Showing papers on "Catalyst support published in 2019"
TL;DR: In this article, a single-atom catalysts have attracted attention because of improved atom efficiency, higher reactivity, and better selectivity, but the major challenge is to achieve high surface concentrations while prev...
Abstract: Single-atom catalysts have attracted attention because of improved atom efficiency, higher reactivity, and better selectivity. A major challenge is to achieve high surface concentrations while prev...
204 citations
TL;DR: In this article, a novel basic heterogeneous catalyst was prepared from purified domestic diatomite supported by CaO/MgO composite, and the maximum obtained biodiesel yield reached 96.47% after 120min at 90°C using 6wt% catalyst and 1:15 oil: methanol ratio.
153 citations
TL;DR: Light is shed on using OV-rich semiconductors as a promising support to design efficient and durable nonprecious electrocatalysts to solve the problem of corrosion of rechargeable zinc-air batteries.
Abstract: The highly oxidative operating conditions of rechargeable zinc-air batteries causes significant carbon-support corrosion of bifunctional oxygen electrocatalysts. Here, a new strategy for the catalyst support design focusing on oxygen vacancy (OV)-rich, low-bandgap semiconductor is proposed. The OVs promote the electrical conductivity of the oxide support, and at the same time offer a strong metal-support interaction (SMSI), which enables the catalysts to have small metal size, high catalytic activity, and high stability. The strategy is demonstrated by successfully synthesizing ultrafine Co-metal-decorated 3D ordered macroporous titanium oxynitride (3DOM-Co@TiOx Ny ). The 3DOM-Co@TiOx Ny catalyst exhibits comparable activities for oxygen reduction and evolution reactions, but much higher cycling stability than noble metals in alkaline conditions. The zinc-air battery using this catalyst delivers an excellent stability with less than 1% energy efficiency loss over 900 charge-discharge cycles at 20 mA cm-2 . The high stability is attributed to the strong SMSI between Co and 3DOM-TiOx Ny which is verified by density functional theory calculations. This work sheds light on using OV-rich semiconductors as a promising support to design efficient and durable nonprecious electrocatalysts.
150 citations
TL;DR: By simple recrystallization, the catalytic activity of deactivated species can be recovered from the isolation yield 46% to 92% for 4-bromobenzonitrile conversion at the same conditions, revealing the great application potentials of HOF-based catalysts.
Abstract: Hydrogen-bonded organic framework (HOF)-based catalysts still remain unreported thus far due to their relatively weak stability. In the present work, a robust porous HOF (HOF-19) with a Brunauer-Emmett-Teller surface area of 685 m2 g-1 was reticulated from a cagelike building block, amino-substituted bis(tetraoxacalix[2]arene[2]triazine), depending on the hydrogen bonding with the help of π-π interactions. The postsynthetic metalation of HOF-19 with palladium acetate afforded a palladium(II)-containing heterogeneous catalyst with porous hydrogen-bonded structure retained, which exhibits excellent catalytic performance for the Suzuki-Miyaura coupling reaction with the high isolation yields (96-98%), prominent stability, and good selectivity. More importantly, by simple recrystallization, the catalytic activity of deactivated species can be recovered from the isolation yield 46% to 92% for 4-bromobenzonitrile conversion at the same conditions, revealing the great application potentials of HOF-based catalysts.
131 citations
TL;DR: In this paper, the authors summarized the recent progress of anode catalysts for methanol oxidation reaction (MOR) in direct DMFCs, and highlighted the major challenges in achieving the optimum DMFC performance from the aspect of tailoring the properties of MOR electrocatalysts.
122 citations
TL;DR: In this article, a novel CoFe2O4@WTRs hybrid was fabricated via a modified chemical co-precipitation combined with calcination method and employed as high-efficient peroxymonosulfate (PMS) activator for the degradation of atrazine (ATZ).
112 citations
TL;DR: In this article, a review presents recent advances in strategies to stabilize heterogeneous catalysts against deactivation for biomass conversion reactions, including leaching, sintering, and poisoning of metals and collapse of catalyst support.
Abstract: Many processes for the conversion of biomass and its derivatives into value-added products (e.g., fuels and chemicals) use heterogeneous catalysts. However, the catalysts often suffer from deactivation under harsh reaction conditions, such as liquid phase at high temperatures and pressures. The catalyst deactivation is a big obstacle to developing industrially relevant biomass conversion processes, including leaching, sintering, and poisoning of metals and collapse of catalyst support. Different approaches have been applied to limit the reversible and irreversible deactivation, highly associated with the kind of catalyst, reactants, reaction conditions, etc. This review presents recent advances in strategies to stabilize heterogeneous catalysts against deactivation for biomass conversion reactions.
