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Abstract: CO2 reforming of CH4 to synthesis gas was investigated on new grounds using Ni-containing phyllosilicates (PS) as catalyst precursors. Ni-containing 1:1 PS and 2:1 PS were synthesized hydrothermally from a gel containing sodium silicate and nickel chloride, then they were reduced under H2 flow before being used as catalysts. Several complementary techniques including XRD, TG-DTA, FTIR, and TPR were used to evaluate the structural, thermal, spectroscopic and redox properties of the samples, respectively. Ni 2:1 PS were found to be more thermally stable and catalytically active than Ni 1:1 PS. Well crystallized Ni 1:1 PS thermally treated at 700°C resulted in a transitional 2:1 PS phase. The reduction of structural nickel in thermally stable PS led to the formation of nanometric Ni0 particles over the surface of the remaining unreduced PS as well as on silica. The unreduced PS structure with surface OH groups appeared as one of the best supports for Ni0 nanoparticles, resulting in less coke formation, and thereby leading to a high catalytic stability. [ABSTRACT FROM AUTHOR]

Abstract: The selective synthesis of phytosterol esters from natural sterols and methyl esters was investigated on new grounds by a chemical process using basic solids that are reusable, active, and more selective than the currently used homogeneous catalysts (e.g., alkali hydroxides, carbonates). Various lanthanum oxides with different synthesis procedures and varying specific surface areas were tested. The catalytic performance of the new solids and, more specifically, the ability of La2O3 oxides in increasing phytosterol ester selectivity, was correlated with their acido-basic properties, which were fully characterized by infrared spectroscopy. All La2O3 oxides involved surface carbonate species with different structural states and strengths, as revealed by propyne adsorption. The selectivity to phytosterol ester varied from 90 to 96%, confirming that the side reaction of dehydration of β-sitosterol was strongly inhibited. The phytosterol ester yield could reach 89% and was related to the basic strength of the carbonate species. The lower the carbonate basicity, the higher the phytosterol ester yield. Moreover, IR spectra of catalysts diluted in KBr powder showed that the higher the intensity of unidentate carbonate bands, the higher the yield. It was concluded that the synthesis of phytosterol esters from fatty methyl esters and sitosterols in the presence of La2O3 catalysts requires ionic carbonate species of medium basic strength. [Copyright &y& Elsevier]

Abstract: A Colombian bentonite was successfully pillared with solutions of Al, Al-Fe or Al-Ce-Fe polyhydroxocations under moderate conditions of synthesis in order to obtain active catalysts for the wet peroxide oxidation of organic pollutants from industrial wastewaters. The catalysts were very efficient in the phenol oxidation reaction in diluted aqueous medium under mild experimental conditions (298K and atmospheric pressure). The addition of Ce in the synthesis step of the inorganic polycations yielded a favorable effect in the pillaring of the materials allowing the increase of the basal spacing and enhancing the catalytic activity of the solids. Besides, the characterization by TEM, EPR and chemical analysis techniques confirms the nanocluster formation of iron species, while no evidence of mixed pillars with isomorphic substitution of Fe for Al was obtained. [Copyright &y& Elsevier]

Abstract: A Colombian bentonite was successfully pillared with mixed polyhydroxocationic solutions of Al–Fe or Al–Ce–Fe, with the iron in small quantities, to generate a modified Fenton process on the surface of the pillared clays with a possible activation of the hydrogen peroxide and the organic substances on the iron sites of the solids in order to obtain active and stable catalysts for the wet peroxide oxidation of organic pollutants from industrial wastewaters. The catalysts were very efficient in the reaction of phenol oxidation in diluted aqueous media under mild experimental conditions (298K and atmospheric pressure) and in the elimination of the different intermediary compounds of the reaction reaching high-mineralization levels. The solids showed high stability in the reaction media due to the strong interaction between the iron species and the catalyst support. The incorporation of Ce in the solids showed a favorable effect in the pillaring of the materials allowing the increase of the basal spacing and enhancing the catalytic activity of the solids. [Copyright &y& Elsevier]

Al–Fe or Al–Cu modified clays were prepared from two natural montmorillonites and employed in the phenol oxidation with hydrogen peroxide in water. The samples were efficient in phenol elimination under mild experimental conditions (atmospheric pressure, 293 K and small quantities of hydrogen peroxide) without considerable leaching of the metal ions. The clays modified with Fe achieved high conversions of phenol and TOC thus showing to be very selective towards the formation of CO2 and H2O. [Copyright &y& Elsevier]

