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Catalytic transfer hydrogenation of furfural to 2-methylfuran in the presence of isopropanol was systematically investigated over a series of sol–gel derived CuZn/FeOx catalysts.

Understanding the essential roles in adiponitrile hydrogenation is a significant factor to design sparkling 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 Ni compositions and chemical structure of catalysts were modulated by the assistant precipitators. Characterizations including the XRD, N2 adsorption-desorption, TEM, XPS, H2-TPD, and NH3-TPD were carried out. Smaller particles could be obtained via the fast deposition of Ni2+ by NaOH in Ni/Al2O3-OH or the uniform crystal seeds by urea in Ni/Al2O3-U. Strong alkali and the formation of nickel hydroxide facilitated the generation of Ni0 with better H2 activation ability. Whilst huge amount of nickel species in oxidative state and strong acidity were simultaneously generated in Ni/Al2O3-U, leading to the easily cycloaddition by-products. Kinetic study revealed that adiponitrile hydrogenation is a second-order reaction with respect to adiponitrile. The numbers of Ni0 active sites and acid sites could be balanced by the precipitation and crystallization via different processes. The yield of 1,6-hexanediamine reached 75.0% at 90 oC by 20 wt% Ni/Al2O3-OH.

Rational design of promising Cu catalyst requires better understanding of the Cu–support perimeter for reactions such as hydrogenation rearrangement of furfural─a pivotal and alternative transforma...

Existing researches about unsupervised cross-domain bearing fault diagnosis mostly consider global alignment of feature distributions in various domains, and focus on relatively ideal diagnosis scenario under the steady speeds. Therefore, unsupervised feature adaptation between all the corresponding subdomains under speed fluctuation remains great challenges. This paper proposes a modified deep subdomain adaptation network (MDSAN) for more practical and challenging cross-domain diagnostic scenarios from the fluctuating speeds to steady speeds. Firstly, to extract the representative features and effectively suppress negative transfer, a novel shared feature extraction module guided by multi-headed self-attention mechanism is constructed. Then, a new trade-off factor is designed to improve the convergence performance and optimization process of MDSAN. The proposed method is used for analyzing experimental bearing vibration data, and the results show that it has higher diagnostic accuracy, faster convergence, better distribution alignment, and is more suitable for unsupervised cross-domain fault diagnosis under speed fluctuation scenario compared with the existing methods.

Gold catalysis had been considered a highly efficient candidate for heterogeneous catalysis. It is well established that reducible-material-supported Au NPs are more reactive than the unreducible materials, unless specific modifications are carried out. However, unreducible materials such as carbon materials, silica, and alumina have particular advantages, including the easily controlled surface property, adjustable microscopic structure, earth-abundant reserves, and facile industrial manufacture. New strategies, influences, and mechanisms of modification to enhance the catalytic performance and thermal stability of unreducible-material-supported gold catalysts are among the most attractive research topics in gold catalysis. However, to the best of our knowledge, reports and reviews focused on unreducible-material-supported gold catalysts are lacking. Herein, the above concept will be thoroughly discussed regarding several typical unreducible supports, including the commonly used silica, alumina, carbon materials, and hydroxyapatite. The currently prevailing modification strategies will be summarized in detail from the aspects of theoretical conceptualization and practical methodology, including the ingenious synthesis method for catalyst with a specific structure, the currently prosperous electrostatic adsorption, colloid immobilization, and the applicative thermal gaseous treatment. The influences of physical and chemical modifications on the surface chemistry, electronic structure, interaction/synergy between Au-support/promoter, catalyst morphology and water precipitation will be also summarized. It is assumed that the review will shed light on significant studies on unreducible support in gold catalysis with the purpose of catalytic promotion and the promotion of the potential industrial demands in advance. Furthermore, the review will provide new insights into unreducible supports that can be potentially applied in gold catalysis.