97 citations
TL;DR: In this article, a novel porous TiO2/ZrO2 photocatalyst derived from UiO-66 and Titania hybrid was reported for degradation of organic pollutants from colored wastewater under LED visible light.
Abstract: Zirconium based metal-organic frameworks (Zr-MOFs) are promising candidates for photocatalytic wastewater treatment due to their excellent properties such as high chemical and thermal stability and high photodegradation ability. Herein, we report a novel porous TiO2/ZrO2 photocatalyst derived from UiO-66 and Titania hybrids. UiO-66 nanoparticles was synthesized through solvothermal method and utilized as catalyst support to grow TiO2 particles on its surface. The prepared Titania/MOF nanocomposite was calcined to obtain porous TiO2/ZrO2 photocatalyst for degradation of organic pollutants from colored wastewater under LED visible light. The prepared materials were fully characterized with FTIR, XRD, SEM/EDS, TEM, BET, UV-DRS and ICP analysis. The results showed that the developed TiO2/ZrO2 enhanced photodegradation ability of Rhodamin B (RhB) in comparison with the mixture of prior UiO-66 and TiO2 and was found to affect the photocatalytic activity by increasing the adsorption of photons in visible region and enhanced the transfer and separation of produced charge. The decolorization kinetics followed first-order kinetic model. In addition, after four times recycling, the regenerated nanocomposite still showed high stability and photodegradation ability (90%).
86 citations
TL;DR: In this paper, an Ag nanoparticle (Ag NP) loaded-eggshell catalysts were successfully synthesized by a simple impregnation method, in which waste eggshells were used as an efficient template and catalyst support.
Abstract: Catalytic oxidation plays a key role in transforming gaseous benzene into harmless matter, in which it is essential to look for a low-cost, environmentally friendly and efficient green catalyst/support. Herein, Ag nanoparticle (Ag NP) loaded-eggshell catalysts were successfully synthesized by a simple impregnation method, in which waste eggshells were used as an efficient template and catalyst support. SEM, XRD and ICP-OES results show that a different number of Ag NPs are uniformly distributed on the surface of eggshells, which are defined as Ag1/eggshell (10.8%), Ag2/eggshell (19.9%) and Ag3/eggshell (34.3%) catalysts according to the amounts of loaded Ag NPs. Then, the activity between the three catalysts and the pure Ag NPs was assessed based on the catalytic oxidation of benzene. Our results show that the Ag NP loaded-eggshell catalysts exhibit superior catalytic activity compared with the pure Ag NPs. Considering the balance between the cost and catalytic performance, the Ag2/eggshell catalyst was selected as the optimum research object in the subsequent work. The Ag2/eggshell catalyst calcined at 500 °C exhibited excellent catalytic activity, which is assigned to the unique channel structure of eggshell, good low-temperature reducibility, and high dispersion of particles (sizes effects) on the surface of eggshell as well as the synergetic interaction between the Ag NPs and eggshell. Furthermore, the Ag2/eggshell catalyst exhibited predominant stability even after 200 h of on-stream reaction. The reaction mechanism is put forward based on the in situ FTIR experimental results, in which some carboxylate intermediate species are confirmed. Accordingly, the waste eggshell is considered as a promising supporting material for the large-scale synthesis of noble metal catalyst with high catalytic performance and stability for VOC oxidation.
86 citations
TL;DR: In this paper, the authors developed an efficient approach for preparation of ultrafine and well-dispersed crystalline Fe-doped TiO2 nanoparticles (Fe-TiO2) with a size distribution of 2.3 ± 0.9 nm under mild conditions by using covalent organic frameworks (COFs) as the interface engineering agent.
