乙烯和丙烯在低聚物-正己烷溶液中的溶解度及体积传质系数测定

Solubility and volumetric mass transfer coefficient of ethylene and propylene in n-hexane solution of low molecular weight polyethylene

在高压搅拌釜中,利用气体间歇物理吸收技术,在温度343～393K、压力0.2～1.45MPa下,测定了乙烯-正己烷、丙烯-正己烷、乙烯-正己烷-低聚物(低分子量聚乙烯)和丙烯-正己烷-低聚物的气体平衡溶解度与液相体积传质系数kLa,并回归出表观溶解热,使用PC-SAFT状态方程关联了汽液平衡数据,拟合得到乙烯/丙烯-正己烷-低聚物的kLa经验关联式,与实验结果吻合良好。实验系统考察了压力、温度和低聚物浓度对平衡溶解度和kLa的影响,结果表明:压力升高,气体溶解度增大,符合亨利定律,kLa略有降低;温度升高,气体溶解度减小,乙烯在正己烷中的kLa增大,丙烯在正己烷中的kLa则减小;低聚物浓度增加,气体溶解度与kLa均降低。

Equilibrium gas solubility and volumetric mass transfer coefficient（kLa）of ethylene/n-hexane,propylene/n-hexane,ethylene/n-hexane/low molecular weight polyethylene（LMW HDPE）and propylene/n-hexane/LMW HDPE systems were obtained in a Buchi autoclave,using the transient physical gas absorption technique,under the pressure from 0.2 MPa to 1.45 MPa,and the temperature from 343 K to 393 K.The apparent dissolution heat was obtained by regression.The PC-SAFT equation of state was used to correlate the gas-liquid equilibrium data, while an empirical correlation to predict the kLa values was proposed, and the model value matched the experimental results well. The effects of pressure, temperature and LMW HDPE concentration on gas solubility and kLa were investigated. The results showed that the gas solubilities obeyed the Henry＇s law, while it decreased with increasing temperature and LMW HDPE concentration. The kLa values were found to drop slightly with increasing pressure and decrease dramatically with increasing LMW HDPE concentration. Particularly, kLa increased for ethylene/ n-hexane and decreased for propylene/n-hexane with increasing temperature.