In this paper, we have produced carboxylic acids by the oxidation of various alcohols in the presence of CO2 using SBA-15/IL supported Cu(II) (SBA-15/IL/Cu(II)) as nanocatalyst. The obtained products showed to have excellent yields by taking into account of SBA-15/IL/Cu(II) nanocatalyst. In addition, the analysis of EDX, SEM, TGA, TEM, XPS, and FT-IR showed the heterogeneous structure of SBA-15/IL/Cu (II) catalyst. It is determined that, after using SBA-15 excess, the catalytic stability of the system was enhanced. Moreover, hot filtration provided a full vision in the heterogeneous catalyst nature. The recycling as well as reuse of the catalyst were studied in cases of coupling reactions many times. Moreover, we have studied the mechanism of the coupling reactions.
Graphic AbstractA monolithic complexed catalyst composed of a piece of Co foam decorated with Ru nanosheets has been fabricated. This catalyst has demonstrated excellent performance in catalyzing NaBH4 hydrolysis under alkaline conditions. Most importantly, the bulky size of the developed catalyst provides convenience to control the start and stop of hydrogen production by manipulating the attachment and detachment between the catalyst and NaBH4 solution. These features endow this catalyst with great potential for on-site hydrogen supply.
Graphic AbstractThe magic number clusters Au102(p-MBA)44 and Au144(p-MBA)60 were synthesized and tested for their ability to catalyze the reduction of 4-nitrophenol. Kinetic and thermodynamic analyses demonstrate that both clusters are effective catalysts with activation energies less than 10 kJ/mol and turnover frequencies approaching 103 h–1 per surface gold atom.
Graphic AbstractLaBO3 (B?=?Fe, Mn, and FeMn) perovskite-type oxides were prepared by sol–gel method and then used as catalysts in CO hydrogenation for light olefins. The catalysts were characterized using XRD, H2-TPR, SEM, CO (CO2)-TPD, and XPS. The results showed that the lattice oxygen migration and oxygen vacancies promoted oxygen mobility by doping Mn2+ at the B site, Moreover, the presence of manganese as a promoter in the catalyst increased olefin selectivity compared with the olefin selectivity of the catalyst containing iron at the B-site and exhibited resistance to carbon deposition; while reducing the metal elements. In CO hydrogenation, potassium-promoted LaFeMnO3 catalysts afforded high catalytic activity and C2=–C4= selectivity. An O/P value of 5.0 and a C2=–C4= fraction of 54% were achieved for all hydrocarbons with low methane selectivity.
Graphic AbstractIn this research, four cholines supported on core–shell iron oxides, Fe2O3@MgO@Ch.OAc (choline acetate), Fe2O3@MgO@Ch.OH (choline hydroxide), Fe3O4@Ch.OAc, Fe3O4@Ch.OH, were synthesized. The synthesized catalysts were tested in 1,2,3-triazoles synthesis by the reaction of nitromethane, aldehyde, and benzyl azide in EtOH as a green solvent. Among four synthesized heterogeneous catalysts, the Fe2O3@MgO@ch.OAc showed superior catalytic activity for the reaction and afforded the desired triazoles in good isolated yields under mild reaction conditions.
Graphic AbstractZSM-48 and ZSM-22 zeolites with similar Si/Al ratio were synthesized and modified by alkali treatment. Moreover, n-dodecane hydroisomerization performance of Pt supported ZSM-22 and ZSM-48 were investigated. The catalytic results showed that the activity and the isomers selectivity of n-dodecane hydroisomerization could be improved by alkali treatment. The isomers distributions were distinct for Pt/ZSM-48 and Pt/ZSM-22. Mono-branched isomers near the end of the chains were more prone to be generated on Pt/ZSM-22 catalyst, which suggested “pore-mouth” catalysis model dominating the hydroisomerization catalysis. However, di-branched isomers and mono-branched isomers with methyl near the middle of the carbon chains were favorable to be formed over Pt/ZSM-48 catalyst according to the “key-lock” catalysis model. Moreover, more central-branched isomers were formed at high reaction temperature (>?320 °C) especially for Pt/ HZSM-22.
