Sodium silicate and that calcined at 400℃ for 2 h were used to catalyze the transesterification of cottonseed oil with methanol. Calcined sodium silicate （CSS） catalyst exhibited much higher catalytic activity and ...Sodium silicate and that calcined at 400℃ for 2 h were used to catalyze the transesterification of cottonseed oil with methanol. Calcined sodium silicate （CSS） catalyst exhibited much higher catalytic activity and stability. A maximum biodiesel yield of 98.9~ was achieved at methanol/oil mole ratio of 12：1, reaction temperature 65℃, reaction time 3.0 h, and CSS/oil mass ratio of 2 Wffo. After 7 consecutive reactions without any treatment, biodiesel yield reduced to 82.5%. Considering technological and economic feasibility, CSS base catalyst supported on 0 rings was prepared for continuous transesterification. The maximum yield was 99.1% under optimum conditions （reaction temperature 55 ~C, methanol velocity 1 ml. rain- 1, oil velocity 3 ml- rain- 1, and 5 tower sec- tions）. These results indicate that this new continuous biodiesel production process and apparatus present a great potential for industrial application in biodiesel.展开更多
The extraction of potassium from K-feldspar via a calcium chloride calcination route was studied with a focus on the effects of the calcination atmosphere, calcination temperature and time, mass ratio of CaCl2 to K-fe...The extraction of potassium from K-feldspar via a calcium chloride calcination route was studied with a focus on the effects of the calcination atmosphere, calcination temperature and time, mass ratio of CaCl2 to K-feldspar ore and particle size of the K-feldspar ore. The results demonstrated that a competing high-temperature hydrolysis reaction of calcium chloride with moisture in a damp atmosphere occurred concurrently with the conversion reaction of K-feldspar with CaCl2, thus reducing the amount of potassium extracted. The conversion reaction started at approximately 600 °C and accelerated with increasing temperature. When the temperature rose above 900 °C, the extraction of potassium gradually decreased due to the volatilization of the product, KCl.As much as approximately 41% of the potassium was volatilized in 40 min at 1100 °C. The mass ratio of CaCl2/K-feldspar ore significantly affected the extraction. At a mass ratio of 1.15 and 900 °C, the potassium extraction reached 91% in 40 min, while the extraction was reduced to only 22% at the theoretical mass ratio of 0.2. Optimal process conditions are as follows: ore particle size of 50–75 μm, tablet forming pressure of 3 MPa, dry nitrogen atmosphere, mass ratio of CaCl2/ore 1.15:1, calcination temperature of 900 °C, and calcination time of 40 min.The XRD analysis revealed that a complex phase transition of the product SiO2 was also accompanied by the conversion reaction of K-feldspar/CaCl2. The SiO2 product formed at the initial stage was in the quartz phase at 900 °C and was gradually transformed into cristobalite after 30 min.展开更多
基金Supported by the National Natural Science Foundation of China(21306088)National Key Technologies R&D Program of China(2015BAD15B07)+1 种基金State Key Laboratory of Chemical Engineering(SKL-Ch E-13A01,Tsinghua University,China)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD,China)
文摘Sodium silicate and that calcined at 400℃ for 2 h were used to catalyze the transesterification of cottonseed oil with methanol. Calcined sodium silicate （CSS） catalyst exhibited much higher catalytic activity and stability. A maximum biodiesel yield of 98.9~ was achieved at methanol/oil mole ratio of 12：1, reaction temperature 65℃, reaction time 3.0 h, and CSS/oil mass ratio of 2 Wffo. After 7 consecutive reactions without any treatment, biodiesel yield reduced to 82.5%. Considering technological and economic feasibility, CSS base catalyst supported on 0 rings was prepared for continuous transesterification. The maximum yield was 99.1% under optimum conditions （reaction temperature 55 ~C, methanol velocity 1 ml. rain- 1, oil velocity 3 ml- rain- 1, and 5 tower sec- tions）. These results indicate that this new continuous biodiesel production process and apparatus present a great potential for industrial application in biodiesel.
基金Supported by the Ministry of Science and Technology(State Key Research Plan2013BAC12B03)the National Natural Science Foundation of China(21236004,21336004)
文摘The extraction of potassium from K-feldspar via a calcium chloride calcination route was studied with a focus on the effects of the calcination atmosphere, calcination temperature and time, mass ratio of CaCl2 to K-feldspar ore and particle size of the K-feldspar ore. The results demonstrated that a competing high-temperature hydrolysis reaction of calcium chloride with moisture in a damp atmosphere occurred concurrently with the conversion reaction of K-feldspar with CaCl2, thus reducing the amount of potassium extracted. The conversion reaction started at approximately 600 °C and accelerated with increasing temperature. When the temperature rose above 900 °C, the extraction of potassium gradually decreased due to the volatilization of the product, KCl.As much as approximately 41% of the potassium was volatilized in 40 min at 1100 °C. The mass ratio of CaCl2/K-feldspar ore significantly affected the extraction. At a mass ratio of 1.15 and 900 °C, the potassium extraction reached 91% in 40 min, while the extraction was reduced to only 22% at the theoretical mass ratio of 0.2. Optimal process conditions are as follows: ore particle size of 50–75 μm, tablet forming pressure of 3 MPa, dry nitrogen atmosphere, mass ratio of CaCl2/ore 1.15:1, calcination temperature of 900 °C, and calcination time of 40 min.The XRD analysis revealed that a complex phase transition of the product SiO2 was also accompanied by the conversion reaction of K-feldspar/CaCl2. The SiO2 product formed at the initial stage was in the quartz phase at 900 °C and was gradually transformed into cristobalite after 30 min.
