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Undecylenic acid methyl ester (UAME) was continuously produced from methyl ricinoleate using a microwave-assisted pyrolysis system with atomization feeding. The UAME yield of 77 wt.% was obtained at 500°C using SiC as the microwave absorbent and heating medium. The methyl ricinoleate conversion and UAME yield from microwave-assisted pyrolysis process were higher than those from conventional pyrolysis. The effect of temperature on the pyrolysis process was also investigated. The methyl ricinoleate conversion increased but the cracking liquid yield decreased when the temperature increased from 460°C to 560°C. The maximum UAME yield was obtained at the temperature of 500°C., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Graphical abstract Highlights • A novel microwave-assisted system for glycerol dehydration to acrolein was developed. • A coated microwave absorbing catalyst WO 3 /ZrO 2 @SiC was prepared and used. • The acrolein selectivity could reach over 70% with complete glycerol conversion. • Much better catalyst stability was obtained by microwave heating than electric heating. • The microwave-heating system was effective for the in-situ catalyst regeneration. Abstract Uniform temperature distribution within solid catalyst particles is important to achieving low coke formation in a high-temperature reaction. However, the issue of uneven temperature distribution exists in most fixed-bed catalytic reaction systems. Here, we developed a microwave-assisted system and used it in catalytic dehydration of glycerol for sustainable production of acrolein. A coated microwave absorbing catalyst WO 3 /ZrO 2 @SiC was prepared and employed in the catalytic reactions. The effects of reaction temperature, ZrO 2 /SiC ratio, and weight hourly space velocity (WHSV) on glycerol conversion and arcolein selectivity were examined. Experimental results showed that the microwave heating proved to be more effective than the conventional electric heating for glycerol dehydration to acrolein at lower temperature. The acrolein selectivity reached over 70% with complete glycerol conversion at 250 ºC by microwave heating. The catalyst acidity was greatly influenced by ZrO 2 /SiC ratio, which in turn determined the acrolein selectivity. More importantly, much better catalyst stability was obtained in the microwave-heating process than the electric-heating process. In addition, the microwave-heating system was effective for the in-situ regeneration of deactivated catalyst. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel microwave-assisted system is developed for acrolein hydration to 3-HPA. • Simultaneous cooling is adopted for continuous microwaves and stable temperature. • Kinetic study indicates reduction in activation energy under microwave irradiation. • Adsorption and reaction behavior of reactants on catalyst is theoretically studied. • The DFT calculations confirm the intensification effect of microwave field. Catalytic hydration of acrolein to 3-hydroxypropionaldehyde (3-HPA) is a key step for the chemical production of 1,3-propanediol (1,3-PDO) from renewable glycerol. However, a main issue of low reaction rate and long reaction time exists in the conventional hydration process. Here, we developed a microwave-assisted system for the efficient conversion of acrolein to 3-HPA. Simultaneous cooling method was adopted to maintain continuous microwave irradiation and meanwhile stable temperature during the reaction. The effects of catalyst type, temperature, catalyst loading and microwave power on acrolein conversion and 3-HPA selectivity were examined. Kinetic study showed that microwave irradiation could help for the reduction in activation energy, which led to acceleration in reaction rate during the acrolein hydration process. In addition, the density functional theory (DFT) calculations on the adsorption and reaction behavior of reactants molecules on the catalyst are consistent with the experimental results, which confirm the intensification effect of the microwave field. [ABSTRACT FROM AUTHOR]