Research On Adsorbents For Separation Of Ethylene And Propylene From Refinery Gas

A dynamic adsorption apparatus was designed and its behaviour was tested. The result shows that it can meet the needs of experiment.A systematic research into adsorbents used for separating ethylene from fluid catalytic cracking(FCC) dry gas was made. The dynamic adsorption apparatus was used to select adsorbents for pretreatment by utilizing FCC dry gas. Experimental result shows that pericarp activated carbon made in Chengde was more excellent. Adsorbents used for separating ethylene were investigated subsequently. Firstly, as for AgNO3/SiO2 adsorbents, GSA silica gel with bigger specific surface area and less average pore size was found to be a better support. Secondly, as for CuCl/ zeolite adsorbents, they were prepared from three different methods and characterized by BET, XRD and XPS. The result shows that 0.22 CuCl/4A adsorbent exhibits superior properties. Thirdly, Cu-based activated carbon adsorbents were systemically investigated, some of which were characterized by BET and XRD. The pericarp activated carbon(AC) made in Chengde was found to be a better support either. The best precursor was CuCl and the second was CuCl2. The suitable preparation conditions using CuCl as the precursor were determined. Because of a lower price and similar performance of CuCl2/AC to CuCl/AC, CuCl2 could be used to replace CuCl as precursor. Furthermore, it was proved that either surface modification of AC by 30% HNO3 or introduction of the second cation could improve the performance of the adsorbents. In addition, the performance of CuCl2-La(NO3)3/AC(modified by 30% HNO3) was improved after the first regeneration, then kept almost constant even after reused for five times. Comparative experiment testified that AgNO3 was better than CuCl2, if supported on the same AC modified by 30% HNO3, while silica gel was better than AC modified by 30% HNO3 as a support, if loaded with the same amount of AgNO3.The adsorptive behavior of ethylene (pure ethylene and ethylene in binary mixture gas) over CuCl2 -La(NO3)3/AC(modified by 30% HNO3) was studied. Breakthrough curves of ethylene were all steep, and moved backwards gradually along with the increase of operation pressure.And the adsorption balance isotherms of ethylene could be fitted by Langmuir equation.Separation of propylene from liquefied petroleum gas (LPG) by adsorption was researched for the first time. Firstly, separation process with two steps was adopted. Secondly, the adsorbents for pretreatment were selected. Activated carbon(TAC4.0) and activated carbon(HAC1.5) supported with 0.8% Cu2+ showed good performance. Thirdly, adsorbents used for separating propylene were studied, and AgNO3/SiO2 with 15.4% Ag+ load showed superior adsorption properties. The adsorptive behavior of propylene was studied and it's adsorption balance isotherm was fitted by Langmuir equation either.