摘要
针对CH_(4)/N_(2)变压吸附用碳分子筛建立统一的表征方法及评价体系,有利于客观评价吸附剂的性能优劣,以便于指导分离CH_(4)/N_(2)用碳分子筛的选择与制备。选用分离效果较优的典型性碳分子筛样品,采用氮吸附脱附法对样品的孔隙结构进行表征,用扫描电镜观察样品的表面形貌,通过X射线衍射和X-射线光电子能谱对样品的表面元素组成和化学状态进行表征,利用自制高压吸附装置、热重分析仪和变压吸附装置对样品平衡吸附、动力学吸附和变压吸附性能进行试验研究。结果表明:碳分子筛中的微孔发挥关键性分离作用,应结合孔容与孔径分布情况开展分离性能评价;碳分子筛表面的含氧官能团可形成活性中心,促进样品的吸附分离;CH_(4)/N_(2)平衡吸附分离比大于3时,可实现对煤层气中CH_(4)/N_(2)的有效分离;由样品动力学吸附表明,吸附初期N_(2)的吸附速率明显大于CH_(4),可用PSA分离CH_(4)/N_(2);在选用碳分子筛时进行强度和变压吸附评价,即可确定商品碳分子筛可否使用;在制备碳分子筛时可结合孔径分析指导制备过程中的炭化、活化和调孔步骤,依据表面化学性质评价以指导制备原料选择和预氧化程序,通过吸附评价得出碳分子筛的吸附容量和分离性能,再通过强度测定评价其使用寿命。
Establishing a unified characterization method and evaluation system for carbon molecular sieves used in CH_(4)/N_(2) pressure swing adsorption is beneficial for objectively evaluating the performance of adsorbents and guiding the selection and preparation of carbon molecular sieves for separating CH_(4)/N_(2).Typical carbon molecular sieve samples with better separation efficiency were selected,and the pore structure of the samples was observed using nitrogen adsorption desorption method,through X-ray diffraction and X-ray photoelectron spectroscopy,the surface elemental composition and chemical state of the sample were characterized.Utilizing self-made high-pressure adsorption equipment,thermogravimetric analyzer and pressure swing adsorption device,the sample equilibrium adsorption,kinetic adsorption,and pressure swing adsorption performance were experimentally researched.The results show that,the micro pores in carbon molecular sieves play a crucial separation role,the separation performance evaluation should be carried out based on the combination of pore volume and pore size distribution;the oxygen-containing functional groups on the surface of carbon molecular sieves can form active centers,the adsorption and separation of samples can be promoted.When the CH_(4)/N_(2) equilibrium adsorption separation ratio is greater than 3,the effective separation of CH_(4)/N_(2) in coalbed methane can be achieved.According to the kinetic adsorption of the sample,the adsorption rate of N_(2) in the initial stage of adsorption is significantly higher than that of CH_(4),PSA can be used to separate CH_(4)/N_(2).Evaluating the strength and pressure swing adsorption when selecting carbon molecular sieves can determine whether commercial carbon molecular sieves can be used.When preparing carbon molecular sieves,pore size analysis can be combined to guide the carbonization,activation,and pore size adjustment steps during the preparation process.Based on the surface chemical properties,the selection of raw materials for preparation and pre oxidation process can be guided.The adsorption capacity and separation performance of carbon molecular sieve can be obtained through adsorption evaluation,and then its service life can be further evaluated through strength testing.
作者
车永芳
马克富
CHE Yongfang;MA Kefu(China Coal Research Institute Corporation Ltd.,Beijing 100013,China;National Coal Quality Inspection and Testing Center,Beijing 100013,China)
出处
《煤质技术》
2023年第6期66-73,79,共9页
Coal Quality Technology
基金
天地科技股份有限公司科技创新创业资金青年资助项目(2022-2-TD-ON003)。
关键词
碳分子筛
特性表征方法
性能评价
孔隙结构
表面化学性质
平衡吸附
动力学吸附
活性中心
carbon molecular sieve
characteristic characterization methods
performance evaluation
pore structure
surface chemical properties
equilibrium adsorption
dynamic adsorption
active center
