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Efficient carbonylation of glycerol using urea with Zn‐Co mixed metal oxide (MMO) catalyst has been achieved. Various methods of catalyst preparation were explored for glycerol carbonate (GC) synthesis. The optimized method of catalyst preparation was found to be co‐precipitation (CP) with a Zn:Co ratio of 70:30, achieving 81% glycerol conversion with 97% GC selectivity. X‐ray diffraction (XRD) studies revealed the formation of ZnO, Co3 O4, and spinel ZnCo2O4 phases. Thermal treatment given to the catalyst allows insertion of Zn cations into Co3O4 lattice forming ZnCo2O4 phase which was also evidenced in X‐ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Herein, for the first time, reaction kinetics was studied to propose the rate equation, based on which a plausible reaction pathway is proposed involving two‐site adsorption of glycerol (basic site) and urea (acidic site), which undergo carbonylation followed by cyclization into GC. A recycle study and hot filtration test have proven the reusability of the catalyst. [ABSTRACT FROM AUTHOR]

Catalytic synergism was observed for a bimetallic Pd−Ir catalyst supported on activated carbon for chemoselective hydrogenation of 5‐hydroxymetahyl furfural (5‐HMF) to 2, 5‐(bishydroxymethyl) furan (BHMF) with complete conversion and 97 % selectivity under very mild reaction conditions. The structural characterization like XRD, N2 sorption, FE‐SEM and TEM suggested formation of fine nanoparticles (1.95–3.08 nm) having very higher surface area, uniform distribution and mesoporous nature of the material. XPS spectra and Pyridine‐IR spectroscopy revealed formation of Pd‐PdO and Ir/IrO2/IrO3 interface on the catalytic surface along with strong Brönsted acidic sites which were responsible for high efficiency of catalyst at 80 °C, 100 psig H2 pressure at 5‐HMF/Catalyst=20 and within 2.5 h of reaction time. A plausible reaction mechanism is also elucidated based on structure activity correlation. [ABSTRACT FROM AUTHOR]

Synthesis of levulinate esters which are known to be excellent sustainable fuel additives, was achieved by alcoholysis of furfuryl alcohol over strong solid acid catalyst, prepared by copolymerization of p‐toluenesulfonic acid with paraformaldehyde. Our catalyst possessed Brønsted acidity (3 mmol/g) with an excellent stability up to 220 °C. XPS, FT‐IR and Pyridine‐IR along with microanalysis studies confirmed the presence of terminal −SO3H functional groups responsible for Brønsted acidity in the catalyst. The catalyst was found to efficiently catalyze the alcoholysis of furfuryl alcohol to give alkyl levulinates under mild reaction conditions. The complete conversion of furfuryl alcohol with 96 % and 97 % selectivities to ethyl and butyl levulinates could be achieved using ethanol and butanol, respectively. Detailed study on effect of various reaction parameters like catalyst loading, reaction time and reaction temperature on conversion and product distribution was also carried out for the ethanolysis of furfuryl alcohol to ethyl levulinate. The catalyst could be easily recovered and recycled for five times successfully, with no loss in its original activity. [ABSTRACT FROM AUTHOR]

Efficient and highly selective isomerization of glucose to fructose was achieved by using the inexpensive Ba−Zr mixed metal oxide catalyst. Catalyst was prepared by varying Ba−Zr ratios using co‐precipitation method. Various phases formed, planes exposed, morphology, elemental composition and particle size, basic site density and strength, oxidation state of elements were well studied by using various characterization techniques. The XRD analysis clearly indicates the presence of Ba+2 and Zr+4 in the form of BaO, ZrO2 and BaZrO3 phases. The SEM and HR‐TEM images indicate that, Ba−Zr (2 : 1) catalyst prepared showed uniform morphology with spherical and rod‐shaped particles ranging from 300 to 600 nm. Under the optimized reaction conditions Ba−Zr (2 : 1) catalyst exhibited excellent results in terms of 57 % of glucose conversion with 89 % selective formation of glucose. The presence of both acidic as well as basic sites play vital roles in activating the substrate molecules to selectively yield fructose. Ba−Zr (2 : 1) catalyst showed excellent recyclability performance up to four recycles. [ABSTRACT FROM AUTHOR]

2‐Methyltetrahydrofuran is a valuable commercial product that can be obtained by direct hydrogenation of furfural. In the present study, among several carbon supported bimetallic Ir−Ni catalysts with different loadings screened, 4% Ir‐4% Ni/C catalyst showed excellent activity in terms of direct conversion (99%) to 2‐MeTHF with a maximum selectivity of ∼74% at 220 °C and 750 psig, suppressing the formation of side chain as well as ring opening products. The catalytic activity was found to be mainly affected by catalyst preparation methods, metal loadings, surface composition, temperature, pressure and catalyst loading. HR‐TEM and STEM revealed well dispersed Ir−Ni NPs having the particle sizes in the range of 2 to 5 nm. Different phases of Ir i. e. Ir° and IrO2 as well as oxygen vacancies were found to be responsible for hydrogenation of furfural to 2‐methyl furan while, Ni° and NiO were responsible for further hydrogenation to 2‐MeTHF. The synergic effect between Ir and Ni was established through XPS, H2‐TPR analysis. With the help of some control experiments, the plausible reaction pathway was also proposed. The catalyst prepared by co‐impregnation method found more effective than prepared by sequential addition method. At lower Ni loadings of 1% and 2%, low temperature of 160 °C as well as at low H2 pressure of 250 psig, mixture of furfuryl alcohol and 2‐methyl furan were formed selectively. Catalyst could be successfully reused up to 3 times without leaching of metals. [ABSTRACT FROM AUTHOR]