In the general context of the development of the use of agricultural products for non-food applications, and particularly in the field of the glycerol valorisation (co-product of the triglycerides hydrolysis or methanolysis process), the selective etherification of glycerol was studied. The objective of this work is the direct and selective synthesis, from glycerol and without solvent, of polyglycerols having a low polymerisation degree (di- and/or triglycerol), in the presence of solid mesoporous catalysts. The main part of this study consists in the synthesis and the impregnation of mesoporous solids with different basic elements in order to make them active, selective and stable for the target reaction. The catalytic results obtained show that this impregnation method gives important activity, which must be correlated to an important active species incorporation. Concerning the selectivity of the modified mesoporous catalysts, the best value to (di-+tri-) glycerol are obtained over solids prepared by caesium impregnation. The re-use of these caesium impregnated catalysts does not affect the selectivity to the (di-+tri-) glycerol fraction. In the presence of lanthanum or magnesium containing catalysts, the glycerol dehydration to acrolein is very significant whereas this unwanted product is not formed when caesium is used as impregnation promoter. [Copyright &y& Elsevier]

Presents information on a study which examined the magnetic anisotropy and granulometry of nickel/cerium oxide catalysts. Methodology of the study; Results and discussion; Conclusion.

The decomposition of 1-chloro-4-ethylbenzene under UV irradiation (λ = 253.7 nm) in the presence of dioxygen and the dioxomolybdenum(VI)dichloro[4,4′-dicarboxylato-2,2′-bipyridine] complex anchored on the TiO surface has been investigated. The catalytic cycle includes the photostimulated transfer of the oxo-oxygen atom from the surface dioxomolybdenum(VI) complex to the substrate followed by the oxidation of reduced Mo(IV) by dioxygen (in the absence of UV irradiation). The major reaction products are chlorobenzene, CO, and HO. Chlorobenzene results from the photocatalytic decomposition of intermediate 4′-chloroacetophenone under the reaction conditions. [ABSTRACT FROM AUTHOR]

Abstract: Commercial relevance of glycerol as a biosourced safe organic building block for valuable commodity chemicals has increased considerably with the rapid development of oleochemistry. Among the various reaction pathways for catalytic conversion of glycerol, oligomerization to polyglycerols (PGs) is one of the viable and demanding processes due to the wide field of applications of PGs in cosmetics, polymers, food-additives, antifogging film industry, pharmaceuticals, biomedicals and drug delivery systems. This short review is dedicated to the selective synthesis of polyglycerols preferentially to low molecular-weight oligomers with emphasis on the pros/cons of reported homogeneous and heterogeneous acidic and basic catalytic processes. In addition, recent advances conducted in our laboratory will be given for a selective glycerol oligomerization in the presence of powdered and shaped alkaline earth-based mesoporous catalysts and of hydrothermally synthesized layered structured materials as newly developed basic catalysts. Some critical issues and challenges regarding the rational design of solid catalysts with emphasis on their stability in hot glycerol as well as alternative reaction engineering to overcome the drawbacks stemming from batch reactions will be addressed. Selectivity to the desired fraction of short-chain oligomers for food and cosmetic applications with respect to the European Union regulations will be also introduced. [Copyright &y& Elsevier]

Abstract: Hydrothermally synthesized Ni-containing 1:1 and 2:1 phyllosilicates (PS) were used as catalyst precursors for the CO2 reforming of CH4 to synthesis gas. The textural properties of the reduced and unreduced Ni-based PS were determined by N2 sorption analyses. In situ X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM) experiments were used to characterize the generated Ni0 nanoparticles after reduction of the Ni-containing PS under various conditions such as H2 concentration and temperature. In the case of thermally stable PS (2:1 type), the reduction of structural nickel led to the formation of nanometric Ni0 particles over the surface of the remaining unreduced PS, while for Ni 1:1 PS phases nickel particles were supported on silica only. All catalysts were also investigated in the reverse water gas shift (RWGS) reaction to elucidate the effect of RWGS on the reforming reaction. The catalytic results obtained over reduced Ni-containing 1:1 and 2:1 PS confirmed that CH4 conversion was favored by very small Ni0 particles size, whereas CO2 conversion was catalyst support dependent. Our study demonstrated that a number of side reactions can compete with CO2 reforming of CH4 over Ni-containing phyllosilicates. However, by choosing the suitable phyllosilicate structure as catalyst precursor, as well as appropriate reduction conditions and reaction temperature, it may be possible to suppress the parallel reactions to some extent, thereby increasing the selectivity towards the products of the reforming reaction (H2 and CO). Reduced Ni-containing 2:1 PS proved to be stable even at high temperature. Highly dispersed homogeneously sized supported nanometric Ni0 particles over the remaining unreduced 2:1 PS structure are the key factors for high catalytic activity in CO2 reforming of CH4. [ABSTRACT FROM AUTHOR]

