PVA, Au particles were highly dispersed and immobilized on all the supports, displaying narrow diameter distributions and almost identical mean sizes of 2.5-3.2 nm. The Au-oxides catalysts were further used to catalyze selective hydrogenation of cinnamaldehyde (CAL) to cinnamyl alcohol (COL). It was found that the selectivity of COL was tightly related to the acidity/basicity of the Au/oxides catalysts. The catalyst with only acidic sites such as the Au/AlO catalyst gave very low selectivity of COL of 15%. The catalysts with only basic sites such as Au/MgO catalyst displayed medium selectivity of COL of 52%. Interesting, the Au catalysts with both acidic and basic sites such as the Au/InO and Au/ZnO catalyts exhibited the highest selectivity of COL of around 86%. The synergistic cooperation of acidic sites and basic sites should be responsible for preferential adsorption and activation of the C=O group than C=C group in CAL, and then preferential hydrogenation of C=O to COL. Graphical Abstract: [ABSTRACT FROM AUTHOR]

Chemoselective liquid phase hydrogenation of cinnamaldehyde (CAL) by employing transition-metal-based heterogeneous catalysts has been investigated by a lot of researchers worldwide with a view to obtain the desired products such as cinnamyl alcohol or hydrocinnamaldehyde. Both the products have significant wide-ranging applications in pharmaceuticals, perfumery, cosmetics and chemical industries. The present review therefore summarizes development in the last five years towards selective CAL hydrogenation over transition metal-based catalysts. The review is categorized into two major sections; selective hydrogenation of CAL to cinnamyl alcohol (COL) and selective hydrogenation of CAL to hydrocinnamaldehyde (HCAL) over various noble metals (Pt, Pd, Ru, Au, Ir and Ag) and non-noble metal-based catalysts (Ni, Co and Cu). A number of tailored metal-based catalytic systems for selective CAL hydrogenation reported in current years have been systematically reviewed based on the above categories. In addition, effect of reaction variables such as catalyst preparation, nature of solvents, reaction conditions has been deliberated. The review has been concluded with discussion on limitations encountered for noble metal as well as non-noble metal-based catalysts for selective CAL hydrogenation along with the future scope. Overall, the present review focuses on the fundamental principles of the transition metal-based catalysts reported for selective CAL hydrogenation. [Display omitted] • Comprehensive review on transition metal-based catalyst for cinnamaldehyde hydrogenation. • Cinnamyl alcohol and hydrocinnamaldehyde products were taken into consideration. • Effect of reaction variables on catalytic activity has been deliberated. • Features such as modification of electronic and geometric properties of active metal is discussed. • The review also discuss limitations encountered for selective CAL hydrogenation. [ABSTRACT FROM AUTHOR]

A series of Pd-Ni bimetallic catalysts supported on SBA-15 (0.2%Pd-x%Ni/SBA-15, x = 0.4, 0.7, and 1.2) were prepared through the impregnation method combined with the NaBH4 reduction method. X-ray diffraction (XRD), N2 adsorption-desorption, X-ray photoemission spectroscopy (XPS) and transmission electron microscope (TEM) were used to characterize the prepared catalysts. All the synthesized catalysts were evaluated for the liquid-phase hydrogenation of cinnamaldehyde (CAL). The addition of Ni obviously enhanced the CAL conversion and selectivity of C=C hydrogenation to hydrocinnamaldehyde (HALD) over the 0.2%Pd-x%Ni/SBA-15 catalysts. Meanwhile, 0.2%Pd-1.2%Ni/SBA-15 showed the best performance with 96.3% conversion and 87.8% selectivity toward HALD. This improvement was attributed to the synergistic effect between the Pd and Ni nanoparticles, enhancing the dispersion of Pd metal particles and increasing the content of surface Pd0 species. In addition, the influences of a few reaction factors including H2 pressure, reaction temperature, and reaction time were studied over 0.2%Pd-1.2%Ni/SBA-15.

