Butyl Rubber Synthesis In Rotating Packed Bed Reactor

Butyl Rubber Synthesis in Rotating Packed Bed Reactor  

Yixian Wu, Jianfeng Chen

State Key Lab of Chemical Resource Engineering, Research Center of Ministry of Education for High Gravity Engineering and Technology, Beijing University of Chemical Technology, Beijing P.R. China 100029

The cationic polymerization features an extremely rapid intrinsic reaction rate with apparent reaction rate affected significantly by micromixing. Micromixing is the final stage of turbulent mixing and consists of the viscous-convective deformation of fluid elements, followed by molecular diffusion. The conventional cationic polymerization reactors include stirred tank reactor, continuous flow stirred reactor, etc.

On the basis of analysis of key engineering factors predominating in cationic polymerization, butyl rubber (IIR) as an example was synthesized by cationic polymerization in the high-gravity environment generated by a rotating packed bed (RPB) reactor. A novel rotating packed bed (RPB) reactor with good micromixing performance is a long sought-after goal in cationic polymerization and of significant importance to further improving the production efficiency and product quality. The cationic polymerization of isobutylene and its copolymerization with isoprene was conducted in RPB reactor with a high-gravity environment via the action of centrifugal force. The influence of the operating parameters, such as rotating speed (N), packing thickness, polymerization temperature on the number average molecular weight (M_n) and molecular weight distribution, chemical structure of terminal group of the resulting polymers was investigated. The molecular weight increased with increasing N and with decreasing polymerization temperature. The optimum experimental conditions were determined as rotating speed of 1200 r·min^-1, packing thickness of 40 mm and polymerization temperature of -100°C, where the copolymer of isobutylene and isoprene with M_n of 289,000 and monomodal molecular weight distribution (M_w/M_n ~ 2.0) could be obtained. In addition, the mean residence time of the reaction process is less than 1s in RPB while that is 30-60 min in conventional stirred tank reactors.

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 This work was supported by the National Natural Science Foundation of China (No. 20934001) and Program for Changjiang Scholars and Innovative Research Teams in Universities (IRT 0706).