Search

The CaO-supported Pt nanoparticle catalysts, herein referred to as the Pt/CaO-P catalysts, were synthesized for the first time to catalyze the selective hydrogenation of styrene oxide. All previously reported Pt- and Pd-based catalysts were prepared and evaluated under identical conditions, with 2-phenylethanol (2-PEA) being identified as the primary product in the selective hydrogenation of styrene oxide. The comparative analysis of the catalytic performance of Pt/CaO-P, Pt/CaO (unpurified), Pt/Ca(OH)2, and Pt/CaCO3 revealed that the purity of CaO is crucial for enhancing the selectivity towards 1-phenylethanol (1-PEA). Notably, the highest selectivity of 1-PEA over Pt/CaO-P reached up to 39%. Our SO-TPD, CO2-TPD and ex situ FT-IR results further indicated that strong basic sites can modify the adsorption site of SO over Pt nanoparticles, leading to the higher selectivity of 1-PEA. A proposed reaction mechanism for the ring opening of styrene oxide suggests that the breakage of conjugation between the benzene ring and the adjacent carbon cation by strong basic sites plays an important role. [ABSTRACT FROM AUTHOR]

The synthesis of a hierarchical SSZ-13 zeolite with mesopores and micropores is one of the most effective strategies to overcome the diffusion limitation imposed by the micropores of SSZ-13 in reactions involving bulky reactants or intermediates. A zeolite with nanosheet morphology possesses the advantages of large inter-sheet mesopore volume, more accessible acid sites and short diffusion path lengths. Nevertheless, only a few works focused on the synthesis of the nanosheet-assembled SSZ-13 zeolite. In this work, a nanosheet-assembled hierarchical SSZ-13-TP0.03 (thickness of 20 nm) zeolite was synthesized in a seed-assisted synthesis system by coupling a small amount of N, N, N-trimethyl-1-adamantylammonium hydroxide (TMAdaOH) with octadecyl-(3-trimethoxysilylpropyl)-ammonium chloride (TPOAC). In this strategy, the Si/Al ratio of the initial gel, seed, TPOAC and TMAdaOH amount in the synthesis system and the synergistic effects among them lead to the synthesis of SSZ-13 samples with various textural properties and morphologies. The distinct textural properties and morphologies of SSZ-13 result in the preparation of Pt/SSZ-13 catalysts with varied Pt dispersions. The catalyst, Pt supported on the nanosheet-assembled hierarchical SSZ-13 (Pt/SSZ-13-TP0.03), exhibits higher hydrogenation ability than its corresponding catalyst, Pt supported on microporous or hierarchical SSZ-13 in the hydrogenation of naphthalene. [ABSTRACT FROM AUTHOR]

Carbon-supported non-precious metal catalysts with highly exposed active sites have great potential for applications in the hydrogenation reduction of nitro compounds. Herein, a strategy for the preparation of carbon-supported Mo-based catalysts (Mo@C/MC) is proposed. Protein–Mo ion networks are first coated on the surface of microsphere carbons (MC). The coated MC employed as a precursor is then pyrolyzed to produce carbon-supported Mo-based catalysts. Notably, neither pore-forming agents nor post-treatment is required in the preparation of the catalyst. The active sites tend to disperse uniformly on the surface of the carbon matrix, facilitating the exposure of the active sites of the catalyst. The as-prepared catalyst Mo@C/MC shows high conversion (>99%) and selectivity (>98%) for the hydrogenation of nitro compounds under mild reaction conditions (100 °C, 5 bar H2). [ABSTRACT FROM AUTHOR]

Non-precious metal catalysts play a significant role in the field of hydrogenation. This study synthesized Co-BTC from cobalt nitrate hexahydrate and 1,3,5-tricarboxylic acid benzene. By changing the calcination temperature of Co-BTC in an inert atmosphere, a series of novel non-precious metal Co/C microsphere catalysts were successfully prepared. The composition and structure of the Co/C-n catalysts were characterised by FESEM, TEM, XRD, IR, XPS and BET. These results confirm that 1,3,5-benzenetricarboxylic acid provides a rich carbon matrix and metallic Co nanoparticles are generated by self-reduction on the carbon matrix. The graphite matrix formed during the calcination process has a rich pore structure and good dispersion of active components on the catalyst surface, which is very favourable for the catalytic reaction. In the hydrogenation of o-chloronitrobenzene (o-CNB) to o-chloroaniline (o-CAN), the Co/C-500 catalyst showed the best catalytic performance. At 80 °C and 2 MPa H2 for 60 minutes, the conversion rate of o-CNB reached 99% and the selectivity reached 99%. When the reaction takes 5 minutes, the conversion rate reaches 10.5%, and the TOF value reaches 36.3 h−1. The Co/C-500 catalyst can be easily recycled and reused after reaction with the help of a magnetic field. Moreover, this catalyst is also effective in the selective hydrogenation of other nitroaromatic hydrocarbons containing halogen or unsaturated groups to corresponding aniline. This simple and direct synthesis method may lead to the economic production of large-scale Co/C catalysts, which is an attractive prospect for the industrial trial production of corresponding aniline. [ABSTRACT FROM AUTHOR]

The hydrogenation of acetic acid-derived cyclohexyl acetate (CHA) is becoming a safe, efficient and promising route for the production of cyclohexanol (CHOL), an important chemical to produce e-caprolactam. In this work, Cu-Zr catalysts were prepared via different methods for the hydrogenation of CHA. The results showed that a Cu3Zr7-SG catalyst prepared by the sol-gel (SG) method was superior to Cu3Zr7-CP and Cu3Zr7-IM catalysts prepared by the coprecipitation (CP) and impregnation (IM) method, respectively. The Cu3Zr7-SG catalyst showed 97.4% CHA conversion and 95.5% selectivity to CHOL along with 96.3% selectivity to ethanol at 250 1C under 3 MPa of H2. Moreover, the Cu3Zr7-SG catalyst showed a mass specific activity of up to 29.8 gCHA gCu-1 h-1, higher than other Cu-based catalysts under similar conditions. Based on detailed characterization studies, it was found that the larger weak acid sites, more weak and moderate basic sites, higher Cu+/(Cu0 + Cu+) and oxygen vacancies on the surface of the Cu3Zr7-SG catalyst were beneficial for the hydrogenation of CHA. [ABSTRACT FROM AUTHOR]

