Catalytic Performance For Hydrogenation Research Articles

Novel mesoporous Ag@SiO2 nanospheres as a heterogeneous catalyst with superior catalytic performance for hydrogenation of aromatic nitro compounds.

Mesoporous core–shell structure Ag@SiO2 nanospheres are constructed to prevent Ag nanoparticles from aggregation during the hydrogenation reaction. The prepared catalyst shows superior catalytic performance for hydrogenation of nitro compounds with 100% conversion and selectivity without any by-products, which also indicates good recycling performance for several times use.

Preparation of MgAl LDH with Various Morphologies and Catalytic Hydrogenation Performance of Pt/LDH Catalysts

Preparation of MgAl LDH with Various Morphologies and Catalytic Hydrogenation Performance of Pt/LDH Catalysts

Understanding the geometric and electronic factors of PtNi bimetallic surfaces for efficient and selective catalytic hydrogenation of biomass-derived oxygenates

Selective and efficient upgrading of furfural over controllable PtNi bimetallic catalyst under mild conditions. Ni-base catalysts are promising candidate for the hydrogenation of furfural (FAL) to high-value chemicals. However, slow intermediate desorption and low selectivity limit its implementation. Identifying the catalytic performance of each active sites is vital to design hydrogenation catalyst, and tuning the geometrical sites at molecule level in PtNi could lead to the modification of electronic structure, and thus the selectity for the hydrogenation of FAL was modulated. Herein, PtNi hollow nanoframes (PtNi HNFs) with three dimensional (3D) molecular accessibility were synthesized, EDX results suggested that Ni was evenly distributed inside of the hollow nanoframes, whereas Pt was relatively concentrated at the edges. DFT calculation demonstrated that PtNi significant decrease the desorption energy of the intermediates. This strategy could not only enhance the desorption of intermediates to improve the catalytic performance, but also transfer the adsorption mode of FAL on catalyst surface to selective hydrogenation of FAL to FOL or THFA. The PtNi HNFs catalyst afforded excellent catalytic performance for selective hydrogenation of a broad range of biomass-derived platform chemicals under mild conditions, especially of FAL to furfuryl alcohol (FOL), in quantitative FOL yields (99%) with a high TOF of 2.56 h −1 . It is found that the superior performance of PtNi HNFs is attributed to its 3D hierarchical structure and synergistic electronic effects between Pt and Ni. Besides, the kinetic study demonstrated that the activation energy for hydrogenation of FAL was as low as 54.95 kJ mol −1 .

Morphology effect of CeO2 on Ni/CeO2 catalysts for selective hydrogenation of cinnamaldehyde

A series of CeO 2 with different morphologies (nanoparticles, nanorods and nanocubes) supported metal nickel catalysts were synthesized successfully using the hydrothermal route. Ni/CeO 2 -R catalyst with nanorods as the support exhibited the best catalytic performance for selective hydrogenation of CAL, which was attributed to the highest concentration of surface oxygen vacancies in Ni/CeO 2 -R. • Ni/CeO 2 with different morphologies were synthesized successfully. • Ni/CeO 2 -R catalyst exhibited the best catalytic performance. • Ni/CeO 2 -R catalyst had the highest concentration of surface oxygen vacancies. • Ni/CeO 2 -R showed excellent catalytic recycling stability. A series of CeO 2 with different morphologies (nanoparticles, nanorods and nanocubes) supported nickel catalysts were synthesized successfully using the hydrothermal route to investigate the morphology effects of CeO 2 on these Ni/CeO 2 catalysts for selective hydrogenation of cinnamaldehyde (CAL). Catalytic activities of three Ni/CeO 2 catalysts were ranked in the order of Ni/CeO 2 -R > Ni/CeO 2 -P > Ni/CeO 2 -C, which was attributed to the the highest concentration of surface oxygen vacancies in Ni/CeO 2 -R. These may lead more active surface oxygen and better redox properties on Ni/CeO 2 -R catalyst. More importantly, Ni/CeO 2 -R also showed excellent catalytic recycling stability, reflecting the morphological effect of nanocatalysis.

HI-Light: A Glass-Waveguide-Based "Shell-and-Tube" Photothermal Reactor Platform for Converting CO2 to Fuels.