Abstract: We have developed an efficient approach for preparation of ultrafine and well-dispersed crystalline Fe-doped TiO2 nanoparticles (Fe–TiO2) with a size distribution of 2.3 ± 0.9 nm under mild conditions by using covalent organic frameworks (COFs) as the interface engineering agent. The as-synthesized Fe–TiO2@COF shows an exceptional photocatalytic activity degrading methylene blue (MB) under ambient light. A trace amount (0.4 mg) of the optimal catalyst 5Fe–TiO2@COF can degrade MB (100 mg L−1, 4 mL) under ambient light. More importantly, the catalyst exhibits excellent stability and can be reused multiple times without any loss of catalytic activity. The use of a crystalline porous COF as a catalyst support has many unique advantages, including controlled-growth of nanoparticles with ultrafine size, stabilization of nanoparticles, efficient sorption of the organic pollutant thus increasing their local concentration around the catalysts, and facilitating the mass transfer through its porous channels. Our study provides an efficient and novel approach for preparation of well-dispersed ultrafine metal oxides with high stability and photosensitivity for energy and environmental applications.
86 citations
TL;DR: This work successfully visualizes the structure and evolution of the catalyst and illuminates the possible nucleation sites of the chirality-specific growth in the Co-W-C ternary SWCNT catalyst.
Abstract: Recently, W-based catalysts have provided a promising route to synthesize single-walled carbon nanotubes (SWCNTs) with specific chirality, but the mechanism of the growth selectivity is vaguely understood. We propose a strategy to identify the atomic structure as well as the structure evolution of the Co-W-C ternary SWCNT catalyst. The key is to use a thin SiO2 film as the catalyst support and observation window. As the catalyst is uniformly prepared on this SiO2 film and directly used for the SWCNT synthesis, this method has an advantage over conventional methods: it creates an opportunity to obtain original, statistical, and dynamic understanding of the catalyst. As a technique, atomic-scale imaging directly on SiO2 serves as a powerful and versatile tool to investigate nanocrystals and high-temperature reactions; for the synthesis of SWCNTs, this work successfully visualizes the structure and evolution of the catalyst and illuminates the possible nucleation sites of the chirality-specific growth.
TL;DR: In this paper, the authors have shown that polymer electrolyte membrane fuel cells (PEMFCs) have shown great promise in subduing various environmental and environmental issues. But, the demand for renewable energy is ever growing.
Abstract: With recent technological advances, the demand for renewable energy is ever growing. Polymer electrolyte membrane fuel cells (PEMFCs) have shown great promise in subduing various environmental and ...
TL;DR: In this article, a one-step hydrothermal method was developed for the preparation of a CuO-ZnO/g-C3N4 ternary composite.
TL;DR: In this article, the composite materials, which are used as the catalyst support, were prepared through the hybridization of Nb2O5 (niobium oxide) with MC (micro-mesoporous carbon).
TL;DR: In this paper, the authors describe progress in the synthesis of C12A7:e− especially in nanosized powder material, and about most important recent challenges towards the suitable cations doping in C 12A7 e− electride and finally its industrial important applications as a catalyst.
TL;DR: In this paper, a cylindrical laminated methanol steam reforming microreactor for hydrogen production was constructed using copper foams with ordered hole arrays and a two-layer impregnation method was used to load the Cu/Zn/Al/Zr catalysts.
TL;DR: In this paper, a crystal facet-dependent catalytic reduction of CO2 to CH4 on ruthenium nanoparticles deposited over TiO2 nanocrystal with exposed (001) and (101) facets was demonstrated.
Abstract: Catalytic reduction of CO2 to methane has been recognized as one of the most important strategic reactions to produce highly valuable chemicals and for storage of renewable energy (power-to-gas). This study demonstrates a crystal facet-dependent catalytic reduction of CO2 to CH4 on ruthenium nanoparticles deposited over TiO2 nanocrystal with exposed (001) and (101) facets. Compared with TiO2 (101) nanocrystal with the same Ru loading, Ru nanoparticles supported by TiO2 (001) exhibited a highly enhanced CO2 conversion rate and significantly improved methanation reactivity, along with a considerable durability. The physicochemical properties of the samples were characterized by HR-TEM, XRD, BET, FT-IR, UV–vis, Raman, ICP, and temperature-programmed reaction with CO2, and CO2 + H2. In view of the difference in catalytic activity and the physicochemical properties of the supported Ru/TiO2 catalysts, the results uncovered that the nature of the catalyst support of Ru/TiO2 strongly affected the dispersion of Ru species and the synergistic effect between Ru and underlying TiO2 supporting materials due to the strong metal-support interaction, and thus affected their capability to activate CO2 and determined the catalytic activity for CO2 methanation. Our work demonstrated the important role of the exposed crystal facets of the underlying support and the resulting Ru particle which had a large effect on CO2 methanation.
