Highly reactive and reusable heterogeneous activated carbons-based palladium catalysts for Suzuki-Miyaura reaction

Suzuki-Miyaura reaction of aryl halides with phenylboronic acid using a heterogeneous palladium catalyst based on activated carbons(AC) was systematically investigated in this work. Two different reaction modes(batch procedure and continuous-flow procedure) were used to study the variations of reaction processing. The heterogeneous catalysts presented excellent reactivity and recyclability for iodobenzene and bromobenzene substrates in batch mode, which can be attributed to stabilization of Pd nanoparticles by the thiol and amino groups on the AC supports. However, significant dehalogenation in the reaction mixture and Pd leaching from the heterogeneous catalysts were observed in continuous-flow mode.This unique phenomenon in continuous-flow mode resulted in a dramatic decline in reaction selectivity and durability of heterogeneous catalysts comparing with that of batch mode. In addition, the heterogeneous Pd catalysts with thiol-and amino-modified AC supports exhibited different reactivity and durability in batch and continuous-flow mode owing to the difference of interaction between Pd species and AC supports.

Preparation of sodium alginate gel microspheres catalysts and its high catalytic performance for treatment of ciprofloxacin wastewater

The discharge of the antibiotic wastewater has increased dramatically in our country with the development of medical science and wide application of antibiotic,resulting in serious harm to human body and ecological environment.In this work,ciprofloxacin(CIP)was selected as one of typical antibiotics and heterogeneous Fenton-like catalysts were prepared for the treatment of ciprofloxacin wastewater.The sodium alginate(SA)gel microspheres catalysts were prepared by polymerization method using double metal ions of Fe^(3+)and Mn^(2+)as cross-linking agents.Preparation conditions such as metal ions concentration,mass fraction of SA,polymerization temperature and dual-metal ions as crosslinking agent were optimized.Moreover,the effects of operating conditions such as initial concentration of CIP,pH value and catalyst dosage on CIP removal were studied.The kinetic equation showed that the effect of the initial concentration of CIP on the degradation rate was in line with second-order kinetics,and the effects of catalyst dosage and pH value on the degradation rate of CIP were in line with first-order kinetics.The SA gel microspheres catalysts prepared by dual-metal ions exhibited a high CIP removal and showed a good reusability after six recycles.The SA gel microspheres catalysts with an easy recovery performance provided an economical and efficient method for the removal of antibiotics in the future.

Activity and Selectivity of Bimetallic Catalysts Based on SBA-15 for Nitrate Reduction in Water

Nitrate from the application of nitrogen-based fertilizers in intensive agriculture is a notorious waste product, though it lacks cost-effective solutions for its removal from potential drinking water resources. Catalytic reduction appears to be a promising technique for converting nitrates to benign nitrogen gas. Mesoporous silica SBA-15 is a frequently used catalyst support that has large surface areas and highly ordered nanopores. In this work, mesoporous silica SBA-15 bimetallic catalysts for nitrate reduction were investigated. The catalyst was optimized for the selection of promoter metal (Sn and Cu), noble metal (Pd and Pt) and loading ratios of these metals at different temperatures and reduction conditions. The catalysts prepared were characterized by FT-IR, N2 physisorption, XRD, SEM, and ICP. All catalysts showed the presence of cylindrical mesoporous channels and uniform pore structures that remained even after metals loading. In the presence of a CO2 buffer, the catalysts 4Pd-1Cu/SBA-15 and 1Pt-1Cu/SBA-15 reduced at 100?C under H2 and 1Pd-1Cu/SBA-15 reduced at 200°C under H2 demonstrated very high nitrate conversion. Furthermore, the forementioned Pd catalysts had higher N2 selectivity (88% - 87%) compared to Pt catalyst (80%). Nitrate conversion by the 4Pd-1Cu/SBA-15 catalyst was significantly decreased to 81% in the absence of CO2.

Enabling heterogeneous catalysis to achieve carbon neutrality: Directional catalytic conversion of CO_(2) into carboxylic acids

The increase in anthropogenic carbon dioxide(CO_(2))emissions has exacerbated the deterioration of the global environment,which should be controlled to achieve carbon neutrality.Central to the core goal of achieving carbon neutrality is the utilization of CO_(2) under economic and sustainable conditions.Recently,the strong need for carbon neutrality has led to a proliferation of studies on the direct conversion of CO_(2) into carboxylic acids,which can effectively alleviate CO_(2) emissions and create high-value chemicals.The purpose of this review is to present the application prospects of carboxylic acids and the basic principles of CO_(2) conversion into carboxylic acids through photo-,electric-,and thermal catalysis.Special attention is focused on the regulation strategy of the activity of abundant catalysts at the molecular level,inspiring the preparation of high-performance catalysts.In addition,theoretical calculations,advanced technologies,and numerous typical examples are introduced to elaborate on the corresponding process and influencing factors of catalytic activity.Finally,challenges and prospects are provided for the future development of this field.It is hoped that this review will contribute to a deeper understanding of the conversion of CO_(2) into carboxylic acids and inspire more innovative breakthroughs.

