Search

Furfuryl alcohol (FA) is an important chemical and has extensive applications in varied fields. To realize the highly selective hydrogenation of furfural (FF) to produce FA, the key is the preparation of the catalysts with excellent performance. Herein, a very simple wet chemical method is developed for the one-step preparation of PdAg nanosponges (NSs). Specifically, with Pd(OAc) 2 and AgNO 3 as precursors, and ethylene glycol (EG) as both solvent and reducing agent, PdAg NSs can be grown and assembled at mild temperature of 40 °C. Throughout the reaction, no any surfactants and additional reducing agents are applied. The as-prepared PdAg NSs possess 3D self-supported alloy structures, "clean" surface, abundant pores, high specific surface area and rich defects. In the FF hydrogenation reaction at 60 °C under 1.5 MPa H 2 pressure in the mixed solvent of ethanol and water (1 : 4 in volume ratio), the self-supported PdAg-1 NSs (1 : 1 in Pd/Ag molar ratio) exhibit superior catalytic performance than other PdAg NSs, pure Pd sample and commercial Pd/C (10%). With PdAg-1 NSs as catalyst in the absence of support, 100% FF can be converted and the selectivity toward FA is as high as 97.1% at 36.0 h of reaction. After 4 cycles, PdAg-1 NSs still maintain the high catalytic activity in FF hydrogenation and high selectivity toward FA, which may originate from the 3D self-supported structures, high specific surface area, "clean" surface, rich defects and electronic synergistic effect between Pd and Ag. This simple fabrication of PdAg NSs introduces new ideas for the synthesis of other nanostructured bi- and multi-metallic catalysts for highly selective FF hydrogenation to FA and other advanced applications. The defect-rich PdAg nanosponges are one-step synthesized in ethylene glycol at 40 °C without the uses of any surfactants, additional reducing agents and supports, and exhibit highly catalytic activity and selectivity for furfural hydrogenation to produce furfuryl alcohol under mild conditions. [Display omitted] • PdAg nanosponges (NSs) were one-step grown in ethylene glycol at 40 °C. • The synthesis was achieved without any seed, surfactant and additional reductant. • The PdAg NSs have rich defects and self-supported structures. • PdAg NSs has excellent catalytic performance for furfural (FF) hydrogenation. • 100.0% conversion of FF and 97.1% selectivity to furfuryl alcohol can be achieved. [ABSTRACT FROM AUTHOR]

Chemoselective reduction of nitroarenes to corresponding arylamines is a significant reaction in the chemical industry. However, in the presence of other reducible groups, including halogenated nitrobenzene, nitrobiphenyl, and nitroquinoline in the same molecule of nitroaromatics, the control of chemoselectivity remains challenging. Here, a facile fabrication of a heterogeneous iron‐based catalyst is reported as a potential alternative to precious metal catalysts for the chemoselective reduction of nitroarenes. The pyrolysis of iron acetate/polyacrylonitrile (PAN) template under an inert atmosphere furnishes active Fe3O4 nanoparticles (NPs) encapsulated in nitrogen‐doped (N‐doped) carbon layers, which can provide more catalytic active sites (Fe3O4/PAN@800). Notably, non‐precious iron oxide NPs supported on N‐doped carbon support prevent aggregation, thereby enhancing the catalytic activity. The sustainable and reusable Fe3O4/PAN@800 catalyst, having only 0.8% metal content as demonstrated by x‐ray photoelectron spectroscopy, delivers excellent yields of corresponding amines from differently functionalized nitroarenes. Hydrogenation of a series of structurally functionalized nitroarenes produced excellent yields of anilines, which serve as building blocks and intermediates for fine and bulk chemicals. Hydrogenation of 2‐chloro‐3‐nitropyridine, 2‐nitro‐1,1′‐biphenyl, ortho‐nitroaniline, and 4‐aminophenyl acrylonitrile yielded respective anilines up to 99%. The active sites of Fe3O4 have magnetic performance, hence, the catalyst can be easily recovered using a magnet and reused for at least five cycles without significant loss of catalytic activity. Therefore, the easily prepared, cost‐effective, and reusable Fe3O4/PAN@800 catalyst presented in this study shows potential for applications in the selective reduction of aromatic nitro compounds. Consequently, this study potentially establishes a guideline for the facile preparation of abundant transition‐non‐noble metal‐based reusable supported catalysts for various applications in the chemical industry. [ABSTRACT FROM AUTHOR]

The direct conversion of furfural (FA) from biomass to pentanediols (PeDs), including 1,2-PeD and 1,5-PeD, is important for replacing fossil resources and developing bio-based polyesters from renewable sources. However, achieving high selectivity for the C–O hydrogenation of the furan ring remains a significant challenge. In this study, we synthesized a series of trimetallic CuCoLa catalysts, using a coprecipitation method with various metal ratios. The reduced CuCoLa catalyst with a metal ratio of 1/3/1, exhibited the highest activity for the selective hydrogenolysis of FA to PeDs. Under optimal reaction conditions (160 °C, 4 MPa H2 for 9 h), CuCoLa(1/3/1)-R achieved yields of 21.7% for 1,2-PeD and 50.1% for 1,5-PeD. Furthermore, the catalyst remained stable after five cycles of FA conversion to PeDs. The high selectivity for PeDs is attributed to the synergistic interaction between Cu and Co and the appropriate number of basic surface sites. [ABSTRACT FROM AUTHOR]

The selection of an appropriate preparation method is crucial to enhance catalytic performance and optimize the resources used in catalyst synthesis. Achieving improvements in conversion rates, desired product yields are essential for increasing interest and competitiveness in the industrial sector. This study aims to analyze the influence of the preparation method of Rh(1%)-Sn(4%)/γ-Al2O3 catalysts on the selective hydrogenation of oleic acid to oleyl alcohol. Results from temperature-programmed reduction (TPR), cyclohexane dehydrogenation (DHC), and X-ray photoelectron spectroscopy (XPS) clearly demonstrate that incorporating sodium borohydride in the preparation process results in a stronger interaction between Rh and Sn. The degree of interaction between Rh and Sn is significantly influenced by the catalyst preparation and activation method, with a strong interaction promoting selectivity towards the formation of oleyl alcohol. [ABSTRACT FROM AUTHOR]

