Showing papers in "Journal of Molecular Catalysis A-chemical in 2015"
TL;DR: In this paper, a novel iron-based metal-organic framework, possessing high surface area and good catalytic activity, was proposed as a heterogeneous Fenton catalyst for degrading high concentration methylene blue.
Abstract: A novel iron-based metal-organic framework, possessing high surface area and good catalytic activity, was proposed as a heterogeneous Fenton catalyst for degrading high concentration methylene blue ( C MB = 500 ppm). The morphology and physicochemical properties of prepared catalysts were characterized by SEM, XRD, XPS, FT-IR, Raman spectra, etc. The obtained results showed that MOF-based catalysts MIL-100(Fe) and Fe II @MIL-100(Fe) possess high surface area of 1646 and 1228 m 2 g −1 , respectively. The MB removal though adsorption by MIL-100(Fe) and Fe II @MIL-100(Fe) is respectively 27 and 6% in 30 min, due to the electrostatic interaction between negative (or positive) adsorbent and positive pollutant. However, Fe II @MIL-100(Fe) exhibited highest Fenton catalytic ability compared to MIL-100(Fe) and Fe 2 O 3 catalysts. The catalytic activity of each active site, evaluated by the turn over frequency (TOF) value, varied in the order of Fe II @MIL-100(Fe) > MIL-100(Fe) > Fe 2 O 3 . The main role of determining the decomposition efficiency, i.e., hydroxyl radical ( OH) generation, surface redox properties and surface reaction, was greatly enhanced by the synergistic effect between Fe II and Fe III in Fe II @MIL-100(Fe). Moreover, iron-based metal-organic framework retained the catalytic performance in a wide pH range of 3–8, and had a relative low iron leaching even in acidic condition.
318 citations
TL;DR: The green synthesis of palladium nanoparticles using Hippophae rhamnoides linn leaf extract and their application as heterogeneous catalysts for the Suzuki-Miyaura coupling in water was reported in this paper.
Abstract: During this study, we report the green synthesis of palladium nanoparticles using Hippophae rhamnoides Linn leaf extract and their application as heterogeneous catalysts for the Suzuki–Miyaura coupling in water. The synthesized nanoparticles are characterized by XRD, SEM, TEM and UV–vis techniques. This method has the advantages of high yields, simple methodology, and elimination of ligand, organic solvent and homogeneous catalysts and easy work-up. Furthermore, the catalyst exhibits high catalytic activity, superior cycling stability and excellent substrate applicability.
235 citations
TL;DR: In this paper, the average size of TiO 2 nanoparticles was decreased from 60-80nm to 40-60nm through the immobilization on MMT and the predicted data from the designed artificial neural network model were found to be in a good agreement with the experimental data ( R 2 ǫ = 0.9864).
Abstract: TiO 2 /MMT nanocomposite was synthesized and characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray fluorescence (XRF) and Brunauer–Emmett–Teller (BET) techniques. The average size of TiO 2 nanoparticles was decreased from 60–80 nm to 40–60 nm through the immobilization on MMT. The main influential factors such as the TiO 2 /MMT dose, ciprofloxacin (CIP) concentration, pH of the solution, UV light regions, reusability of the catalyst and electrical energy determination were studied. The addition of radical scavengers (e.g. chloride, iodide, sulfate and bicarbonate) and enhancers (e.g. hydrogen peroxide, potassium iodate and peroxydisulfate) on the degradation efficiency was studied. The predicted data from the designed artificial neural network model were found to be in a good agreement with the experimental data ( R 2 = 0.9864). The main intermediates of CIP degradation were determined by GC–Mass spectrometry.
156 citations
TL;DR: In this paper, mesoporous TiO2 supported catalysts (M-TiO2) were synthesized using facile one-step synthesis method and were characterized using BET, XRD, TGA-DSC, TEM, SEM-EDX, ICP-OES, and H2-TPR studies.
