Synthesis and Application of Novel NiMoK/TS-1 for Selective Conversion of Fatty Acid Methyl Esters/Triglycerides to Olefins.

Methyl palmitate (or triglyceride) was converted into C15 olefin with remarkable selectivity using nickel-molybdenum oxides on the mesoporous titanosilicate support. The olefin has one carbon atom less than the acid portion of the ester. A new catalyst NiMoK/TS-1 was synthesized in which the effect of acidity of supports and molybdenum loading on the decarboxylation conversion along with product selectivity was investigated in methyl palmitate conversion into C15 olefin. The prepared catalysts were analyzed using ammonia-temperature-programmed desorption (NH3-TPD), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET) techniques. The reaction was carried out using a vapor-phase fixed-bed downflow reactor system at atmospheric pressure. The NiMoK/TS-1 catalyst at a weight hourly space velocity (WHSV) of 5.6/h was found to be selective toward C15 olefin. The catalyst was stable up to 15 h, and it can be regenerated with no considerable decrease in the activity even after fourth reuse. Beyond 653 K, the conversion of methyl palmitate increased but the selectivity for C15 products and C15 olefin was decreased.

Intensification of heterogeneously catalyzed Suzuki-Miyaura cross-coupling reaction using ultrasound: Understanding effect of operating parameters.

Palladium-catalyzed Suzuki-Miyaura cross-coupling reaction is a significant reaction for obtaining industrially important products. The current research work deals with intensification of reaction of 4-bromoanisole and phenylboronic acid catalyzed with 5wt% Pd/C (5% by weight Pd supported on C available as commercial catalyst) using ultrasound and more importantly, without use of any additional phase transfer catalyst. Heterogeneous catalyst has been selected in the present work so as to harness the benefits of easy separation and the possible limitations of heterogeneous operation are minimized by introducing ultrasonic irradiations. The effect of operating parameters such as ultrasound power, temperature, catalyst loading and molar ratio on the progress of reaction has been investigated. It has been observed that an optimum power, temperature and catalyst loading exist for maximum benefits whereas higher molar ratio was found to be favourable for the progress of the reaction. Also, the use of ultrasound reduced the reaction time from 70min required in conventional approach to only 35min under conditions of frequency of 22kHz, power dissipation of 40W and catalyst loading as 1.5mol% (refers to total quantum of catalyst used in the work) in ethanol-water system under ambient conditions. The work also demonstrated successful results at ten times higher volume as compared to the normally used volumes in the case of simple ultrasonic horn. Overall, the work has successfully demonstrated process intensification benefits obtained due to the use of ultrasound for heterogeneously catalyzed Suzuki-Miyaura cross-coupling reaction.

Ultrasound assisted selective catalytic transfer hydrogenation of soybean oil using 5% Pd/C as catalyst under ambient conditions in water.

Catalytic transfer hydrogenation (CTH) is an alternative approach that does not require the use of potentially dangerous hydrogen gas. Pd/C is the most favoured catalyst for the selective hydrogenation of soybean oil yielding lower extent of formation of stearic acid and trans-isomer, which have adverse health effects. The present work deals with intensification of catalytic transfer hydrogenation of soybean oil in the presence of 5wt.% Pd/C using ultrasound under ambient reaction conditions. The effect of important operating parameters such as ultrasound power, temperature, type of hydrogen donor, catalyst loading and donor concentration on the progress of reaction has been investigated. It was established that the maximum extent of hydrogenation as indicated by reduction in iodine value from 135 to 95 was observed under optimized conditions of irradiation power as 100W, 22kHz frequency, 90% duty cycle, ammonium formate concentration of 0.32mol/50ml water and 2% (w/w) Pd/C loading at ambient temperature and pressure in the presence of water as solvent. The approach also offered excellent selectivity with much lower trans-isomer formation as compared to the conventional approach of high pressure hydrogenation. Overall, the work has successfully demonstrated process intensification benefits due to the use of ultrasound for the Pd/C catalyzed transfer hydrogenation of soybean oil.

A review of engineering aspects of intensification of chemical synthesis using ultrasound.

Cavitation generated using ultrasound can enhance the rates of several chemical reactions giving better selectivity based on the physical and chemical effects. The present review focuses on overview of the different reactions that can be intensified using ultrasound followed by the discussion on the chemical kinetics for ultrasound assisted reactions, engineering aspects related to reactor designs and effect of operating parameters on the degree of intensification obtained for chemical synthesis. The cavitational effects in terms of magnitudes of collapse temperatures and collapse pressure, number of free radicals generated and extent of turbulence are strongly dependent on the operating parameters such as ultrasonic power, frequency, duty cycle, temperature as well as physicochemical parameters of liquid medium which controls the inception of cavitation. Guidelines have been presented for the optimum selection based on the critical analysis of the existing literature so that maximum process intensification benefits can be obtained. Different reactor designs have also been analyzed with guidelines for efficient scale up of the sonochemical reactor, which would be dependent on the type of reaction, controlling mechanism of reaction, catalyst and activation energy requirements. Overall, it has been established that sonochemistry offers considerable potential for green and sustainable processing and efficient scale up procedures are required so as to harness the effects at actual commercial level.