Designing a highly active, stable and cost-effective electrocatalyst with multiple functionalities toward hydrogen evolution and oxygen reduction applications is crucial for the development of renewable energy sources. Here, the synthesis of hollow PtNi nanostrings via a facile two-step template method is reported. The PtNi nanostrings own Pt-rich rough surfaces, and hollow string-like structure with the structural disorder morphology. Impressively, the unique hollow PtNi nanostrings exhibit excellent electrocatalytic activity toward the hydrogen evolution and oxygen reduction reactions. The obtained overpotential is only 44.60 mV at current density of 10 mA cm-2 for hydrogen evolution reaction. Furthermore, the hollow PtNi nanostrings exhibit a high mass activity of 2.5 A mg-1Pt and a superior specific activity of 3.89 mA cm-2 at 0.90 V versus reversible hydrogen electrode in oxygen reduction reaction, respectively, which are 10 and 9 times higher than those of the commercial Pt/C. This work provides a promising approach for the synthesis of highly bifunctional electrocatalysts with a hollow sting-like structure to promote their application in the hydrogen evolution and oxygen reduction reactions.

Nickel based catalysts were decorated by metal oxide (MOx = CeO2, La2O3 or MgO) and used for the selective hydrogenation of adiponitrile to hexamethylenediamine. Additional MOx sub-nanoclusters were dispersed on surface to manipulate the electron and surface structures of nickel particles. The functional role of, e.g. CeO2 decorator, was to benefit the formation of Ni-CeO2 interfaces and acted as electron donor for the Ni active sites, rather than to change the morphology, crystallization, or the H2 activation energy barrier. The d-band center calculated by Density Functional Theory was altered and close to the Fermi-level after CeO2 loading, rationally accounting for the accelerated reaction rate. The decorated CeO2 behaved like a double-edge sword. Excessive loading of ceria easily led to the coverage of Ni sites and destroyed the elaborated Ni-CeO2 synergy. By using Ni-Ce3/Al2O3 with only 3 at% CeO2, adiponitrile can be completely transformed at 90 °C in 7 MPa H2 for 3 h with 90% yield of hexamethylenediamine. The additional CeO2 also resulted in the enhanced stability of Ni catalyst, which maintains its high catalytic stability even after 5 reaction cycles.

In this work, a series of colloidal gold nanoparticles with controllable sizes were anchored on carbon nanotubes (CNT) for the aerobic oxidation of benzyl alcohol. The intrinsic influence of Au particles on the catalytic behavior was unraveled based on different nanoscale-gold systems. The Au/CNT-A sample with smaller Au sizes deserved a faster reaction rate, mainly resulting from the higher dispersion degree (23.5%) of Au with the available exposed sites contributed by small gold particles. However, monometallic Au/CNT samples lacked long-term stability. CeO

International audience; Gold nanoparticles have been increasingly used in catalysis, biomedical imaging, biological and chemical sensing, drug delivery, etc. In this study, a straightforward method that allows one to monitor the synthesis of gold sols and their aging, before their fine characterization by sophisticated techniques and before their use is described. Indeed, the "Colloid Thin-Layer Chromatography" method allows one to check the quality of gold colloidal sols during the synthesis. It is also well adapted for monitoring the aging of the sol before the visual observation of its degradation.

Tiny gold nanoparticles were successfully anchored on carbon nanotubes (CNT) with NiO decoration by a two-step synthesis. Characterizations suggested that Ni species in an oxidative state preferred to be highly dispersed on CNT. During the synthesis, in situ reduction by NaBH4 and thermal treatment in oxidation atmosphere were consequently carried out, causing the formation of Au-Ni-Ox interfaces and bimetal hybrid structure depending on the Ni/Au atomic ratios. With an appropriate Ni/Au atomic ratio of 8:1, Ni atoms migrated into the sub-layers of Au particles and induced the lattice contraction of Au particles, whilst a higher Ni/Au atomic ratio led to the accumulation of NiO fractions surrounding Au particles. Both contributed to the well-defined Au-Ni-Ox interface and accelerated reaction rates. Nickel species acted as structure promoters with essential Au-Ni-Ox hybrid structure as well as the active oxygen supplier, accounting for the enhanced activity for benzyl alcohol oxidation. However, the over-layer of unsaturated gold sites easily occured under a high Ni/Au ratio, resulting in a lower reaction rate. With an Au/Ni atomic ratio of 8:1, the specific rate of AuNi8/CNT reached 185 μmol/g/s at only 50 °C in O2 at ordinary pressure.