TL;DR: The composite system also shows good recyclability of the materials and advocates the promising nature of the designed system for multiple hazardous environmental contaminants.
TL;DR: In this article, the authors demonstrate that a balance between pore size, pore volume and large surface area of activated carbon material helps in achieving increased hydrogen uptake at room temperature and moderate pressures.
TL;DR: In this article, Ni-based catalysts for the hydrodeoxygenation (HDO) reaction of guaiacol were prepared using a series of alumina-silica supports characterized by a different amount of silica.
TL;DR: In this article, the authors demonstrate a covalently coupled ultrahigh quaternary-N-doped reduced graphene oxide/carbon nanotube (QN-rGO@CNT) network through electrostatic interaction as a novel enzyme support for EBFCs.
Abstract: Carbonaceous materials are currently the most extensively researched materials as catalyst supports for enzymatic biofuel cells (EBFCs). N-doping is an extremely effective strategy to tailor the unique electronic properties of carbon materials. However, the coexistence of electron-accepting pyridinic- and pyrrolic-N with electron-donating quaternary-N weakens the n-type behavior, resulting in lower electron mobility than that of pristine graphene, thus impacting a range of device applications. Herein, we demonstrate a covalently coupled ultrahigh quaternary-N-doped reduced graphene oxide/carbon nanotube (QN-rGO@CNT) network through electrostatic interaction as a novel enzyme support for EBFCs. It is found that N bond types are controllable via thermal treatment, and the as-made QN-rGO@CNT composite with an interconnected porous structure, covalent coupling, and ultrahigh electron-donating quaternary-N-doping exhibits superior electrochemical properties. As a result, the present glucose/O2 EBFCs equipped with enzyme-functionalized QN-rGO@CNT electrodes can deliver a high open circuit potential of 0.89 V, a short-circuit current density of 2.25 mA cm−2 and a maximum power density of 0.9 mW cm−2. Using the high-throughput fabrication method reported in this work, the monotype N-doped carbon hybrid can be commercially utilized as a promising supporting electrode in BFC applications.
TL;DR: The cyclic voltammetry and linear sweep voltammograms results indicate that the CMO/NCNTs/3D graphene hybrid possesses remarkable electrocatalytic performance toward ORR in alkaline conditions, even outperforming the commercial 20 wt % Pt/C catalyst.
Abstract: Great efforts have been focused on studying high-efficiency and stable catalysts toward oxygen reduction reaction (ORR) in metal-air batteries. In view of synergistic effects and improved properties, carbon nanotubes and three-dimensional graphene (CNTs-3D graphene) hybrid catalysts developed via a well-controlled route are urgently required. Herein, a CoMn2O4 (CMO) nanoneedle-supported nitrogen-doped carbon nanotubes/3D graphene (NCNTs/3D graphene) composite was prepared by in situ chemical vapor deposition (CVD) along with hydrothermal methods over a Ni foam substrate. The cyclic voltammetry and linear sweep voltammograms results indicate that the CMO/NCNTs/3D graphene hybrid possesses remarkable electrocatalytic performance toward ORR in alkaline conditions compared with NCNTs/3D graphene, CMO/3D graphene, and 3D graphene catalysts, even outperforming the commercial 20 wt % Pt/C catalyst. Moreover, the Al-air coin cell employing CMO/NCNTs/3D graphene as cathode catalysts obtains an open circuit voltage of 1.55 V and a specific capacity of 312.8 mA h g-1, which are superior to the Al-air coin cell with NCNTs/3D graphene as catalysts. This work supplies new insights to advanced electrocatalysts introducing NCNTs/3D graphene as a catalyst support to develop scalable transition-metal oxide/NCNTs/3D graphene hybrids with excellent catalytic activity toward ORR in Al-air systems.
TL;DR: In this paper, a mesoporous catalyst support material was synthesized by incorporation of zirconia into the structure of MCM-41 through a one-pot procedure.
TL;DR: In this article, the use of C. Vulgaris microalgal strain containing cellulose in the modified form to be used as a catalyst support material for the production of hydrogen from the methanolysis reaction of sodium borohydride (NaBH4).
TL;DR: In this article, mesoporous nanocrystalline 5-wt%M-95 -95 -mgAl 2 O 4 (M: CeO 2, ZrO 2, La 2 O 3 ) powders were prepared by a novel on-step sol-gel process and employed as a support for the synthesis of 5-wwt%Ni catalysts for synthesis gas production via dry reforming.