Catalytic effect in lithium metal batteries: From heterogeneous catalyst to homogenous catalyst

Lithium metal batteries are regarded as prominent contenders to address the pressing needs owing to the high theoretical capacity.Toward the broader implementation,the primary obstacle lies in the intricate multi-electron,multi-step redox reaction associated with sluggish conversion kinetics,subsequently giving rise to a cascade of parasitic issues.In order to smooth reaction kinetics,catalysts are widely introduced to accelerate reaction rate via modulating the energy barrier.Over past decades,a large amount of research has been devoted to the catalyst design and catalytic mechanism exploration,and thus the great progress in electrochemical performance has been realized.Therefore,it is necessary to make a comprehensive review toward key progress in catalyst design and future development pathway.In this review,the basic mechanism of lithium metal batteries is provided along with corresponding advantages and existing challenges detailly described.The main catalysts employed to accelerate cathode reaction with emphasis on their catalytic mechanism are summarized as well.Finally,the rational design and innovative direction toward efficient catalysts are suggested for future application in metal-sulfur/gas battery and beyond.This review is expected to drive and benefit future research on rational catalyst design with multi-parameter synergistic impacts on the activity and stability of next-generation metal battery,thus opening new avenue for sustainable solution to climate change,energy and environmental issues,and the potential industrial economy.

Biodiesel from Palm Vegetable Oil

Energy obtained from a variety of non-renewable sources is considered unsustainable. Various fossil fuels, such as petroleum, coal, and natural gas, are among these sources. The combustion of fossil fuels resulted in the generation of greenhouse gases, which increased the amount of carbon dioxide in the atmosphere. Global warming and ozone layer degradation are the negative consequences. In a country like India, where consumable oils are still imported, it is sense to look at the possibility of using such unpalatable oils in CI engines that aren’t often utilized as cooking oil. Palm oil is a vegetable oil obtained from the monocarp of the oil palm’s crop. The main goal is to provide a low-cost, high-performance alternative to diesel. The possibility of palm oil as a realistic, modest, and effective hotspot for the generation of biodiesel is investigated in this research. The article is focused on the comparison of palm oil and diesel in terms of characteristics.

A design of experiments approach for the development of plasma synthesized Sn-silicate catalysts for the isomerization of glucose to fructose

The use of non-equilibrium plasmas for the synthesis of heterogeneous catalysts is a field that has not been explored intensively. The main reasons for the recent increase of research activity in this field are related to the advantages that go with the technique of plasma enhanced chemical vapor deposition （PECVD）. The most principal of these advantages are the possibility to avoid the use of environmentally harmful solvents and the one-step nature of the procedure, making it very time and labor efficient. Non-equilibrium plasma technology, more in particular dielectric barrier discharge （DBD） technology, has been applied in this work for the synthesis of hybrid tin-silicate materials to be used as a heterogeneous catalyst in the isomerization of glucose into fructose. Atomizers, innovative devices which make it possible to inject nanosized precursor liquids into the plasma zone, are used instead of applying vapor phase techniques, where the amount of precursor is limited by the vapor pressure of the liquid. A design of experiments approach has been employed to investigate the effect of the plasma parameters, namely gas flow, frequency and power density, on the catalytic properties of the catalysts within a well-defined parameter field. It has been found that indeed these parameters, together with the molar ratio of Si/Sn, have an important influence on the activity, selectivity, and thus yield of the produced chemicals.

Ruthenium promotion of Co/SBA-15 catalysts for Fischer-Tropsch synthesis in slurry-phase reactors

The aim of this work was to evaluate the catalytic properties of a Ru promoted Co/SBA-15 catalyst for Fischer-Tropsch synthesis （FTS）. The Ru promoted Co/SBA-15 catalyst was prepared by wet impregnation method and was characterized by X-ray diffraction, X-ray energy dispersion spectrophotometer, N2 adsorption-desorption, temperature-programmed reduction and transmission electron microscopy. The Fischer-Tropsch synthesis using the catalyst was carried out to evaluate the catalyst activity and its effect on FTS product distribution. The synthesis was carried out in a slurry reactor operating at 513 K, 20 atm, CO ： H2 molar ratio of 1 ： 1. X-ray diffraction showed that the calcined cobalt catalyst did not modify the structure of SBA-15, proving that Co was present in the form of Co3O4 in the catalyst. The addition of cobalt in SBA-15 decreased the specific superficial area of the molecular sieve. Fischer-Tropsch synthesis activity and C5＋ hydrocarbon selectivity increased with the addition of Ru. The increases in activity and selectivity were attributed to the increased number of active sites resulting from higher reducibility and the synergetic effect of Ru and Co. Ru/Co/SBA-15 catalysts showed moderate conversion （40%） and high selectivity towards the production of C5＋ （80 wt%）.