Graphic AbstractIn this study, we describe the synthetic of uranyl nitrate ion functionalized MOFs linked by carboxyl, which displays block shape crystals structure. The as-prepared uranyl-MOF has been efficiently utilized as heterogeneous catalyst for selective aerobic oxidation of sulfides under visible-light irradiation. Photochemistry of extended MOFs including uranyl nitrate ion has been examined. The sulfoxidation reaction proceeds with good yields for a large variety of different sulfides. This process is carried out under visible light conditions, methanol as single solvent, and the uranyl-MOF material can be recycled up to five times. Sulfoxidation reaction mainly proceeds through an electron and energy transfer mechanism of oxygen in uranyl nitrate ion.
Graphic AbstractIn this study, we describe the synthetic of uranyl nitrate ion functionalized MOFs. The as-prepared uranyl-MOF was efficiently utilized as heterogeneous catalyst for selective aerobic oxidation of sulfides under visible-light irradiation. Photochemistry of extended MOFs including uranyl nitrate ion has been examined.
The paper presents a short review of strategies used to develop coke resistant, nickel-based, catalysts for autothermal reforming of ethanol to hydrogen. Autothermal reforming of ethanol can be used in conjunction with pronton-exchange membrane fuel cells (PEMFCs) in the transportation sector, stationary and portable applications to replace the use of fossil fuels. Nickel-based catalysts are used in commercial processes for their high carbon–carbon bond cleavage and low cost compared to noble metals. However, the use of nickel-based catalysts is challenged by rapid deactivation caused by coke formation. A considerable effort is expended on innovating strategies to develop coke resistant nickel-based catalysts. The strategies reviewed in this paper are (i) the use of catalysts’ preparation methods targeting high dispersion of nickel nanoparticles smaller than the critical size of 10 nm (nm); (ii) modifying commonly used acidic supports (alumina, silica et cetera) to passivate the acidity to inhibit the production of coke precursor-ethylene; (iii) the addition of promoters and second active metals to promote supports and the active phase; (iv) controlling operating conditions to inhibit coke formation and the use of precursors with well-defined structures to stabilize highly dispersed nickel nanoparticles.
Graphical AbstractIn this study, the porous ultrathin graphitic carbon nitride (CN) nanosheets with rich C and nitrogen defects were prepared by one-step calcining the mixture of melamine and glucose (Glu) in air atmosphere (Glu-CN). Introducing simultaneously rich C atoms and nitrogen defects into CN structures continuously modulates the bandgaps from 2.67 to 1.81 eV of CN photocatalysts. Due to large surface area, more active sites, remarkably longer lifetime of charge carriers and adjustable band gap structure, the prepared ultrathin porous CN nanosheets show the enhanced photocatalytic performance for the degradation of methyl orange (MO) under visible light. The degradation efficiency of optimal CN nanosheet photocatalyst for MO is 5.75 times that of bulk CN. This work provides a facile and universal relevance approach to engineer the band structures of CN by introduction of rich C and porous morphology for high-performance photocatalytic, which can provide informative principles for the design of efficient photocatalysis systems for solar energy conversion.
Graphic AbstractAn efficient solvent-free catalyst system for hydrosilylation of aldehydes and ketones was developed based on iron pre-catalyst Fe2(CO)9/C6H4-o-(NCH2PPh2)2BH. The reactions were tolerant of many functional groups and the corresponding alcohols were isolated in good to excellent yields following basic hydrolysis of the reaction products. The reaction is likely catalyzed by an in situ generated pincer ligated iron hydride complex.