Abstract: Mesoporous TiO2 supported Cu, Co, Ni, Pd, Sn and Zn catalysts (M-TiO2) were synthesized using facile one-step synthesis method and were characterized using BET, XRD, TGA-DSC, TEM, SEM-EDX, ICP-OES, and H2-TPR studies The catalysts were further tested for steam reforming of methanol (SRM) to investigate their comparative catalytic performance Depending on the nature of the metal component, the catalysts exhibited surface area, pore sizes, and TiO2 crystallite sizes in the range of 99–309 m2/g, 263–469 nm and 68–172 nm, respectively N2-physorption, TGA-DSC and XRD analysis demonstrated that the presence of metal in the TiO2 matrix stabilized the mesoporous structure by hindering the crystal growth during heat treatment and thereby preventing the collapse of porous structure Furthermore, the characterization of 5–20% Zn-TiO2 catalysts indicated that there exist an optimum Zn loading to obtain highest surface area which was found to be 15% in the present study giving a high surface area of ∼258 m2/g This was consistent with the SRM studies where the activity increased up to 15% and then decreased significantly with further increase in Zn loading to 20% The results of the SRM studies coupled with extensive TPR analysis of different M-TiO2 catalysts suggest that the specific metal-support interactions play a crucial role in controlling its performance on H2 production The SRM activity order for different metals incorporated in mesoporous TiO2 was observed to be: Pd > Ni > Zn > Co >> Cu >> Sn The Zn-TiO2 catalyst showed the lowest CO selectivity among the different catalysts studied
156 citations
TL;DR: In this paper, a green synthesis of Pd/Fe 3 O 4 nanoparticles using Euphorbia condylocarpa M. bieb root extract as reducing agents and stabilizers was reported.
Abstract: This work reports on the green synthesis of Pd/Fe 3 O 4 nanoparticles using Euphorbia condylocarpa M. bieb root extract as reducing agents and stabilizers and their catalytic applications in ligand- and copper-free Sonogashira and Suzuki coupling reactions. This method has such advantages as high yields, simple methodology and easy work up. In addition, the catalyst can be recovered by using a magnet and reused several times without significant loss of its catalytic activity. The catalyst was characterized using UV–vis, powder XRD, SEM and EDS techniques.
153 citations
TL;DR: In this paper, the photocatalytic activity for degradation of a mixture of tetracycline (TC) and cephalexin (CPX) in aqueous solution under Hg lamp irradiation was investigated.
Abstract: Supported PbS–CdS onto clinoptilolite nano-particles (PbS–CdS–NCP) showed good photocatalytic activity for degradation of a mixture of tetracycline (TC) and cephalexin (CPX) in aqueous solution under Hg lamp irradiation. Samples were characterized by XRD, FT-IR, DRS, and TEM. The degradation extent was followed by UV–vis spectrophotometry and the obtained results confirmed by COD. While, the best degradation efficiencies were obtained in the optimal experimental parameters (1.5 g L −1 of the photocatalyst, 100 folds diluted solution at pH 3.0), but significant decrease in the degradation efficiencies was observed in the presence of NaCl, Na 2 CO 3 , H 2 O 2 , and Na 2 S 2 O 8 . The results confirmed that OH is responsible for the degradation of the pollutants because adding of isopropanol, as an effective OH scavenger, into the suspension significantly decreased the degradation efficiency.
149 citations
TL;DR: In this paper, a series of zirconium-based metal organic frameworks (UiO-66, UiO67, Zr6-NDC, MIL-140A, MIL140B, and MIL- 140C) were used for selective hydrogenation of furfural to furfuryl alcohol under mild conditions.
Abstract: Selective hydrogenation of furfural to furfuryl alcohol under mild conditions was evaluated over Ru nanoparticles supported on a series of zirconium based metal organic frameworks (UiO-66, UiO-67, Zr6-NDC, MIL-140A, MIL-140B, and MIL-140C). The particle size and oxidation state of Ru in the catalysts was characterized by TEM, H2-TPR, and XPS. The consecutive reduction by N2H4·H2O and hydrogen flow led to Ru metal nanoparticles, unless the interaction of the Ru precursor with the organic linkers was strong as found for the carboxylic acid groups in MIL-140C. Although the Ru nanoparticle surface was oxidized when exposed to air, the surface RuOx could be reduced under reaction conditions for Ru/UiO-66, consistent with its high catalytic activity. This catalyst exhibited 94.9% yield of furfuryl alcohol and could be reused in five consecutive reaction cycles without appreciable loss in performance.