The availability of catalytic sites for contact with reactants is a key issue to improve the performance of a catalyst, where constructing hollow structured nanomaterials has been considered as an effective strategy. Here, an N-doped carbon supported Ru catalyst with an interior cavity was synthesized by etching a MOF-derived core–shell precursor, in which metal Ru can be highly dispersed in the porous shell. This catalyst shows 98.7% conversion and >99% selectivity towards p-chloroaniline in the hydrogenation of p-chloronitrobenzene, which is better than the corresponding supported catalyst. Moreover, it also displays excellent stability with 5 cycle runs and good substrate universality for the hydrogenation of extensive substituted nitroarenes. Various characterization techniques and control experiments reveal the advantage of the unique structure to promote the mass transport and adsorption of reactant molecules on Ru sites. This work provides a novel strategy to design an efficient Ru-based catalyst for chemoselective hydrogenation. [ABSTRACT FROM AUTHOR]

In this study, 13-Ni/ZrO2, 13-Ni3P/ZrO2, 13-Ni/SiO2, and 13-Ni3P/SiO2 catalysts were used in the hydrogenation of diethyl oxalate (DEO) to ethyl glycolate (Egly) to investigate the modulating effect of phosphorus. XRD, TEM, and FT-IR spectroscopy results indicated that phosphorus acts as a distributor of Ni metallic particles and thereby shows a segregation effect. The presence of P transformed the linkage of surface metals from an original Ni–Ni–Ni–Ni– to a P–Ni–P–Ni–P state, and FT-IR spectra showed that the former adsorbed CO in a combination of linear and bridging adsorption modes, whereas the latter predominantly in CO linear adsorption. Bridging adsorption occurs via dual sites and makes preliminary hydrogenation products less likely to detach from the catalyst surface, thus facilitating deep hydrogenation, while linear adsorption facilitates partial hydrogenation via rapid detachment of intermediate products such as Egly. Different loadings of Ni3P/SiO2 catalysts show incomplete phosphorylation with an increase in nickel loading, giving rise to a state of coexistence of Ni and Ni3P crystalline phases. This may lead to a coexistence of surface Ni–Ni–Ni–Ni and P–Ni–P–Ni–P and an increase in the corresponding bridging adsorption/linear adsorption ratios, making deep hydrogenation occur partially besides stepwise hydrogenation. [ABSTRACT FROM AUTHOR]

Carbon materials show great potential in catalytic applications, due to their advantages of wide raw material sources, stable chemical properties, and large specific surface area. In this paper, N-doped biochar was prepared from Pennisetum giganteum for supporting PdLa bimetallic nanoparticles to achieve efficient conversion of acetylene. The results showed that the conversion and ethylene selectivity of the Pd0.25La0.25/N-pgBC bimetallic catalyst could reach 100% and 94.2%, respectively. From the characterization results, it could be inferred that the electron transfer from lanthanum to palladium can weaken the ethylene adsorption onto the negatively charged Pd sites and thus improve the selectivity of Pd0.25La0.25/N-pgBC. It is noted that the bimetallic PdLa/N-pgBC catalyst showed strong component dependence, which may be caused by the difference in electronic or geometric modification caused by different metal ratios. This work has shown that the active site separation effect formed by doping inert metals is of great significance to the whole catalytic field. [ABSTRACT FROM AUTHOR]

Hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) is a key reaction in the conversion of biomass to renewable fuels and value-added chemicals. Developing low-cost, highly efficient and reusable non-noble metal-based heterogeneous catalysts is vital but challenging. Herein, non-noble Ni–Mn/SiO2 catalysts with a low Ni loading (2.0 wt%) were designed for the selective hydrogenation of LA to GVL. The results showed that the optimal Ni–Mn/SiO2 (Ni/Mn = 2) catalyst with well-dispersed and small-sized metal nanoparticles (2.21 nm) and moderate acid sites exhibited excellent activity and selectivity and achieved a 100% yield of GVL in a 1,4-dioxane solvent under mild reaction conditions (e.g., 0.8 mol% Ni, 140 °C and 2.0 MPa H2) for 5.5 h and a 100% GVL yield at 180 °C for 2 h with a turnover frequency (TOF) of 190.2 h−1, which is better than most non-noble metal catalysts reported. Furthermore, the catalyst exhibited excellent reusability and could be recycled at least five times with only slight activity loss. This work provides new insights for the rational design of highly efficient and stable non-noble metal catalysts for the conversion of LA to GVL. [ABSTRACT FROM AUTHOR]

The present work describes an unprecedented blueprint for the chiral (S)-1,1′-Bi-2-naphthol ligand (BINOL) immobilized on amine functionalized mesoporous silica nanoparticles (MSNs) via a linker, which is then converted into a ruthenium complex, i.e., Ru-BINOL-AP@MSNs (where AP = (3-aminopropyl)trimethoxysilane), without the use of deprotecting or protecting groups. Using a variety of techniques, such as FTIR, N2 adsorption–desorption isotherms, solid-state 13C CP MAS NMR, powder XRD, FESEM, HRTEM, XPS, and thermogravimetric analysis, the as-synthesized catalyst was persuasively verified. Asymmetric transformations of enantiomerically enriched chiral alcohols can be achieved with the aforesaid active catalytic precursors, making the proposed method even more appealing. During the asymmetric hydrogenation reaction, the Ru-BINOL-AP@MSNs catalyst proved to be catalytically competent, leading to an 84% conversion with an enantioselectivity >90% of the R-isomer. Furthermore, the synthesized catalyst was capable of being recycled five consecutive times with only a minute loss of its effectiveness, thereby reducing solvent waste and precious metal or ligand losses. [ABSTRACT FROM AUTHOR]

Supported Pt catalysts play an important role in selective hydrogenation reactions for upgrading bio-derived chemicals, and they are traditionally prepared by methods such as deposition–precipitation (DP), wet impregnation (WI) and chemical reduction (CR) using NaBH4 and H2 under thermal conditions. This study developed a new reduction method to produce supported Pt NPs on nanofibers, in which Ti3AlC2 (a typical MAX phase) and chloroplatinic acid (H2PtCl6) were employed as raw materials, using as-produced H2 as a reducing agent under hydrothermal synthetic conditions. In the selective hydrogenation of furfural to furfuryl alcohol, the newly-developed catalyst of Pt2.0/Ti3AlxC2Ty exhibited high furfural (FUR) conversion (86.3%) and excellent furfuryl alcohol (FA) selectivity (98.1%) under optimized reaction conditions of 600 rpm, 100 °C, 3 h, and 1 MPa H2 in aqueous media. Moreover, these fibrous catalysts exhibited strong reusability and recyclability for five runs without loss of activity and selectivity. [ABSTRACT FROM AUTHOR]

