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An efficient and convenient method for synthesis of 7,10,11,12-tetrahydrobenzo[c]acridin-8(9H)-one derivatives using Cu/MCM-41 (20 mg) as heterogeneous catalyst. The advantages have an excellent product yield within a short time and easy work-up procedure, and the products have directly recrystallized from hot methanol with cost-effective catalyst. One-pot three-component reaction from aromatic aldehydes, cyclic 1,3-dicarbonyl compounds, and 1-naphthyl amine has been carried under ethanol as a solvent with reflux condition. Moreover, the catalyst can be recovered conveniently and reused efficiently, and recyclable. [ABSTRACT FROM AUTHOR]

Hierarchical TS-1 materials were synthesized using hydrothermal synthesis and a post modification technique through desilication. They were evaluated for hydroxylation of anisole to produce industrially important chemicals, o-methoxyphenol (OMP) and p-methoxyphenol (PMP). The detailed characterization of the prepared catalysts, such as morphology, structure, nature of Ti and surface area were obtained by SEM, HR-TEM, XRD, UV-VIS spectroscopy and the BET technique. The effects of various operational parameters such as substrate/H2O2 molar ratio, reaction temperature, catalyst concentration and solvent effect on the hydroxylation of anisole have been studied in detail. The microporous TS-1 catalyst showed 32% anisole conversion with 34% selectivity to PMP, while the micro/mesoporous DTS-1 catalyst showed enhanced activity for anisole hydroxylation, i.e. 54% conversion with 55% selectivity towards PMP. The increased framework Ti and improved accessibility of the active sites located in the channels of DTS-1, which permit the mass transfer of reactants, transition states and products from the mesopores of DTS-1, were responsible for the enhanced catalytic activity and selectivity towards p-methoxyphenol. [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]

Esterification of glycerol with acetic acid has been studied with different solid acid catalysts, prepared by impregnating phospotungustic, silicotungstic, and phosphomolybdic acids on polymeric material polyvinylpyrrolidone. These results were compared with commercially available montmorillonite KSFO catalyst showed that PVP-DTP gave higher selectivity to di- and triacetins. This study was mainly focused on increasing the selectivity toward triacetin which is an excellent alternative to fossil fuel based fuel additives. The detail characterization was done for the PVP-DTP catalyst which gave complete conversion of glycerol and maximum selectivity of 34% toward triacetin. Complete conversion of glycerol was achieved at 110 °C within 6 h of reaction time. The characterization of the catalyst was performed by SEM/EDX, X-ray diffraction, thermogravimetic techniques, and FT-IR analysis.TPD-NH3 characterization showed that DTP supported on PVP increases the catalyst acidity of PVP. The highest acidity of PVP-DTP is also confirmed using NH3-TPD analysis. [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]

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]

Non-chromium Cu:Al nano catalyst prepared by simultaneous co-precipitation and digestion method without any template or stabilizer, showed three times higher activity than the bulk Cu–Cr catalyst for hydrogenolysis of glycerol in both isopropanol and water solvents, with the selectivity to 1,2-Propanediol (1,2-PDO) as high as 91% at 493 K and H2 pressure of 7 MPa in 5 h. XRD pattern showed the presence of Cu+ species in the activated Cu:Al nano catalyst. Although Cu+ is catalytically inactive in glycerol hydrogenolysis reaction, the presence of Cu+ helps to stabilize the particle size in a narrow range of 7–11 nm by inhibiting the sintering of copper particles under reaction conditions. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The effects of acidity and variation in concentration of acid sites of dodecatungstophosphoric acid (DTP), supported DTP and montmorillonite-K catalysts were studied for various organic reactions such as the hydroxyalkylation of phenols to bisphenols, intramolecular rearrangement of benzyl phenyl ether (BPE) to 2-benzyl phenol (2-BP) and selective cleavage of tert-butyldimethylsilyl (TBDMS) ether into the corresponding alcohol. Both dodecatungstophosphoric acid (DTP) impregnated on silica (SiO2) and montmorillonite catalysts showed the highest catalyst activity with 90-95% selectivity to bisphenol for the hydroxyalkylation of phenols to give bisphenol. Temperature Programmed Desorption (TPD) of ammonia and activity results of various catalysts showed that an appropriate combination of both strong and weak acidic sites in the catalyst was highly desirable for high bisphenol selectivity. A 10% DTP/SiO2 catalyst was found to be highly selective for the cleavage of TBDMS ether into the corresponding alcohol at room temperature giving a high TON of 9.5 x 105 even after the 4th recycle. DTP was also found to be a promising solid acid catalyst for the intramolecular rearrangement of BPE giving 2-BP. [ABSTRACT FROM AUTHOR]