A mesoporous SBA-15 doped iron oxide (Fe2O3/SBA-15) was synthesized by co-codensation, characterized and used as heterogeneous catalysts for the photo-Fenton decolorization of azo dye Orange II under UV irradiation. Response surface methodology (RSM) was used to investigate operating condition effects, such as hydrogen peroxide concentration, initial pH and catalyst loadings, on the decolorization rate. UV irradiation is found to enhance the activity of the catalyst in the process. RSM analysis evidenced the influence of the initial pH value and H2O2 concentration on the dye degradation rate. The coupled UV/Fe2O3/SBA-15/H2O2 process at room temperature is revealed as a promising friendly process for wastewater treatment. Indeed, the use of a heterogeneous catalyst allows an easy active phase recycling without multi-step recovering while the heterogeneous catalyst used here exhibits high catalytic activity for the reaction considered. [ABSTRACT FROM AUTHOR]

Abstract: A lumped thermal model was developed in order to analyse the transient gas temperature rise and fall in a dielectric barrier discharge reactor. A laboratory reactor was employed to validate the model by means of the experimental data. It has been shown that this simple model is of sufficient accuracy for engineering applications. [Copyright &y& Elsevier]

Abstract: Iron-based mesoporous silica materials were prepared according to different impregnation and co-condensation procedures. Several complementary techniques, including XRD, TEM/EDX and nitrogen sorption isotherms were used to evaluate the final structural and textural properties of the calcined Fe/SBA-15 materials. While Fe2O3 isolated particles of which the size is close to the silica pore diameter (∼7–8nm) were obtained using classical wet impregnation procedure, smaller iron oxide particles (∼2–4nm) homogeneously dispersed within the hexagonal pore structure of the SBA15 host support were generated by self-combustion of an impregnated iron-glycinic complex. By contrast, the various co-condensation routes used in this work were less efficient to generate iron oxide nanoparticles inside the silica mesopores. Catalytic performances of the materials were evaluated in the case of total phenol oxidation by H2O2 in aqueous solution at ambient conditions. Large differences in terms of catalytic activity and iron species stability were observed. While the impregnated solids proved to be the most active catalysts (highest Fe2O3 nanoparticles dispersion), iron leaching was observed in aqueous solution, accounting for a homogeneous catalytic contribution. In contrast, the co-condensed samples exhibiting larger iron oxide clusters stabilized over the silica surface proved more efficient as active sites in Fenton catalysis. [Copyright &y& Elsevier]

Abstract: Nanometric Fe2O3 particles could be inserted inside the internal pore volume of SBA-15 mesoporous silica when Fe(III) chelates (EDTA, gluconate and citrate) were used as impregnating precursors. Fe(III) nitrate preferentially yields 8nm uniformly sized Fe2O3 clusters that selectively plug the SBA-15 channels through a geometric confinement effect. An oxidative degradation of Fe-chelate precursors yielded Fe(III) oxidic particles of various sizes and dispersion, depending on the nature and geometry of chelate anion. Fe(EDTA) precursors specifically generated Fe2O3 nanoparticles that selectively migrate towards two types of positions where the silica surface exhibits a high curvature. In samples involving low Fe loadings, Fe2O3 particles first creep towards the silica micropore mouths (nests), in which they are readily confined and stabilized. For higher Fe loadings, when most of the micropore nests were filled, oxidic particles eventually settle as a superficial film on the mesopore walls and undergo stabilization onto the surface roughness that can also favors their confinement, as theoretically predicted by Derouane and co-workers. Upon further reduction, as selectively followed by combined cyclic voltammetry and TPR, Fe2O3 readily yield FeO nanoslabs that remain even more efficiently confined within their respective nest positions through a further acid–base type stabilization. [Copyright &y& Elsevier]

Nanometric Fe2O3 particles could be inserted inside the internal pore volume of SBA-15 mesoporous silica and mesoporous alumina supports, when Fe(III) chelates (EDTA, gluconate or citrate) were used as impregnating precursors. The oxidative degradation of the chelating anions was followed by combined TG-DTA. Strong chelate-SiOH interactions (case of bulky EDTA), favored by the mesopore curvature, yield sub-nanometric extremely well dispersed Fe2O3 particles preferentially located at the micropore mouths (confinement effect). Fe2O3 even more strongly interacts with alumina walls, generating either (Fe,Al)2O3 mixed phases or Fe-aluminate micro domains. These iron-based mesoporous alumina composites proved very active catalysts in total oxidation of phenol at ambient conditions, with extremely low iron leaching (0.2%). [ABSTRACT FROM AUTHOR]