Supported gold nanoparticles with sizes below 5 nm display attractive catalytic activities for heterogeneous reactions, particularly those promoted by secondary metal (e.g., Cu) because of the well-defined synergy between metal compositions. However, the specific atomic structure at interfaces is less interpreted systematically. In this work, various bimetallic Au-CuOx catalysts with specific surface structures were synthesized and explored by aberration-corrected scanning transmission electron microscopy (AC-STEM), temperature-programmed experiments and in situ DRIFT experiments. Results suggest that the atomic structure and interfaces between gold and CuOx are determined by the nucleation behaviors of the nanoparticles and result in subsequently the distinctive ability for CO activation. Bimetallic CuO*/Au sample formatted by gold particles surrounded with CuOx nanoclusters have rough surface with prominently exposed low-coordinated Au step defects. Whereas the bimetallic Au@CuO sample formatted by copp...

The design of cost-efficient earth-abundant catalysts with superior performance for oxygen evolution reaction (OER) is extremely important for future renewable energy production. The synthesis of high-surface-area catalysts with high intrinsic activity remains challenging. In this work, in-situ surface selective removal method by electrochemical oxidation is used to synthesize nickel (oxy)hydroxide covered Ni3Sn2 supported on carbon nanotubes (Ni3Sn2@NiOxHy/CNT), which exhibits 10, 100, 200 and 300 mA cm−2 at overpotential of 250, 317, 329 and 335 mV in OER, respectively. In-situ surface selective removal of Sn from the crystal lattices and oxidation of Ni under anodic oxidation provide highly active amorphous NiOxHy with abundant surface defects, leading to the high apparent activity (current density) and intrinsic activity (TOF) of the Ni3Sn2@NiOxHy/CNT. This work develops a general method to synthesize high-surface-area water oxidation catalysts, which can be used to prepare a series of catalysts for oxygen evolution reaction in the near future.

2-Methylfuran production through catalytic transfer hydrogenation (CTH) of furfural in liquid phase has been investigated over CuZnAl catalysts using alcohol as hydrogen donor. Results suggested that furfuryl alcohol was generated immediately and subsequently transformed into 2-methylfuran. The cleavage of C–O(H) was the rate-determining step and positively relied on the copper content. Prereduction of CuZnAl by H2 provided surface reduced Cu0 and Cu+ species with the preservation of the CuAl2O4 phase. By using the Cu2.5Zn–Al-600 catalyst with a Cu/Zn molar ratio of 2.5, we can achieve a 72% 2-methylfuran yield and a specific rate of 7.5 mmolMF/(gCat. h) under ordinary pressure in N2 at 180 °C, which is even superior to the reported noble metal catalysts. After six reaction cycles, the catalytic activity remained almost unchanged. The low cost and facile availability of the CuZnAl catalyst make it available for the potential use in industry.

Intermetallic nanoparticles (NPs) with a well-defined atom binding environment and a long-range ordering structure can be used as ideal models to understand their physical and catalytic properties. In this work, several kinds of nanostructured and carbon nanotube (CNT)-supported Pt-based intermetallic compounds (IMCs) have been synthesized by one-step lithium naphthalenide-driven reduction at room temperature without the use of surfactants in light of the reduction potential of metals. In the chemoselective hydrogenation of cinnamaldehyde, the second metal in Pt-M IMCs significantly creates a suitable reaction environment through construction of a good geometric and electronic structure. The Pt

The creation of specific catalytic functionalities in the nanocarbon materials is an important approach to develop the metal-free nanocarbon materials (carbocatalysts). We report herein a functionalization strategy by treatment of N-doped carbon nanotubes (NCNT) with ozone/water to create oxygen groups nearby the N groups (N-C=O). These groups, different from those present in conventionally oxidized NCNT, show peculiar catalytic behavior. The N atom adjacent to carbonyl group (N-C=O) modifies the reactivity of carbonyl towards C-H activation and simultaneously activate O2 molecule for bifunctionality. Efficient performance for oxidative coupling of benzylamine to imine (>99% imine selectivity) can be obtained under solvent-free conditions at ambient pressure. The benzylamine productivity reaches as high as 131.3 μmol m−2 h−1, which is the highest among any other reported carbon-based catalysts. This work not only highlights a sustainable strategy for tuned surface chemistry of carbon materials by using mild ozonation process, but also reports a novel green aerobic synthesis method of benzylamine using tailored metal-free carbon nanomaterials.