Pd particles coated with ZIF-67 (Pd@ZIF-67) was prepared from the self-reduction of palladium acetate. With isopropanol as the solvent, the furfural hydrogenation reaction performances of Pd@ZIF-67 and ZIF-67 heated at different temperatures were tested in H2 and N2 reaction atmosphere, respectively. The pyrolytic carbonization of Pd@ZIF-67 and ZIF-67 produced Pd–Co@C and Co@C in carbon coating structures, respectively. It was found that furfural hydrogenation reaction systems with different catalytic active sites included direct hydrogenation with H2 as the hydrogen source, and transfer hydrogenation with isopropanol as the hydrogen donor. The Pd–Co@C and Co@C with metal active sites both experienced direct hydrogenation and transfer hydrogenation simultaneously, and the direct hydrogenation activity was higher. The ZIF-67 with Lewis acidic sites experienced transfer hydrogenation, and the catalytic activity was higher than the transfer hydrogenation activity of Pd–Co@C and Co@C. Moreover, reaction routes in which furfural direct hydrogenation and transfer hydrogenation occurred in metal active sites and Lewis acidic sites were identified. [ABSTRACT FROM AUTHOR]

The effects of Zr single atom modification on the hydrogenation mechanism of CO2 to methanol on the Cu(111) surface were investigated by density functional theory (DFT). In the HCOO pathway, 11 elementary steps were involved, which were analyzed from the aspects of kinetics and thermodynamics of each elementary reaction. bi-HCOO*, HCOOH*, H2COO*, H2COOH*, H2CO* and H3CO* are the key intermediates that are most likely to be generated. The elementary reactions of H2COO*, H2CO* and H3CO* hydrogenation have relatively high activation barriers of about 1 eV, and they are the rate-limiting steps in this pathway. The desorption barriers of HCOOH* and H2CO* are much higher than the energy barriers required for continued hydrogenation; therefore, the formation of by-products is inhibited on the Zr1–Cu single atom catalyst surface. In the COOH pathway, the hydrogenation product trans-COOH* of CO2 can further hydrogenate to t,t-COHOH* through the formation of O-H bonds; then, it facilely dissociates into COH*, and COH* continues to hydrogenate into HCOH*, H2COH* and the final product of CH3OH. The last step is the rate-limiting step, with an activation energy of 1.48 eV. In the RWGS pathway, trans-COOH* transforms to cis-COOH*, and its continued hydrogenation is more favorable than dissociation in terms of kinetics and thermodynamics. The generated HCOOH is incorporated into the HCOO pathway. The results show that the HCOO pathway is more likely to occur and has higher selectivity on Zr-modified Cu-based catalysts. [ABSTRACT FROM AUTHOR]

Metal organic frameworks (MOFs) have been applied to stabilize metal nanoparticles due to their excellent properties, but there are many different viewpoints about the interaction between MOFs and nanoparticles, which is important for catalyst activity and selectivity. Herein, Pt nanoparticles supported on ZIF-8 and ZIF-67 with the same topological structure other than the metal joint were synthesized, and crotonaldehyde hydrogenation was chosen to investigate their catalytic performance. The results indicated that both the activity and crotyl alcohol selectivity over ZIF-67 were much higher than those over ZIF-8, in which the TOF was 188.3 h−1 for Pt@ZIF-67 and 7.5 h−1 for Pt@ZIF-8. More importantly, the selective hydrogenation product of the C＝O bond (crotyl alcohol) was not detected regardless of whether Pt nanoparticles were located in the interior or exterior of ZIF-8. A series of characterizations were carried out to explore the essential difference between the two supported ZIF catalysts, such as H2-spillover property tests, TEM, XPS, CO-DRIFTS, and operando-FTIR reaction. These results suggested that the H2-spillover of the ZIFs could play an important role in hydrogenation, besides the electron transfer between Pt and the metals in the ZIFs. [ABSTRACT FROM AUTHOR]

Catalysts of 0.54% (Pt, Rh, Pd or Ru)/Co(OH)2 and 1.23% Rh/Co(OH)2 were successfully synthesized via simple hydrothermal and precipitation methods for the selective hydrogenation of nitroarenes. It was found that 0.54% Rh/Co(OH)2 outperformed other catalysts, for example, 2-chloronitrobenzene hydrogenation (with a turnover frequency (TOF) of 575 h−1) under 3.0 MPa H2 at 100 °C for 1 h (much higher than that of 1.23% Rh/Co(OH)2; TOF, 398 h−1). Through characterization of the nanostructure (XRD, TEM, HRTEM, AC-STEM (spherical aberration-corrected scanning transmission electron microscopy), AC-STEM-EDX elemental mapping and line-scanning, H2-TPD, etc.), it was confirmed that Rh was dispersed in the form of single atoms and ultrasmall nanoclusters on Co(OH)2 for 0.54% Rh/Co(OH)2. Moreover, 0.54% Rh/Co(OH)2 also exhibited high selectivity for –NO2 hydrogenation for other selected nitroarene substrates hydrogenation reactions. This was mainly attributed to the presence of Rh as single atoms or super tiny nanoclusters in 0.54% Rh/Co(OH)2, leading to a significant increase in the number of active sites, beneficial adsorption of the –NO2-group at defect-rich Co(OH)2, and an interfacial synergy effect of Rh–Co(OH)2, thus improving the catalytic performance. [ABSTRACT FROM AUTHOR]

Biofuels have generated considerable interest as a direct substituent for fossil fuels due to the energy crisis and greenhouse effect. In this article, bifunctional Pt–Mo catalyst supported on activated carbon (AC) was fabricated for in situ hydrogenation of methyl stearate to alkanes using small amounts of formic acid (FA) as a hydrogen source. A total yield of 75.3% is obtained under 290 °C for 2 h with a small FA/methyl stearate mole ratio of 3.9. Prolonging the reaction time to 6 h results in a total yield of 100%. The experimental and characterization results indicate that the strong interaction of β-Mo2C and Pt over Pt–Mo/AC catalysts give rise to excellent catalytic performance and that Pt active sites are responsible for FA dehydrogenation and decarbonylation of methyl stearate to heptadecane and Pt-doped β-Mo2C active sites catalyzing hydrodeoxygenation of methyl stearate to octadenane. This catalyst is stable during three recycles and is versatile for various feedstocks. [ABSTRACT FROM AUTHOR]