The location control of single atoms relative to supports is challenging for single‐atom catalysts, leading to a large proportion of inaccessible single atoms buried under supports. Herein, a “sequential thermal transition” strategy is developed to afford single‐atom Pt preferentially dispersed on the outer surface of TiO2. Specifically, a Ti‐MOF confining Pt nanoparticles is converted to PtNPs and TiO2 composite coated by carbon (PtNPs&TiO2@C‐800) at 800 °C in N2. Subsequent thermal‐driven atomization of PtNPs at 600 °C in air produce single‐atom Pt decorated TiO2 (Pt1/TiO2‐600). The resulting Pt1/TiO2‐600 exhibits superior p‐chloroaniline (p‐CAN) selectivity (99 %) to PtNPs/TiO2‐400 (45 %) and much better activity than Pt1@TiO2‐600 with randomly dispersed Pt1 both outside and inside TiO2 in the hydrogenation of p‐chloronitrobenzene (p‐CNB). Mechanism investigations reveal that Pt1/TiO2‐600 achieves 100 % accessibility of Pt1 and preferably adsorbs the –NO2 group of p‐CNB while weakly adsorbs –Cl group of p‐CNB and p‐CAN, promoting catalytic activity and selectivity. [ABSTRACT FROM AUTHOR]

Structural engineering, coupled with crystalline phase engineering and surface engineering, serves as a practical and effective strategy for enhancing catalytic performance through the fine design of catalysts in terms of their structure, physical phases and surface defects. In this work, a set of strategies were employed for structural transformation and crystalline phase transition of Ru/TiO2 catalysts, utilizing multidimensional regulation. Ru nanoparticles loaded on a unique TiO2 nanosheet flowers (Ru/TSFs) enriched with pores and Ti3+ defects were prepared by solvothermal and impregnation‐chemical reduction methods. The Ru/TSFs exhibited an outstanding catalytic performance in the reaction of selective hydrogenation of benzene for the preparation of cyclohexene, with a selectivity of 79 % and a maximum yield of 52.8 % along with a benzene conversion of 45.9 % and a good stability. The excellent catalytic performance attributes to the distinctive structure of three‐dimensional nanosheet flowers, which offers a high specific surface area and improvs the effective contact between the catalyst and the reaction substrate. Meanwhile, the porous Ru/TSFs exhibit exceptional hydrophilicity and abundant Ti3+ defects on their surface, which is quite favorable for the desorption of cyclohexene from the reaction system, thus improving the selectivity of cyclohexene. The multidimensional engineering may provide an efficient approach for constructing high‐performance loaded catalysts for potential industrial applications. [ABSTRACT FROM AUTHOR]

Selective hydrogenation of alkynes to alkenes using a low‐cost non‐noble metal catalyst is urgently desirable but challenging because of their over‐hydrogenation to undesired alkanes. Herein, a series of hierarchical N‐doped carbon nanosheets anchored bimetallic oxides were successfully fabricated. The resultant composite catalysts had advantages associated with not only two‐dimensionality (2D) nanosheets with highly active sites and fast mass transfer, but also bimetallic oxides that dissociate and transfer hydrogen with the assistance of the oxygen vacancies. Furthermore, the bimetallic oxides combined with the advantages of high activity of Ni and the selectivity regulation of Co. Benefiting from these advantages, the catalytic performance of CoNiO2−ZnCo2O4/NC NSs can reach nearly full conversion with 92 % selectivity at moderate reaction conditions and can keep excellent selectivity even prolonging the reaction time to 12 h, outperforming CoNiO2−ZnCo2O4/NC NPs, CoO−ZnCo2O4/NC NSs, and the commercial Lindlar catalysts, which demonstrate the huge potential for selective hydrogenation applications. [ABSTRACT FROM AUTHOR]

5‐Hydroxymethylfurfural (5‐HMF) derived from lignocellulose represents an important platform molecule that could be employed in the selective hydrogenation of the furan ring to prepare 5‑hydroxymethyltetrahydrofurfural (HMTHF). However, the reported catalytic systems for the synthesis of HMTHF using 5‐HMF still require additional hydrogen pressure. In this study, the Pd/ZrO2 catalyst with uniformly dispersed Pd nanoparticles was prepared via a simple impregnation reduction process. This catalyst exhibited excellent catalytic activity and selectivity for the hydrogenation of 5‐HMF to HMTHF. High HMTHF yields up to 92.3% were produced under mild reaction conditions of ambient hydrogen pressure and room temperature in methanol solvent. This result was superior to the most catalytic systems that had been reported so far. The mechanism study revealed that the active hydrogen species on the surface of the Pd nanoparticles and the reaction solvent in this study were the pivotal factors influencing the hydrogenation of furan rings in 5‐HMF. [ABSTRACT FROM AUTHOR]

Au single atoms and clusters were stabilized on Mg−Al layered double hydroxide nanoparticles (LDH NPs), and the obtained Au@LDH NPs were supported on SiO2 and CeO2. After hydrogen reduction, Au single atoms were found together with Au clusters on LDH/SiO2. In contrast to Au single‐atom catalysts which are deposited in metal vacancies of oxide supports, the LDH NPs stabilize very small Au species despite the absence of metal vacancies. The obtained Au(0)@LDH/SiO2 catalyzed aerobic oxidation of alcohols, and Au single atoms maintained after the reaction. Given that only Au NPs were observed on bulk LDH, the abundant surface OH group of LDH NPs would contribute to stabilize Au, resulting in higher activity than Au/LDH‐bulk. After calcination to transform LDH to mixed metal oxide (MMO), the obtained Au(0)@MMO/SiO2 also exhibited high catalytic activity. Moreover, Au(0)@LDH/CeO2 exhibited higher activity and excellent selectivity for hydrogenation of 4‐nitrostyrene to 4‐aminostyrene than conventional Au catalysts such as Au/CeO2 and Au/TiO2. We demonstrated that Au size can be minimized using LDH NPs, exhibiting high catalytic performance. The basic surface OH groups of LDH would be also beneficial for deprotonation of alcohols and heterolytic dissociation of H2 in the catalytic reactions. [ABSTRACT FROM AUTHOR]

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]