Nanocarbon materials have been reported as an alternative robust metal-free catalyst in the field of the catalytic dehydrogenation with improved catalytic performance as well as stability. In this study, the hybrid metal-free catalyst consisting of dispersed nanodiamonds within a nitrogen-doped mesoporous carbon (ND@NMC) phase was investigated. Such material with high effective surface area and porosity was prepared under different thermal treatment temperatures and further evaluated for the direct dehydrogenation (DDH) of ethylbenzene (EB) to styrene (ST). The characterization techniques such as N 2 adsorption-desorption, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy and Raman spectroscopic analysis were used to investigate the surface properties and structures of the as-prepared ND@NMC composites. The ND@NMC-700 catalyst annealed at 700 °C presented a ST specific reaction rate and a relative areal activity of 5.8 mmol ST g catalyst −1 h −1 and 0.28 μmol ST m −2 h −1 with a ST selectivity of 99.6%, which is the highest DDH activity among the investigated nanocarbons including ND, carbon nanotubes, NMC and ND@MC (ND covered by mesoporous carbon) catalysts. The superior dehydrogenation performance could be attributed to the high dispersion of the metal-free nanodiamond centers within the NMC layer which provided a well surface contact with the reactant. It can also be confirmed that the rational contents of ketone (C O) functional groups, as well as the opened porous network in ND@NMC-700 catalyst resulted to the superior DDH activity and styrene selectivity. Moreover, the presented nitrogen groups are beneficial for construction of surface defects and porosity as well as the improvement of styrene selectivity.

A new self-propagated flaming (SPF) technique was applied to the synthesis of highly active layered CuO-δ-MnO2 hybrid composites, for the de-polluting catalytic total oxidation of gaseous toluene vapor. Other transition metal oxide-doped MnO2 hybrid composites were also successfully prepared and investigated, ensuring a feasible strategy for the fabrication of various layered MOx-δ-MnO2 (M═Co, Ni, or Zn) hybrids. By changing the molar ratio of the precursors (KMnO4 and acetate salt) and the type of transition metal oxide introduced, it is possible to control the crystal structure and reducibility of the sheetlike hybrid composites as well as the catalytic activity for the total oxidation of toluene. The catalyst sample (CuO-δ-MnO2) with a Mn/Cu molar ratio of 10:1 exhibited the highest catalytic performance, with a lower reaction temperature of 300 °C for complete toluene removal, which was comparable to the reaction temperature for total toluene conversion by the Pt-based catalyst. The SPF technique prov...

The varied surface structures of a Pd catalyst showed different catalytic performances in the partial hydrogenation of acetylene. The exposed Pd (1 0 0) facet is considered to be the most selective of all other facets for the formation of ethylene, but it is unstable and the fine structure needs to be revealed during the reaction. Herein, the evolution of the surface structure of cubic Pd nanoparticles, which are all bound with (1 0 0) facets, was studied by transmission electron microscopy in the partial hydrogenation of acetylene. Furthermore, the relation between the varying surface structure and the activity/selectivity was correlated. The (1 0 0) facets of Pd were transformed into stepped facets during the reaction, derived by adsorption/desorption of the reactants and energy compensation, which was the main reason for the decrease in the selectivity towards ethylene.

The surface activity and charged nature of ionic surfactants (sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB)) are used as in situ probes for the Coulombic nature of active sites in N-doped nanocarbon. In this report, we demonstrate that, by selectively masking charge-carrying sites, the active nitrogen sites in N-doped nanodiamond for oxygen reduction reaction are positively charged moieties, rather than those uncharged or negatively charged groups. From the N group analysis by X-ray photoelectron spectroscopy (XPS) and temperature-programmed desorption in a hydrogen gas atmosphere (H2-TPD), we put forth the concern that the active nitrogen groups in N-doped nanocarbon may contain oxygen and should not be simply classified by the four conventional nitrogen types by XPS binding energy.

Developing highly selective and stable catalysts for acetylene hydrogenation is an imperative task in the chemical industry. Herein, core-shell Pd@carbon nanoparticles supported on carbon nanotubes (Pd@C/CNTs) were synthesized. During the hydrogenation of acetylene, the selectivity of Pd@C/CNTs to ethylene was distinctly improved. Moreover, Pd@C/CNTs showed excellent stability during the hydrogenation reaction.

