Current Catalysis - Volume 3, Issue 3, 2014

The catalytic activity of pyrite ore from coal mining was studied in the direct liquefaction process of high volatile bituminous coal from the south of Brazil. The process consisted of mixing pulverized coal with tetralin in the presence of catalyst. It was possible to obtain fractions of preasphaltenes, asphaltenes, and oils. Pressure had little influence on the direct coal liquefaction process, while temperature had a strong effect on liquefaction yields. The results of total conversions obtained were nearly 16 % at 300 °C, 26.5 % at 350 °C and 38.5 % at 380 °C, in spite of high inertinite-group maceral content (34 vol.%). The pyrite ore catalyst had a fundamental role in this reaction, leading to thermal cracking of the coal structure and hydrogenation of the fragments. However, the most significant result related to catalyst presence was the increase in selectivity of the oil fraction.

Zirconium (IV) tetradentate Schiff base (salphen) complex has been successfully used for efficient condensation of various 1,2-diamine and 1,2- dicarbonyl compounds in EtOH as a standard green solvent under mild conditions. The investigation of turnover number and reusability of the catalyst indicate well the high efficiency and relative stability of the Zr-complex in this reaction.

A direct, simple and green protocol describes synthesis of 1H-pyrazolo[1,2-b] phthalazine-5,10-diones and 2Hindazolo[ 2,1-b] phthalazine-triones derivatives using deep eutectic mixture (choline chloride: malonic acid) as a homogeneous catalyst as well as solvent at reflux temperature. This method provides significant advantages such as short reaction time, easy workup, and high yield of product, atom economy and recyclability of catalyst.

This work reports environmentally benign route for the hydroarylation of styrene with p-cresol for the synthesis of 4-methyl-2-(1-phenylethyl)phenol. The Montmorillonite K-10 was found to be stable, active, economical and recyclable catalyst for the hydroarylation reaction. The catalyst is well characterized with various techniques like XRD, SEM, EDAX, BET surface area, TPD-TPR and TGA. The effect of different reaction parameters like speed of agitation, catalyst loading, mole ratio and temperature was investigated. Furthermore, a second order rate equation was developed to describe the reaction kinetics and validated with experimental results. The activation energy was found to be 45.48 kcal/mol.

In this work, the synthesis of silver (Ag) supported on hierarchically porous silica (SiO2), and cobalt oxide (Co3O4) monoliths and the catalytic activity of these monoliths for the hydrogenation of methylene blue (MB) and methyl orange (MO) dyes in water is reported. The SiO2 monoliths were synthesized using a sol-gel technique. The Co3O4 monoliths were prepared by nanocasting, using the SiO2 monoliths as template. Loading of Ag nanoparticles on the SiO2 and Co3O4 monoliths, was done by a solution infiltration method using aqueous silver nitrate (AgNO3) solution followed by reduction with ethylene glycol. The resulting monoliths were characterized by XRD, BET-SA, and SEM, and the catalytic activity of the monoliths was studied for the hydrogenation of MB and MO by sodium borohydride (NaBH4). Careful control experiments allowed the overall rate of the Ag catalyzed reaction to be corrected for the rates of the non-catalyzed reaction and the rates of dye adsorption on the supports and Ag nanoparticles. Ag supported on SiO2 gave the fastest hydrogenation for MB, Ag on Co3O4 gave the fastest MO hydrogenation.

Solvent-free Claisen-Schmidt condensation (CSC) for the synthesis of chalcone has been studied using MoO3/ZrO2 material as solid acid catalyst. A series of MoO3/ZrO2 catalysts with various MoO3 loadings (10-30 wt%) were prepared using modified precipitation method. The catalysts were extensively characterized using various techniques viz., TG-DTA, XRD, N2 Sorption, BET-surface area, NH3-TPD, Raman and FT-IR spectroscopies, AAS, EDX, TEM and SEM. The detailed parametric studies were carried out to optimize the reaction parameters in order to achieve maximum selectivity with high % yield of chalcones. Substituted benzaldehyde and acetophenone were used as reactants to study the effect of electron withdrawing and electron donating groups on the activity of catalyst. 15 wt% MoO3/ZrO2 catalyst prepared using modified preparation technique proved to be an excellent heterogeneous catalyst for solvent free synthesis of chalcone with yield as high as 93 %, by using only 1.5 wt% of catalyst.

A dual carbon-carbon bond formation between 2,3-dibromo-1,4-naphthoquinone and terminal alkynes in EtOH was efficiently facilitated by a combination of catalysts e.g. 10%Pd/C-Cu-PPh3 affording a handy and single-step synthesis of 2,3-diyne-1,4-naphthoquinones. The methodology afforded desired products possessing potential medicinal value in acceptable yields. A probable mechanism accounting the dual C-C bond forming reaction has been proposed.

In the present work, silica supported imidazolium based sulphonic acid was developed via a simple route as a hybrid organic-inorganic solid acid catalyst. The covalent anchoring to the silica support gave a stable catalyst in quantitative yield, while the ionic tag assisted in increasing the solubility of the reactants to facilitate the reaction under solventless conditions, being a homogeneous -heterogeneous catalytic system and having the distinct advantages of both. The catalytic efficacy of the solid acid catalyst was tested for the N-Boc protection of amines. The reactivity order followed by amines was aliphatic >aromatic> hetrocyclic>aminoalcohols. This efficient protocol has advantages of better workability of catalyst, reduced reaction time, improved yield, high TON and the catalyst is both recyclable and recoverable upto seven cycles.

The ability of five substances – Amberlite IRA-900 anion exchange resin in the Cl- form, CuCl4 2- supported on Dowex 2-X8 anion exchange resin (CuCl4 2-/Dowex), FeCl4- supported on Dowex 2-X8 (FeCl4-/Dowex), FeCl3 supported on silica gel (FeCl3/SiO2), and unmodified MCM-41 mesoporous silica – to catalyze the photodecomposition of chloroform to COCl2 and HCl in a suspension irradiated under oxygen at wavelengths above 345 nm was compared, choosing amounts of each catalyst to optimize the decomposition rate. Amberlite, FeCl4-/Dowex, and MCM-41 were the most active. The same comparison was made for chloroform irradiated under air by sunlight, for which Amberlite, CuCl4 2- /Dowex, and MCM-41 were the most active. After irradiation, all samples had a COCl2 to HCl ratio greater than 10:1. A photodecomposition mechanism different from that observed in the gas phase is proposed that includes the participation of trichloromethylhydroperoxide.