Liquid phase oxidation of p-cresol was carried out over a Co-saponite catalyst in a temperature and pressure range of 333–393 K and 20–827 kPa, respectively in n-propanol. Co-saponites with varying cobalt content (5–30%) were prepared and screened among which 13% Co-saponite gave the highest conversion of 92% of p-cresol with 92% selectivity to p-hydroxybenzaldehyde without formation of any non-oxidation products. [ABSTRACT FROM AUTHOR]

The hydrogenation behavior of tetralin in the presence and absence of benzothiophene was studied over a charcoal-supported rhodium catalyst in supercritical carbon dioxide solvent. The catalyst activity, as well as cis-decalin selectivity, decreased in the presence of benzothiophene. [ABSTRACT FROM AUTHOR]

Abstract: An heteropoly acid (phosphotungstic acid, PTA) was found to be a promising solid acid catalyst as an alternative to the conventional stoichiometric reagents for the rearrangement of benzyl phenyl ether giving 2-benzyl phenol as a major product and 4-benzyl phenol and dibenzylated phenols as side products. Catalyst was recovered from the reaction mixture and reused again without loss of activity. Based on the observed product distribution for various substrates a plausible catalytic reaction pathway has also been proposed. [Copyright &y& Elsevier]

Catalytic hydrogenation of naphthalene to decalin was studied over a carbon-supported rhodium catalyst in supercritical carbon dioxide solvent at 333 K, and the results were compared with those in an organic solvent. cis-, trans-Decalin and tetralin were formed from the beginning of the reaction in supercritical carbon dioxide. Higher concentration of hydrogen in carbon dioxide solvent and on the active site, and also the suppression of desorption of partially hydrogenated tetralin molecules from the active site would be responsible for higher selectivity to cis-decalin in supercritical carbon dioxide than that in an organic solvent. [ABSTRACT FROM AUTHOR]

Presents a study which examined the activities of various catalysts for the hydrogenation of tetralin to cis-decalin. Importance of hydrogenation of tetralin for the production of a high performance diesel fuel; Advantages of hydrogenation with supported metal catalysts in supercritical carbon dioxide solvent; Reaction profile for the hydrogenation of tetralin.

cis-4-tert-Butylcyclohexanol was obtained with a high cis ratio (cis/(cis + trans) = 0.9) in the hydrogenation of 4-tert-butylphenol over a carbon-supported rhodium catalyst along with hydrochloric acid in supercritical carbon dioxide solvent. [ABSTRACT FROM AUTHOR]

Abstract: Nano-structured, spinel Co3O4 catalyst was developed for the aqueous phase oxidation of veratryl alcohol, which showed the highest conversion of 85% with 96% selectivity to veratryl aldehyde. The co-existence of Co3+ and Co2+ species in the octahedral and tetrahedral positions respectively, was confirmed by XPS, cyclic voltammogram, TPR and TPO characterization. The rod-like morphology of Co3O4 catalyst was confirmed by HRTEM. The effects of various reaction parameters namely, catalyst concentration, temperature and partial oxygen pressure on conversion and selectivity patterns were also studied for the oxidation of veratryl alcohol. This catalyst also showed an excellent stability as evidenced by successful reusability for three times. [Copyright &y& Elsevier]

Abstract: Hydrogenation of benzothiophene-free naphthalene was examined over various transition metal (rhodium, ruthenium, palladium, and platinum) catalysts supported on charcoal in supercritical carbon dioxide (scCO2) solvent at low temperature (313K). Among these, a charcoal-supported rhodium catalyst was found to be the most active, while a charcoal-supported ruthenium catalyst was found to give the highest cis-decahydronaphthalene (cis-decalin) selectivity. A systematic investigation of hydrogenations of naphthalene and tetrahydronaphthanele (tetralin) in scCO2 revealed that naphthalene hydrogenation is a consecutive and cis- and trans-decalin were formed via tetralin. [Copyright &y& Elsevier]