The domain-limited catalyst, with its unique design of encapsulating active sites within nanoscale domains, significantly enhances catalytic efficiency and selectivity, while improving the stability and recyclability of the catalyst, which holds great significance for industrial applications. This paper presents a design strategy for a Ru-RuO2/N–C domain-limited catalyst. This catalyst utilizes the porous structure of metal–organic frameworks (ZJU-100) to optimize the stability and selectivity of the ruthenium active site through spatial confinement effects. During the preparation process, the ruthenium complex (Ru-(bpy)3Cl2·6H2O) is first introduced in situ into the synthetic system of ZJU-100 (Zn-MOFs), followed by high-temperature pyrolysis of the precursor at 900 °C. In this process, the zinc metal nodes in the MOFs are reduced and evaporated, while the nitrogen from the ruthenium complex and the carbon from the MOFs framework confine the growth and distribution of ruthenium species, resulting in a uniform particle size distribution of 2–5 nm. The presence of Ru(0) and RuO2 species in the catalyst is confirmed through XPS and HRTEM characterizations. This structural characteristic greatly promotes the selective hydrogenation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). Further studies reveal the reaction mechanism, finding that the formation of Ru–O bonds and the modulation of the oxidation state of ruthenium atoms play a crucial role in the catalytic activity of ruthenium catalysts. This provides an important theoretical foundation for designing efficient and stable ruthenium-based catalysts. [ABSTRACT FROM AUTHOR]

With the rapid development of modern society, the consumption of fossil fuels during the industrial production process produces a significant amount of carcinogens. Converting the highly toxic biphenyl (BP) to the valuable product cyclohexylbenzene (CHB) can decrease the emission of carcinogenic aromatic hydrocarbons. In this study, we prepared a series of 20%Ni/SiO2 catalysts with different specific surface areas (SSAs) using the over-volume impregnation method, as well as 20%M/SiO2 (M = Fe, Cu, Co, and Ni) catalysts to highlight the effects of support SSAs and active metal on the performance of BP selective hydrogenation to CHB. The catalysts were characterized by XRD, N2 physisorption, TEM, and H2-TPR, which demonstrated that a high SSA would be helpful for the dispersion of the active metal. The evaluation results revealed that 20%Ni/SiO2-300 exhibited excellent activity and stability in the selective hydrogenation of BP to CHB (BP conversion: 99.6%, CHB yield: 99.3% at the conditions of 200 °C, 3 MPa, 4 h and isopropanol as the solvent) among the catalysts with different SSAs, which was also superior to the performance over the catalysts with other transition metals as the active sites. The structure–activity relationship of the employed catalysts for the selective hydrogenation of BP to CHB was also discussed. [ABSTRACT FROM AUTHOR]

Furfuryl alcohol represents a pivotal intermediate in the high-value utilization of renewable furfural, derived from agricultural residues. The industrial-scale hydrogenation of furfural to furfuryl alcohol typically employs Cu-based catalysts, but their limited catalytic activity necessitates high-temperature and high-pressure conditions. Here, we develop robust CuNi bimetallic catalysts through direct calcination of dried sol–gel precursors under H2 atmosphere, enabling the complete conversion of furfural to furfuryl alcohol under mild conditions. By adjusting the calcination atmosphere and introducing small amounts of Ni, we achieve the formation of highly dispersed, ultrasmall Cu nanoparticles, resulting in a significant enhancement of the catalytic activity. The optimized 0.5%Ni-10%Cu/SiO2-CA(H2) catalyst demonstrates superior catalytic performance, achieving 99.4% of furfural conversion and 99.9% of furfuryl alcohol selectivity, respectively, at 55 °C under 2 MPa H2, outperforming previously reported Cu-based catalysts. The excellent performance of CuNi bimetallic catalysts can be attributed to the highly dispersed Cu nanoparticles and the synergistic effect between Cu and Ni for H2 activation. This research contributes to the rational design of Cu-based catalysts for the selective hydrogenation of furfural. [ABSTRACT FROM AUTHOR]

The strong metal-support interaction and its chemical nature was examined over a Ir/TiO2 catalyst, constructed by dispersing 2 nm Ir colloids on the {001} facets of anatase TiO2. Air-calcination of the Ir/TiO2 sample led to the oxidation of Ir particles into IrOx clusters. Upon H2-reduction at 573 K, the IrOx species were reduced into metallic with a prominent character for H2-chemisrption. As further raising the temperature to 673–773 K for H2-reduction, strong metal-support interactions occurred pronouncedly and the amounts of chemically adsorbed hydrogen dropped significantly. Spectroscopic and microscopic analysis found that the formation of surface Ir-Ti alloys on the Ir particles dominated the metal-support interactions, rather than the traditional encapsulation of the metal particles by TiOx overlayers. The surface Ir-Ti alloy, thus formed, promoted the selectivity for hydrogenating the C = O bond in acetophenone by altering the adsorption model of the C = O bond in the substrate. [ABSTRACT FROM AUTHOR]

The strong metal-support interaction and its chemical nature was examined over a Ir/TiO2 catalyst, constructed by dispersing 2 nm Ir colloids on the {001} facets of anatase TiO2. Air-calcination of the Ir/TiO2 sample led to the oxidation of Ir particles into IrOx clusters. Upon H2-reduction at 573 K, the IrOx species were reduced into metallic with a prominent character for H2-chemisrption. As further raising the temperature to 673–773 K for H2-reduction, strong metal-support interactions occurred pronouncedly and the amounts of chemically adsorbed hydrogen dropped significantly. Spectroscopic and microscopic analysis found that the formation of surface Ir-Ti alloys on the Ir particles dominated the metal-support interactions, rather than the traditional encapsulation of the metal particles by TiOx overlayers. The surface Ir-Ti alloy, thus formed, promoted the selectivity for hydrogenating the C = O bond in acetophenone by altering the adsorption model of the C = O bond in the substrate. [ABSTRACT FROM AUTHOR]

While supported metal nanoparticles (NPs) have shown significant promise in heterogeneous catalysis, precise control over their interaction with the support, which profoundly impacts their catalytic performance, remains a significant challenge. In this study, Pt NPs are incorporated into thioether‐functionalized covalent organic frameworks (denoted COF‐Sx), enabling precise control over the size and electronic state of Pt NPs by adjusting the thioether density dangling on the COF pore walls. Notably, the resulting Pt@COF‐Sx demonstrate exceptional selectivity (> 99 %) in catalytic hydrogenation of p‐chloronitrobenzene to p‐chloroaniline, in sharp contrast to the poor selectivity of Pt NPs embedded in thioether‐free COFs. Furthermore, the conversion over Pt@COF‐Sx exhibits a volcano‐type curve as the thioether density increases, due to the corresponding change of accessible Pt sites. This work provides an effective approach to regulating the catalysis of metal NPs via their microenvironment modulation, with the aid of rational design and precise tailoring of support structure. [ABSTRACT FROM AUTHOR]