5-Hydroxymethylfurfural (HMF) is a versatile furanic compound used for producing various value-added chemicals, including 2,5-dihydromethylfuran (DHMF) and 2,5-dihydromethyltetrahydrofuran (DHMTHF), via selective hydrogenation of HMF. In order to reduce the cost of highly efficient noble metal catalysts, nickel (Ni) and copper (Cu) have been developed as cheaper catalysts for this reaction. These two catalysts show good efficiency but have different selectivity towards HMF hydrogenation products. This work applied plane-wave based density functional theory (DFT) to understand the different activity and selectivity of the Ni and Cu catalysts. The interaction of precursors/products on the Ni(111), Ni(100), Cu(111) and Cu(100) facets was investigated via the adsorption calculation in gas and aqueous phases. The temperature effect was also investigated. Our results revealed that not only the energetic properties but the structural and electronic charge properties are also important for describing the different catalytic behaviors in HMF hydrogenation. [ABSTRACT FROM AUTHOR]

Novel ionic materials derived from ruthenium cluster cation and tungstoaluminate anions have been developed and are proved to be robust, efficient and recyclable catalysts toward the selective hydrogenation of methyl levulinate (ML) to gamma-valerolactone (GVL) or methyl 4-hydroxypentanoate (4-HPTM) by tuning the acidity. The structure and properties of the catalysts were characterized using elemental analysis, 1H NMR, 27Al NMR, FT-IR, X-ray diffraction, and pyridine absorbed FT-IR, etc. The catalysts not only afforded excellent conversion and selectivity for GVL (99%) or 4-HPTM (88%) in the aqueous phase under very mild conditions (25 °C) but also showed good recyclability in five consecutive cycles without any significant loss in catalytic activity. In contrast to the direct intramolecular esterification of 4-HPTM in most previous reports, further characterization revealed that intramolecular cyclization proceeded via a metal and counterion (tungstoaluminate)-assisted mechanism on the anchored Ru cluster catalyst; moreover, the strong acidity on the catalysts can hamper the conversion of 4-HPTM into GVL. This rendered the Ru cation complex/tungstoaluminate ionic materials a potential candidate for the efficient production of either GVL or 4-HPTM from ML hydrogenation under very mild conditions. [ABSTRACT FROM AUTHOR]

Herein, Cu/ZrO2 catalysts containing different Cu contents with or without La-doping were used for the selective hydrogenation of dimethyl oxalate (DMO) to ethylene glycol (EG). Effects of La addition and the optimal Cu content were thoroughly investigated. It was found that the Cu0/Cu+ pairs located at interfacial sites for CuO/ZrO2 catalysts with different Cu contents played an important role in the hydrogenation of DMO to EG. Interestingly, the La-doping could make the copper dispersion increase obviously. Besides, it greatly inhibited the crystal phase transformation from tetragonal to monoclinic zirconia regardless of being calcined at 750 °C. Meanwhile, the incorporation of La promoted the activation of hydrogen although resulting in a small increase in acidic/basic sites over the catalyst surface, which led to a higher conversion of DMO while the selectivity of EG decreased slightly. As a result, 97.2% selectivity of EG, which corresponds to 100% conversion of DMO, was achieved over the La-doped CuO/ZrO2 catalyst with 33 wt% Cu content, which was also stable for more than 168 h on stream. This results revealed that the strong interaction between La promoters and Cu species was another type of important active site with high catalytic efficiency in addition to the Cu0/Cu+ site of La-doped CuO/ZrO2 catalyst. [ABSTRACT FROM AUTHOR]

Combining glucose dehydration and the subsequent hydrogenation in one pot is a preferable approach for process development as such a method allows in situ generation of the reactive intermediate to undergo further reaction without extra energy-intensive separation. Herein, phosphotungstic acid and various types of titania (anatase, rutile, P25) supported Ru-based catalysts were considered as the dehydration and hydrogenation catalysts, respectively. Modulating the different reactant media (N2, H2), various products were obtained with GBL–H2O as the solvent. A considerable yield (42%) of levulinic acid (LA) and γ-valerolactone (GVL) (40%) were obtained in nitrogen and subsequent hydrogen. Ru/TiO2 (rutile) was the favorable hydrogenation catalyst among the three types of Ru/TiO2. Meanwhile, a certain amount of sorbitol (36%) was obtained in pure hydrogen. The hydrogenation of glucose is more likely to occur than the glucose dehydration. The physicochemical properties of the catalysts were characterized by XRD, BET, TPR, STEM and in situ CO/FT-IR, and the results show that well-dispersed Ru particles are located on the rutile crystallites, which facilitated the hydrogenation of LA. A strong metal support interaction (SMSI) was responsible for the various microstructure properties and the different hydrogenation reactivity. This work allows a better understanding of the reaction paths of glucose conversion. [ABSTRACT FROM AUTHOR]

The effect of supports (SiO2, ZnO, ZrO2 and Al2O3) on the hydrogenation and water-tolerance of copper catalysts were studied at reaction condition containing water. The copper catalysts with different supports showed different hydrogenation and water-tolerance performances. The result of XRD, BET, Raman, TPR, XPS, N2O titration and TEM confirmed the interactions between copper and supports, and the formation of Cu–MxOy (M = Zn, Zr, and Al) interfaces had great effects on the catalytic activity and water-tolerance performance. In particular, too strong interactions suppressed the reduction of copper oxides, resulting in a low catalytic activity. Nevertheless, the formation of Cu–MxOy could provide more active sites, which provided more chances for the reactants to touch the active sites. By this method, the loss of active sites due to competitive adsorption between water and ethyl acetate could be made up, so that the water-tolerance of copper catalysts was improved. [ABSTRACT FROM AUTHOR]

Selective hydrogenation of cinnamaldehyde to hydrocinnamaldehyde is captivating due to its industrial relevance. Herein, a two-step synthesis method was adopted to develop oxygen vacancies in Pd@ZrO2 catalysts. The oxygen vacancies were developed in Pd@ZrO2 catalysts during impregnation of Pd which was confirmed by XPS and HR-TEM analyses. The characterization results revealed that there was a synergistic role of oxygen vacancies and nano-sized active Pd metals in Pd@ZrO2 catalysts that assisted in achieving selectivity for hydrocinnamaldehyde which has been discussed in this study. We also studied the effects of different reaction parameters which revealed that 4 wt% Pd loading in a Pd@ZrO2 catalyst provided enough active sites for complete conversion of CAL. Additionally, 100 °C temperature and 10 bar H2 pressure provided enough energy for effective collisions and activation of reactants and catalysts to form the desired product in a reaction time of 9 h. Therefore, a defect-rich 4-Pd@ZrO2 catalyst demonstrated complete CAL conversion with 86% yield towards HCAL which is the best result amongst various Pd@ZrO2 catalysts with different Pd loading investigated for the hydrogenation of cinnamaldehyde. Moreover, a plausible mechanism was proposed to support the chemoselective hydrogenation of cinnamaldehyde over a 4-Pd@ZrO2 catalyst. Along with high catalytic performance, the 4-Pd@ZrO2 catalyst also showed impressive recyclability performance for up to six recycles. Thus, the oxygen-vacancy-rich Pd@ZrO2 can be considered as an efficient catalyst for the chemoselective hydrogenation of cinnamaldehyde. [ABSTRACT FROM AUTHOR]