EFFECT OF ELECTRON DONORS ON THE SELECTIVE HYDROGENATION OF DIENE TO MONOENE OVER HETEROGENIZED Pd CATALYST

In the selective hydrogenation of diene (or alkyne) using heterogenized homogeneous catalyst, the high selectivity of monoene formation only appears in a very short time interval. The addition of suitable electron donors can decrease or even cease the monoene hydrogenation and thereby keep the high monoene selectivity after reaching its maximum.

Efficient conversion of CO_(2) into cyclic carbonates under atmospheric by halogen and metal-free poly(ionic liquid)s

A novel series of halogen free, hydroxyl group containing poly(ionic liquid)s(PILs) was first synthesized from glycerol dimethyl acrylate(GDA) and 1-vinyl imidazole(1-VIM) through free radical polymerization, follow by an alkylation step and an ion-exchange procedure to form the final imidazolium hydrogen carbonate heterogenous catalyst poly(HCO_(3)-OH-n). The chemical and physical properties were investigated by varying the monomer ratio between GDA and 1-VIM. Among them, poly(HCO_(3)-OH-2) exhibited the highest catalytic activity for CO_(2)cycloaddition, with the yield of chloropropene carbonate 90% under mild conditions(80℃, 0.1 MPa, 12 h, 0.15 g catalyst for 32 mmol epichlorohydrin) in the absence of any cocatalyst, metal or solvent. A range of substrates with good to excellent yields under atmosphere was obtained. The poly(HCO_(3)-OH-n) catalyst is collectable and still remains acceptable catalytic activity after six runs. Finally, a preliminary kinetic is calculated on the basis of poly(HCO_(3)-OH-2) with the activation energy value of 79.5 kJ·mol^(-1). This study highlights that the poly(HCO_(3)-OH-n) enable to reach efficient CO_(2) conversion under mild conditions.

Methanation of CO/CO_(2)for power to methane process:Fundamentals,status,and perspectives

Power-to-methane(P2M)processes,by converting electricity from renewable energy to H2and then into other high value-added and energy-intense chemicals in the presence of active catalysts,have become an effective solution for energy storage.However,the fluctuating electricity from intermittent renewable energy leads to a dynamic composition of reactants for downstream methanation,which requires an excellent heterogeneous catalyst to withstand the harsh conditions.Based on these findings,the objective of this review is to classify the fundamentals and status of CO/CO_(2)methanation and identify the pathways in the presence of various catalysts for methane production.In addition,this review sheds insight into the future development and challenges of CO_(2)or CO methanation,including the deactivation mechanisms and catalyst performance under dynamically harsh conditions.Finally,we elaborated on the advantages and development prospects of P2M,and then we summarized the current stage and ongoing industrialization projects of P2M.

Oxide-supported metal catalysts for anaerobic NAD+regeneration with concurrent hydrogen production

We report SiO_(2)-supported monometallic Pt,Pd,Au,Ni,Cu and Co catalysts for proton-driven NAD+regeneration,co-producing H_(2).All metals are fully selective to NAD+where the order of turnover frequencies(Pt>Pd>Cu>Au,Ni and Co)coincides with those otherwise observed in electrochemical hydrogen evolution reactions.This has revealed that NADH is capable of converting the metal sites into a“cathode”without an external potential and the NADH to NAD+reaction involves transferring electron and hydrogen atom separately.Electron-deficient Ptδ+(on CeO_(2))enhances TOF and the heterogeneous Pt/CeO_(2) catalyst is recyclable without losing any activity/selectivity.

Cobalt-based heterogeneous catalysts for photocatalytic carbon dioxide reduction

Solar light-driven CO_(2)reduction to high value-added chemicals has considered as an outstanding way to solve energy crisis and climate warming.Recently,various photocatalysts have been developed to achieve this reaction.Among them,cobaltbased heterogeneous catalysts have attracted great interest because of their promising performance,product selectivity and stability.Herein,we systematically summarize the research progress of various cobalt-based heterogeneous catalysts for the photoreduction of CO_(2),such as single-atom cobalt,and cobalt-based oxides,nitrides,sulfi des,phosphides,metal-organic frameworks and covalent-organic frameworks.Meanwhile,the advantages and structure-activity relationship of these catalysts in photocatalytic CO_(2)reduction reaction are discussed.Finally,the challenges and prospects for constructing cobaltbased heterogeneous catalysts with high effi ciency are highlighted.