Nanosized copper is an interesting alternative to noble metal‐based catalysts in gas phase selective hydrogenation, but little is known about its performance in liquid phase catalysis. We investigated the activity and selectivity of 2 and 7 nm Cu on SiO2 catalysts for the three‐phase partial hydrogenation of 2‐methyl‐3‐butyn‐2‐ol, a highly relevant reaction for fine chemical synthesis. Next to the desired 2‐methyl‐3‐buten‐2‐ol, also 2‐methyl‐2‐butanol was formed as a result of over‐hydrogenation. The 7 nm Cu nanoparticles were intrinsically 2.5 times more active than 2 nm Cu (in terms of turnover frequency), and they were also more selective. At 180 °C the selectivity was only 15 % at 50 % conversion, but lowering the reaction temperature to 160 and 140 °C led to 80 % and even ~100 % selectivity (at 50 % conversion). The unselective step was around two times faster than the selective one, hence the high selectivity is due the stronger adsorption of the reactant than of the desired product, which limits over‐hydrogenation. [ABSTRACT FROM AUTHOR]

The selective hydrogenation of acetylene is of industrially indispensable in the production of polymer-grade ethylene. The design of non-precious metal catalysts with outstanding performance is of pivotal importance in order to replace the supported Pd–Ag catalysts. Our previous work showed that a copper carbide (CuxC)-containing catalyst exhibited high hydrogenation activity and selectivity under mild conditions. In the present work, Mg(OH)2 was used to modify the CuxC-containing catalyst in order to improve its catalytic performance. Mg(OH)2-modified CuxC-containing catalyst was prepared from a coprecipitate of Cu(OH)2 and Mg(OH)2, which was obtained by precipitation of Cu(NO3)2 and Mg(NO3)2 solution with dropwise addition of NaOH solution, by thermal treatment in C2H2/Ar (0.5%) at 120 ℃ followed by H2 reduction at 150 ℃. The introduction of Mg(OH)2 led to reduced CuxC crystalline size and to increased amount of CuxC crystallites. In addition, the basic nature of Mg(OH)2 is favorable to suppress the undesired oligomerization. The prepared catalyst showed excellent catalytic performance with complete acetylene conversion, low selectivity to unwanted ethane (24%), and high stability at 100 °C and atmospheric pressure in the presence of large excess ethylene in 100 h. [ABSTRACT FROM AUTHOR]

[Display omitted] • FeO x can optimize the catalyst structure and stabilize the catalyst performance. • FeO x more conducive to the adsorption of nitro and the desorption of the product. • FeO x can effectively mask some acid sites, inhibit the hydrolysis of CHO. • The Cu+ interface carries out the adsorption and desorption of the reactants. • CuFeAl catalyst showes best performance for converting NCH to CHO (yield: > 93 %). Nitrocyclohexane (NCH) hydrogenation to cyclohexanone oxime (CHO) is of great significance in the production of caprolactam. In this work, CuFeAl-Layered Double Hydroxide (CuFeAl-LDH) catalysts with lamellar structure were prepared by co-precipitation method and applied for NCH hydrogenation, and the promoting role of FeO x was discussed. It was found that FeO x species promote the reduction of Cu2+ and control the ratio of Cu+ to Cu0. In situ DRIFT and density-functional theory (DFT) calculation results confirm that the presence of FeO x species can act as lewis base site to reduce the acid sites and facilitate the isomerization of nitrosocyclohexane to CHO, and promotes the adsorption of NCH and the desorption of the formed CHO to prevent its further reaction to form byproducts. CuFe 0.05 Al shows the best catalytic performance of 100 % NCH conversion and 93.35 % selectivity to CHO under mild conditions. This work provides a new idea for the design of non-noble metal-based catalysts with high activity for the selective hydrogenation of nitro compounds. [ABSTRACT FROM AUTHOR]

The selective hydrogenation of nitroaromatics plays an essential role in the chemical industry for the synthesis of anilines and their derivatives, which are known as crucial fine chemicals and pharmaceuticals. In this study, we demonstrate the preparation of Pd/Ti monolith catalyst containing well‐isolated metallic Pd sites on Ti substrate through a simple impregnation method, showing remarkable catalytic properties in the selective hydrogenation of nitroaromatics containing various functional groups. Kinetic analyses reveal an apparent activation energy of 61 kJ/mol and the kinetic isotope effect (KH2/KD2) of ~1.7 in the hydrogenation of 3‐chloronitrobenzene over Pd/Ti‐200 ppm catalyst, indicating the facile dissociation of dihydrogen and the subsequent efficient hydrogenation. The Pd/Ti‐200 ppm catalyst also demonstrates good stability and recyclability, maintaining its performance over multiple cycles. This simple but innovative approach not only enhances the efficiency of Pd catalysts in the selective hydrogenation of nitroaromatics but also offers significant potential for industrial applications in aniline production. [ABSTRACT FROM AUTHOR]

This work demonstrates that supported ruthenium phosphides (RuP2) are attractive catalysts for selective production of alditols by sugar hydrogenation. In our studies, carbon supported RuP2 with a ruthenium content of 5 wt.– % led to the highest activity in xylose hydrogenation and to nearly 100 % yield for xylitol. ICP‐OES and XRD measurements revealed the stability of this novel RuP2/C catalyst under typical hydrogenation conditions (50 barH2, 120 °C) in aqueous phase. Furthermore, STEM‐EDX illustrated the close proximity of ruthenium and phosphorous on the catalyst site and the formation of nanoparticles in the size of 2–4 nm. The catalyst system was successfully applied for the selective hydrogenation of further sugar substrates, including glucose, fructose, and disaccharides, such as cellobiose and sucrose. Here, the RuP2/C revealed its bifunctional acidic/metallic character, enabling in a tandem reaction the hydrolysis of disaccharides, directly followed by a selective hydrogenation to form sugar alcohols in high yield. [ABSTRACT FROM AUTHOR]

