Sui Hongguang, Zhang Fengyun, Zhang Lei, Wang Diansheng, Wang Yudou, Yang Yongfei, Yao Jun
College of Science, China University of Petroleum (East China), Qingdao 266580, PR China.
College of Science, China University of Petroleum (East China), Qingdao 266580, PR China.
Sci Total Environ. 2024 Jan 15;908:168356. doi: 10.1016/j.scitotenv.2023.168356. Epub 2023 Nov 8.
The effect of functionalization of modified silica (FMS) surfaces on the adsorption behaviors for CH, CO and the mixture have been studied by combining a grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) methods. The isotherms, gas distribution, sorption sites, isosteric heat, interaction energy and adsorption selectivity for CO/CH mixture are computed and discussed. And the effects of pressure and temperature on adsorption behavior are also studied. The adsorption capacity (C) of surface with various functional groups for CH is as follows: C(SiO-COOH) > C(SiO-SH) > C(SiO-OH) > C(SiO-CH) > C(SiO-NH) > C(SiO-H) and for CO is as follows: C(SiO-COOH) > C(SiO-SH) > C(SiO-NH) > C(SiO-OH) > C(SiO-CH) > C(SiO-H). Increasing temperature is not advantageous for gas adsorption on all FMS surfaces. The CO/CH selectivity (S) for FMS surfaces decrease in the following order of S(SiO-COOH) > S(SiO-NH) > S(SiO-OH) > S(SiO-SH) > S(SiO-CH) > S(SiO-H). As the pressure increase, the CO/CH selectivity decrease early and then flatten out to a constant value. The isosteric heat of adsorption (Q) for gas adsorbed on each FMS surface are also calculated, the value of isosteric heat for CO is much higher than that for CH due to the stronger interaction between CO molecules and functional groups of FMS surface. The result of the smallest self-diffusion coefficients of gas in SiO-COOH slit pores is consistent with the adsorption capacity in the slit pore with corresponding functional group. The electronegative atoms in the functional group act as basic adsorption sites for gas adsorbate molecules, which generates a larger electrostatic contribution on the selectivity of CO over CH.
通过结合巨正则蒙特卡罗（GCMC）方法和分子动力学（MD）方法，研究了改性二氧化硅（FMS）表面功能化对CH、CO及其混合物吸附行为的影响。计算并讨论了CO/CH混合物的等温线、气体分布、吸附位点、等量吸附热、相互作用能和吸附选择性。同时还研究了压力和温度对吸附行为的影响。具有不同官能团的表面对CH的吸附容量（C）如下：C（SiO-COOH）＞C（SiO-SH）＞C（SiO-OH）＞C（SiO-CH）＞C（SiO-NH）＞C（SiO-H）；对CO的吸附容量如下：C（SiO-COOH）＞C（SiO-SH）＞C（SiO-NH）＞C（SiO-OH）＞C（SiO-CH）＞C（SiO-H）。升高温度对所有FMS表面上的气体吸附均不利。FMS表面的CO/CH选择性（S）按以下顺序降低：S（SiO-COOH）＞S（SiO-NH）＞S（SiO-OH）＞S（SiO-SH）＞S（SiO-CH）＞S（SiO-H）。随着压力增加，CO/CH选择性先降低，然后趋于恒定值。还计算了吸附在每个FMS表面上气体的等量吸附热（Q），由于CO分子与FMS表面官能团之间的相互作用更强，CO的等量吸附热值远高于CH。气体在SiO-COOH狭缝孔中自扩散系数最小的结果与相应官能团狭缝孔中的吸附容量一致。官能团中的电负性原子作为气体吸附质分子的碱性吸附位点，对CO相对于CH的选择性产生更大的静电贡献。