142 citations
TL;DR: In this paper, three supported Cu-catalysts (Cu/SiO2, Cu/Al2O3, and Cu/ZnO) were prepared by the typical precipitation method, and they exhibited the best catalytic performance with an 89.5% yield to 2-MF.
Abstract: Our work focuses on exploring Cr-free Cu-catalysts for the highly efficient conversion of biomass-derived furfural to value-added bio-fuel 2-methylfuran. Three supported Cu-catalysts (Cu/SiO2, Cu/Al2O3, and Cu/ZnO) were prepared by the typical precipitation method, and Cu/SiO2 catalyst exhibited the best catalytic performance with an 89.5% yield to 2-MF. A series of characteristic results indicated that the high yield of 2-methylfuran on Cu/SiO2 catalyst was assigned to synergistic effect of metal and the weak acid sites. Among them, Cu/ZnO catalyst exhibited maximum furfuryl alcohol selectivity because of the large Cu particles, while Cu/Al2O3 catalyst had low 2-methylfuran selectivity due to the insufficient weak acid sites. For Cu/SiO2 catalyst, the highly dispersed Cu particles and the strong metal-support interaction are propitious to its superior catalytic activity. Therefore, copper species are composed on different supports as a result of the different interaction of metal-support to affect their catalytic activity, while products selectivity is related to the acidic property of catalyst. In addition, temperature programmed desorption of furfural indicated that the adsorption–desorption properties of catalyst surface species would influence the rate of furfural hydrogenation.
137 citations
TL;DR: In this article, a review of the catalytic activity of sulfonic acid-functionalized SBA-15 has been performed and it has been shown that the SBA can be easily removed from the reaction mixture by simple filtration, recovered and reused without significant loss of activity.
Abstract: Mesoporous silica SBA-15 has been functionalized with sulfonic acid to create highly powerful heterogeneous solid acid catalysts (SBA-Pr-SO 3 H). The catalyst can be easily removed from the reaction mixture by simple filtration, recovered and reused without significant loss of activity. In this review, the catalytic activity of sulfonic acid-functionalized SBA-15 has been widely studied.
134 citations
TL;DR: In this paper, room temperature synthesis of solketal from acetalization of glycerol with acetone was carried out over various types of Bronsted solid acid catalysts in the liquid phase.
Abstract: Room temperature synthesis of solketal from acetalization of glycerol with acetone was carried out over various types of Bronsted solid acid catalysts in the liquid phase. Among the catalysts screened, H-Beta zeolite showed the best performance in less time period with 86% glycerol conversion and 98.5% selectivity to solketal. The chemical and structural properties of modified and unmodified beta catalysts were studied by X-ray diffraction, AAS, SEM, NH3-TPD and FTIR-pyridine adsorption. The H-Beta catalyst with lower crystallite size gave better conversion and solketal selectivity compared to H-Beta with higher crystallite size. The effect of acidity of the catalyst on acetalization of glycerol was studied by modified beta catalysts of varying acidities. Glycerol conversion decreased with decrease in total acidity of beta catalysts. Strong to weak acidity ratio of the catalysts was found to have a direct correlation with catalyst performance.
133 citations
TL;DR: In this article, the facile synthesis of environmentally benign Cu NPs/perlite composites without employing any toxic reductants or capping agents was reported, and the structural investigation was performed using XRF, XRD, SEM, EDS, TEM, TG-DTA, BET and FT-IR.
Abstract: We report the facile synthesis of environmentally benign Cu NPs/perlite composites without employing any toxic reductants or capping agents. Renewable natural Euphorbia esula L. not only functioned as a reductant, but also served as a stabilizer for the formation of Cu NPs. Cu NPs synthesized using aqueous extract of the leaves of E. esula L. was immobilized on perlite by a very simple and inexpensive method. The structural investigation was performed using XRF, XRD, SEM, EDS, TEM, TG–DTA, BET and FT-IR. The Cu NPs/perlite shows favorable activity and separability on the catalytic reduction of 4-nitrophenol, and can be reused several times without a decrease in the catalytic activity. Their reaction rate constant was calculated according to the pseudo-first-order reaction equation.