A sample of a catalytic system based on nickel and a carbon-containing material, microcellulose, was obtained using a hydrothermal synthesis method. A catalytic study of the synthesized system in the process of selective hydrogenation of carbon monoxide and carbon dioxide was carried out with calculation of the apparent activation energy. The sample was demonstrated to be highly active in the selective hydrogenation reactions of carbon oxides. A 100% conversion of carbon monoxide and carbon dioxide and selectivity for methane of 90 and 80%, respectively, were obtained. [ABSTRACT FROM AUTHOR]

Catalyst preparation, reaction process conditions and kinetics of the selective hydrogenation of fatty acid methyl esters (FAME) over a noble metal catalyst were studied. Two catalysts were prepared by impregnation of γ-Al2O3 with Ru (1% mass content) as active metal and Sn and B as modifiers (2% mass content), and with different Sn/Ru ratios of 2 and 4. FAME derived from biomass, an environment friendly raw material, was used for the preparation of fatty alcohols by selective hydrogenolysis of the ester group to an alcohol group. The results were analyzed with a simple kinetic model using lumped pseudocomponents. When comparing the two catalysts it was found that the most effective catalyst for producing oleyl alcohol was the one with a Sn/Ru ratio of 2, RuSn2–B. The maximum production of alcohols and alkanes was achieved with this catalyst at 290 °C. At 270 °C a lower production of alkanes was obtained but with a similar yield of alcohols. Both reaction conditions and catalyst composition were found to be important factors influencing alcohol production. Two types of active sites were identified on the studied catalysts: the unmodified Ru0 metal for dissociating hydrogen and the modified metal, (Ru0–(SnOx)2, for adsorbing the C=C carbons. RuSn2–B seemingly exhibited an appropriate balance of these sites. The kinetic model included the reactions of esters, hydrogen, alcohols and deoxygenated hydrocarbons. These were studied with lumped variables with no distinction of individual specific molecules. In spite of this, the model provided a very good fit of the experimental data indicating that the reaction is rather insensitive to secondary features like carbon chain length or group positions. [ABSTRACT FROM AUTHOR]

Metal‐Organic Frameworks (MOFs) represent a highly promising class of materials with diverse applications, particularly as catalytic materials. However, their synthesis typically yields powders available only at laboratory‐scale quantities, usually in the gram range or less. This study addresses the challenge of testing limited amounts of MOF catalysts for demanding applications, such as multiphase gas‐liquid‐solid reactions in flow, utilizing a packed‐bed microreactor. Specifically, we investigate the performance of a nanoparticle (NP) ‐immobilized Pd@UiO‐66 MOF catalyst in the selective semi‐hydrogenation of phenylacetylene to styrene, serving as a model reaction. Maintaining the Taylor flow regime upstream of the catalyst bed was crucial to ensure reproducible and reliable experimental results. We conducted 88 experiments at varying liquid flow rates, temperatures ranging from 15 to 45 °C, and relative pressures spanning 0.28 to 8 bar. Styrene selectivity within the range of 80–92.3 % was achieved at phenylacetylene conversions below 20 %. Notably, the optimal condition for styrene selectivity (70 %) was attained at 98.9 % phenylacetylene conversion under the lowest H2 pressure and highest temperature, demonstrating the significance of low H2 concentration for achieving optimal styrene selectivity. Remarkably, the catalyst exhibited stable activity and selectivity over a 20 h testing period, indicating its robust performance under prolonged reaction conditions. This study demonstrates the potential of the proposed catalyst testing system as a rapid and efficient approach for early‐stage exploration studies, particularly when limited quantities of catalyst, typically in the gram scale or less, are available. [ABSTRACT FROM AUTHOR]

Solvent effects add a new dimension for tuning the activity and selectivity of heterogeneous catalytic reactions, which is extensively employed in the hydrogenation of unsaturated compounds with multiple functional groups. In this concept, we briefly summarize recent developments on how the solvent effects affect the catalytic performance from the following aspects: 1) the polarity of the solvent can influence the interaction between the solvent and the reactant or intermediate; 2) the composition of mixed solvent can influence the reactivity of the reactant or intermediate; 3) solvent effect varies with the metal identity and support; 4) the solvent can induce surface modification of the supported catalysts. This summarization will provide insights into the rational development of efficient and selective heterogeneous hydrogenation catalytic system to realize the precise synthesis of desired chemicals. [ABSTRACT FROM AUTHOR]

We successfully constructed an ultrathin Ti3C2Tx supported Pt nanocluster catalyst for highly selective and efficient hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN) under mild conditions (30 °C, 0.1 MPa H2). The Pt/Ti3C2Tx catalyst displayed a very high conversion (>99%) and selectivity (>99%). In addition, a higher reaction rate (41 mol h–1 g–1) was obtained in comparison with the previously reported catalysts. The excellent catalytic activity of Pt/Ti3C2Tx was attributed to the strong metal–support interactions between Pt nanoclusters and the support, in which the electrons were transferred from Ti3C2Tx to Pt sites, affording a high electron density of Pt active sites. Moreover, the electrostatic repulsion between C–Cl moiety and Pt sites inhibited the dechlorination process. In addition, the Pt/Ti3C2Tx catalyst also exhibited excellent performance in substrate scope (reducible heterocyclics such as pyridine and phthalimide), stability (10th cycles, conversion >99% and selectivity 98%), and gram-scale reaction (99% yield, 1.89 g). This work will promote the research in constructing efficient and highly selective noble metal-based catalysts for hydrogenation of halogenated nitroarenes. [ABSTRACT FROM AUTHOR]

Mixed metal oxides with perovskite ABO3 or spinel AB2O4 structure can provide uniformly and highly dispersed metal oxides, which can be adopted as catalyst supports, as catalysts directly or as catalysts after reduction. When they are used as catalyst supports, the spatial isolation of A‐site ions with B‐site ions not only makes these ions highly dispersed, but also enhances the intimate contact with the active components supported on them, leading to electron transfer or synergistic effect to promote the catalytic ability. After reduction, highly dispersed A/B nanoparticles supported on BOx/AOx can be achieved for the relevant applications. Herein, recent developments in the liquid–phase selective hydrogenation of α,β‐unsaturated aldehydes, with metal oxides derived from perovskite or spinel as supports or catalyst precursors, were summarized. [ABSTRACT FROM AUTHOR]