TL;DR: A dip catalyst made of cellulose, isolated from agriculture residue (sugarcane bagasse), in which biogenically synthesized palladium nanoparticles were dispersed and was found to give excellent conversion with 15 recycles.
TL;DR: In this paper, the authors investigated the influence of temperature, gas hourly space velocity (GHSV), and H2:CO2 ratio on the production of methane by carbon dioxide hydrogenation through optimization of the operating parameters.
Abstract: The production of methane by carbon dioxide hydrogenation through optimization of the operating parameters to enhance methane yield and carbon dioxide conversion in a two‐stage fixed bed reactor is investigated. The influence of temperature, gas hourly space velocity (GHSV), and H2:CO2 ratio on the production of methane is studied. In addition, different methanation catalysts in terms of metal promoters and support materials are investigated to maximize methane production. The results show that the maximum methane yield and maximum carbon dioxide conversion are obtained at a catalyst temperature of 360 °C with a H2:CO2 ratio of 4:1 and total GHSV of 6000 mL h−1 g−1catalyst and reactant GHSV of 3000 mL h−1 g−1catalyst. The optimum metal‐alumina catalyst investigated for CO2 conversion and methane yield is the 10 wt%‐Ni‐Al2O3 catalyst. However, reduction in the methane yield is observed with the addition of Fe and Co promoters because of catalyst sintering and nonuniform dispersion of metals on the support. Among the different catalyst support materials studied, i.e., Al2O3, SiO2 and MCM‐41, the highest catalytic activity is shown by the Al2O3 catalyst with 83 mol% CO2 conversion, producing 81 mol% CH4 with 98% CH4 selectivity.
TL;DR: Transient measurements under up to industrial reaction conditions show a pronounced transient increase of the activity for methanol formation from CO2/H2 after exposure to a CO/H 2 reaction gas mixture, while the steady-state activity is similar to that observed directly after oxidative pre-treatment.
Abstract: The impact of CO on the activation and reaction characteristics of Au/ZnO catalysts in methanol synthesis from a CO2/H2 mixture was studied by kinetic, near ambient pressure X-ray photoelectron spectroscopy and X-ray absorption spectroscopy at the O K-edge, together with in situ Foureir transform infrared measurements. Transient measurements under up to industrial reaction conditions (50 bar, 240 °C) show a pronounced transient increase of the activity for methanol formation from CO2/H2 after exposure to a CO/H2 reaction gas mixture, while the steady-state activity is similar to that observed directly after oxidative pretreatment. For the reaction in CO/H2, the much longer activation phase is accompanied by formation of CO2 due to reaction of CO with the ZnO catalyst support. This leads to O-vacancy formation on the support at an extent significantly higher than in CO2/H2. The consequences of these findings on the mechanistic understanding of methanol formation from CO2/H2 on Au/ZnO and for ZnO-supported ...
TL;DR: A series of catalysts consisting of plasmonic Ag nanoparticles (NPs) deposited on CeO2 coated mesoporous silica, SBA-15, prepared by MW-assisted alcohol reduction method were tested for the chemoselective hydrogenation of p-nitrostyrene as mentioned in this paper.
18 Mar 2019
TL;DR: In this article, the composition, chemical structure, and morphology of a Ni-Mo nanopowder electrocatalyst for alkaline water electrolysis were clarified, and the as-synthesized catalyst is mixed phase, comprising crystalline Ni-rich alloy nanoparticles embedded in a Mo-rich oxide matrix and exhibits low activity toward hydrogen evolution.
Abstract: Alkaline water electrolysis offers the use of low-cost active materials and ancillary components, making it attractive for hydrogen production from renewables. Nevertheless, the practical performance of nonprecious electrocatalysts for alkaline hydrogen evolution still lags behind platinum-group metals. This disparity motivates work to understand how the solid-state chemistry of nonprecious transition metal alloys influences their activity toward alkaline hydrogen evolution. To this end, we have clarified the composition, chemical structure, and morphology of a previously reported Ni–Mo nanopowder electrocatalyst. The as-synthesized catalyst is mixed phase, comprising crystalline Ni-rich alloy nanoparticles embedded in a Mo-rich oxide matrix, and exhibits low activity toward hydrogen evolution. Its activity markedly increases upon activation by postdeposition reductive annealing or by including carbon black as a catalyst support. These results are consistent with a physical picture in which activity is li...