Cerium d-Block Element (Co, Ni) Bimetallic Oxides as Catalysts for the Methanation of CO2: Effect of Pressure

Nickel– and cobalt–cerium bimetallic oxides were used as catalysts for the methanation of CO2 under pressure. The catalysts’ activity increases with pressure and an increase of just 10 bar is enough to double the yield of methane and to significantly improve the selectivity. The best results were those obtained over nickel–cerium bimetallic oxides, but the effect of pressure was particularly relevant over cobalt–cerium bimetallic oxides, which yield to methane increases from almost zero at atmospheric pressure to 50–60% at 30 bar. Both catalyst types are remarkably competitive, especially those containing nickel, which were always more active than a commercial rhodium catalyst used as a reference (5wt.% Rh/Al2O3) and tested under the same conditions. For the cobalt–cerium bimetallic oxides, the existence of a synergetic interaction between Co and CoO and the formation of cobalt carbides seems to play an important role in their catalytic behavior. Correlation between experimental reaction rates and simulated data confirms that the catalysts’ behavior follows the Langmuir–Hinshelwood–Hougen–Watson kinetic model, but Le Chatelier’s principle is also important to understand the catalysts’ behavior under pressure. A catalyst recycle study was also performed. The results obtained after five cycles using a nickel–cerium catalyst show insignificant variations in activity and selectivity, which are important for any type of practical application.

Rhodium nanoparticles inside well-defined unimolecular amphiphilic polymeric nanoreactors: synthesis and biphasic hydrogenation catalysis

Triphenylphosphine-stabilised rhodium nanoparticles embedded in well-defined core-crosslinked micelles have been generated and used in aqueous biphasic catalysis. The conditions allowing core confinement and efficient catalyst recycle are outlined.

Hydroformylation of Higher Olefins in Aqueous Biphasic Medium Using Rhodium-Sulfoxantphos Catalyst: Activity and Selectivity Study

Hydroformylation of higher olefins such as 1-hexene, 1-octene, 1-decene and 1-dodecene has been studied in an aqueous biphasic medium using water-soluble Rh-sulfoxantphos complex catalyst. The effect of temperature, presence of various co-solvents and concentration of co-solvent on the reaction rate and chemo and regioselectivity was investigated. N-Methyl pyrrolidone (NMP) was found to be the best co-solvent, which enhances the rate dramatically (4-96 fold) as compared to the reactions in aqueous-organic biphasic medium for hydroformylation of higher olefins. Catalyst recycle study was performed to check the leaching of metal in organic phase.

An automated repeating batch with catalyst recycle approach to nitro group hydrogenolysis

An automated repeating batch approach with sequestered catalyst has been applied as a method for nitro group hydrogenolysis.

Ultrasonic-Assisted Biodiesel Production from Palm Oil Using Adsorption of Homogeneous Catalysts over Solid Sodium Silicate

Biodiesel is an alternative energy resources, which produced from transesterification of oils and alcohols using homogeneous and heterogeneous catalysts. Ultrasonic was used as pre-mixer for KOH, Na2SiO3, palm oil and methanol before increasing the reaction temperature to 60°C using a water bath. All experiments were conducted at a molar ratio of methanol:oil of 6:1, reaction time of 60 min, reaction temperature of 60C and well mixing. The suspension was filtered after the end of the reaction. Purified biodiesel was obtained by water washing processes after crude biodiesel was separated from glycerol by 2 hr standing in a separating funnel. Filter solid cake was instantly used as supporter in next batch of the reaction. Effects of four variables, namely, pre-mixing period in the range of 0-10 s, number of filter cake recycle (2-4 cycles), sonicator power (10-90% of max. power of 200 watt and 20 kHz) and amount of KOH addition (0.25-0.75 g) were investigated. Response surface methodology was employed to evaluate and optimize the biodiesel production processes using Na2SiO3adsorbed with KOH as catalyst. The design of experiment was carried out using the MINITAB RELEASE 16 and a result of 31 experiments was suggested to be made. The result showed the optimum condition of pre-mixing period of 14 s, the number of catalyst recycle to be 2 cycle, sonicator power of 36.3%and KOH addition of 0.3 g.

A Textile Waste Water Treatment System Using Photocatalytic Reactor and Catalyst Recycle Unit

A photocatalytic system for wastewater treatment from textile industries was constructed and tested for its efficiency. The system consisted of two units – a photoreactor for dye decomposition and a catalyst recovery unit. The photoreactor was an annular plug flow photoreactor under irradiation of 36 W Toshiba blacklight. The catalyst recovery unit was 42 L of sediment tank for TiO2 catalyst recovery. In our study, a Cibra Cron red R-W 150% (an anionic azo dye) was used to prepare a synthetic textile wastewater. The experimental parameters such as flow rate, pH, dye initial concentration, catalyst loading and setteled time that affected the system performance were investigated. The photodegradation kinetics were found to follow the Langmuire - Hinshelwood model and also depended on the TiO2 concentration and the pH. The optimum condition for photocatalytic decomposition was at pH 3 and at 1 g/L of TiO2 catalyst loading. The reaction rate constant, k and the adsorption constant, K for the scale-up photoreactor were 3.345 mg/L-min and 0.0204 L/mg, respectively. For the catalyst recycle unit, the overflow and underflow concentration of the TiO2 catalyst were 2.00 and 0.002 mg/L, respectively, at 100 ml/min of inlet flow rate, 50 ml/min of overflow and 50 ml/min of underflow.