TL;DR: In this article, a series of WO x promoted Pt/Al 2 O 3 catalysts were investigated for selective production of 1,3-propanediol from glycerol hydrogenolysis.
Abstract: Despite 1,3-propanediol possessing high economic value, its production from glycerol hydrogenolysis is a challenging task. Herein, a series of WO x promoted Pt/Al 2 O 3 catalysts with various WO x contents were prepared and investigated for selective production 1,3-propanediol from glycerol hydrogenolysis. To explore the structure feature, these catalysts were fully characterized by BET, CO chemisorption, HRTEM, XRD ( in situ XRD), Raman, NH 3 –TPD, Py–IR, H 2 –TPR, and XPS. Among them, Pt–10WO x /Al 2 O 3 achieved the highest 1,3-propanediol yield up to 42.4%, which was ascribed to the large concentration of Bronsted acid sites, strong electronic interaction between Pt with WO x and hydrogen spillover. The strong correlation between 1,3-propanediol yield and Bronsted acid site indicated its essential role for the formation of 1,3-propanediol. Meanwhile the linear correlation between 1,2-propanediol yield and Lewis acid site gave direct evidence that Lewis acid site preferentially generated 1,2-propanediol.
TL;DR: In this article, the photocatalytic properties of GQDs under visible light irradiation were investigated for degradation of organic pollutant dyes based on photocatalysis properties.
Abstract: In this paper, we have introduced a novel property of graphene quantum dots (GQDs) as efficient nano-materials for degradation of organic pollutant dyes based on the photocatalytic behavior of GQDs under visible light irradiation GQD samples were synthesized directly through pyrolyzing citric acid method The synthesized GQDs were characterized by various techniques including colorimetry, transmission electron microscopy (TEM), and UV–vis absorption, Raman spectroscopy, fluorescence spectroscopy, and zeta potential measurements In this study, a cationic dye (ie, New Fuchsin) was chosen as a model molecule to investigate catalytic behavior of the prepared GQDs as green nanomaterials The influence of experimental parameters such as pH of the dye solution, contacting time, dosage of GQDs, and initial concentration of NF dye on the degradation efficiency of GQD were studied The possible mechanisms of degradation of NF based on GQDs under visible light were discussed, too
TL;DR: In this article, a Pd supported on diaminoglyoxime (DAG)-functionalized Fe3O4 hybrid materials was fabricated for the first time and yields of the products were in the range from 70% to 98%.
Abstract: A Pd supported on diaminoglyoxime (DAG)-functionalized Fe3O4 (Fe3O4/DAG/Pd) hybrid materials was fabricated for the first time. In this fabrication, DAG played an important role as a capping agent. The immobilized palladium catalyst was an efficient catalyst without added phosphine ligands for the Suzuki cross-coupling reaction of several aryl halides with phenylboronic acid in aqueous phase at room temperature. The yields of the products were in the range from 70% to 98%. The prepared heterogeneous nanocatalyst was characterized by XRD, XPS, EDS, FT-IR, ICP, FESEM, VSM and TEM. Interestingly, the novel catalyst could be recovered in a facile manner from the reaction mixture by applying an external magnet device and recycled eight times without any significant loss in activity.
TL;DR: In this paper, green and aqueous-based synthesis routes were performed for chemical preparation of pure and transition metal ions doped ZnS quantum dots at room temperature, and the average particle size of QDs was found to be around 1-3nm.
Abstract: In this research, green and aqueous based synthesis routes were performed for chemical preparation of pure and transition metal ions doped ZnS quantum dots at room temperature. Doping of ZnS QDs by three transition metal ions (Mn2+, Co2+, Ni2+ ions) as dopants have been investigated by various techniques. In the optical absorption studies, a broad absorption band in the wavelength range of 280–300 nm clearly reveals quantum size effect in ZnS QDs. The crystal structure and the approximate size of QDs were measured by XRD pattern. The average particle size of QDs was found to be around 1–3 nm. In addition, the photocatalytic activities of the prepared ZnS QDs as their abilities to remove methyl violet (MV) cationic dye, as a model molecule, were studied. Effect of the experimental parameters, such as the type of dopant and the amount of QDs, pH of the initial dye solution, irradiation time, ionic strength of reaction media, and initial dye concentration on the decolorization efficiency (DE) of QDs as green nano-semiconductors were studied. The results demonstrated that doped QDS (for 5% of dopants) effectively bleached out MV, showing positive photocatalytic enhancement over pure ZnS nanoparticles.