SummaryIn this work, we introduce HI-Light, a surface-engineered glass-waveguide-based “shell-and-tube” type photothermal reactor which is both scalable in diameter and length. We examine the effect of temperature, light irradiation, and residence time on its photo-thermocatalytic performance for CO2 hydrogenation to form CO, with a cubic phase defect-laden indium oxide, In2O3-x(OH)y, catalyst. We demonstrate the light enhancement effect under a variety of reaction conditions. Notably, the light-on performance for the cubic nanocrystal photocatalyst exhibits a CO evolution rate at 15.40 mmol gcat−1 hr−1 at 300°C and atmospheric pressure. This is 20 times higher conversion rate per unit catalyst mass per unit time beyond previously reported In2O3-x(OH)y catalyst in the cubic form under comparable operation conditions and more than 5 times higher than that of its rhombohedral polymorph. This result underscores that improvement in photo-thermocatalytic reactor design enables uniform light distribution and better reactant/catalyst mixing, thus significantly improving catalyst utilization.

Development of bimetallic Ni-Cu/SiO2 catalysts for liquid phase selective hydrogenation of furfural to furfuryl alcohol

Bimetallic Ni-Cu/SiO2 catalysts with different Cu loading (2–5 wt%) were developed for liquid phase selective hydrogenation of furfural to furfuryl alcohol. Among these, bimetallic 2%Ni-X%Cu/SiO2 (X = 2, 5) catalysts exhibited better catalytic performances than monometallic 2%Ni/SiO2 and 2%Cu/SiO2. Moreover, the bimetallic 2%Ni-5%Cu/SiO2 catalyst showed the best catalytic performance with 94% of furfural conversion and 64% of furfuryl alcohol selectivity. The synergetic effect of NiCu alloy particles that are present on bimetallic Ni-Cu/SiO2 catalysts change the adsorption configuration of furfural on the catalyst surface resulting in high catalytic performance in liquid phase selective hydrogenation of furfural to furfuryl alcohol.

Structural evolution of ZIF-67-derived catalysts for furfural hydrogenation

Zeolitic imidazolate framework-67 (ZIF-67) can be converted to metallic Co nanoparticles supported on N-doped carbon (Co/NC) through reduction. However, its unique properties, including extremely high surface area, isoreticular pore structure, and regular metal–organic network, disappear after high-temperature (>500 °C) reduction. Aggregated CoOx particles reduce the number of surface-active sites, resulting in poor catalytic activity. If the original ZIF-67 structure is maintained after the high-temperature reduction, promoting the uniform distribution of active sites in the porous carbon, the catalytic performance can be further improved. Herein, the correlation between the catalytic furfural hydrogenation performance, Co/NC morphology, and oxidation state of Co was investigated as a function of the H2 reduction temperature and time. The reduction of ZIF-67 at 400 °C for 6 h yields a highly dispersed Co/NC catalyst, while preserving the overall morphology. The resulting Co/NC-400-6 catalyst exhibits the highest activity, promoting high selectivity toward 2-methylfuran. The product selectivity can be further altered by incorporating Cu into ZIF-67 to produce furfuryl alcohol. With proper H2 treatment to minimize the damage to the intrinsic surface area and pore structure, metal–organic frameworks can be utilized as high-performance heterogeneous catalysts by maximizing the distribution of active sites.

Surface interactions with the metal oxide surface control Ru nanoparticle formation and catalytic performance

Here, we report the development of novel Ru-containing catalysts based on porous metal oxide supports such as SnO2, Nb2O5, and Nb2Sn5O15. We assessed structure, porosity, acidity and morphology of both supports and catalysts and established a relationship between surface interactions and catalytic performance in hydrogenation of biomass based levulinic acid (LA) to γ-valerolactone (GVL). All metal oxide supports stabilize small Ru-containing nanoparticles (NPs), whose makeup includes a prevailing fraction of Ru(OH)3. Yet, Nb2O5 stabilizes ∼1 nm Ru-containing NPs which are homogeneously distributed on the metal oxide surface, while for SnO2 and Nb2Sn5O15, sub-nanometer NPs are formed, which are prone to aggregation to minimize surface energy. These differences are assigned to nucleation of NPs on support oxygen vacancies, whose amounts vary and are consistent with NP characteristics. The catalytic testing shows that the 100 % conversion and selectivity as well as high turnover frequency are achieved for Ru/Nb2O5, whose surface morphology includes well-dispersed 1 nm Ru-containing NPs. These and high stability of catalytic performance upon multiple reuse, make Ru/Nb2O5 promising for practical applications. Furthermore, this work validates the usefulness of surface interactions on metal oxides in development of efficient catalytic systems.

