乙醇改性钙基脱氯剂实验及动力学分析

Experimental and kinetics analysis of ethanol-hydrated calcium-based adsorbents

利用乙醇溶液对分析纯氧化钙进行消化改性,制备HCl脱氯剂。通过固定床实验,考察不同反应温度和初始HCl浓度下该脱氯剂对HCl的吸附性能,利用四种反应动力学模型对实验数据进行拟合分析。结果表明:乙醇有机物分子的覆盖和动态沉积过程,使脱氯剂CA-ET-33的表面呈现为多孔隙、大比表面积的结构,同时大大增加了2~10nm孔占比,促进了其对HCl的吸附脱除。表观反应动力学模型对实验结果的拟合效果从优到差依次为:准二级吸附动力学模型、Elovich模型、准一级动力学模型、颗粒内扩散模型。准二级动力学模型可准确描述脱氯剂对HCl的吸附机理,吸附以化学吸附为主。温度升高为化学吸附提供了足够的活化能,HCl浓度的升高增大了从气相到固相表面的传质驱动力。脱氯剂的累计吸附量随温度的升高而增大,达到平衡所消耗的时间随HCl浓度的增加而缩短。确定了一个通用的动力学方程,可用于预测钙基脱氯剂对HCl的吸附过程。

An efficient HCl removal adsorbent was obtained by hydrating pure calcium oxide with ethanol solution.The adsorption performance on HCl at different reaction temperatures and initial HCl concentrations was investigated in a fixed bed reactor.The experimental data were fitted and analyzed using four reaction kinetic models.The results showed that the adsorbent surface of CA-ET-33 indicated a porous and large specific surface area structure due to the covering and dynamic deposition process of the ethanol organic molecules,while greatly increasing the 2—10nm pore occupancy ratio,which promoted its adsorption of HCl.The apparent reaction kinetic models fit the experimental results in the following order from best to worst:pseudo-second-order kinetic model,Elovich model,pseudo-first-order kinetic model and intra-particle diffusion model.The pseudo-second-order kinetic model can describe the actual adsorption behavior of the adsorbent,showing the adsorption was mainly chemisorption-based.The elevation of temperature provided sufficient activation energy for chemisorption,and the rise of initial HCl concentration enhanced the driving force of the mass transfer from the gas phase to the adsorbent surface.The cumulative adsorption capacity ascended with the addition of temperature,and the increase of HCl initial concentration shortened the period to reach the equilibrium.A general kinetic equation was determined that can predict the adsorption process of HCl of a Ca-based adsorbent.