Study On The π-Complexation Adsorbents For Ethylene-Ethane Separation

Olefin-paraffin separations represent a class of the most important as well as most expensive separations in the chemical and petrochemical industry, especially for ethylene-ethane separation. Cryogenic distillation has been used for many years for these separations from olefin plants. They remain to be the most energy-intensive distillations because of the close relative volatilities of the components. The large energy and capital investment requirement provides the incentive for ongoing olefin-paraffin separation technology research. A number of alternatives have been investigated. The most promising one appears to beÏ€-complexation and development of efficientÏ€-complexation adsorbents has received increasing attention in recent years.The present study was based on the previous work in our research groups and aimed at developing highly efficientÏ€-complexation adsorbent for ethylene-ethane separation. Some new explorations had been made in the adsorption mechanism, modification of activated carbon, optimization of CuCl adding amount, effect of rare-earth added and new adsorption substrate materials and so on. The main contents of this thesis were briefly summarized as follows:Molecular orbital theory calculations were performed to study the adsorption mechanism and determine the optimized geometry structure of ethylene on activated carbon loaded with cuprous chloride. The results show that cuprous chloride prefers to disperse at the top site and bridge site of activated carbon surface in the copper end and the top site is better. One cuprous chloride can only adsorb one ethylene molecule at most. The adsorption bond energy and bond length calculation results show that the interaction between Cu(I) and C₂H₄ has been weakened sharply considering the influence of carbon substrate.In order to improve the separation effect of ethylene over ethane, surface modification of the commercial coal-based activated carbon and the amount optimizing of CuCl loading had been investigated. CuCl/AC adsorbent with high ethylene selectivity was prepared by thermal dispersion method. Surface properties of CuCl/AC were studied by a series of characterization analyses. It was found that the main reason why NAC adsorbent could not be efficiently used for ethylene-ethane...