Different transfer hydrogenation pathways of halogenated nitrobenzenes catalyzed by Fe-, Co- or Ni-based species confined in nitrogen doped carbon

In this work, by the simple pyrolysis of Fe2+, Co2+ or Ni2+ and 1,10-phenanthroline (Phen) complexes under the presence of activated carbon and dicyandiamide in nitrogen atmosphere, different nonprecious transition metal-based species that well confined in nitrogen doped carbon (M-N-C, M = Fe, Co or Ni) were prepared. The Fe-N-C showed the best catalytic performance for the transfer hydrogenation of halogenated nitrobenzenes. More importantly, through the catalytic results comparison of the three catalysts estimated by gas chromatography-mass spectrometer, two speculations might be presented for the reaction pathway depending on the catalyst used. The transfer hydrogenation reaction route over Fe-N-C might follow the indirect way like the Co-N-C and Ni-N-C. Another assumption was the Fe-N-C might go through the direct pathway in contrast to the Co-N-C and Ni-N-C which resulted in formation of azoxybenzene and azobenzene intermediates before complete conversion to aniline. Those differences were found to be correlated with the different valence states and active metal components in different catalysts. In addition, the optimal Fe-N-C could be efficiently recovered by using an applied magnetic field and reused without significant decrease of activity. Therefor the catalyst may possess important potential for the industrial application in the selective hydrogenation of halogenated nitrobenzenes.

Tuning interaction of surface-adsorbed species over Fe/K-Al2O3 modified with transition metals (Cu, Mn, V, Zn or Co) on light olefins production from CO2 hydrogenation

The presence of transition metals (Cu, Co, Zn, Mn or V) in Fe/K-Al2O3, modifying the adsorption-desorption properties of CO2 and H2 with the catalyst surface remarkably influences the catalytic performance for CO2 hydrogenation to light olefins. The addition of either Cu or Zn to Fe/K-Al2O3 significantly increases the number of weakly adsorbed H atom, yielding the high CO2 conversion and shifting the product distribution towards longer chain hydrocarbon with a higher content of paraffins. The addition of Co to Fe/K-Al2O3 also enhances the CO2 conversion but it provides the short chain hydrocarbon (C1-C4) and thus achieving the highest light olefins yield of 16.2%. The presence of either Mn or V inhibits the CO hydrogenation to hydrocarbon, leading to the low CO2 conversion. The Mn promoter reduces the number of weakly adsorbed H atom, lowering the hydrogenation ability of the catalyst, resulting in the highest olefin to paraffin ratio of 7.4.

Carbonyl oxygen-coordinated metallic cobalt nanoparticles anchored on hybrid mesoporous silica matrix to enhance 4-nitrophenol hydrogenation

In this paper, urea group functionalized periodic mesoporous organosilica was utilized as matrix to introduce cobalt precursor into framework. After pyrolysis in nitrogen atmosphere, urea group was decomposed into carbon species and simultaneously the cobalt precursor was reduced to metallic cobalt nanoparticles. The metallic cobalt nanoparticles can be stabilized by coordinating to carbonyl oxygen atoms in carbon species. The supported metallic cobalt exhibited excellent catalytic performance towards 4-nitrophenol hydrogenation reaction. The largest turnover frequency number can reach up to 164.8 h−1, and the reaction rate constant can be as high as 0.77 min−1. The influence of pyrolysis temperature on catalytic performance was also investigated. Compared with the results obtained by samples prepared with wet impregnation method or different pyrolysis rate, it can be concluded that the coordination to carbonyl oxygen atom in carbon species plays a crucial role in improving electron transfer between metallic cobalt and carbon species during catalytic procedure. Metallic cobalt nanoparticles with high dispersion were introduced into urea group functionalized mesoporous silica matrix via pyrolysis in nitrogen atmosphere. The coordination to carbonyl oxygen atom enhances the catalytic performance in 4-nitrophenol hydrogenation.

Gold Nanoparticles Supported on Ce–Zr Oxides for Selective Hydrogenation of Acetylene

Gold nanocatalysts have been reported to be active in the selective hydrogenation of acetylene. In this paper, a series of Au/Ce1−xZrxO2 (x = 0.03 to 0.5) supported catalysts with different ratios of Ce to Zr were prepared and their catalytic performance for selective hydrogenation of acetylene was investigated. The structure and surface defects of the catalyst can be changed by altering the amount of Zr incorporation. Compared to both Au/CeO2 and Au/ZrO2, the synthesized Au/Ce1−xZrxO2 showed the higher catalytic activity with keeping almost 100% ethylene selectivity at 300 °C. The TEM observation indicated that the incorporation of Zr led to the formation of hollow spherical solid solutions. The specific surface area also has a certain influence on the catalytic activity. Considering the catalytic activity of Au/Ce1−xZrxO2 and their characterizations by XPS and Raman, the concentration of Ce4+ and the oxygen vacancy of the Ce1−xZrxO2 support play an important role in the selective hydrogenation of acetylene.