TL;DR: In this article, the effect of incorporation of transition metals (i.e., Co, Mn, Cr, and Ni) into the magnetite on the reactivity towards Oxone activation was investigated at neutral pH.
Abstract: In this study, the effect of incorporation of transition metals (i.e., Co, Mn, Cr, and Ni) into the magnetite on the reactivity towards Oxone activation was investigated at neutral pH. The magnetite samples were characterized by XRD and EXAFS. Co, Cr, and Ni were in the valences of +2, +3, and +2, respectively, while Mn was in the valences of +2 and +3. These cations occupied the octahedral sites of magnetite, but the distribution of Mn and Ni on the octahedral sites of magnetite surface increased with an increase of substitution extent. The activity of magnetites in Oxone activation was investigated through Acid Orange II (AOII) degradation at an initial pH of 7.0 with or without phosphate-buffered solution. In neutral medium, the AOII degradation by Mn, Cr, and Ni substituting magnetites followed pseudo-first-order kinetics. The incorporation of Co, Mn, and Ni improved the catalytic activity of magnetite in the order Mn tert -butyl alcohols. The different effects of studied substitutions on the reactivity of magnetite were discussed in views of reactive radical species and microstructural environment.
TL;DR: In this paper, two new O-carboxymethyl chitosan Schiff bases supported Pd(II) catalyst were synthesized (OCMCS-3aPd and OCMCS-4 aPd).
Abstract: In this study, two new O-carboxymethyl chitosan Schiff bases supported Pd(II) catalyst were synthesized (OCMCS-3aPd and OCMCS-4aPd). The catalysts were characterized with FTIR, TG/DTG, SEM/EDAX, XRD, ICP-OES, UV–vis, magnetic moment and molar conductivity. The catalytic activities of these catalysts were tested in the synthesis of biaryl compounds by Suzuki cross-coupling reactions. Characterizations of the biaryls were performed with GC–MS and 1H NMR. In synthesis of the biaryl compounds in the presence of the Pd(II) catalyst, high selectivity was observed; no homo-coupling byproducts were detected in the spectra. A reusability test demonstrated that the catalysts were highly efficient even after ten run. The mercury poisoning and leaching tests indicated that the catalysts have heterogeneous nature.
TL;DR: A simple and facile chemical method to synthesize SnO2 doped ZnO nanostructures has been investigated in the presence of polyethylene glycol (PEG) as a surfactant for highly efficient photocatalyst as discussed by the authors.
Abstract: A simple and facile chemical method to synthesize SnO2 doped ZnO nanostructures has been investigated in the presence of polyethylene glycol (PEG) as a surfactant for highly efficient photocatalyst. The structural investigation indicated that the XRD patterns reveal highly crystalline ZnO nanoparticles. The FE-SEM images show that the synthesized SnO2 doped ZnO has aggregated layers with caves like structure. The newly prepared SnO2 doped ZnO nanostructures have been evaluated for photodegradation of methylene blue (MB) under visible light. The photodegradation of MB proceeds much more rapidly in the presence of SnO2 doped ZnO compared to the undoped ZnO nanoparticles. The photocatalytic performance was in the order of 0.5% SnO2/ZnO > 1.0% SnO2/ZnO > 0.2% SnO2/ZnO > undoped ZnO, suggesting that doping of SnO2 improves the photocatalytic activity of ZnO. These results indicate that SnO2 doped ZnO nanostructures are very promising to fabricate highly efficient photocatalysts.
TL;DR: In this article, a magnetically supported ionic liquid on Fe 3 O 4 @SiO 2 nanoparticles (MNPs@ SiO 2 -IL) was synthesized and evaluated as a recoverable catalyst for the one-pot synthesis of 1,3-thiazolidin-4-ones in high to excellent yield under solvent-free conditions.