Abstract: Laser pyrolysis is a promising and versatile method allowing the synthesis of various nanoparticles, with well defined chemical composition, size and structure. This procedure is based on the interaction of a powerful IR laser beam with a mixture of gaseous or liquid precursors, with one of them absorbing the laser radiation. This paper presents the synthesis of nanoPt/TiO2 and nanoPd/TiO2 by laser pyrolysis and preliminary results about their efficiency for elimination of volatile organic compounds (deVOC). The nanoparticles have been synthesized by adding a metallic precursor in a liquid precursor (titanium isopropoxide). X-ray diffraction, transmission electron microscopy, thermogravimetric analysis and IR spectroscopy have been used to analyse their nanostructures and morphologies. The volatile organic compounds elimination (deVOC) tests performed on these nanomaterials demonstrate that Pd-catalysts are very efficient in the total elimination of chloro-compounds. These catalytic properties are unusual, especially because conventional Pd supported catalysts are generally not used for this application due to a production of a high amount of polychlorinated compounds. These results showed that the laser pyrolysis method allows the synthesis of well dispersed titanium-based catalysts not previously reported in the literature. [Copyright &y& Elsevier]

The perovskite type oxide LaNiO3 was used as starting material for the CO2 reforming of methane. The reaction was studied by a pulse technique using a CH4/CO2 ratio close to one, in order to understand the catalyst behavior. LaNiO3 was reduced prior to the reaction by temperature programmed reduction (TPR) under hydrogen. The catalyst was thus composed of La2O3 and Ni0. We have shown that good catalytic performances were obtained at 700 °C and 800 °C. At 800 °C all the CH4 was transformed whereas the CO2 conversion reached 92% with a H2/CO ratio equal to 0.91. The crystallographic phases present after catalyst stabilization by the reaction depends on the reaction temperature. At 800 °C the only phases present are La2O3 and metallic nickel whereas at 700 °C the spinel phase La2NiO4 was identified leading to the conclusion that the CO2 reforming of CH4 involve consecutive reactions occurring simultaneously in our experimental conditions:Ni0+La2O3+CO2↔CO+La2NiO4 and CH4+La2NiO4→CO+2H2+La2O3+Ni0. [Copyright &y& Elsevier]

Review: 37 refs. [ABSTRACT FROM AUTHOR]

The selective preparation of monoalkylglyceryl ethers (MAGEs) is a task for researchers owing to their broad range of applications. In this work, green feedstocks such as glycidol and alcohols were used to prepare MAGEs under mild reaction conditions (80 °C, 3 h, 0.5 mol % catalyst) in the presence of acid heterogeneous catalysts. Nafion shows the best performances in terms of conversion and selectivity to MAGES and also high stability. A comparison of the environmental performances with the most consolidated pathway from glycerol has shown that the usage of glycidol (recovered as a value-added product from Epicerol process) and Nafion leads to a lower impact on ecosystems. In addition, results achieved from a simplified socio-economic analysis show that the innovative route here proposed has potential (at the laboratory scale) of enhancing potential gains and of reducing the social implications resulting from externalities associated with environmental impacts (e.g., CO 2 equivalents)., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A ferric smectite clay material was synthesized and further intercalated with Al2O3 pillars for the first time with the aim of evaluating its ability to be used as heterogeneous catalyst for the photo-Fenton decolorization of azo dye Orange II. UV irradiation was found to enhance the activity of the catalyst in the heterogeneous photo-Fenton process. Catalyst loading of 0.5g/L and hydrogen peroxide concentration of 13.5mM yielded a remarkable color removal, accompanied by excellent catalyst stability. The decolorization of Orange II followed the pseudo-first-order kinetics for initial dye concentrations from 20 to 160mg/L. The central composite design (CCD) based on the response surface methodology (RSM) was applied to evaluate the effects of several operating parameters, namely initial pH, catalyst loading and hydrogen peroxide concentration, on the decolorization efficiency. The RSM model was derived and the response surface plots were developed based on the results. Moreover, the main intermediate products were separated and identified using gas chromatography-mass spectrometry (GC-MS) and a possible degradation pathway was proposed accordingly. The acute toxicity experiments illustrated that the Daphniamagna immobilization rate continuously decreased during 150min reaction, indicating that the effluent was suitable for sequential biological treatment., (Copyright © 2015 Elsevier B.V. All rights reserved.)