Pd Nanoparticles Loaded on Two-Dimensional Covalent Organic Frameworks with Enhanced Catalytic Performance for Phenol Hydrogenation

Covalent organic frameworks (COFs) have emerged as an excellent support for heterogeneous catalysis due to their regular pore structure and high specific surface area. Herein, a series of porous Tp...

C, N Co-Decorated Alumina-Supported Au Nanoparticles: Enhanced Catalytic Performance for Selective Hydrogenation of Acetylene

The modifications of support for the dispersion and immobilization of gold nanoparticles were examined for the selective hydrogenation of acetylene to ethylene. The catalyst, denoted as Au/CNA, was prepared by the carbonization of C and N atom-containing organic precursors on Al2O3, which were subsequently used as supports for gold nanoparticles. The TOF value of Au/CNA was five times higher than that of Au/Al2O3 at 250 °C. The carbonization modification of Al2O3 support without N species showed almost no change in catalytic activity. Therefore, the improved catalytic performance of Au/CNA is related to the interactions of the N species on the CNA support with nano-gold particles. From the XPS analysis, electron transfer between gold and C, N co-doped species may play an important role in the high levels of Au active site utilization. This study may provide new avenues for the construction of organic/inorganic composite materials for efficient catalytic hydrogenation applications.

High Performance and Sustainable Copper-Modified Hydroxyapatite Catalysts for Catalytic Transfer Hydrogenation of Furfural

Designing and developing non-noble metal-based heterogeneous catalysts have a substantial importance in biomass conversion. Meerwein-Ponndorf-Verley (MPV) reaction is a significant pathway for eco-friendly catalytic transfer hydrogenation (CTH) of biomass derived furfural into furfuryl alcohol. In this work, a series of copper-supported hydroxyapatite (HAp) catalysts with different copper loadings (2–20 wt.%) were prepared by a facile impregnation method and tested in the reduction of furfural to furfuryl alcohol using 2-propanol as a hydrogen donor. The structural and chemical properties of the synthesised catalysts were analysed by using various techniques (XRD, N2 sorption, SEM, TEM, UV-DRS, ICP, FTIR, TPR, TPD-CO2 and N2O titration). The effect of copper loading was found to be significant on the total performance of the catalysts. The results demonstrate that 5CuHAp catalyst possess highly dispersed copper particles and high basicity compared to all other catalysts. Overall, 5CuHAp exhibited highest conversion (96%) and selectivity (100%) at 140 °C at 4 h time on stream. The optimised reaction conditions were also determined to gain the high activity.

Controllable Synthesis of 1D Pd@N-CNFs with High Catalytic Performance for Phenol Hydrogenation

Achieving both high conversion and selectivity under mild conditions still remains a big challenge in the selective hydrogenation of phenol to cyclohexanone. Herein, one-dimensional (1D) N-doped carbon nanofibers (N-CNFs) were successfully fabricated by electrospinning with one-step carbonization, and used to load Pd nanoparticles for synthesizing Pd@N-CNFs catalysts. The dicyandiamide (DICY) and citric acid in the spinning solution exhibited a significant synergistic effect in controlling the morphology and surface property of N-CNFs and the corresponding catalytic activity of Pd@N-CNFs in the selective hydrogenation of phenol to cyclohexanone. The as-prepared Pd@N-CNFs-1.5 catalyst possessed good fibrous morphology, larger surface area, and more amounts of surface N and OH group, and exhibited a phenol conversion of 99.7% with a cyclohexanone selectivity of 97.3% under mild reaction conditions. In addition, the catalytic activity of Pd@N-CNFs-1.5 increased by 2.75 times as compared to Pd@N-CNFs-0 and 1.22 times in comparison with Pd@N-CNFs-100. Furthermore, the 1D Pd@N-CNFs-1.5 was easy to be recovered from the reaction mixture, and showed good reusability. The proper molar ratio of dicyandiamide (DICY) and citric acid could significantly adjust the fibrous characteristic and surface properties of the Pd@CNFs catalyst, which contributed to the higher N and OH group contents, thereby improving the loading and distribution of Pd nanoparticles and the dispersibility of Pd@CNFs in water. These properties jointly led to the superior phenol hydrogenation efficiency of the Pd@CNFs catalyst.

