The performance of ion-exchange resin catalysts during isobutene (IB) dimerization was investigated under different IB contents,temperatures and liquid-volume hourly space velocity (LHSV) using a plug flow reactor in the absence of any selectivity enhancing component.High IB content and temperature resulted in a high conversion and C12 selectivity bu low C8 selectivity.The influence of LHSV was related with the IB content:LHSV had great effect at high IB content,while the performance of ion-exchange resin changed little with LHSV if IB content was low.The effect of water on the stability of resins was also studied.Desulfonation was observed during the C4 dimerization reaction when water was added to the feed.Chlorinated resin was more stable than conventional polystyrene-based resins during the test.
Tan SongweiWang HongjunJiang HongliangWang LiqunWilbert TsaoLin Xiangzhou
Three model drugs with different function groups were chosen to dialyze with dextran-graft-poly （N-isopropylacrylalaide）. Only ibuprofen could induce the formation of drug loaded micelles, which was contirmed with dynamic light scattering and transmission electron microscope. Hydrogen-bonding between the amide groups of poly （N-isopropylacrylamide） and the carboxyl groups of ibuprofen was driving force for the drug-loaded micelle. It was also found thai the diameter of the ibuprofen-loaded micelles changed reversibly against temperature.
Song Wei Tan Hong Jun Wang Ke Hua Tu Hong Liang Jiang Li Qun Wang
The thermal stability of five commercial ion-exchange resin catalysts was studied by means of thermal gravimetric analysis （TGA） at elevated temperatures of up to 600℃ and isothermal temperatures in the range of 150℃ and 200 ℃. Resin samples with different initial water contents were also investigated. The study indicated that TGA, as a complementary evaluating method for the plug flow reactor system approach, could be used as a fast analyzing means for study on the thermal stability of ion-exchange resin catalysts. The stoichiometric calculation of the isothermally treated resin catalysts based on the FTIR analysis and acid capacity confirmed that the weight loss of the resins at 150℃ and 200℃ was caused by the desulfonation process and that desulfonation occurred mainly at the para-position of the benzene ring in the resins. H＋ ions and moisture played an important role in the desulfonation process.
Tan SongweiWang HongjunJiang HongliangWang LiqunWilbert TsaoLin Xiangzhou