Abstract: A magnetically supported ionic liquid on Fe 3 O 4 @SiO 2 nanoparticles (MNPs@ SiO 2 -IL) was synthesized and evaluated as a recoverable catalyst for the one-pot synthesis of 1,3-thiazolidin-4-ones in high to excellent yield under solvent-free conditions. The MNPs@SiO 2 -IL catalyst was characterized via Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). Moreover, the catalyst could be easily recovered by magnetic separation and recycled for 10 times without significant loss of its catalytic activity.
TL;DR: In this paper, the photocatalytic degradation of 4-methylbenzoic acid (MBA) and 2-chloro-5-nitro benzoic acids (CNBA) as aqueous solution mixture was studied using ZnO-SnO 2 /nano-clinoptilolite under UV irradiation.
Abstract: The photocatalytic degradation of 4-methylbenzoic acid (MBA) and 2-chloro-5-nitro benzoic acid (CNBA) as aqueous solution mixture was studied using ZnO–SnO 2 /nano-clinoptilolite under UV irradiation. The clinoptilolite nano-particles (CNP) were obtained via ball-mill method and ion exchanged in Zn 2+ –Sn 4+ aqueous solutions with different concentrations. The ion exchanged samples (Zn(II)–Sn(IV)/CNP) were calcined at 450 °C for 12 h to obtain ZnO–SnO 2 /CNP catalysts. XRD, DRS, FT-IR and TEM techniques were applied for characterization of samples. The experimental parameters which influenced degradation process were optimized and the optimum values were obtained as: 1 g L −1 of the photocatalyst, pH 5 and 5 mg L −1 of MBA and CNBA in the mixture. The degradation/ mineralization extents were confirmed by COD and HPLC.
TL;DR: In this article, a two-step hydrothermal method was used to synthesize modified TiO2 nanobelts (TiO2-MoS2) with tunable decoration amount of MoS2 nanparticles.
Abstract: MoS2 nanoparticles modified TiO2 nanobelts (TiO2-MoS2) with tunable decoration amount of MoS2 nanparticles have been successfully synthesized via a two-step hydrothermal method, which involves preparation of TiO2 nanobelts and decoration of the MoS2 nanoparticles. The as-prepared samples were carefully characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray and detector (EDX), X-ray photoelectron spectroscopy (XPS), respectively. The photocatalytic activity of the as-prepared samples was evaluated by photocatalytic degradation of Rhodamine B (RhB) under visible light irradiation. The photocurrent measurement was also tested to confirm the results of photocatalytic activity. It can be found that TiO2-MoS2 heterojunction structures with MoS2 decoration amount of 40 wt% (TM-4) possess the highest photocatalytic activity since it has the suitable amount of MoS2 for prohibiting the recombination of photogenerated electrons and holes. In addition, highly apparent photocatalytic reaction rate constant of TM-4 is about 4.78 times than that of pure TiO2 nanobelts.
TL;DR: In this article, MnOx/TiO2 composites with various metal species (M = Mn, Ce, Co, Fe) were synthesized and employed as in the catalytic oxidation of benzene.
Abstract: MOx/TiO2 composites with various metal species (M = Mn, Ce, Co, Fe) were synthesized and employed as in the catalytic oxidation of benzene. Among those materials, MnOx/TiO2 showed the highest catalytic efficiency. The catalytic activities of MnOx/TiO2 with different MnOx contents were also studied. XRD, BET, SEM, TEM, and XPS characterizations were conducted to analyze the physiochemical properties of the MnOx/TiO2 catalysts. Moreover, the reaction mechanism of benzene oxidation over MnOx/TiO2 was studied through the in situ FTIR experiments. (C) 2015 Elsevier B.V. All rights reserved.
TL;DR: In this paper, a simple technique to synthesise porous TiO 2 nanoparticles with increased surface area through a scaffold template technique was proposed and validated by analysing the degradation of malachite green (MG).