We report herein a green and economical strategy for oxidative modification of carbon nanotubes (CNT) by a facile ozone treatment in the presence of solvent vapor (H2O, 30% H2O2 solution and ethanol). This procedure is able to introduce a considerable level of oxygen groups with a dominant population of carboxyl groups at near ambient temperature. The optimization study of the process provides the reaction temperature and time, as well as the source and partial pressure of the vapor, key parameters determining the oxidation efficiency. The process efficiency and sustainability are assessed to compare with conventional oxidative treatment (e.g., nitric acid oxidation). Ozone treatment assisted by water or H2O2/H2O vapor can introduce abundant oxygenated groups on the sidewalls of CNT, and the process with H2O2/H2O vapor can deliver a much higher selectivity towards carboxyl species on the sidewalls of CNT. With the appropriate functionalization temperature (40 °C) and incremental partial pressure of vapor, the surface defect and oxygen content on the CNT could be dramatically increased. The ozone treated CNT can be used for diverse applications such as metal-free catalyst and support; the modified CNT display higher activity for the ring-opening reaction of styrene oxide than HNO3 treated CNT and develop strong interaction for anchoring iron oxide nanoparticles even up to 350 °C. This ozone treatment in the presence of vapor could also be accomplished by using compressed air as the carrier gas, which can be considered an efficient and eco-friendly functionalization process.

Nanocarbons with unique physicochemical properties have been considered typical sustainable materials for use as catalyst supports and directly as catalysts. Unfortunately, the powder form of nanocarbons renders them difficult to use in industrial processes due to the high pressure drop, their difficulty of handling as well as health injuries caused to human beings. Herein, hierarchical carbon fibers/carbon nanofibers (CF/CNF) composites, with high effective surface areas and controlled macroscopic shapes, were successfully synthesized through a combination of electrospinning (ES) and chemical vapour deposition (CVD). A web of poly(acrylonitrile)/poly(vinyl pyrrolidone) (PAN/PVP) composite fibers embedding a nickel salt was firstly produced by electrospinning. After a carbonization step, the polymeric material was converted into porous carbon embedding nickel nanoparticles, available on the fiber surface. Then, the catalytic growth of the CNFs was carried out from the nickel nanoparticles by CVD leading finally to the formation of a hierarchical carbon web of hairy fibers with a high effective surface area. The density, diameters and lengths of the CNFs attached on the surface of the CFs could be finely tuned by adjusting the CVD conditions. The specific surface area of the CF/CNF monolith amounted to more than 200 m2 g−1 along with high accessibility due to the small dimensions. The hierarchical CF/CNF composite has been used as a metal-free catalyst for the steam- and oxygen-free catalytic dehydrogenation of ethylbenzene to styrene. The catalytic results have pointed out that such a monolith can be efficiently used as a material platform for different applications , going from catalysis to wastewater treatment, thanks to the high effective surface area and reactivity of the CNF with prismatic planes.

Supported gold nanoparticles with sizes below 5 nm display attractive catalytic activities for heterogeneous reactions, particularly those promoted by secondary metal (e.g., Cu) because of the well-defined synergy between metal compositions. However, the specific atomic structure at interfaces is less interpreted systematically. In this work, various bimetallic Au-CuO

The fabrication of bimetallic catalysts has been taken great focus in the concept of heterogeneous catalysis due to their high efficiency and economic concerns. In this work, a series of bimetallic Ru-Re catalysts were designed and synthesized for the selective hydrogenation of dimethyl terephthalate (DMT) to 1,4-cyclohexane dicarboxylate (DMCD) under mild condition. Characterization techniques including the XRD, TEM, STEM-HAADF EDX elemental mapping, H2-TPR, and XPS were used to study the surface chemical property, the morphology, as well as the catalytic behavior of different samples. It was revealed that the monometallic Ru catalyst already has the capacity to activate and transform DMT into DMCD. Whilst the promotion effect can be optimized to a maximum with only small amount of Re, with the mass ratio of Ru/Re as 10:1. It was also revealed that the addition of Re could largely enhance the distribution of surface active metal species, facilitate the charge transfer between Ru and Re, as well as strengthen the Ru-Re synergistic interaction, which further led to the modification of the redox ability and the catalytic performances of samples. However, excessive addition of Re caused strong interaction between Ru and Re, and further limited the H₂ activation and the seasonable release of the active reducible metal species, which was responsible for the depressed catalytic performances in the presence of higher Re loading. The Ru1.25Re0.13/AC catalyst displayed the DMT conversion of 82% with DMCD selectivity of 96% under mild condition of 70 °C at 3 MPa. The specific rate of Ru1.25Re0.13/AC based on per gram of Ru was 0.44 mol·g-1 Ru·h-1.