Synthesis of an easily separable and efficient catalyst is of great significance for selective hydrogenation of unsaturated functional groups. In this work, novel magnetic flower-like carbonaceous Pd catalysts are constructed for the selective reduction of the C＝C bond. According to the characterization results, a flower-like architecture is observed in the catalysts containing both Fe3O4 and Pd NPs, which is constructed by the secondary self-assembly in the preparation process due to the interaction between Pd and magnetic nitrogen-doped graphene (Fe3O4-NG). More flower-like structures are formed by increasing the Pd loading amount, further enhancing the specific surface area of the catalyst. The specific surface area of Pd-FONG-3 is the highest (521.17 m2 g−1). Combining the results of characterization and experiments, it is found that the catalytic activity is positively related to the flower-like architecture and the interaction between Pd NPs (6.0 nm) and Fe3O4 NPs (6.7 nm). Fe3O4 is not only beneficial to the magnetic recovery of the catalyst, but also acts as a cocatalyst, which can significantly improve the reactant conversion. Moreover, N species play an important role in protecting the C＝O bond, resulting in the selective hydrogenation of the C＝C group. Herein, Pd-FONG-3 exhibits excellent activity in the selective hydrogenation of cinnamaldehyde (CAL) with 99.5% conversion and 96.5% hydrocinnamaldehyde (HCAL) selectivity, and its catalytic performance is much better than that of the commercial 5% Pd/C catalyst (100% conversion and 69.1% HCAL selectivity). This work provides a new strategy to construct highly active catalysts with magnetic recovery properties for selective hydrogenation of C＝C bonds, and Pd-FONG-3 shows tremendous application foreground. [ABSTRACT FROM AUTHOR]

Cellulose-derived levulinic acid (LA) can be converted into gamma-valerolactone (GVL), a sustainable platform chemical for the production of bio-based chemicals. However, LA as an organic acid causes severe metal leaching during the heterogeneous hydrogenation of LA to GVL, especially in the presence of water. Various endeavors for preventing metal leaching have focused more on the process and less on the intrinsic nature of catalysts. The aim of this work is to derive a novel metal-leaching-resistant catalyst for the aqueous-phase hydrogenation of LA into GVL by using a nanocomposite containing three components, Ag, ZrO2, and graphene oxide (GO). The AgZrO2GO catalyst without pre-reduction treatment resulted in complete conversion of LA and approximately 100 mol% selectivity to GVL in the aqueous reaction, and metal leaching from the catalyst was completely eliminated. The relationship between the catalytic performance and the distinct physicochemical properties of the catalyst was extensively discussed. [ABSTRACT FROM AUTHOR]

As a novel alkane isomerization catalyst, namely CoH/Hβ, was prepared by the reduction of CoH(P(OPh)3)4, which was pre-impregnated on Hβ as support. The as-prepared CoH/Hβ catalyst was structurally compared with CoH(P(OPh)3)4, CoH(P(OPh)3)4/Hβ via FT-IR, TPR, SEM, XRD and other techniques. The results show that the new organometallic hydride catalyst was synthesized successfully and exhibited excellent catalytic performance for the isomerization of n-hexane. For the best performance of the CoH/Hβ catalyst, the optimal catalytic reaction temperature, pressure, space velocity, and hydrogen/oil molar ratio were 300 °C, 2.0 MPa, 1.0 h−1, and 4.0, respectively, in the isomerization process of n-hexane. Under the optimal reaction conditions, the conversion of n-hexane, the yield of isomerization, and the selectivity towards iso-paraffins were 80.2%, 63.0%, and 78.6%, respectively. This performance is mainly attributed to the new structure of Co–H hydride in the CoH/Hβ catalyst, which has strong hydrogenation/dehydrogenation activity in the isomerization of n-hexane. [ABSTRACT FROM AUTHOR]

Ru–carbon catalysts with different physical morphologies and chemical states of Ru were prepared by different methods and used to catalyze the hydrolytic hydrogenation of cellulose at high temperatures. The physical morphology of Ru particles and the chemical state of Ru significantly influenced the catalytic performance. The Ru nanoparticles in Ru@MC prepared by the in situ carbothermal reduction method exhibited a special chemical state due to the strong interaction with carbon. The special structure could not only prevent the growth of Ru particles but also enhance the hydrogen spillover effect and improve the hydrogenation efficiency. Among the Ru–carbon catalysts, Ru@MC showed the best catalytic performance with a 72.4% yield of sorbitol. Furthermore, the embedded structure of Ru@MC stabilized the Ru nanoparticles, and the catalyst could be reused at least 6 times. [ABSTRACT FROM AUTHOR]

The effects of the ZnO/SiO2 ratio on the water tolerance of Cu/SiO2 and Cu/ZnO catalysts were studied by ethyl acetate with 5 wt% water hydrogenation. Notably, the addition of an appropriate amount of ZnO endows Cu/SiO2 catalysts with satisfactory water-tolerant hydrogenation performance by a decrease in the reaction temperature without sacrificing conversion. At the same time, agglomeration can be alleviated for Cu/ZnO catalysts due to the optimal addition of SiO2, which is considered as a partition material that effectively hinders the agglomeration of the Cu/ZnO catalyst. However, the addition of ZnO was not favourable for the copper dispersion of Cu/SiO2. The stability of Cu/SiO2 catalyst quickly degraded due to excessive ZnO being introduced by sintering. The copper dispersion of Cu/ZnO catalysts initially increased with increasing SiO2 content, but then decreased. The addition of excess SiO2 also led to decreased activity and rapid deactivation of the Cu/ZnO catalyst. In our study, the appropriate addition of ZnO (5 wt%) and SiO2 (5 wt%) had a positive effect on the Cu/SiO2 and Cu/ZnO catalysts, respectively. [ABSTRACT FROM AUTHOR]

