Separation and Purification of Essential Oil by Supercritical Pressure Swing Adsorption

提出了一种新的柑橘油分馏工艺。以硅胶为吸附剂，研究了超临界二氧化碳(SC-C02)变压吸附过程。采用示踪响应法和穿透分析法研究了橙油011硅胶对主要溶质的吸附-解吸过程。芳樟醇(香气)比柠檬烯(萜烯)更能选择性地吸附在硅胶上。吸附平衡常数随温度升高或压力降低而增大。根据van‘t Hoff图计算了表观吸附热。芳樟醇的粒内有效扩散系数大于柠檬烯。传质特性表明，轴向弥散阻力对色谱峰展宽的贡献随着雷诺数的增加而减小，说明颗粒内扩散阻力的相对重要性。橙油在…上的吸附等温线在313K和8.8 Mpa下的穿透分析得到了更多的结果。吸附等温线符合Langmuir方程。吸附平衡常数的密度依赖性使得对各种条件的外推成为可能。测定了橙油在313K和8.8 Mpa下的超临界CO2吸附和313K和19.4 Mpa下溶质解吸的动态行为。在超临界CO2中用硅胶吸附柑橘油时，低压力下的吸附和高压下的解吸是一个连续的循环操作(变压吸附)，包括清洗脱除吸附器空隙区域的溶质。在解吸和排污两个步骤中成功地获得了无萜类柑橘油。随着半周期时间的增加，浓缩系数增大。得到了较高的浓缩系数，达到了25倍以上，达到了工业要求。在超临界CO_2中变压吸附柑橘油的数学模型与实验结果吻合较好。对塔内溶质浓度分布的计算表明，吸附剂再生不充分，用于循环操作的吸附剂所占比例较小。在解吸过程中，在较高的CO2流量下操作的吸附过程可以回收吸附的有价值的溶质。该系统表明了循环吸附过程连续运行的可行性。较少

A new technique for fractionation of citrus oil was proposed. A pressure swing adsorption process in supercritical carbon dioxide (SC-C0_2) was developed with silica gel as adsorbent. The adsorption-desorption process of major solutes in orange oil 011 silica gel was evaluated by the tracer response technique and the breakthrough analysis. Linalool (aroma) was more selectively adsorbed on silica gel than limonene (terpene). The adsorption equilibrium constant was increased with the increase in temperature or the decrease in pressure. The apparent heat of adsorption was calculated from the van't Hoff plot. The intraparticle effective diffusivity for linalool was larger than that of limonene. Mass transport properties showed that the contribution of axial dispersion resistance on the broadening of the chromatographic response peak decreased with the increase in Reynolds number, resulting in the relative importance of intraparticle diffusion resistance. Adsorption isotherm of orange oil w … More as obtained by breakthrough analysis at 313 K and 8.8 MPa. The adsorption isotherm was represented by the Langmuir equation. The density dependency of the adsorption equilibrium constant enabled the extrapolation to the various conditions. Dynamic behaviors of adsorption of orange oil in SC-C0_2 at 313 K and 8.8 MPa and desorption of solutes at 313 K and 19.4 MPa were measured.A continuous cyclic operation (Pressure Swing Adsorption) between the adsorption at a lower pressure and the desorption at a higher pressure, involving the rinse step to remove the solutes in the void region of the adsorber, was demonstrated for citrus oil processing with silica gel adsorbent in SC-CO_2. Effects of feed concentration and half cycle time on the concentration factor of oxygenated compounds were studied. Terpeneless citrus oil was successfully obtained in the desorption step and blowdown step. The increase in half cycle time increased the concentration factor. Higher concentration factor up to 25 was obtained, and tile concentration factor satisfied the commercially required value. The mathematical model for the citrus oil processing by a pressure swing adsorption in SC-CO_2 agreed well with the experimental results. Calculated concentration profile of the solutes in the column showed that the regeneration of the adsorbent was not sufficient and the portion of the utilized adsorbent for tile cyclic operation was small. Adsorption process operated at a higher flow rate of CO_2 during the desorption step may recover the adsorbed valuable solutes. The proposed system showed the feasibility of the continuous operation of the cyclic adsorption process. Less