白土补充精制过程中环烷酸的吸附动力学、吸附平衡及热力学研究

研究了白土补充精制过程中，酮苯脱蜡油中的环烷酸在白土上的吸附问题。首先，借助电喷雾傅立叶变换-离子回旋共振质谱(ESI FT-ICR MS)对采自炼厂的酮苯脱蜡油中的环烷酸进行了分析鉴定，并对白土样品进行了XRD, BET, TG/DTA及SEM表征。其次，采用间歇操作的方式开展了一系列吸附实验，考察了温度、时间、初始酸浓度及剂油比对吸附过程的影响。Langmuir, Freundlich, Tempkin及 Dubinin-Radushkevich (D-R) 吸附模型被用于研究环烷酸在白土上的吸附平衡。同时，拟一级动力学模型、拟二级动力学模型及内扩散模型被用于研究环烷酸在白土上的吸附动力学。结果表明，D-R模型、拟一级动力学模型可分别较好地描述该过程的吸附平衡、吸附动力学行为。热力学计算数据表明该吸附过程可自发进行，且为吸热过程。本研究可为环烷酸在白土上的吸附脱除过程提供一个较为清晰的认识与理解。

Adsorption of Naphthenic Acids from De-waxed Vacuum Gas Oil by Activated Clay: Kinetic,Equilibrium and Thermodynamic Studies

This work mainly concentrated on the removal of naphthenic acids (NAs) from dewaxed vacuum gas oil (VGO) by a commercial grade activated clay (AC) adsorption in lube base oil refining. The NAs in dewaxed VGO cut-4 were identified by negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). The AC sample from a refinery was characterized by XRD, BET, TG/DTA, and SEM. A series of experiments were carried out to investigate the performance of adsorption of NAs onto AC by a batch adsorption technique, in which some key experimental parameters such as temperature, contact time, initial concentration of NA in oil sample as well as the dosage of adsorbent were investigated. Equilibrium isotherms were analyzed using Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich (D-R) adsorption models. The pseudo-first order, the pseudo-second order, and intraparticle diffusion models were employed to describe the kinetics data. The results revealed that D-R isotherm provided a better fit to the experimental data than other isotherms, and the adsorption kinetics followed the pseudo-first order kinetic equation. The thermodynamic data indicated that the adsorption process is feasible and spontaneous as an endothermic process. The results provide a clear understanding to the NAs adsorption onto AC in lube base oil processing of refineries.