This work describes the removal of tetracycline (TC) from aqueous solution using a mesoporous alumina (meso-Al2O3) as adsorbent in the presence of ultrasonic irradiation. Adsorption of TC was investigated under various operating conditions, including pH, adsorbent dosage, ultrasound power, and initial TC concentration. The results showed that the rate of TC sorption was enhanced with the assistance of ultrasound. The TC removal increased with the increase in sorbent dosage, pH and ultrasound power, but decreased with the increase in initial TC concentration. The adsorption isotherm data were fitted properly with the Freundlich model under ultrasonic irradiation, and the adsorption process followed a pseudo-second-order kinetic model.

MCC Hammer: Microcrystalline cellulose (MCC) is dissolved and subsequently regenerated in a CO2 -based switchable solvent system, drastically reducing its crystallinity index and thereby its recalcitrance to hydrolysis. Among the investigated systems, based on cheap, widely available chemicals, is one capable of dissolving up to 15 wt % MCC within 1 h at room temperature. Break it down!, (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The intershell spacing in different regions of a multi-walled carbon nanotube (MWCNT) was determined by analysis of high resolution transmission electron (HR-TEM) micrographs. Three general effects can be pointed out, (1) the regular intershell spacing of a CNT is bigger than that in a graphitic carbon because the curvature generates geometrical and electronic deformations which increase repulsion forces between the graphene sheets, (2) when an extra curvature appears, e.g. at the tip of a closed CNT or in a bamboo-like structure, the intershell spacing is expanded due to the extra repulsion caused by the combination of pentagonal and heptagonal rings imbibed in the hexagonal lattice, and (3) when a metal particle interacts with a CNT, the intershell spacing is compressed due to strong metal-CNT interactions., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Fête DES sciences: The dehydration of fructose and inulin to HMF is conveniently performed in a cheap and sustainable choline chloride/CO(2) deep eutectic solvent (DES) system. The medium is capable of converting high contents of fructose (>100 wt %) without affecting the yield of HMF (up to 72 %). The purity of the recovered HMF is >98%, and the reaction medium can be recycled., (Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Ionic liquids (ILs) can be partially substituted by glycerol or glycerol carbonate as cheap, safe, and renewably sourced co-solvents in the acid-catalyzed dehydration of fructose and inulin to 5-hydroxymethylfurfural (HMF). In the particular case of glycerol, we found that HMF can be conveniently extracted from the IL/glycerol (65:35) mixture with methylisobutylketone, limiting the reactivity of glycerol with HMF and allowing the recovery of HMF with a high purity (95 %). Influences of the fructose content, temperature, and the nature of the ionic liquid are also discussed. The possible use of industrial-grade glycerin is also investigated. We demonstrate that by using glycerol carbonate, up to 90 wt % of the IL can be successfully substituted, decreasing the environmental costs of traditional IL-based processes.

Here we report that sulfonated crystal-like benzene-silica is much more robust and active than conventionally used periodic mesoporous silica for catalyzing aqueous organic reactions.

Glycerol is the main co-product of the vegetable oils industry (especially biodiesel). With the rapid development of oleochemistry, the production of glycerol is rapidly increasing and chemists are trying to find new applications of glycerol to encourage a better industrial development of vegetable oils. In this Review, attention is focused on the selective use of glycerol as a safe organic building block for organic chemistry. An overview is given of the different heterogeneous catalytic routes developed by chemists for the successful and environmentally friendly use of glycerol in sustainable organic chemistry. In particular, the effects of different catalyst structural parameters are discussed to clearly highlight how catalysis can help organic chemists to overcome the drawbacks stemming from the use of glycerol as a safe organic building block. It is shown that heterogeneous catalysis offers efficient routes for bypassing the traditional use of highly toxic and expensive epichlorohydrin, 3-chloro-1,2-propanediol, or glycidol, which are usually used as a glyceryl donor in organic chemistry.

Coating of silica-supported sulfonic acid catalysts with hydrophobic ionic liquid leads to a significant improvement of catalyst selectivity. Many organic reactions, including Prins cyclization, cycloaddition of epoxide to aldehyde, and dehydrative etherification of secondary benzyl alcohols, proceed well in formalin or pure water. In particular, tandem dehydration/Prins cyclization reactions of tertiary and secondary alcohols with formaldehyde were developed for the first time.

Thanks to strong hydrophilic interactions between reaction products and the catalyst surface, mesoporous silica supported sulfonic sites were found to be much more selective than homogeneous and common solid acid catalysts.