The pyrolysis behavior of three typical agricultural residues including rice husk, rice straw and wheat straw, was studied at different heating rates(15℃/min, 40℃/min and 100℃/min) in a dynamic nitrogen flow ...The pyrolysis behavior of three typical agricultural residues including rice husk, rice straw and wheat straw, was studied at different heating rates(15℃/min, 40℃/min and 100℃/min) in a dynamic nitrogen flow of 80mL/min by TG analysis coupled with Fourier Transform Infrared Spectroscopy (FT-IR). The various gaseous products released during biomass pyrolysis were examined. The kinetic parameters under different heating rates were acquired by kinetics analysis. The correlation coefficients are above 0.99. The results show that as heating rate increases the TG curve shifts to low temperature zone and the peak of DTG curve goes to low temperature area accordingly, but the total weight loss and activation energy of pyrolysis fluctuate little. The releasing behavior of gaseous products during pyrolysis of the three samples is similar. CO, CO2, H2O, CH4 and organics are the main gaseous products during biomass pyrolysis. When the heating rate increases, the yield of gaseous products released increases, so does the releasing rate.展开更多
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
Based on thermogravimetric analysis, kinetic parameters of Shenhua coal, such as activation energy and frequency factor have been got from the TG / DTG results. It showed that activation energy is the smallest at the ...Based on thermogravimetric analysis, kinetic parameters of Shenhua coal, such as activation energy and frequency factor have been got from the TG / DTG results. It showed that activation energy is the smallest at the temperature from 850℃ to 930℃ with heating rate of 15℃·min-1 . Pyrolysis was further carried out on a fixed-bed reactor with different heating rate. The production of hydrogen has been studied in particular. It gave the highest hydrogen production at the heating rate of 15℃·min-1 . And it also found the increase of hydrogen production with the raise of temperature. Furthermore, catalytic pyrolysis of coal was done at adding 2% of transition-metal oxides to discover the impact of catalysts upon coal pyrolysis at heating rate of 15℃·min-1 . It indicated that both N-type and P-type oxide enhanced hydrogen production in coal pyrolysis. However, it showed that N-type oxide increased hydrogen production at medium temperatures, and P-type oxides improved hydrogen production at higher temperatures.展开更多
Reducing the manufacturing cost of solar cells is necessary to their industrial production. Electrodepositing is an effective, non-vacuum method which is very suitable for cutting the manufacturing cost of thin films ...Reducing the manufacturing cost of solar cells is necessary to their industrial production. Electrodepositing is an effective, non-vacuum method which is very suitable for cutting the manufacturing cost of thin films as well as developing its large-scale industrial production. In this study, about 1-μm-thick Cu（In,Ga）Se2（CIGS） precursors were electrodeposited on Mo/glass substrates in aqueous solution utilizing a three-electrode potentiostatic system.Triethanolamine was used as complexing agent, and all parameters of electrodeposition were precisely controlled.After that, the electrodeposited precursors were selenized in a Se atmosphere with different heating ramp rates（60 and 600℃·min^（-1））. High-quality CIGS films were obtained, and their characteristics were investigated by X-ray fluorescence, scanning electron microscopy, energydispersive spectroscopy, X-ray diffraction, Raman spectra and near-infrared-visible（NIR-Vis） spectra. The results reveal that there are many differences between the properties of the films under different heating rates. Finally,CIGS solar cells were fabricated using a fast and a slow heating rate. The maximum efficiencies achieved for the films selenized at 60 and 600℃-min^（-1） are 3.15% and 0.71%, respectively.展开更多
文摘The pyrolysis behavior of three typical agricultural residues including rice husk, rice straw and wheat straw, was studied at different heating rates(15℃/min, 40℃/min and 100℃/min) in a dynamic nitrogen flow of 80mL/min by TG analysis coupled with Fourier Transform Infrared Spectroscopy (FT-IR). The various gaseous products released during biomass pyrolysis were examined. The kinetic parameters under different heating rates were acquired by kinetics analysis. The correlation coefficients are above 0.99. The results show that as heating rate increases the TG curve shifts to low temperature zone and the peak of DTG curve goes to low temperature area accordingly, but the total weight loss and activation energy of pyrolysis fluctuate little. The releasing behavior of gaseous products during pyrolysis of the three samples is similar. CO, CO2, H2O, CH4 and organics are the main gaseous products during biomass pyrolysis. When the heating rate increases, the yield of gaseous products released increases, so does the releasing rate.
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Financial support from National Natural Science Foundation of China (No. 90610014) is gratefully acknowledged
文摘Based on thermogravimetric analysis, kinetic parameters of Shenhua coal, such as activation energy and frequency factor have been got from the TG / DTG results. It showed that activation energy is the smallest at the temperature from 850℃ to 930℃ with heating rate of 15℃·min-1 . Pyrolysis was further carried out on a fixed-bed reactor with different heating rate. The production of hydrogen has been studied in particular. It gave the highest hydrogen production at the heating rate of 15℃·min-1 . And it also found the increase of hydrogen production with the raise of temperature. Furthermore, catalytic pyrolysis of coal was done at adding 2% of transition-metal oxides to discover the impact of catalysts upon coal pyrolysis at heating rate of 15℃·min-1 . It indicated that both N-type and P-type oxide enhanced hydrogen production in coal pyrolysis. However, it showed that N-type oxide increased hydrogen production at medium temperatures, and P-type oxides improved hydrogen production at higher temperatures.
基金financially supported by the National High Technology Research and Development Program of China(No.2015AA034201)the National Natural Science Foundation of China(No.11474355)the Chinese Universities Scientific Fund(No.2017LX002)
文摘Reducing the manufacturing cost of solar cells is necessary to their industrial production. Electrodepositing is an effective, non-vacuum method which is very suitable for cutting the manufacturing cost of thin films as well as developing its large-scale industrial production. In this study, about 1-μm-thick Cu（In,Ga）Se2（CIGS） precursors were electrodeposited on Mo/glass substrates in aqueous solution utilizing a three-electrode potentiostatic system.Triethanolamine was used as complexing agent, and all parameters of electrodeposition were precisely controlled.After that, the electrodeposited precursors were selenized in a Se atmosphere with different heating ramp rates（60 and 600℃·min^（-1））. High-quality CIGS films were obtained, and their characteristics were investigated by X-ray fluorescence, scanning electron microscopy, energydispersive spectroscopy, X-ray diffraction, Raman spectra and near-infrared-visible（NIR-Vis） spectra. The results reveal that there are many differences between the properties of the films under different heating rates. Finally,CIGS solar cells were fabricated using a fast and a slow heating rate. The maximum efficiencies achieved for the films selenized at 60 and 600℃-min^（-1） are 3.15% and 0.71%, respectively.