The utilization of CO2 to synthesize environmentally benign liquid fuels offers a solution to replacing depleting petroleum resources. Herein, a ternary CuZnZr (CZZ) metal oxide catalyst and a SAPO-34 zeolite were synthesized by co-precipitation and hydrothermal synthesis, respectively. Different metals were impregnated into the latter to obtain MeSAPO-34 (Me = Mn, Zn and Zr). A granule mixture of CZZ and MeSAPO-34 components (CZZ/MeSAPO-34 catalyst) was then effectively utilized in a tandem catalytic process for one-step CO2 hydrogenation to liquefied petroleum gas (LPG). The CZZ/MeSAPO-34 catalysts were characterized by using XRD, H2-TPR, BET, SEM-EDS and NH3-TPD techniques. SEM-EDS and XRD results indicated that an appropriate amount of Zr metal loading induced minimum zeolite framework collapse compared to a similar amount of Mn and Zn, which was more favorable for higher activity. In addition, NH3-TPD results revealed that the acidity of SAPO-34 could be altered after impregnation with different metals in different quantities. Tuning the acid density and strength, together with adjusting the CZZ to MeSAPO-34 weight ratio, had a collectively critical effect on LPG selectivity. An effective hydrogenation microenvironment which favors lower alkane formation (C3–C4) was enhanced after the acidity of the molecular sieve was tuned. LPG selectivity could reach 86% over the CZZ/5% ZrSAPO-34 catalyst at 2 MPa, 350 °C, a W/F ratio of 6, a H2/CO2 ratio of 3 and a weight ratio of 1. [ABSTRACT FROM AUTHOR]

Gamma valerolactone (GVL) is an important chemical feedstock from which several value-added fine chemicals, fuels and fuel additives are manufactured. GVL is the product obtained in the hydrogenation of levulinic acid (LA), which in turn is generally manufactured from several renewable resources such as pentoses and hexoses. The present work deals with the synthesis of SBA-15 and Sn loaded catalysts [x% Sn/Al-SBA-15 (x = Si/Sn = 10, 25, 50, 75 and 100 with Si/Al = 25)] using a hydrothermal in situ method. A variety of both bulk and surface characterization techniques such as XRD, FT-IR, BET, FE-SEM, HR-TEM, XPS, TGA/DTA and UV-DRS were used to characterize the bare and Sn/Al-SBA-15 catalysts. The characterization studies revealed the presence of Sn species well dispersed in the uniform pore channels of Al-SBA-15. All the synthesized catalysts were tested in the liquid-phase catalytic transfer hydrogenation of levulinic acid at atmospheric N2 pressure under mild reaction conditions. Among them, the Sn/Al-SBA-15 (Si/Sn = 25) catalyst showed remarkable conversion of levulinic acid (99%) and very high selectivity towards GVL (100%). The various reaction parameters such as metal loading, reaction temperature, reaction time and catalyst weight were optimized to get the maximum conversion of levulinic acid with high selectivity towards the desired product. The stability and reusability of the best catalysts were also tested up to five cycles and there was not much variation in the catalytic activity in terms of conversion. [ABSTRACT FROM AUTHOR]

In combination with a planetary ball-milling machine, a Ni–Al2O3 catalyst was prepared by a mechanochemical method. The effect of Ni loading on the crystal structure, reduction characteristics, and hydrogenation performance of the Ni–Al2O3 catalyst was investigated. The prepared catalysts were characterized using EDX, XRD, H2-TPR, BET, TEM and NH3-TPD methods. The results of the XRD characterization showed that the peak intensity of the active Ni component increased with an increase in the Ni content. The ratio of the measured Ni content to the theoretical Ni content of the MC25% and MC30% samples exceeded 1.1. As the Ni addition was increased up to 10%, the sample consisted of uniform spherical particles, which could provide more contact surfaces. The medium acid peak temperature shifts towards the high temperature direction as the Ni loading increased from 5% to 20%, and then (>20%) decreased to a lower temperature. The corresponding peak area firstly increased and then decreased, presenting a visual representation of changes in the number of acid centers on the catalyst. Evaluation of the results showed that the MC20% catalyst presented a large specific surface area of 279 m2 g−1, and it showed good hydrogenation performance, with a BYD conversion of 25.0%, BED selectivity of 89.3%, and BED yield of 22.3%. [ABSTRACT FROM AUTHOR]

A series of Ni-based catalysts, including Ni/SiO2–ZrO2, Ni/HZSM-5, Ni/Al2O3, Ni/SiO2, Ni/AC and Ni/CMK-3, were prepared to produce H2 from the aqueous phase reforming (APR) of methanol. This H2 was then used in the in situ hydrogenation of phenolic compounds for bio-fuel. The effect of different promoters was investigated with the addition of Co, La, Fe and Cu to the Ni/CMK-3 catalyst coupled with analysis using BET, XRD and SEM. The results showed that Ni/SiO2, Ni/AC and Ni/CMK-3 yielded the most hydrogen and they were chosen for further investigation in the in situ hydrogenation of phenol, guaiacol and lignin depolymerization products (LDP). Using these Ni-based catalysts, the APR of methanol provided hydrogen for the hydrogenation of the phenolic compounds. Of the modified Ni/CMK-3 catalysts, La–Ni/CMK-3 exhibited the highest activity for the conversion of phenol (80.88%) with a satisfactory cyclohexanol yield (76.64%) at 240 °C for 4 h without an external H2 source. When using La–Ni/CMK-3, the content of the phenolic compounds in LDP decreased from 75.25% to 25.38% while the content of saturated alcohols increased from 1.34% to 31.19%. It has been shown that it is possible to use the APR of methanol for the hydrogenation of LDP over a series of Ni/CMK-3 catalysts. [ABSTRACT FROM AUTHOR]

The influence of Cu loading on the structural evolution and catalytic behavior in selective hydrogenation of dimethyl oxalate (DMO) by Mg2+ doped nanoscaled Cu–Mg/ZnO catalysts has been investigated. It is found that the accessible Cu0 surface area and ZnO dispersion increased gradually with the Cu loading increasing from 10.0 wt% to 40.0 wt%, and that the Cu and ZnO NP size distribution has a great effect on the chemical interaction between the Cu and ZnO phase, further determining the surface chemical properties of the catalysts. On the other hand, the catalytic behavior of the Cu–Mg/ZnO catalyst in DMO hydrogenation is closely related to the Cu loading introduced into the system. Most of all, the 30Cu–Mg/ZnO catalyst with 30 wt% Cu loading exhibits 100.0% DMO conversion and 98.0% ethylene glycol (EG) yield even under LHSV = 3.5 h−1, superior to those of the other catalysts. This excellent catalytic behavior should be attributed to the strengthened Cu–Zn synergistic effect and suppressed strong surface basic sites, originating from the enhanced Cu–ZnO interface area. Additionally, the correlation between catalytic activity and Cu species distribution suggests that the DMO dissociation on the Cu+ sites generated on the Cu–ZnO interface is the rate-determining step in the presence of enough exposed Cu0 sites over the Cu–Mg/ZnO catalysts. [ABSTRACT FROM AUTHOR]