Abstract: There is always a market for cost effective methods of pollution degradation and one of the best areas to keep costs down is through synthesis techniques. This paper provides a simple technique to synthesise porous TiO 2 nanoparticles with increased surface area through a scaffold template technique. Their photocatalytic activity is enhanced by incorporating sulphur as a dopant and were validated by analysing the degradation of malachite green (MG). The materials were doped at a molar ratio of 100:1 (Ti:S) and calcined at different temperatures to adjust the anatase/rutile content. Detailed characterisation of the materials was undertaken using XRD, BET, XPS, TEM and FTIR. The nanoparticles displayed a microporous structure and had an increased surface area of 115 m 2 g −1 which was reduced by doping and temperature induced phase transformation. Photocatalytic testing showed that the doped materials calcined at 700 °C preformed the best in. It was observed that 20 mg l −1 of MG was decomposed in 30 min using a 40 W UV bulb at pH 9 and the results surpassed those achieved by the commercial catalyst P25 which was also tested for comparison.
TL;DR: In this article, the three-dimensional Zr-based metal-organic framework UiO-66-NH2 was functionalized with salicylaldehyde using a post-synthetic modification (PSM) strategy, and then three kinds of copper (II) salts were successfully immobilized onto the surface of the amino-functionalized ZrMOF.
Abstract: The three-dimensional Zr-based metal-organic framework UiO-66-NH2 was functionalized with salicylaldehyde using a post-synthetic modification (PSM) strategy, and then three kinds of copper (II) salts were successfully immobilized onto the surface of the amino-functionalized Zr-MOF. The SEM and PXRD results showed that the morphology and structure of Zr-MOF were retained after multiple transformations. The obtained UiO-66-Sal-CuCl2 catalyst exhibited excellent activity for the selective aerobic oxidation of primary aromatic alcohols using molecular oxygen as the oxygen source. Furthermore, the UiO-66-Sal-CuCl2 catalyst showed a good cycle performance.
TL;DR: In this article, first-principle methods are employed to build thermodynamic models for both the pure and sulfur atom modified g-C3N4 photocatalysts.
Abstract: In this work, first-principle methods are employed to build thermodynamic models for both the pure and sulfur atom modified g-C3N4 photocatalysts. Three possible mechanisms of oxygen evolution reaction (OER) following four one-electron pathway are investigated. The hydroxyl (OH) species as a key intermediate is found to strongly interact with the catalyst and its newly observed stability indeed significantly affects the overpotential of OER. On pure g-C3N4, the first removal of proton from water, the rate-determining step, can not become surmountable at room temperature until an overpotential of 0.88 V (2.11 V vs SHE) is appended, in accord with the experimental observation that water photooxidaton hardly occurs on g-C3N4 without any modification. Interestingly, the sulfur doping not only leads to a different reaction mechanism but also lowers the overpotential, consistent with the experimental finding that the reaction rate for OER could be further enhanced by sulfur-modified g-C3N4. Our theoretical results provide useful insights for designing better anodes to achieve high OER activity on graphitic carbon nitride based photocatalysts.
TL;DR: Nano-WO3-supported sulfonic acid [n-WOW3-SO3H (nWSA) as mentioned in this paper was used as an efficient and recyclable catalyst for some organic reactions such as synthesis of 1,8-dioxo-octahydroxanthene, tetrahydrobenzoxanthene and benzimidazolo quinazolinone derivatives.
Abstract: Nano-WO3-supported sulfonic acid [n-WO3-SO3H (n-WSA)] is easily prepared from the reaction of nano WO3 with chlorosulfonic acid as sulfonating agent. This new catalyst is characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), FT-IR spectroscopy, thermal gravimetric analysis (TGA), pH analysis and Hammett acidity function. Nano-WO3-supported sulfonic acid is used as an efficient and recyclable catalyst for some organic reactions such as synthesis of 1,8-dioxo-octahydroxanthene, tetrahydrobenzoxanthene and benzimidazolo quinazolinone derivatives. All of the reactions are very fast and the yields are excellent. The used catalyst was easily separated and reused for 10 runs without appreciable loss of its catalytic activity.
TL;DR: In this paper, a novel heterogeneous copper nano catalyst supported on modified silica mesopore KIT-5 was successfully prepared, which showed high catalytic activity in water as a green solvent.