纤维素催化转化为高附加值化学品的研究进展(英文)

Currently,under huge pressure from energy demands and environmental problems,much attention is being paid to biomass conversion,which will play an important role in meeting the requirements for a sustainable society.As the most abundant biomass on earth, cellulose is usually used as the first research target for biomass conversion.In this review,the recalcitrant structure of cellulose is discussed and non-catalytic hydrolysis by hot-compressed water and catalytic hydrolysis using solid acids are then considered.We also review the catalytic conversion of cellulose into valuable chemicals including hexitols(sorbitol and mannitol),ethylene glycol,and related compounds using various heterogeneous catalysts.

Photocatalytic reduction of carbon dioxide to methanol by Cu_2O/SiC nanocrystallite under visible light irradiation

The Cu2O/SiC photocatalyst was obtained from SiC nanoparticles （NPs） modified by Cu2O. Their photocatalytic activities for reducing CO2 to CH3OH under visible light irradiation have been investigated. The results indicated that besides a small quantity of 6H-SiC, SiC NPs mainly consisted of 3C-SiC. The band gaps of SiC and Cu2O were estimated to be about 1.95 and 2.23 eV from UV-Vis spectra, respectively. The Cu2O modification can enhance the photocatalytic performance of SiC NPs, and the largest yields of methanol on SiC, Cu2O and Cu2O/SiC photocatalysts under visible light irradiation were 153, 104 and 191μmol/g, respectively.

Synthesis and applications of MOF-derived porous nanostructures

Metal organic frameworks(MOFs) represent a class of porous material which is formed by strong bonds between metal ions and organic linkers. By careful selection of constituents, MOFs can exhibit very high surface area, large pore volume, and excellent chemical stability.Research on synthesis, structures and properties of various MOFs has shown that they are promising materials for many applications, such as energy storage, gas storage, heterogeneous catalysis and sensing. Apart from direct use, MOFs have also been used as support substrates for nanomaterials or as sacrificial templates/precursors for preparation of various functional nanostructures. In this review, we aim to present the most recent development of MOFs as precursors for the preparation of various nanostructures and their potential applications in energy-related devices and processes. Specifically, this present survey intends to push the boundaries and covers the literatures from the year 2013 to early 2017,on supercapacitors, lithium ion batteries, electrocatalysts, photocatalyst, gas sensing, water treatment, solar cells, and carbon dioxide capture.Finally, an outlook in terms of future challenges and potential prospects towards industrial applications are also discussed.

Silica supported perchloric acid(HClO_4-SiO_2):A mild,reusable and highly efficient heterogeneous catalyst for the synthesis of amidoalkyl naphthols

An efficient and direct procedure has been developed for the preparation of amidoalkyl naphthols by a one-pot condensation of aryl aldehydes, 2-naphthol and urea or amides, in the presence of HClO4-SiO2 as a heterogeneous catalyst. The reactions were carried out under reflux and solvent-free conditions. The present methodology offers several advantages such as excellent yields, simple procedure, easy work-up and ecofriendly reaction condition. The catalyst is easily prepared, stable, reusable and efficient under the reaction conditions.

Co纳米粒子催化无溶剂条件下一锅四组分法高效合成1,4-二氢吡啶衍生物(英文)

A straightforward and general method has been developed for the synthesis of C5-unsubstitiuted 1,4-dihydropyridines by a reaction using dimedone, acetophenone, aromatic aldehydes, and ammonium acetate in the presence of a catalytic amount of Co nanoparticles as a heterogeneous and eco-friendly catalyst with high catalytic activity at room temperature under solvent-free conditions. This catalyst is easily separated by magnetic devices and can be reused without any apparent loss of activity for the reaction. In addition, it is very interesting that when using Co nanoparticles as a catalyst, spatially-hindered aldehydes such as 2-methoxy-, 2-fluoro-, and 2-chloro-aldehydes are suitable for this reaction.

Macroporous magnetic poly(GMA-EGDMA-DVB) microspheres supported palladium complex as an efficient catalyst for Heck reaction

Macroporous magnetic poly(GMA-EGDMA-DVB) microspheres synthesized by suspension polymerization were used as supports for palladium catalyst.The results showed the novel magnetic catalyst can promote Heck reaction of aryl halides with acrylic acid efficiently without an inert atmosphere.In addition,the novel catalyst can be conveniently recovered by applying an external magnet and reused at least five times without significant loss of its activity.