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Experiments on thermal decomposition of nano-sized calcium carbonate were carried out in a thermo-gravimetric analyzer under non-isothermal condition of different heating rates (5 to 20K·min-1). The Coats and Redfern's equation was used to determine the apparent activation energy and the pre-exponential factors. The mechanism of thermal decomposition was evaluated using the master plots, Coats and Redfern's equation and the kinetic compensation law. It was found that the thermal decomposition property of nano-sized calcium carbonate was different from that of bulk calcite. Nano-sized calcium carbonate began to decompose at 640℃, which was 180℃lower than the reported value for calcite. The experimental results of kinetics were compatible with the mechanism of one-dimensional phase boundary movement. The apparent activation energy of nano-sized calcium carbonate was estimated to be 151kJ·mol-1 while the literature value for normal calcite was approximately 200kJ·mol-1. The order of magnitude of pre-e 相似文献
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随着纯碱行业的迅速发展,副产大量的氯化铵。本文以氧化钙或氢氧化钙为原料,采用固相反应分解氯化铵生产氨,探讨了原料配比、反应时间对氯化铵分解率的影响,并对其反应过程进行了研究。固相反应具有工艺简单,投资低,转化率较高,无污染,能耗低等优点符合当今社会绿色化学发展要求。研究表明:氧化钙/氯化铵摩尔比1.05∶1、反应时间60min或氢氧化钙/氯化铵摩尔比1.02∶1、反应时间50min,氯化铵的分解率可达到99.5%。反应的固体产物经XRD和SEM分析为羟基氯化钙,为六方晶系,晶胞参数为:a=b=3.8498nm,c=9.8706nm,c/a=2.56,α=β=90°,γ=120°;羟基氯化钙为不规则纳米小颗粒,粒径在100nm左右。 相似文献
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氢氧化钠水溶液吸收羰基硫反应级数研究 总被引:5,自引:0,他引:5
常压下温度为30-50℃,用鼓包反应器测定了羰基硫(COS)在浓度为1.313-4.4088kmol/m^3NaOH水溶液中的吸收速率,通过理论分析得到该吸收为一级不可逆快反应吸收过程。 相似文献
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非冷冻碳化法工业化生产针状纳米碳酸钙 总被引:4,自引:0,他引:4
通过开发复合型结晶导向剂,在实验室试验和中试的基础上,实现了在非冷冻(高温35~75℃)、氢氧化钙高浓度(质量分数7%~12%)条件下碳化生产针状(晶须)纳米碳酸钙。将该方法应用在石家庄博达钙业有限公司2.5万T/A的轻质碳酸钙工业装置上,经扫描电镜、透射电镜、X射线衍射和比表面积测定分析表明,产品纳米碳酸钙的晶形为针状,粒度均匀、分布窄,粒径10~20 NM,长径比15~20,比表面积≥90 M2/G,总孔容≥0.26 ML/G。 相似文献
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