Efficacious waste utilization is vital in context of sustainability. The past decade has witnessed attempts of usage of land biomass and wastes for various applications, contributing towards a sustainable society. Exploitation of the marine biomass, which does not compete with habitation and food production like land biomass has been largely unnoticed and therefore not being utilized judiciously. Researchers have mainly exploited these resources as functional materials having significant potential applications. However, a catalytic perspective for the valorisation of these polymers arising from oceanic waste widens their scope and ameliorates its use. The objective of the present review is to demonstrate the effectiveness of chitin/chitosan as a catalyst and as a feedstock for deriving important fuels and chemicals. It displays all the reactions heterogeneously catalyzed by them along with the strategic methodology. Their important catalytic organic transformations attempted so far, have also been discussed. The future perspectives are also presented which if inculcated would improve the value addition of the waste, paving a way for greener and imperishable world. [ABSTRACT FROM AUTHOR]

The combination of supported rhodium metal catalysts and supercritical carbon dioxide solvent was effective for the stereoselective ring hydrogenations of aromatic compounds at low temperature. Higher solubility of hydrogen in supercritical carbon dioxide provides higher concentration of hydrogen on the rhodium surface, but lower that of the intermediate on rhodium surface, which suppresses the flipping of surface intermediate, leading to higher catalyst activities and cis selectivities to the corresponding ring‐hydrogenated products as compared with those in organic solvents. [ABSTRACT FROM AUTHOR]

Bentonite clay supported cuprous iodide nanoparticles (BENT‐CuI NPs) were prepared and demonstrated for the first time as an efficient heterogeneous catalyst in diversity oriented, green synthesis of 1,2,3‐triazoles by one‐pot, three component reaction between alkyl halides, arylboronic acids, or epoxides with alkynes and sodium azide in aqueous medium. The catalyst was characterized by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP‐AES), Energy Dispersive X‐ray Spectroscopy(EDS), Scanning Electron Microscopy (SEM), X‐Ray Powder Diffraction (XRD), Transmission Electron Microscopy (TEM) as well as Brunauer‐Emmett‐Teller (BET) techniques and was found to be reusable for five consecutive runs without significant loss of activity. [ABSTRACT FROM AUTHOR]

Etherification of furanic compounds such as furfuryl alcohol (FA) and 5‐(Hydroxymethyl) furfural (5‐HMF) to the corresponding ethers was successfully achieved over Zr‐SBA‐15 catalyst. For this purpose, various Zr‐SBA‐15 catalysts with different Zr/Si molar ratios in self‐generated acidic environment were prepared by one‐pot strategy in self‐generated acidic environment. XRD analysis revealed the increase in the d‐spacing from 9.021 nm for parent SBA‐15 to 11.66 nm for Zr‐SBA‐15, confirming the incorporation of Zr into the framework without disturbing the mesoporous structure of SBA‐15. For the lowest Zr concentration of 0.09 M, hexagonally ordered porous structure was found to be retained as confirmed by TEM while, increase in Zr/Si molar ratio to 0.14, resulted in loss of long range order mesoporosity. The presence of both Lewis and Brønsted acid sites in Zr‐SBA‐15 catalyst as evidenced by py‐IR, were due to the introduction of Zr in the frame work of SBA‐15. The co‐existence of Lewis and Brønsted acid sites in Zr‐SBA‐15 was responsible to catalyze etherification of FA and esterification of levulinic acid producing 2‐(Ethoxymethyl) furan and ethyl levulinate selectively, both of which are bio‐derived fuel additives. Dual‐sites For Fuel (DFF) The adjacent Lewis and Brønsted acid sites introduced due to Zr incorporation into the mesoporous SBA‐15 catalyzed the etherification of furfuryl alcohol with 92% selectivity to 2‐(Ethoxymethyl) furan (2‐EMF). This catalyst was successfully explored for C1‐C4 alcohols for etherification of furfuryl alcohol (FA), 5‐(hydroxymethyl) furfural (5‐HMF) and levulinic acid (LA). [ABSTRACT FROM AUTHOR]

