Cosden process

The ionic liquid process has a number of advantages over traditional cationic polymerization processes such as the Cosden process, which employs a liquid-phase aluminium(III) chloride catalyst to polymerize butene feedstocks [30]. The separation and removal of the product from the ionic liquid phase as the reaction proceeds allows the polymer to be obtained simply and in a highly pure state. Indeed, the polymer contains so little of the ionic liquid that an aqueous wash step can be dispensed with. This separation also means that further reaction (e.g., isomerization) of the polymer s unsaturated ot-terminus is minimized. In addition to the ease of isolation of the desired product, the ionic liquid is not destroyed by any aqueous washing procedure and so can be reused in subsequent polymerization reactions, resulting in a reduction of operating costs. The ionic liquid technology does not require massive capital investment and is reported to be easily retrofitted to existing Cosden process plants. 

The ionic liquid process has a number of significant advantages over the industrial Cosden process. This system uses a supported or liquid phase aluminum(lll) chloride catalyst. Using the ionic liquid process, the polymer forms a separate layer, which is substantially free of catalyst and ionic liquid solvent. This effect greatly enhances the degree of control available to reduce undesirable secondary reactions (i.e., isomerization) without requiring alkali quenching of the reaction. 

Other polymerization processes. Polyisobutene, traditionally prepared by the Cosden process, is a valuable lubricant, and also a route to higher value-added materials. In general it was observed that the catalytic activity of the ionic liquids increases towards higher degrees of polymerization from short-chain ohgomers as the alkylchain length of the l-alkyl-3-methylimidazohum or N-alkylpyridinium cation is increased. ... 

Cosden A process for polymerizing isobutene to a polyisobutene having a molecular weight between 300 and 2,700. 

T2BX [Toluene to benzene and xylenes] A process for converting toluene to a mixture of benzene and xylenes. Toluene vapor, mixed with hydrogen, is passed over a zeolite catalyst at 430 to 370°C the hydrogen is separated and the products fractionated. The production of benzene is its main purpose. Developed by Cosden Technology, United States. 

The differences between these processes are essentially technologicaL In Cosden s initia] version, a sales of three 62 m columns is used, with a diameter of 4.6 m for a production capacity of 22,700 t/year. 

Chronologically, several steps can be distinguished in the industrial development of the processes. The earliest, some of which are still used in smaller units, are those of Dow, Hiils, IG Farben. Koppers. Scientific Design, Shell. Union Carbide-Cosden BaJger etc. The latest second-generation processes are those of BASF iBadische Anilin und Soda Fabrik), CdF-Chimie-Technip. Dow and Monsamo-bmmus. 

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