Graphic AbstractMicro-mesoporous aluminosilicates based on ZSM-5 zeolite, obtained by a dual template method, as well as in the presence of a dual-functional template (i.e. a Gemini-type surfactant), were tested in the oxidation of furfural with hydrogen peroxide. Even substantial changes in acidity and porosity of the catalysts result in minor variations of selectivity towards the desired products. Application of the synthesized zeolite-based materials in the oxidation of furfural with hydrogen peroxide leads to formation of 2(5H)-furanone (yield up to 28.5%) and succinic acid (up to 19.5%) as the main C4 reaction products. The kinetic model developed previously to treat the results for oxidation of furfural over sulfated zirconia was able to describe the data also for micro-mesoporous aluminosilicates.
Graphical AbstractThe efficient SBA-15 supported silver catalysts(Ag/SBA-15) were prepared and characterized by ICP-OES, XRD, TEM, SEM, XPS and N2 adsorption–desorption techniques. The catalysts exhibited an excellent catalytic activity for the aerobic oxidation of toluene to benzaldehyde under solvent-free conditions. Conversion of toluene and selectivity of benzaldehyde were 50% and 89% respectively over catalyst with 9.1 wt% Ag loading (10Ag/SBA-15). A wide range of substrates were tolerated under the selected reaction conditions. The kinetic study shows that the oxidation of toluene over 10Ag/SBA-15 is pseudo-first-order reaction and the activation energy Ea is 45.1 kJ/mol. A plausible mechanism involving oxygen free radicals was proposed for the aerobic oxidation reaction. Compared with the traditional method, the newly designed heterogeneous catalytic system shows better economic applicability, environmental friendliness and broader application prospects.
Graphical abstractVanadium(IV) oxido complex of 1-Phenyl-1,3-butanedione [VIVO(bzac)2] (1) was prepared, characterized, and heterogenized onto APTMS modified graphene oxide, as well as imidazole modified polystyrene beads. Graphene oxide supported complex GO-APTMS-[VIVO(bzac)2] (2) and polymer anchored complex PS-im-[VIVO(bzac)2] (3) were used for the oxidative bromination of a number of small organic molecules and oxidation of a series of thioethers. Both 2 and 3 evolve as excellent heterogeneous catalysts. The nature of solid support does not impact substrate conversion (%) during the oxidative bromination of salicylaldehyde, phenol, or styrene, whereas it influences the substrate conversion (%) as well as the product selectivity (%) during the oxidation of thioethers.
Graphic AbstractAPO-11 aluminophosphate molecular sieve was prepared by hydrothermal method of aluminum hydroxide with diisopropylamine. Ni–P/APO-11 amorphous alloy catalysts were prepared by chemical reduction method and used for the hydrogenation of α-pinene reaction. The catalysts were characterized by X-Ray photoelectron spectroscopy (XPS), Nitrogen adsorption–desorption isotherms (BET), scanning electron microscope (SEM), transmission electron microscope (TEM) and fourier transform infrared spectrometer (FT-IR).The prepared conditions of the Ni–P/APO-11 catalysts played important roles on the hydrogenation of α-pinene reaction. It was found that the preparation temperature, P/Ni molar ratio and pH value had great influence on the reduction dosage, dispersion and particle sizes of the catalysts, thus affecting the reactivity of the catalysts. The appropriate reaction conditions explored were at 30 °C, n(P/Ni)?=?5 and pH?=?8, obtaining a 90.65% conversion of α-pinene and 97.87% selectivity to cis-pinane. Under these conditions, the catalysts exhibited better repeatability and stability.
Graphic AbstractMXenes, as recently emerging lamellar two-dimensional (2D) materials of transition metal carbides and/or nitrides, have attracted intensive attention for various applications in sensors, catalysis, energy storage, and biomedicine owing to their fascinating and technologically useful properties. This review presents the current progress of MXene-based materials applied in the field of electrochemical sensors. Firstly, how synthetic strategies and surface modification affect the properties of MXene was emphasized. Secondly, MXene as an electrode material for constructing electrochemical sensors based on MXene nanocomposites, especially metal nanoparticles (MNPs)/MXene, conductive polymers (CPs)/MXene, and carbon materials/MXene nanocomposites, was well discussed. Finally, the challenges and outlooks in this field with possible solutions and future opportunities are discussed.