Single‐atom alloys (SAAs) have gained increasing prominence in the field of selective hydrogenation reactions due to their uniform distribution of active sites and the unique host‐guest metal interactions. Herein, 15 SAAs are constructed to comprehensively elucidate the relationship between host‐guest metal interaction and catalytic performance in the selective hydrogenation of 4‐nitrostyrene (4‐NS) by density functional theory (DFT) calculations. The results demonstrate that the SAAs with strong host‐guest metal interactions exhibit a preference for N─O bond cleavage, and the reaction energy barrier of the hydrogenation process is primarily influenced by the host metal. Among them, Ir1Ni SAA stands out as the prime catalyst candidate, showcasing exceptional activity and selectivity. Furthermore, the Ir1Ni SAA is subsequently prepared through precise synthesis techniques and evaluated in the selective hydrogenation of 4‐NS to 4‐aminostyrene (4‐AS). As anticipated, the Ir1Ni SAA demonstrates extraordinary catalytic performance (yield > 96%). In situ FT‐IR experiments and DFT calculations further confirmed that the unique host‐guest metal interaction at the Ir‐Ni interface site of Ir1Ni SAA endows it with excellent 4‐NS selective hydrogenation ability. This work provides valuable insights into enhancing the performance of SAAs catalysts in selective hydrogenation reactions by modulating the host‐guest metal interactions. [ABSTRACT FROM AUTHOR]

The selective hydrogenation of the biomass platform molecule furfural (FAL) to produce furfuryl alcohol (FA) is of great significance to alleviate the energy crisis. Cu-based catalysts are the most commonly used catalysts, and their catalytic performance can be optimized by changing the preparation method. This paper emphasized the effect of calcination atmosphere on the performance of a Cu/Al2O3 catalyst for the selective hydrogenation of FAL. The precursor of the Cu/Al2O3 catalyst prepared by the ammonia evaporation method was treated with different calcination atmospheres (N2 and air). On the basis of the combined results from the characterizations using in situ XRD, TEM, N2O titration, H2-TPR and XPS, the Cu/Al2O3 catalyst calcined in the N2 atmosphere was more favorable for the dispersion and reduction of Cu species and the reduction process could produce more Cu+ and Cu0 species, which facilitated the selective hydrogenation of FAL to FA. The experimental results showed that the N2 calcination atmosphere improved the FAL conversion and FA selectivity, and the FAL conversion was further increased after reduction. Cu/Al2O3-N2-R exhibited the outstanding performance, with a high yield of 99.9% of FA after 2 h at 120 °C and an H2 pressure of 1 MPa. This work provides a simple, efficient and economic method to improve the C=O hydrogenation performance of Cu-based catalysts. [ABSTRACT FROM AUTHOR]

Cu catalysts with different compositions and different Cu and promoter contents were prepared by precipitation‐gel method and studied for the selective hydrogenation of syngas or biomass‐based diethyl malonate (DEM) to valuable 1,3‐propanediol (1,3‐PDO). The Ga‐promoted 70Cu6Ga/SiO2 catalyst was found to exhibit the highest catalytic performance, achieving 100 % DEM conversion and 76.6 % 1,3‐PDO selectivity under reaction conditions of 160 °C and 8 MPa H2. The 70Cu6Ga/SiO2 bimetallic catalyst also presented obviously better stability than that of the monometallic 70Cu/SiO2 catalyst in a continuous flow reactor over 180 h time‐on stream. Characterization results showed that the incorporation of Ga increased the interaction between Cu and Ga species, hindered the full reduction of Cu2+ species, and thus increased the proportion of Cu+ and the number of Lewis acidic sites on the catalyst surface. The synergistic effect between Cu0 and Cu+ enhanced the adsorption and activation of ester carbonyl groups and their subsequent hydrogenation, eventually contributed to the outstanding performances of the CuGa/SiO2 bimetallic catalysts. [ABSTRACT FROM AUTHOR]

The selective hydrogenation has attracted increasing attention to chemists for the production of value‐added products in chemical industry. Over the past several decades, substantial effort has been devoted to the design of catalyst for the selective hydrogenation of light alkynes and α, β‐unsaturated aldehydes, two classic cases for selective hydrogenation in chemical industry. Despite the great progress, it remains great challenges to achieve the selective hydrogenation because the desired products are generally thermodynamically unfavored. Here, we summarize the recent advances on selective hydrogenation using noble metal nanocrystals, with an emphasis on the surface engineering of noble metal nanocrystals for the selective hydrogenation of light alkynes and α, β‐unsaturated aldehydes. We will highlight the strategies for surface engineering, the advanced techniques for characterizations, as well as mechanism studies. We hope this review will promote chemists to develop efficient and robust catalysts for selective hydrogenation. [ABSTRACT FROM AUTHOR]

The selective hydrogenation of α,β-unsaturated aldehydes using unsupported nanoporous platinum–iron–aluminum (PtFeAlNPore) as a heterogeneous catalyst was investigated in depth. A PtFeAlNPore trimetallic catalyst with a highly bicontinuous nanostructure was synthesized by a two-step chemical dealloying method. The catalyst exhibited a good yield with high selectivity for the hydrogenation of α,β-unsaturated aldehydes into allyl alcohols under mild reaction conditions. A series of characterizations revealed that a decrease in the Pt electronic density (exhibiting superior hydrogen-activation ability), a nanoporous structure (providing increased reaction active sites), Lewis acidity (promoting the adsorption and activation of the carbonyl group in α,β-unsaturated aldehydes), and intimate PtFe–Fe3O4 heterointerfaces (facilitating the selective hydrogenation of α,β-unsaturated aldehydes into allyl alcohols) led to the excellent catalytic performance. [ABSTRACT FROM AUTHOR]