The understanding of the interactions between the different components of supported metal doped gold catalysts is of crucial importance for selecting and designing efficient gold catalysts for reactions such as CO oxidation. To progress in this direction, a unique supported nano gold catalyst Au/SS was prepared, and three doped samples (Au/SS@M) were elaborated. The samples before and after test were characterized by Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). It is found that the doping metal species prefer to be located on the surface of gold nanoparticles and that a small amount of additional reductive metal leads to more efficient reaction. During the catalytic test, the nano-structure of the metal species transforms depending on its chemical nature. This study allows one to identify and address the contribution of each metal on the CO reaction in regard to oxidative species of gold, silica and dopants. Metal doping leads to different exposure of interface sites between Au and metal oxide, which is one of the key factors for the change of the catalytic activity. The metal oxides help the activation of oxygen by two actions: mobility inside the metal bulk and transfer of water species onto of gold nanoparticles.

Silica supported gold nanoparticles were synthesized and promoted by lanthanum oxide as dopant. The influences of La2O3 and silica textural structure on the gold dispersion, formation of active species, crystalline composition and the reacting role of dopants were studied in detail. The characterization results suggested that the dispersion of gold nanoparticles depended on the textural structure of silica without lanthanum oxide doping where small mesopores are more preferable to disperse gold nanoparticles. The addition of lanthanum oxide largely increased the dispersion of gold nanoparticles and oxygen active sites independent of the textural structure of silica support. The interaction between lanthanum oxide and silica enhanced by the synergy facilitated the release of oxygen vacancies and transition of active oxygen species. In addition, the chemical properties were greatly changed after lanthanum oxide addition which was only inconspicuously impacted by the initial textural structure of silica supports, shedding light on the further design of economic gold catalyst based on simple synthesis method.

Copper-based catalysts have been widely recorded as efficient catalysts of CO2 hydrogenation reaction for producing chemicals and fuels, which not only contributes to decreasing CO2 emissions benefiting for environmental issue, but also alters the industrial concepts for fine chemicals production. CuO-ZnO-ZrO2 (CZZ) composite is intensively investigated for methanol production through CO2 hydrogenation which is due to its high CO2 activation and water tolerance abilities during the reaction. In this work, highly dispersed metallic Cu° species from the CuO-ZnO-ZrO2 catalyst have been fabricated with the assistance of the mesoporous aluminosilicate support Al-TUD-1. The amorphous 3D-structured Al-TUD-1 presents extremely high surface areas (>600 m2 g−1) and abundant Bronsted acid sites that could play a role for Cu partial incorporation into the siliceous structure and as an anchor for Cu° nanoparticles stabilization. As a result, the metallic Cu surface area of the hybrid CZZ@Al-TUD-1 catalyst (Si/Al atomic ratio of 25) could be increased to the maximum value of 49.0 m2 gcopper−1, which is higher than the value for the initial pure CZZ (38.7 m2 gcopper−1). Theoretical DFT simulation confirms that the Al atoms in the aluminosilicate support’s framework form hydroxyl sites for anchoring efficiently metallic Cu species thus creating highly dispersed and stable Cu° nanoparticles in the CZZ@Al-TUD-1 hybrid materials. The catalytic results obtained over the hybrid CZZ@Al-TUD-1 (Si/Al atomic ratio of 25) catalyst in the CO2 hydrogenation into methanol are following: the methanol production over 840 g kgCu−1 h−1 or 180 g kgcat−1 h−1 at 280 °C and 20 bar. Furthermore, the physically mixed composite catalysts obtained from CZZ and Al-TUD-1 could be used as bi-functional catalysts for the direct CO2 hydrogenation into dimethyl ether with relatively high productivity in DME (41 g kgcat.−1 h−1 at 260 °C and 20 bar). The results herein provide an understanding of the nature of the strong metal-support interaction and a new insight into designing the Cu-based catalysts for CO2 hydrogenation reactions.