ZnO-Fe2O3 mixed oxides and supported gold nanocatalysts were prepared by using coprecipitation and deposition–precipitation methods, respectively. Cinnamaldehyde hydrogenation over various ZnO-Fe2O3 mixed oxides supported gold nanocatalysts have been investigated at 140 °C and a hydrogen pressure of 1.0 MPa. The molar ratio of Fe to Zn was found to greatly affect the selective hydrogenation catalytic activity of ZnO-Fe2O3 mixed oxide supported gold nanocatalysts. Among these supported gold nanocatalysts in this work, Au/Zn0.7Fe0.3Ox (Au loading of 1.74 wt %) exhibited the highest conversion of cinnamaldehyde and high selectivity to cinnamal alcohol. The excellent catalytic activity of Au/Zn0.7Fe0.3Ox was tightly associated with a large surface area, small gold nanoparticles, and good H2 dissociation ability at low temperature.

A novel type of high-pressure membrane reactor has been developed for hydrogenation in supercritical carbon dioxide (scCO2). The main objectives of the design of the reactor are the separate feeding of hydrogen and substrate in scCO2 for safe reactions in a continuous flow process, and to reduce the reaction time. By using this new reactor, hydrogenation of cinnamaldehyde into hydrocinnamaldehyde has been successfully carried out with 100% selectivity at 50 °C in 10 MPa (H2: 1 MPa, CO2: 9 MPa) with a flow rate of substrate ranging from 0.05 to 1.0 mL/min.

A rotating stirrer reactor using aluminum oxide (Al 2 O 3 ) and platinum (Pt) loaded silicon carbide (SiC) foam as both the stirring blade and active catalyst was applied for selective hydrogenation of cinnamaldehyde (CAL). The variations of the catalyst activity and selectivity against the CAL concentration and rotating speed were studied. The reaction rate increased with the increasing of stirring speed and showed a maximum value at 300 rpm, while the highest selectivity of 75% could be achieved at conversion as high as 90% at 100 rpm. [ABSTRACT FROM AUTHOR]

Pt-Co alloy supported on SBA-15 catalysts (Pt-Co/SBA-15) were prepared by impregnation and NaBH reduction method. Their catalytic performances were investigated for selective hydrogenation of cinnamaldehyde. It was found that the formation of Pt-Co markedly enhanced the conversion to cinnamaldehyde and selectivity to cinnamyl alcohol compared with Pt/SBA-15. Meanwhile, the Pt-Co/SBA-15-0.6 catalyst performed the best catalytic activity that 71 % CAL conversion and 91 % selectivity to COL were attained. Moreover, no obvious deactivation was observed after using 4 times for Pt-Co/SBA-15-0.6. This improvement was contributed to the formation of Pt-Co alloy, which increased the amount of the Pt species on the catalysts. Graphical Abstract: Pt-Co alloy supported on SBA-15 catalyst shows excellent catalytic selective hydrogenation of cinnamaldehyde to cinnamyl alcohol [ABSTRACT FROM AUTHOR]

A highly selective and stable catalyst based on Pt nanoparticles confined in Mesoporous TiO 2 –SiO 2 frameworks were prepared and employed for selective hydrogenation of cinnamaldehyde to cinnamyl alcohol. The as-prepared Pt/MesoTiO 2 –SiO 2 -M catalyst displayed excellent selectivity to cinnamyl alcohol (around 91%) at nearly complete conversion. Ti 2+ and stronger metal-support interaction (SMSI) played key roles on the adsorption behavior of cinnamaldehyde and activation of C O bonds. The existence of amorphous SiO 2 and mixed TiO 2 phases (anatase and rutile) was helpful for the formation of Ti 2+ sites and SMSI. The electron-enriched Pt surfaces and the formed Pt-TiO x system benefited the enhanced activity and selectivity. [ABSTRACT FROM AUTHOR]

Pt nanoparticles supported on sheetlike mixed metal oxides (MMO) derived from layered double hydroxides are found to be highly efficient catalysts for the selective hydrogenation of cinnamaldehyde. A series of characterizations are employed to investigate the structure and composition of the support and catalyst. Divalent species have a significant influence on the activity and selectivity. CoAl MMO-supported catalysts achieve an increase in both conversion and selectivity to cinnamyl alcohol through the formation of PtCo alloy on the surfaces of catalysts during preparation. A possible reaction path is proposed. The effects of Co/Al ratio and calcination temperature on catalytic performance are researched in this work. [ABSTRACT FROM AUTHOR]