Carbon aerogels (CA) were applied in the synthesis of Cu/CA catalysts by the impregnation method and the catalysts with boron-doped CA supports were systematically characterized and evaluated in the hydrogenation of dimethyl oxalate (DMO). The Cu/xB–CA catalyst with 25 wt% copper showed 100% DMO conversion and the highest ethylene glycol (EG) or methyl glycolate (MG) selectivity of 70% at 230 °C as well as a lifetime of over 150 h. The characterization results disclosed the reason the performance of the catalysts could be tuned facilely by changing the amount of boron doping, which effectively influenced the interrelation between copper and CA, acidity and alkalinity of catalysts and Cu dispersion. Both the original carbon aerogels and that promoted with little B could provide larger surface areas and high dispersion of the metal. The species, size of copper particles and the ratio of Cu+/(Cu+ + Cu0) could be regulated by boron doping, thus adjusting the type of hydrogenation products. [ABSTRACT FROM AUTHOR]

Carbon-encapsulated Fe3O4 (Fe3O4@C) catalysts were prepared by a solvothermal method using glucose as the carbon source and their physicochemical properties were characterized via various analytical techniques. Catalytic transfer hydrogenation of furfural over Fe3O4@C catalysts was investigated with isopropanol as the solvent and hydrogen donor. The Fe3O4@C catalysts exhibited high catalytic furfural transfer hydrogenation activity, selectivity of furfuryl alcohol, and high reusability. The mechanism of catalytic transfer hydrogenation of furfural by Fe3O4@C obeys the Meerwein–Ponndorf–Verley reduction on a Lewis acid site (Fe3O4). [ABSTRACT FROM AUTHOR]

Aiming at the preparation of metal catalysts with nanoscale structures, Ni–Cu/Al2O3 nanoparticle catalysts (i.e., Ni&Cu-NP/γ-Al2O3), containing a certain amount of Ni and Cu were prepared for the hydrogenation of acetylene. The highly dispersed and stable Ni&Cu-NP/γ-Al2O3 catalyst with a Ni : Cu atomic ratio of 1 : 1 was obtained from a NiCl2/CuCl2 precursor by a modified co-precipitation method, the average size of which was controlled at 10.0 ± 0.3 nm. Under optimal reaction conditions, approximately 100% conversion and 71% selectivity at 130 °C were achieved using the Ni&Cu-NP/γ-Al2O3 catalyst. The enhanced selectivity was attributed to the formation of nickel–copper alloys, which have been identified by both diffuse reflectance infrared Fourier transform spectroscopy and theoretical calculation results. [ABSTRACT FROM AUTHOR]

In this dissertation, silver–palladium (AgPd) bimetallic nanoparticles were synthesized by a green biosynthesis method using Cacumen platycladi leaf extract, which provided both reductive and protective agents. Then the supported AgPd/γ-Al2O3 catalysts were obtained by the sol-immobilization method, and the as-biosynthesized AgPd/γ-Al2O3 catalysts with different particle sizes and compositions were used for 1,3-butadiene hydrogenation. Optimization of the catalyst preparation and selective hydrogenation parameters was performed. Using the catalyst, a 1,3-butadiene conversion of 98.2% and a butene selectivity of 88.1% were achieved. The durability experiment of AgPd/γ-Al2O3 catalysts was carried out for 50 h, and the activity decreased slightly and the selectivity almost remains the same during the 50 h, indicating their remarkable stability. The results of TEM and TG analysis showed that the size of the AgPd nanoparticles was nearly the same before and after the durability experiment, and the existence of residual biomolecules on the catalyst surface helped to prevent agglomeration and modification of the surface properties of the catalyst, which would promote desorption of the product, and then avoid intensifying the level of further hydrogenation. [ABSTRACT FROM AUTHOR]

A new catalyst was developed for selective hydrogenation of dioctyl phthalate (DOP) to produce the environmentally friendly plasticizer di(2-ethylhexyl)hexahydrophthalate (DEHHP) by incorporating rhodium via chemical fluid deposition into an aluminum-modified mesocellular foam (MCF). The Al-modified MCF containing a Si/Al molar ratio of 5 and 1 wt% Rh achieved 100% conversion of DOP to DEHHP with no side products at 80 °C and 68 atm H2 pressure in one hour reaction time. On the other hand, a 1 wt% Rh/MCF catalyst without any surface modification with Al yielded only 29% conversion. The interaction of Rh with the support became stronger when Al was incorporated onto the MCF support. An effective control of the acidity provided by Al by closely monitoring the Si/Al ratio was key in improving the catalytic activity of the Rh/Al-MCF catalysts. [ABSTRACT FROM AUTHOR]

Polystyrene (PS) resin bead supported palladium nanoparticles (Pd NPs@PS resin) were prepared and their catalytic activity for the hydrogenation of olefins was investigated under microwave heating. The hydrogenation of styrene was effectively carried out in EtOH/H2O, in the presence of 0.00035 mmol of the catalyst to afford the corresponding ethylbenzene in high yield within 20 min under microwave heating. The catalyst efficiency measured in terms of turn over number (TON) and turn over frequency (TOF) was found to be 2829 and 8573 (h−1), respectively. The encapsulated palladium nanoparticles were easily recovered by a simple filtration method and reused several times without significant loss in their catalytic activity. Further, the method showed a wide substrate scope under mild reaction conditions, making it a green versatile and highly sustainable protocol. [ABSTRACT FROM AUTHOR]

In Cu/ZnO/Al2O3 catalysts, the Cu–ZnO interface is crucial for the hydrogenation of CO2 to methanol, which is beneficial to H2 adsorption and CO2 activation. In this research, a series of Cu/ZnO/Al2O3 catalysts (named CZA-X-Y, X is the sample number and Y is the sample state) with different Cu–ZnO interface contents were prepared by adjusting the components of zinc-malachite. The CZA-2-R catalyst, which was prepared from zinc-malachite with a zinc substitution amount of 27.13%, had small Cu particle sizes and uniform distribution of Cu and ZnO particles, creating a rich Cu–ZnO interface. As a result, the CZA-2-R catalyst had more catalytic active sites and displayed a good methanol yield of 11.2% as well as a long-term catalytic stability of 120 h. This study proposes a simple and feasible strategy to optimize the commercial Cu/ZnO/Al2O3 catalyst performance from the perspective of Cu–ZnO interface regulation. [ABSTRACT FROM AUTHOR]