Rhenium, although viewed as one of the noble metals with lower-price, has been commonly used as doping element in the bimetallic catalysts due to its middlebrow to activate hydrogen. Its major role as catalyst is less frequently mentioned. In this work, rhenium has been decorated on the surface of activated carbon and used for the selective hydrogenation of dimethyl 1, 4-cyclohexanedicarboxylate (DMCD) to 1, 4-cyclohexanedimethanol (CHDM). Characterizations suggested that ReOx particles were anchored occupying the surface oxygenated groups on pre-functionalized carbon. Rhenium decoration modified both the textural and chemical properties of the samples. Electrons were easily transferred from Re to the neighboring C atoms as a result of the formation of fine ReOx particles. Medium strong acid sites were generated and rhenium species in the reduced states could be still maintained under appropriate rhenium dispersion. The moderate hydrogenation ability of rhenium catalyst partially restrained the excessive hydrogenation of CHDM to other by-products. Rational decoration of 5 wt% Re performed the better catalytic performance with complete conversion of diester and 66 % yield of diol. The specific rate reached 9.5 × 10 2 m m o l D M C D ∙ g R e - 1 ∙ h - 1 at 220 °C under 10 MPa H2.

Although supported gold nanoparticles (AuNPs) display exceeding performances, challenges exist for carbon supported small and stable AuNPs used for liquid-phase oxidation. Au/CNT decorated by ceria has been designed for oxidation of benzyl alcohol. CeO2 decoration directly led to the formation of active oxygen species and surface defects. Supplementary lattice oxygen in CeO2, rather than the oxygenated groups on CNT, accounted for the storage/release ability of oxygen. Interfaces and synergy between Au-CeO2 were constructed with appropriate CeO2 crystallization, revealed as promoted electron transfer and surface property. 77.9% yield of benzaldehyde was reached (40 °C) after ceria decoration with enhanced stability.

A macroscopic composite consisting of nitrogen-doped carbon fibers (N@CFs) was synthesized by electrospinning. The as-prepared N@CF material was further applied as a metal-free catalyst in the catalytic oxidation of H2S to sulfur, which is one of the most important purification processes for raw chemical resources (that is, biogas, natural gas, and petrochemical compounds). The catalyst, after a carbonization step at T=800 °C, exhibits a high and stable desulfurization activity for more than 100 h of testing with 57 % H2S conversion and 95 % sulfur selectivity at T=230 °C, which is two times higher than that of the most active metal-based catalyst (Fe2O3/SiC). The desulfurization performance could also be improved by changing the reactant velocity. Moreover, the macroscopic shaping with an inner hierarchical structure network allows the avoidance of problems linked with the transport and handling of nanoscopic carbon-based materials and also enhances the mass diffusion during the oxidation reaction.

Although nanosized Au clusters have been well developed for many applications, fundamental understanding of their adsorption/activation behaviors in catalytic applications is still lacking, especially when other elements provide promotion or hybridization functions. Au hybridized with Cu element is a highly investigated system; Cu is in the same element group as Au and thus displays similar physicochemical properties. However, their hybrids are not well understood in terms of their chemical states and adsorption/activation properties. In this work, typical γ-Al2O3-supported Au and CuO as well as Au–CuO nanoparticles were prepared and characterized to explore their adsorption/activation properties in depth using CO as a probe molecule using advanced techniques, such as XPS, HR-TEM, temperature programmed experiments and operando DRIFT combined with mass spectra. It was found that gold and copper can both act as active sites during CO adsorption and activation. The CO-TPD and operando DRIFT results also revealed that CO molecules were able to react with surface oxygenated species, resulting in the direct formation of CO2 over the three samples in the absence of gaseous O2. The gold step sites (Austep) participated more readily in the reaction, especially under gaseous O2-free conditions. During adsorption, CO molecules were more preferentially adsorbed on Au0 sites at lower temperature comparing with those on the Cu0 sites. However, competitive adsorption occurred between CO adsorbed on Au0 and Cu0 with increased reaction temperature, and the synergy between the Au and Cu compositions was too strong to suppress the adsorption and activation of the CO molecules. The dynamic adsorption equilibrium over 120 °C to 200 °C resulted in the appearance of a hysteresis performance platform.

A new self-propagated flaming (SPF) technique was applied to the synthesis of highly active layered CuO-δ-MnO

Vanadium compounds have attracted much attention because they have widely been used for homogeneous and heterogeneous catalysis field, especially in the selective oxidation of light alkanes, where vanadium-based catalysts were announced to be one of the most efficient catalysts. The present mini-review analyzed the recent developments for the preparation using new synthesis approaches of vanadium based catalysts, and their catalytic performances in the selective oxidation reactions of light alkanes. The influences of several synthesis strategies on the catalytic performances were illustrated in detail, while the samples characterizations were briefly presented.