A new protocol of cascade synthesis for biologically active 2-cyanoacrylamides ( 1) was developed. The reaction proceeds over a novel magnetically retrievable solid-acid composite of iron oxide, poly(vinylpyrrolidone) and phosphotungstic acid (Fe3O4/PVP-PWA) in AcOH-H2O medium under reflux conditions. This transformation is facilitated through single-site Brønsted acid catalyzed cascade reactions involving deacetalization and/or Knoevenagel condensation followed by selective monohydration of nitriles starting from acetals ( 5) and aldehydes ( 2) with malononitrile ( 3). A series of aldehydes, dimethyl and diethyl acetals, along with some heterocyclic aldehydes were successfully transformed to 2-cyanoacrylamides with >95 % yields. TEM images confirmed the coating of the PVP over nanosized Fe3O4. Stereoselective monohydration of 2-benzylidenemalononitriles ( 4) to E isomers was demonstrated by NOESY experiments. The catalyst could be efficiently recycled seven times on employment of both acetals and aldehydes as substrates, as a result of its magnetic nature. [ABSTRACT FROM AUTHOR]

A composite of graphene oxide (GO) with mixed oxide (MnCo) was prepared by using a solvothermal method. During the synthesis, both the reduction of GO and growth of metal oxides took place simultaneously. The as-prepared composite material was highly selective for the liquid-phase oxidation of p-cresol to form p-hydroxybenzaldehyde in 71% yield within 1 h. The composite material was characterised by SEM, X-ray photoelectron spectroscopy, high-resolution TEM and cyclic voltammetry (CV). A CV study revealed that the increase in the redox potential of the mixed oxide after being supported on GO, led to its higher activity of the catalyst for the oxidation reaction. The stability of the catalyst under the reaction conditions was studied by its successful reuse in three cycles. [ABSTRACT FROM AUTHOR]

We investigated various Cu species responsible for highly efficient Cu-Al oxide catalyst for the water-gas shift reaction (WGSR). The formation of various Cu species was achieved by systematically varying the Cu-Al composition in the coprecipitated mixed Cu-Al oxides. The Cu-Al composition of 70:30 (Cu-Al-7) was the best for WGSR using the reformate gas composition. In addition, the Cu-Al-7 catalyst reduced under 100 % H2, was relatively stable with time on stream of 100 h, at higher gas hourly space velocity of 36 201 h−1.The structural investigation of our coprecipitated catalysts with varying Cu-Al compositions revealed the formation of nonzero oxidation state copper and metallic Cu to be essential for the observed WGSR activity. In addition, the highest activity and stability of Cu-Al-7 catalysts reduced under 100 % H2 at lower temperature was attributed to particle-size stabilization and a lower extent of Cu aggregation by Cu2O and boehmite phases, respectively, along with the formation of various Cu species during the activation protocol for 12 h. Complete CO2 selectivity without methanation was observed for all the Cu-Al compositions irrespective of their pretreatment conditions. [ABSTRACT FROM AUTHOR]

A novel, nonleachable hybrid of heteropoly acid and polyvinylpyrrolidone (or povidone) catalyzes the acetalization of aldehydes in methanol at room temperature followed by reaction with indole to give bis(indolyl)methanes (BIMs) and tris(indolyl)methanes (TIMs) in quantitative yields (90-97 %). The catalyst was shown by pyridine FTIR spectroscopy to possess Brønsted acidity, and the hybrid formation was confirmed by XRD and 31P NMR studies. Friedel-Crafts alkylation of indole as well as the tandem synthesis of BIMs and TIMs were established with several types of carbonyl and indole substrates to give the corresponding products quantitatively. The catalyst was recycled efficiently for three successive runs without losing its original activity. [ABSTRACT FROM AUTHOR]

Manganese-doped cobalt mixed oxide (MnCo-MO) catalyst was prepared by a solvothermal method. The as-prepared catalyst was characterised by X-ray photoelectron spectroscopy, H2 temperature-programmed reduction, O2 temperature-programmed oxidation and XRD. This catalyst gave 62 % conversion with 83 % selectivity to vanillin in 2 hours for the liquid-phase air oxidation of vanillyl alcohol without using base. Three different types of metal oxides were observed in the prepared catalyst, which could be identified as Co3O4, Mn3O4 and CoMn2O4. Among these, the tetragonal phase of CoMn2O4 was found to be more active and selective for vanillyl alcohol oxidation than Co3O4 and Mn3O4. High-resolution TEM characterisation revealed the morphology of MnCo-MO nanorods with a particle size of 10 nm. Successful recycling of the catalyst was also established in this oxidation reaction. [ABSTRACT FROM AUTHOR]

The success of diffraction experiments from weakly scattering samples strongly depends on achieving an optimal signal-to-noise ratio. This is particularly important in single-particle imaging experiments where diffraction signals are typically very weak and the experiments are often accompanied by significant background scattering. A simple way to tremendously reduce background scattering by placing an aperture downstream of the sample has been developed and its application in a single-particle X-ray imaging experiment at FLASH is demonstrated. Using the concept of a post-sample aperture it was possible to reduce the background scattering levels by two orders of magnitude. [ABSTRACT FROM AUTHOR]

The cover feature highlights the distinct advantages of heterogeneously catalyzed multi-phase hydrogenation in supercritical carbon dioxide solvent, resulting in not only easy separation of products and catalyst, but also control of the product selectivity and activity. Hydrogenation, supercritical carbon dioxide, stereoselectivity, rhodium catalyst. [Extracted from the article]