Abstract: A novel heterogeneous copper nano catalyst supported on modified silica mesopore KIT-5 was successfully prepared. The 3-aminopropyltriethoxysilane (APTES) on KIT-5 was coordinated with copper(I) and accurately characterized. In addition a comparative survey on the metal-ligand interactions in the syntheses of catalyst in two different solvents via density functional theory calculations was performed. A one-pot procedure for syntheses of 1,4-disubstituted 1,2,3-triazole derivatives via a three-component reaction between terminal alkynes, alkyl halides, and sodium azide, namely click reaction in the presences of 3 mol% nanoparticles copper/APTES-KIT-5 (Cu/AK) as a catalyst was developed to give the products in good to excellent yields. This catalyst showed high catalytic activity in water as a “green” solvent. This reaction was performed under open air conditions and required no special reaction conditions and chromatographic separation for purification.
TL;DR: In this paper, the photocatalytic degradation of methyl orange (MO) under visible light irradiation (λ < 420 nm) was evaluated using a facile hydrothermal method.
Abstract: Novel visible-light-driven WO3/BiOI heterojuncted photocatalysts were fabricated by a facile hydrothermal method and were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV–vis DRS) and photoluminescence spectroscopy (PL). The photocatalytic activity of the as-prepared samples was evaluated by photocatalytic degradation of methyl orange (MO) under visible light irradiation (λ > 420 nm). The results indicated that the optimum rate constant of the WO3/BiOI heterojunction catalyst at a weight content of 1.0% WO3 for the degradation of MO was 1.6 times as high as that of pure BiOI and 54 times larger than that of pure WO3, respectively. The enhancement could be attributed predominantly to improving photogenerated electron–hole pairs separation and migration efficiency because of the p–n heterojunction formed between p-type BiOI and n-type WO3. Additionally, the superoxide radical anions ( O 2 − ) and holes (h+) were considered as the dominant reactive species during the photodegradation MO process, and a possible photocatalytic mechanism was proposed.
TL;DR: In this paper, a detailed study combining the kinetic studies and in-situ FTIR experiments to investigate the oxidation behavior of chlorobenzene over V2O5/TiO2 catalysts was presented.
Abstract: In this article, we present a detailed study combining the kinetic studies and in-situ FTIR experiments to investigate the oxidation behavior of chlorobenzene over V2O5/TiO2 catalysts. The catalytic data show the 3-5 wt.% V2O5/TiO2 catalysts are best fit for the oxidation of chlorobenzene. The calculated apparent reaction orders are about 0.6 and 0.2, respectively. The results of in-situ FTIR provided mechanism insights into the catalytic reaction, which supports the following proposal: (i) a nucleophilic substitution on V=O species and (ii) attacking by surface oxygen through a electrophilic substitution, then (iii) followed by the cracking of ring structure, and further oxidation of the resulting species to form final products. The above results further suggest that the nucleophilic substitution process and surface reaction are kinetically significant steps for chlorobenzene oxidation, determining the overall rate of the reaction. Furthermore, 1,2-dichlorobenzene, 1,3-dichlorobenzene and 1,2,4-trichlorobenzene as additional reactants were tested together with chlorobenzene in binary mixtures to examine their competition reactions. (C) 2015 Elsevier B.V. All rights reserved.
TL;DR: In this paper, the best conditions of dehydration of D-xylose using FeCl3 were investigated by varying temperature, reaction time, pentose loading and influence of NaCl.
Abstract: Production of furfural from biomass using less corrosive acids and minimizing the formation of undesired by-products is great challenge. Dehydration of D-xylose to furfural was carried out under microwave irradiation in biphasic system consisting of CPME and aqueous inorganic salts solution. Best conditions of dehydration of D-xylose using FeCl3 were investigated by varying temperature, reaction time, pentose loading and influence of NaCl. Highest furfural yield of 74% was achieved at 170 °C for 20 min in presence of 10 mol% of iron chloride and 100 mol% of sodium chloride in water-CPME, 1:3, v/v. Addition of NaCl was found to increase the catalytic activity of FeCl3 and allowed to reduce the amounts of FeCl3 used from 20 mol% to 10 mol%. This approach was tested with success starting from L-arabinose and xylan, a pentose-rich polysaccharide.