The selective conversion of levulinic acid (LA) obtained from lignocellulosic biomass represents a crucial pathway for producing the key value‐added chemical compound γ‐valerolactone (GVL). Herein, we constructed a series of Pt‐based titanium‐silicalite‐1 (TS‐1) bifunctional catalysts modified with rare earth metal Ce through a simple spin‐coating impregnation method, and the catalytic performance was significantly improved compared to the unmodified Pt1.2/TS‐1. Pt0.7‐Ce0.5/TS‐1 exhibited the best aqueous‐phase catalytic activity (with a GVL yield of 99.4%). The introduction of CeOx can reduce the particle size of Pt nanoparticles and promote the formation of electron‐rich Pt species while delivering abundant oxygen vacancies (OV) for the catalysts. The characterization and testing results highlight the synergistic effect of OV and electron‐rich Pt sites on the oriented adsorption and selective hydrogenation of LA, providing new insights into constructing more efficient noble metal‐based zeolite catalysts for biomass conversion. [ABSTRACT FROM AUTHOR]

A series of inexpensive electroplating sludge-derived magnetic copper-containing catalysts were developed for the selective hydrogenation of biomass-based furfural (FFR) into furfuryl alcohol (FA) and 2-methylfuran (MF). The specific structural characteristics of as-prepared magnetic copper-containing samples were clearly identified through various techniques, including XRD, XPS, N2 adsorption–desorption, NH3-TPD, SEM and so on. The characterizations revealed that the hydrogen pre-activated magnetic catalysts supplied metallic Cu species, medium acidity and porosity for the catalytic upgrading of FFR in hydrogen atmosphere. As for FFR-to-FA as well as FFR-to-MF transformations, the magnetic copper-containing catalyst with calcination temperature of 800 °C exhibited excellent performance towards the formation of FA and MF, wherein desirable FA yield of 98.5 mol% and MF yield of 71.3 mol% were achieved at reaction temperatures of 160 °C and 240 °C, respectively. The reuse experiments indicated that the recycled catalysts still maintained excellent activity and stability even after four-time recycling. The present study thus highlights a new approach for the resource utilization of electroplating sludge, which also supplies low-cost and efficient catalytic materials for the selective upgrading of various biomass-derived platform molecules. [ABSTRACT FROM AUTHOR]

The hydrogenation of nitrogen-containing heterocyclic compounds and their derivatives to obtain the corresponding valuable products is of great practical significance. In this work, a highly active and selective Ni/NC hydrogenation catalyst was developed by utilizing melamine-modified high-specific surface carbon (NC) as a carrier for nickel nanoparticles (NPs), which showed excellent catalytic activity in the selective hydrogenation of methyl nicotinate, where the Ni/NC catalyst was first used for this reaction (selective hydrogenation of methyl nicotinate). It was found that nitrogen species on the surface of NC significantly promoted the decomposition of the nickel precursor and the high dispersion of nano-Ni, which effectively affected the agglomeration of the nickel metal, resulting in the distribution of nickel metal with a smaller particle size. In the selective hydrogenation of methyl nicotinate under mild conditions (130 °C, 3 h), the conversion of methyl nicotinate reached the optimal catalytic activity over the catalyst of 10% Ni/NC-1-M-I-300, in which the conversion of methyl nicotinate was 98.5% and the selectivity of methylpiperidine-3-carboxylate was 97.2%. After 5 recycles, the catalyst maintained a conversion of 95.4% for methyl nicotinate. The Ni/NC catalyst has good substrate adaptability in the selective hydrogenation of N-heterocyclic carboxylate, O-heterocyclic carboxylate, and aromatic carboxylate. [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]

Changes in the composition of immobilized [M(COD)Cl]2–NH2–C3H6–SiO2 and [M(COD)Cl]2–P(Ph)2–C2H4–SiO2 (where M = Ir, Rh) catalysts in the gas-phase selective hydrogenation of propylene, propyne, and 1,3-butadiene with parahydrogen (p-H2) have been studied by the XPS method. It has been proposed that the M/Cl atomic ratio should be used as an indicator of the structural stability of the anchored complex both at the sample synthesis stage and in the reaction. Based on comparison of XPS data and results of catalytic tests using parahydrogen-induced nuclear polarization, it has been shown that the stability of the anchored {[M(COD)Cl]2–Linker–SiO2} complex during hydrogen activation is a key factor in the catalytic behavior of the systems. The stability of the complex is affected not only by the chosen metal and linker, but also by the nature of the substrate subjected to hydrogenation. [ABSTRACT FROM AUTHOR]

Cost‐effective non‐noble metal‐based catalysts for selective hydrogenation with excellent activity, selectivity, and durability are still the holy grail. Herein, an oxygen‐doped carbon (OC) chainmail encapsulated dilute Cu–Ni alloy is developed by simple pyrolysis of Cu/Ni‐metal–organic framework. The CuNi0.05@OC catalyst displays superior performance for atmospheric pressure transfer hydrogenation of p‐chloronitrobenzene and p‐nitrophenol, and for hydrogenation of furfural, all in water and with exceptional durability. Comprehensive characterizations confirm the close interactions between the diluted Ni sites, the base Cu, and optimized three‐layered graphene chainmail. Theoretical calculations demonstrate that the properly tuned lattice strain and Schottky junction can adjust electron density to facilitate specific adsorption on the active centers, thus enhancing the catalytic activity and selectivity, while the OC shell also offers robust protection. This work provides a simple and environmentally friendly strategy for developing practical heterogeneous catalysts that bring the synergistic effect into play between dilute alloy and functional carbon wrapping. [ABSTRACT FROM AUTHOR]

The catalytic conversion of naturally rich and renewable biomass into high-value chemicals is of great significance for pursuing a sustainable future and a green economy. The preparation of pentanediol from furfuryl alcohol is an important means of high-value conversion of biomass. The Pt-based catalyst supported on MgO was applied to the selective hydrogenation of biomass furfuryl alcohol to prepare pentanediol. By adjusting parameters such as catalyst loading, reduction temperature, reaction temperature, and pressure, a highly active catalyst was designed and the optimal catalytic hydrogenation conditions were determined. The hydrogenation experiment results showed that the selectivity of the 2Pt/MgO-200 catalyst for 1,2-pentanediol and 1,5-pentanediol reached 59.4% and 15.2%, respectively, under 160 °C and 1 MPa hydrogen pressure. The catalyst was characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectrometer (XPS), CO2-temperature programmed desorption (CO2-TPD), and other methods. The characterization results indicate that the reduction temperature has a significant impact on the metal Pt, and an appropriate reduction temperature is beneficial for the hydrogenation performance of the catalyst. In addition, the basic sites on the carrier are also another important factor affecting the activity of the catalyst. In addition, stability tests were conducted on the catalyst, and the reasons for catalyst deactivation were studied using methods such as thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). The results showed that the activity of the catalyst decreased after five cycles, and the deactivation was due to the hydrolysis of the carrier, the increase in metal particle size, and the surface adsorption of organic matter. [ABSTRACT FROM AUTHOR]

