Effects of adding rare-earth lanthanum on ethylene/ethane adsorption separation

Effects of rare earth lanthanum added into Cu(I)/active carbon adsorbent for ethylene/ethane separation were studied. The influences of different lanthanum compounds, such as lanthanum oxide, nitrate and chloride, and their adding amounts were investigated. Equilibrium adsorption isotherms for ethylene and ethane at 40°C and normal pressure were measured. Compared with the other two compounds, lanthanum chloride shows the highest ethylene selectivity, especially, when its added amount is about 11.2% (wt), by which the ethylene selectivity is increased by 100%. BET and pore size distribution tests indicate that adding lanthanum compound increases the surface area and pore volume, especially in micropore, which may help to improve ethylene adsorption capacity. SEM results show that rare earth lanthanum disperses on the sites of carbon surface which have not been occupied by cuprous chloride. In this way, rare earth lanthanum could seriously inhibit the adsorption of ethane on the carbon surface. This is the reasonable explanation for why the selectivity of ethylene/ethane separation can be improved by adding lanthanum into Cu(I)/active carbon adsorbent.