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查明高岭石与CO2、水相互作用规律为深煤层注CO2提高煤层气采收率提供依据.在温度为25,35,45℃条件下,测定高岭石与pH值为4.3,5.0,5.7的碳酸溶液反应后硅元素、铝元素的溶出量,利用能谱分析(EDS)、X射线衍射分析(XRD)等测试方法,探讨了高岭石反应前后的元素和晶体结构变化,并建立了动力学模型.研究结果表明:高岭石与碳酸溶液反应后硅元素溶出量比铝元素溶出量大,硅元素溶出量随反应时间呈先增大后减小的趋势,并伴随震荡现象,铝元素无明显规律;反应过程中高岭石中硅元素含量呈先变小后增大的变化趋势,内部晶体结构无明显变化;硅元素溶出量随温度升高而增大,随pH值减小而增大,温度对溶出量影响较大;硅元素溶出规律符合扩散控制界面模型,表达式为1-(1-X)1/3=kt,pH值为4.3,5.0,5.7的表观活化能分别为27.56,29.62,30.48kJ/mol,pH值越小时,反应活化能越小,反应速率越大.
It was found that the law of interaction between kaolinite and CO2 and water provided the basis for improving coalbed methane recovery by injecting CO2 into deep coal seams.Under the conditions of 25, 35 and 45 ℃, 5.7 after the reaction of carbonic acid solution of silicon and aluminum elution amount, the use of energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and other test methods to explore the elemental and crystal structure changes before and after the kaolinite reaction and the establishment of The kinetic model was established.The results show that the dissolution rate of silicon element is higher than that of aluminum element after the reaction between kaolinite and carbonic acid solution, and the content of silicon element increases first and then decreases with the reaction time, The content of silicon in kaolinite decreases first and then increases, and the internal crystal structure has no obvious change. The content of silicon increases with the increase of temperature and decreases with the decrease of pH While the temperature has a significant effect on the dissolution rate. The dissolution law of the silicon element accords with the diffusion control interface model and the expression is 1- (1-X) 1/3 = kt, and the apparent activation of pH value is 4.3, 5.0 and 5.7 Can be 27.56,29.62,30.48kJ / mol, the smaller the pH value, the smaller the reaction activation energy, the more the reaction rate Big.