Graphic abstractNi–Mo2C and Ni–WC were evaluated in dry reforming of methane employing different CH4/CO2 ratios. Ni–Mo2C remained active under an excess of CH4, but deactivation occurred under an excess of CO2. Ni–WC was resistant to excess of CO2 but showed carbon deposition under excess of CH4.
Graphic AbstractAlthough numerous efforts have been made in direct syngas conversion to higher alcohols via Fischer–Tropsch synthesis, the higher alcohols distribution remains a challenge. Here, we introduce alkaline earth metal oxide as promoter into activated carbon supported cobalt catalyst to tune distribution of higher alcohols. With the addition of Mg, the distribution of C2-5 alcohols increase from 41.2 to 75.8% accompanying with distribution of C6-18 alcohols decrease from 52.8 to 14.0%. Ba-promoted Co based catalyst (CoBa/AC) presents similar alcohols distribution to un-promoted catalyst, while the alcohol selectivity over CoBa/AC is higher than Co/AC. For promoted catalysts, the distribution of C6-18 alcohols increased in the order of Mg?<?Ca?<?Sr?<?Ba. The characterization results exhibit that the promoter addition facilitates the cobalt carbide formation, which leads to enhancement of selectivity to higher alcohols. The available active cobalt sites of promoted Co based catalysts increase in the same above order of Mg?<?Ca?<?Sr?<?Ba.
Graphic AbstractBenzyl alcohol can be oxidized selectively to benzaldehyde over platinum-based catalysts using either oxygen (O2, supplied in the form of synthetic air) or the more powerful hydrogen peroxide (H2O2) as the oxidant. Here we compare these oxidants in the aqueous phase oxidation of benzyl alcohol in a batch reactor at 363.15 K or 393.15 K over monodisperse Pt and Pt–Ni nanostructures synthesized with molybdenum hexacarbonyl (Mo(CO)6) as a reductant. The initial catalytic activity of either Pt or a Pt–Ni alloy anchored on titania support (TiO2) is much higher when using H2O2 than when using O2 (supplied in the form of synthetic air). However, the high initial activity using H2O2 is accompanied by a strong decrease in the activity over Pt. Alloying Pt with Ni results in a reduction in the activity in the benzyl alcohol oxidation when using O2 but enhances the initial activity when using H2O2. The results are rationalized based on a change in the relative surface concentration of oxygen-containing species upon changing the oxidant or alloying Pt with Ni.
Graphic AbstractThis work proposed a new path to synthesize Ni-phyllosilicate through the reaction of nickel hydroxide and silica sol on the surface of Ni-foam to form the monolithic Ni-phyllosilicate/Ni-foam catalyst. Ni-phyllosilicate could reprint the morphology of nickel hydroxid and firmly anchor on the framework of Ni-foam, which obtained fine Ni particles of 2.8 nm after reduction in H2 at 650 °C, resulting in high catalytic activity for CO2 methanation. In addition, the Ni-phyllosilicate/Ni-foam catalyst showed high long-term stability in a 100 h-lifetime test owing to the combined effects of surface confinement of Ni-phyllosilicate, firm anchoring between Ni-phyllosilicate and Ni-foam, as well as the high heat transfer property of Ni-foam.
Graphical AbstractIn order to further improve the catalytic activity and stability of heterogeneous acid catalysts, a polystyrene microspheres modified sulfonic acid-based catalyst (PS-SO3H) was prepared. PS-SO3H was characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscope, transmission electron microscope, N2 adsorption–desorption, and X-ray photoelectron spectroscopy. Catalytic efficiency was determined using the reaction of furfuryl alcoholysis to ethyl levulinate (EL). The obtained results showed that PS-SO3H had excellent catalytic performance, with EL yield of 94.7%. In addition, PS-SO3H was easily separated from the reaction system and recycled multiple times without significant reduction in activity. High catalytic activity stemmed from the effect of Brønsted acid sites and appropriate structural properties.
Graphical Abstract