针对氯化铵废液综合利用存在的问题,提出氧化钙与氯化铵溶液反应制取氯化钙的工艺,包括氧化钙与氯化铵的反应过程和氯化钙溶液浓缩除氨过程。对反应过程中的反应温度、原料配比、氯化铵溶液质量分数以及减压蒸发过程中的真空度、蒸发温...针对氯化铵废液综合利用存在的问题,提出氧化钙与氯化铵溶液反应制取氯化钙的工艺,包括氧化钙与氯化铵的反应过程和氯化钙溶液浓缩除氨过程。对反应过程中的反应温度、原料配比、氯化铵溶液质量分数以及减压蒸发过程中的真空度、蒸发温度、蒸发时间对体系中氨和氯化钙质量分数的影响进行了研究。氧化钙与氯化铵反应最佳条件:反应温度为80℃,氧化钙与氯化铵物质的量比为1.3∶2,氯化铵溶液质量分数为35%。脱氨最佳条件:真空度为80 k Pa、蒸发温度为100℃,蒸发时间为90 min。蒸发浓缩后溶液中氨的质量分数为0.03%、氯化钙质量分数为62%。该工艺在生产氯化钙的同时回收氨再利用,实现了氯化铵的综合利用。展开更多
Effects of carrier gas composition（N2/air） on NH3 production, energy efficiency regarding NH3 production and byproducts formation from plasma-catalytic decomposition of urea were systematically investigated using an...Effects of carrier gas composition（N2/air） on NH3 production, energy efficiency regarding NH3 production and byproducts formation from plasma-catalytic decomposition of urea were systematically investigated using an Al2 O3-packed dielectric barrier discharge（DBD） reactor at room temperature. Results show that the presence of O2 in the carrier gas accelerates the conversion of urea but leads to less generation of NH3. The final yield of NH3 in the gas phase decreased from 70.5%, 78.7%, 66.6% and 67.2% to 54.1%, 51.7%, 49.6% and 53.4% for applied voltages of 17, 19, 21 and 23 kV, respectively when air was used as the carrier gas instead of N2.From the viewpoint of energy savings, however, air carrier gas is better than N2 due to reduced energy consumption and increased energy efficiency for decomposition of a fixed amount of urea. Carrier gas composition has little influence on the major decomposition pathways of urea under the synergetic effects of plasma and Al2 O3 catalyst to give NH3 and CO2 as the main products. Compared to a small amount of N2 O formed with N2 as the carrier gas, however,more byproducts including N2O and NO2 in the gas phase and NH4 NO3 in solid deposits were produced with air as the carrier gas, probably due to the unproductive consumption of NH3, the possible intermediate HNCO and even urea by the abundant active oxygen species and nitrogen oxides generated in air-DBD plasma.展开更多
Ring-opening polymerization of Ε-caprolactone was successfully carried out by diisopropylamido bis (methylcyclopentadienyl) erbium as the catalyst. It is found that organoerbium amide is a very active catalyst for Ε...Ring-opening polymerization of Ε-caprolactone was successfully carried out by diisopropylamido bis (methylcyclopentadienyl) erbium as the catalyst. It is found that organoerbium amide is a very active catalyst for Ε-caprolactone ring-opening polymerization. The activity increases with the increasing of polymerization temperature. Under certain conditions, the polymerization system shows a living characteristic.展开更多
文摘针对氯化铵废液综合利用存在的问题,提出氧化钙与氯化铵溶液反应制取氯化钙的工艺,包括氧化钙与氯化铵的反应过程和氯化钙溶液浓缩除氨过程。对反应过程中的反应温度、原料配比、氯化铵溶液质量分数以及减压蒸发过程中的真空度、蒸发温度、蒸发时间对体系中氨和氯化钙质量分数的影响进行了研究。氧化钙与氯化铵反应最佳条件:反应温度为80℃,氧化钙与氯化铵物质的量比为1.3∶2,氯化铵溶液质量分数为35%。脱氨最佳条件:真空度为80 k Pa、蒸发温度为100℃,蒸发时间为90 min。蒸发浓缩后溶液中氨的质量分数为0.03%、氯化钙质量分数为62%。该工艺在生产氯化钙的同时回收氨再利用,实现了氯化铵的综合利用。
基金supported by the National Natural Science Foundation of China (Nos. 21547004, 51638001)the Beijing Natural Science Foundation (No. 8152011)the Scientific Research Program of Beijing Municipal Education Commission (No. KM201510005009)
文摘Effects of carrier gas composition（N2/air） on NH3 production, energy efficiency regarding NH3 production and byproducts formation from plasma-catalytic decomposition of urea were systematically investigated using an Al2 O3-packed dielectric barrier discharge（DBD） reactor at room temperature. Results show that the presence of O2 in the carrier gas accelerates the conversion of urea but leads to less generation of NH3. The final yield of NH3 in the gas phase decreased from 70.5%, 78.7%, 66.6% and 67.2% to 54.1%, 51.7%, 49.6% and 53.4% for applied voltages of 17, 19, 21 and 23 kV, respectively when air was used as the carrier gas instead of N2.From the viewpoint of energy savings, however, air carrier gas is better than N2 due to reduced energy consumption and increased energy efficiency for decomposition of a fixed amount of urea. Carrier gas composition has little influence on the major decomposition pathways of urea under the synergetic effects of plasma and Al2 O3 catalyst to give NH3 and CO2 as the main products. Compared to a small amount of N2 O formed with N2 as the carrier gas, however,more byproducts including N2O and NO2 in the gas phase and NH4 NO3 in solid deposits were produced with air as the carrier gas, probably due to the unproductive consumption of NH3, the possible intermediate HNCO and even urea by the abundant active oxygen species and nitrogen oxides generated in air-DBD plasma.
文摘Ring-opening polymerization of Ε-caprolactone was successfully carried out by diisopropylamido bis (methylcyclopentadienyl) erbium as the catalyst. It is found that organoerbium amide is a very active catalyst for Ε-caprolactone ring-opening polymerization. The activity increases with the increasing of polymerization temperature. Under certain conditions, the polymerization system shows a living characteristic.