Mesoporous silica gel doped with dysprosium, lanthanum and modified with silver (Dy-Ag/MPS, La-Ag/MPS) was obtained by the template method. The physicochemical characteristics of the obtained catalyst were studied by scanning electron microscopy, X-ray fluorescence and X-ray diffraction analysis, inductively coupled plasma mass spectrometry and temperature-programmed reduction. In addition, the possibility of using obtained materials as an efficient and selective catalysts in the hydrogenation of a 1-heptyne/1-heptene mixture (with 30% of alkyne content) in a temperature range of 140–160 °C and a hydrogen pressure of 3 atm was studied. It was found that after 15 min from the start of the hydrogenation reaction at 140 °C on the La-Ag/MPS catalyst, total conversion of 1-heptyne was observed and selectivity for 1-heptene was 84%. Moreover, it was shown that on a Dy-Ag/MPS at 150 °C 1-heptyne conversion was 84%, the selectivity for alkene was 79%. Furthermore, with an increase in temperature to 160 °C, the conversion of 1-heptyne reaches 95%, the selectivity for 1-heptene—84%. [ABSTRACT FROM AUTHOR]

Rationally designed polymers can function as supports or promoters for metal catalysts, imparting distinct catalytic properties in selective hydrogenation. With strongly metal–ligating functional groups, mobile polymer chains can spontaneously decorate the metal catalyst surfaces under mild conditions, forming stable metal–polymer interfaces. We have termed this phenomenon 'dynamic metal–polymer interaction (DMPI),' which can be roughly considered as an organic version of the strong metal–support interaction (SMSI) concept. The polymer chains that dynamically interact with the metal surface can control the adsorption of reactants and products through competitive adsorption, significantly improving selectivity and catalyst stability. One of the remarkable advantages of using polymers as catalytic materials is that their molecular structures, such as molecular weight, crystallinity, and chemical functionality, can be tailored using rich organic chemistry. This, in turn, allows us to precisely tune the metal–polymer interactions and catalytic properties. In this Concept, we will discuss how metal–polymer interfaces can be designed and utilized for selective hydrogenation, with a particular emphasis on the industrially relevant acetylene partial hydrogenation reaction. [ABSTRACT FROM AUTHOR]

Upgrading of polyethylene terephthalate (PET) waste into valuable oxygenated molecules is a fascinating process, yet it remains challenging. Herein, we developed a two‐step strategy involving methanolysis of PET to dimethyl terephthalate (DMT), followed by hydrogenation of DMT to produce the high‐valued chemical methyl p‐methyl benzoate (MMB) using a fixed‐bed reactor and a Cu/ZrO2 catalyst. Interestingly, we discovered the phase structure of ZrO2 significantly regulates the selectivity of products. Cu supported on monoclinic ZrO2 (5 %Cu/m‐ZrO2) exhibits an exceptional selectivity of 86 % for conversion of DMT to MMB, while Cu supported on tetragonal ZrO2 (5 %Cu/t‐ZrO2) predominantly produces p‐xylene (PX) with selectivity of 75 %. The superior selectivity of MMB over Cu/m‐ZrO2 can be attributed to the weaker acid sites present on m‐ZrO2 compared to t‐ZrO2. This weak acidity of m‐ZrO2 leads to a moderate adsorption capability of MMB, and facilitating its desorption. Furthermore, DFT calculations reveal Cu/m‐ZrO2 catalyst shows a higher effective energy barrier for cleavage of second C−O bond compared to Cu/t‐ZrO2 catalyst; this distinction ensures the high selectivity of MMB. This catalyst not only presents an approach for upgrading of PET waste into fine chemicals but also offers a strategy for controlling the primary product in a multistep hydrogenation reaction. [ABSTRACT FROM AUTHOR]

A Ru-decorated porous melamine polymer is found to be an active catalyst upon selective hydrogenation of aqueous 5-hydroxymethylfurfural to 2,5-bis-(hydroxymethyl)furan (yield > 99%) under mild (20 bar H2, 30–90 °C), base/additive free conditions. Owing to its porous structure and unique surface chemistry presenting abundant weakly basic N-sites (amine and triazine), the polymeric catalyst could outperform various benchmark Ru catalysts (viz. Ru/AC, Ru/SBA-15, Ru/Nb2O5, Ru/NbOPO4, Ru/NC, and Ru/g-C3N4) in terms of activity and desired product selectivity. The catalytic material was also found to be reusable and maintained good performance during multiple recycles under kinetic regime in batch mode. Furthermore, the polymeric catalyst also showed good performance for selective HMF hydrogenation under intensified conditions in a fixed-bed reactor achieving constant BHMF yield during 20-h steady-state operation under relatively mild conditions (70 °C, 20 bar, WHSV 0.2 h−1). [ABSTRACT FROM AUTHOR]

Zinc-included intermetallic compound catalysts of RhZn, PtZn, and PdZn with a molar ration of Zn/metal = 1/1, which are generally prepared using a hydrogen reduction approach, are known to show excellent catalytic performance in some selective hydrogenations of organic compounds. In this study, in order to reduce the incorporated mounts of the expensive noble metals, we attempted to prepare zinc-rich intermetallic compounds via a CaH2-assisted molten salt synthesis method with a stronger reduction capacity than the common hydrogen reduction method. X-ray diffraction results indicated the formation of RhZn13 and Pt3Zn10 in the samples prepared by the reduction of ZnO-supported metal precursors. In a hydrogenation reaction of p-nitrophenol to p-aminophenol, the ZnO-supported RhZn13 and Pt3Zn10 catalysts showed a higher selectivity than the RhZn/ZnO and PtZn/ZnO catalysts with the almost similar conversions. Thus, it was demonstrated that the zinc-rich intermetallic compounds of RhZn13 and Pt3Zn10 could be superior selective hydrogenation catalysts compared to the conventional intermetallic compound catalysts of RhZn and PtZn. [ABSTRACT FROM AUTHOR]