Catalyst consisting of Ag nanoparticles anchored on amine-derivatized mesoporous silica nanospheres for the selective hydrogenation of dimethyl oxalate to methyl glycolate

Developing efficient catalysts for the selective hydrogenation of dimethyl oxalate (DMO) is of great significance for the coal-based production of methyl glycolate (MG), but designing processes for this conversion is challenging. Herein we report an unprecedented catalytic performance for the selective hydrogenation of DMO to MG, achieved by using a catalyst based on Ag nanoparticles anchored inside the mesopores of amine-derivatized silica nanospheres (NH2-MSNS). It was determined that the unique microenvironment endowed by the amine-derivatized channel surfaces helps this Ag catalyst promote the activation of DMO and H2 to yield MG with high selectivity, and also prevents sintering and coking, hence improving stability. Accordingly, the resulting Ag/NH2-MSNS catalyst was shown to be capable of promoting the hydrogenation reaction with a turnover frequency of 230 h−1 and a MG selectivity of 97% at nearly 100% of DMO conversion, a performance that was sustained for at least 250 h; these results are significantly better than those seen with other reported catalysts. Our study points to a promising route for the development of high-performing Ag catalysts to be used in the coal-based MG production.

Role of metal Cu species on methyl laurate catalytic hydrogenation to oxygen-containing compounds

The Cu/γ-Al2O3 catalysts with different Cu loadings were prepared by impregnation method. The physicochemical properties of these Cu/γ-Al2O3 catalysts were characterized by H2-TPR, XRD, and in-situ XPS. The catalytic hydrogenation performances of methyl laurate over Cu/γ-Al2O3 catalysts were studied. The results show that the hydrogenation performances of methyl laurate on Cu/γ-Al2O3 catalyst are related to the dispersion, crystallite size, and content of the active component Cu0. The 10CA catalyst has the best hydrogenation performances for methyl laurate to produce C12 alcohol. At 300 °C, the conversion of methyl laurate and the selectivity of C12 alcohol are 55.6% and 30.4%, respectively.

Graphitic phosphorus coordinated single Fe atoms for hydrogenative transformations

Single-atom metal-nitrogen-carbon (M-N-C) catalysts have sparked intensive interests, however, the development of an atomically dispersed metal-phosphorus-carbon (M-P-C) catalyst has not been achieved, although molecular metal-phosphine complexes have found tremendous applications in homogeneous catalysis. Herein, we successfully construct graphitic phosphorus species coordinated single-atom Fe on P-doped carbon, which display outstanding catalytic performance and reaction generality in the heterogeneous hydrogenation of N-heterocycles, functionalized nitroarenes, and reductive amination reactions, while the corresponding atomically dispersed Fe atoms embedded on N-doped carbon are almost inactive under the same reaction conditions. Furthermore, we find that the catalytic activity of graphitic phosphorus coordinated single-atom Fe sharply decreased when Fe atoms were transformed to Fe clusters/nanoparticles by post-impregnation Fe species. This work can be of fundamental interest for the design of single-atom catalysts by utilizing P atoms as coordination sites as well as of practical use for the application of M-P-C catalysts in heterogeneous catalysis.

Asymmetric Hydrogenation of 1-aryl substituted-3,4-Dihydroisoquinolines with Iridium Catalysts Bearing Different Phosphorus-Based Ligands

Starting from the chiral 5,6,7,8-tetrahydroquinolin-8-ol core, a series of amino-phosphorus-based ligands was realized. The so-obtained amino-phosphine ligand (L1), amino-phosphinite (L2) and amino-phosphite (L3) were evaluated in iridium complexes together with the heterobiaryl diphosphines tetraMe-BITIOP (L4), Diophep (L5) and L6 and L7 ligands, characterized by mixed chirality. Their catalytic performance in the asymmetric hydrogenation (AH) of the model substrate 6,7-dimethoxy-1-phenyl-3,4-dihydroisoquinoline 1a led us to identify Ir-L4 and Ir-L5 catalysts as the most effective. The application of these catalytic systems to a library of differently substituted 1-aryl-3,4-dihydroisoquinolines afforded the corresponding products with variable enantioselective levels. The 4-nitrophenyl derivative 3b was obtained in a complete conversion and with an excellent 94% e.e. using Ir-L4, and a good 76% e.e. was achieved in the reduction of 2-nitrophenyl derivative 6a using Ir-L5.