添加稀土镧对吸附分离乙烯/乙烷的影响

考察了添加稀土镧, 氧化镧、硝酸镧和氯化镧,对载铜活性炭吸附剂分离乙烯/乙烷的影响.测定了乙烯,乙烷40℃吸附等温线.乙烯选择性实验结果表明,氯化镧的添加效果最佳.合适的添加量在11.2%(wt)附近,可使乙烯的选择性提高到原来的两倍以上. 比表面及孔径分布数据表明, 添加适量稀土镧增大了吸附剂孔的比表面和孔体积, 特别是对微孔,因而更有利于提高吸附剂表面的利用率.通过SEM对稀土络合吸附剂的形貌观察可知,稀土分散于未被活性组分CuCl利用的活性炭表面.由于稀土对乙烷吸附量极小,从而极大抑制了活性炭载体对乙烷的物理吸附,这是此复合吸附剂提高乙烯乙烷分离性能的主要原因.

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.