An understanding of the essential roles in adiponitrile hydrogenation is a significant factor in designing promising nickel catalysts. A series of Ni/Al2O3 catalysts have been synthesized by the deposition–precipitation method and used for the selective hydrogenation of adiponitrile. The formation of the Ni compositions and the chemical structures of the catalysts were modulated by the assisting precipitators. Characterization, including XRD, N2 adsorption–desorption, TEM, XPS, H2-TPD and NH3-TPD, were carried out. Smaller particles could be obtained via fast deposition of Ni2+ using NaOH in Ni/Al2O3–OH, or uniform crystal seeds using urea in Ni/Al2O3–U. The use of a strong alkali, and the formation of nickel hydroxide, facilitated the generation of Ni0 with a better H2 activation ability. Meanwhile, a huge number of nickel species in various oxidative states and strong acidity were simultaneously generated in Ni/Al2O3–U, leading easily to the cycloaddition by-products. A kinetics study revealed that adiponitrile hydrogenation is a second-order reaction with respect to adiponitrile. The number of Ni0 active sites and acid sites could be balanced via different precipitation and crystallization methods. The yield of 1,6-hexanediamine reached 75.0% at 90 °C with 20 wt% Ni/Al2O3–OH. [ABSTRACT FROM AUTHOR]

The synthesis of γ-valerolactone (GVL) from butyl levulinate (BL) hydrogenation over sulfonated activated carbon (SAC) supported SnRuB bifunctional catalysts was studied. These catalysts were characterized by ICP, nitrogen physisorption, XRD, HRTEM, XPS and NH3-TPD techniques. The SnRuB hydrogenation active site and surface acidic site of the SAC support are effectively retained by the co-impregnation followed by a chemical reduction process and display a prominent synergetic effect for BL hydrogenation to GVL. Under the optimal reaction conditions (180 °C, 3 MPa, 800 rpm, 3 h), BL conversion of 99.2% and GVL selectivity of 83.8% were obtained over the optimal 20Sn1RuB/SAC catalyst. The highest total fraction of the C＝O group, lattice oxygen (Oα) and oxygen vacancies (Oβ) and active SnOx species on the surface of the catalyst contribute to the best adsorption and hydrogenation ability for BL conversion to GVL over the 20Sn1RuB/SAC catalyst. The sulfonated carbon-supported SnRuB bifunctional catalyst also showed outstanding recyclability in six runs due to enhanced reduction degree of Snn+ species, and strong interaction between the SnRuB active site and SAC support. In sum, the sulfonated carbon-supported SnRuB bifunctional catalyst with low costs, high activity and good recyclability is a potential candidate for butyl levulinate hydrogenation to GVL. [ABSTRACT FROM AUTHOR]

The hydrogenation of carbon dioxide to methanol is perceived as an effective way to mitigate global warming and drive fossil-fuel companies towards sustainable energy sources. In this study, a series of Cu/ZnO–CeO2 catalysts were prepared by a co-precipitation method, and the effect of the CeO2 content on the catalytic performance of the Cu/ZnO–CeO2 catalysts for the hydrogenation of CO2 to CH3OH was analysed. The physicochemical properties of the catalysts were investigated using XRD, H2-TPR, CO2-TPD, BET, XPS, TEM, and DRIFTS. The CZC-3 catalyst (CZC stands for Cu/ZnO–CeO2 catalyst and 3 indicates a 30% CeO2 content) had the best catalytic activity at 280 °C in a 3 MPa CO2/H2 (1/3) atmosphere, exhibiting a CO2 conversion rate of 15.6% and a methanol yield of 10.06%. More dispersed CuO species and oxygen vacancies were detected on the CZC-3 catalyst, leading to good activation of H2 and CO2, respectively. In situ DRIFTS results for the catalysts showed that the hydrogenation of CO2 to methanol over Cu/ZnO–CeO2 catalysts occurs via the formate pathway. The CeO2-rich Cu/ZnO–CeO2 catalyst facilitated the conversion of formate to CH3OH, and the presence of a large number of intermediate species on the surface of the CZC-3 catalyst greatly contributed to its catalytic performance for CO2 hydrogenation. [ABSTRACT FROM AUTHOR]

Sol–gel method was used to prepare Ni12P5/N-doped carbon and amorphous Ni–P–C materials where the dried gel precursors were heated under N2 atmosphere in a tube furnace. By using ethylene diamine tetraacetic acid (EDTA) as the chelating agent, Ni12P5/N-doped carbon catalysts can be obtained when the heating temperatures were 700 °C and 800 °C. The Ni12P5/N-doped carbon nanomaterial heated at 800 °C exhibited high catalytic performance toward the hydrogenation reduction reaction of 4-nitrophenol (4-NP) using NaBH4 as the reducing agent. Pseudo first-order kinetics of the reaction can be observed, where catalytic activity parameters were 450.0 s−1 g−1 and 54.5 s−1 g−1 when the molar ratios of NaBH4 : 4-NP were 1000 : 1 and 100 : 1, respectively. When EDTA was replaced by ethylene glycol, amorphous Ni–P–C materials could be obtained when the heating temperatures were 350 °C, 450 °C, 550 °C, 600 °C and 700 °C. Unexpectedly, all the amorphous materials had desirable catalytic performances toward the hydrogenation of 4-NP. However, the kinetics of the reaction was pseudo zero-order over the amorphous catalysts. Our results provide new insight into the design of useful catalysts toward the hydrogenation reactions of 4-NP via the sol–gel method. [ABSTRACT FROM AUTHOR]

Fe–Mn/Al2O3 catalysts were prepared via a co-precipitation procedure and used for light olefin production via a CO hydrogenation reaction. The effect of preparation parameters including the precipitation ageing time, pH and temperature on the catalytic performance has been investigated. The ageing time was changed from 60 to 300 min, the precipitation pH was changed from 6.5 to 10.5 and the precipitation temperature was investigated in the range of 40–80 °C. Modeling and optimization processes were performed using response surface methodology (RSM). Polynomial equations for each response were successfully fitted to the experimental data. According to the optimization results the best preparation conditions were found to be aageing time = 160 min, pH = 8.78 and precipitation temperature = 74.16 °C. At these optimized conditions the maximum selectivity toward (C2–C4) light olefins and CO conversion% and minimum selectivity toward methane were achieved. The effect of the preparation parameters was also investigated on the various surface reaction rates. Catalyst characterization was performed using XRD, BET, TGA, DSC and SEM. [ABSTRACT FROM AUTHOR]

The article discusses a study that examined the recoverable catalyst for hydrogenation and Suzuki reaction of palladium supported on hollow magnetic mesoporous spheres. Topics discussed include the development of a high-performance palladium catalyst by the covalent binding of a Schiff base ligand and high activity in hydrogenation and Suzuki coupling reaction.