Despite the fact that a few countries in the Mediterranean and the Middle East have limited crude oil reserves, they have abundant biomass feedstocks. For instance, Jordan relies heavily on the importation of natural ...Despite the fact that a few countries in the Mediterranean and the Middle East have limited crude oil reserves, they have abundant biomass feedstocks. For instance, Jordan relies heavily on the importation of natural gas and crude oil for its energy needs;but, by applying thermochemical conversion techniques, leftover olive oil can be used to replace these energy sources. Understanding the chemical, physical, and thermal characteristics of raw materials is essential to obtaining the most out of these conversion processes. Thermogravimetric analysis was used in this study to examine the thermal behavior of olive-solid residue (kernel) at three different heating rates (5, 20 and 40 C/min) in nitrogen and oxygen atmospheres. The initial degradation temperature, the residual weight at 500 and 700˚C and the thermal degradation rate during the devolatilization stage (below 400˚C) were all determined. It was found that in N<sub>2</sub> and O<sub>2</sub> atmospheres, both the initial degradation temperature and the degradation rate increase with increasing heating rates. As heating rates increase in the N<sub>2</sub> atmosphere, the residual weight at 500 or 700˚C decreases slightly, but at low heating rates compared to high heating rates in the O<sub>2</sub> atmosphere, it decreases significantly. This suggests that a longer lignin oxidation process is better than a shorter one. Coats and Redfern approach was used to identify the mechanism and activation energy for the devolatilization stage of pyrolysis and oxidation reactions. The process mechanism analysis revealed that the model of first-order and second-order reactions may adequately describe the mechanism of heat degradation of the devolatilization step of olive-solid waste for pyrolysis and oxidation processes, respectively.展开更多
Due to the existence of poly-hydroxyl structures,the temperature may have an effect on the thermal stability of oleuropein for its applications.In the current study,the thermal decomposition process and kinetics behav...Due to the existence of poly-hydroxyl structures,the temperature may have an effect on the thermal stability of oleuropein for its applications.In the current study,the thermal decomposition process and kinetics behavior of oleuropein from the olive resource were researched by thermogravimetric theoretical analysis methods and non-isothermal kinetics simulation.The results of thermogravimetry analysis showed the whole thermal decomposi-tion process of oleuropein involved two stages,with 21.22%of residue.It was also revealed that high heating rates of more than 20 K min^(-1) led to significant thermal hysteresis and inhibited the whole thermal decomposition behavior of oleuropein.Moreover,an investigation of the thermal decomposition kinetics indicated that the non-isothermal decomposition behavior followed a D3 model during thefirst stage(three-dimensional diffusion,Jander equation)and a D1 model in the second stage(one-dimensional diffusion).For thefirst and second ther-mal decomposition stages,the Kissinger,Friedman,Flynn-Wall-Ozawa,and Coats–Redfern four methods were applied to determine the activation energy(E=143.72 and 247.01 kJ mol^(-1))and Arrhenius preexponential factor(ln A=26.34 and 42.45 min^(-1)),respectively.Therefore,the study will provide good theoretical guidance for ther-mal stability and thermal transformation application of oleuropein.It will be suitable for low-temperature appli-cations in the cosmetic,food supplement and pharmaceutical industries.展开更多
文摘Despite the fact that a few countries in the Mediterranean and the Middle East have limited crude oil reserves, they have abundant biomass feedstocks. For instance, Jordan relies heavily on the importation of natural gas and crude oil for its energy needs;but, by applying thermochemical conversion techniques, leftover olive oil can be used to replace these energy sources. Understanding the chemical, physical, and thermal characteristics of raw materials is essential to obtaining the most out of these conversion processes. Thermogravimetric analysis was used in this study to examine the thermal behavior of olive-solid residue (kernel) at three different heating rates (5, 20 and 40 C/min) in nitrogen and oxygen atmospheres. The initial degradation temperature, the residual weight at 500 and 700˚C and the thermal degradation rate during the devolatilization stage (below 400˚C) were all determined. It was found that in N<sub>2</sub> and O<sub>2</sub> atmospheres, both the initial degradation temperature and the degradation rate increase with increasing heating rates. As heating rates increase in the N<sub>2</sub> atmosphere, the residual weight at 500 or 700˚C decreases slightly, but at low heating rates compared to high heating rates in the O<sub>2</sub> atmosphere, it decreases significantly. This suggests that a longer lignin oxidation process is better than a shorter one. Coats and Redfern approach was used to identify the mechanism and activation energy for the devolatilization stage of pyrolysis and oxidation reactions. The process mechanism analysis revealed that the model of first-order and second-order reactions may adequately describe the mechanism of heat degradation of the devolatilization step of olive-solid waste for pyrolysis and oxidation processes, respectively.
基金This work was funded by Guangdong Basic and Applied Basic Research Foundation(No.2019A1515111159)Characteristic Innovative Projects for Education Department of Guangdong Province 2021 Year(No.2021KTSCX302).
文摘Due to the existence of poly-hydroxyl structures,the temperature may have an effect on the thermal stability of oleuropein for its applications.In the current study,the thermal decomposition process and kinetics behavior of oleuropein from the olive resource were researched by thermogravimetric theoretical analysis methods and non-isothermal kinetics simulation.The results of thermogravimetry analysis showed the whole thermal decomposi-tion process of oleuropein involved two stages,with 21.22%of residue.It was also revealed that high heating rates of more than 20 K min^(-1) led to significant thermal hysteresis and inhibited the whole thermal decomposition behavior of oleuropein.Moreover,an investigation of the thermal decomposition kinetics indicated that the non-isothermal decomposition behavior followed a D3 model during thefirst stage(three-dimensional diffusion,Jander equation)and a D1 model in the second stage(one-dimensional diffusion).For thefirst and second ther-mal decomposition stages,the Kissinger,Friedman,Flynn-Wall-Ozawa,and Coats–Redfern four methods were applied to determine the activation energy(E=143.72 and 247.01 kJ mol^(-1))and Arrhenius preexponential factor(ln A=26.34 and 42.45 min^(-1)),respectively.Therefore,the study will provide good theoretical guidance for ther-mal stability and thermal transformation application of oleuropein.It will be suitable for low-temperature appli-cations in the cosmetic,food supplement and pharmaceutical industries.
