| abstract |
A process for isomerising a C3-7 (hydro)(halo)fluoroalkene comprising (a) providing a reactor feed stream comprising the C3-7 (hydro)(halo)fluoroalkene; and (b) contacting the C3-7 (hydro)(halo)fluoroalkene with a catalyst comprising alumina to isomerise the C3-7 (hydro)(halo)fluoroalkene, wherein the catalyst has a sodium content of less than about 800 ppm. In another aspect, a process for preparing a C3-7 (hydro)(halo)fluoroalkene by dehydrohalogenation of a reactor feed comprising C3-7 (hydro)(halo)fluoroalkane to produce a C3-7 (hydro)(halo)fluoroalkene, the process comprising the above process for isomerising a C3-7 (hydro)(halo)fluoroalkene. The preferred type of isomerisation is geometric isomerisation, i.e. from a cis-isomer to a trans-isomer or vice versa. The preferred catalyst is alumina-supported chromia or alumina-supported zirconia and the preferred C3-7 (hydro)(halo)fluoroalkane is 1,1,1,3,3,3-pentafluoropropane (245fa). The preferred C3-7 (hydro)(halo)fluoroalkenes that are isomerised are cis-1,3,3,3-tetrafluoropropene (1234ze(Z)), cis-1,1,1,4,4,4-hexafluorobut-2-ene (1336mzz(Z)), cis-1-chloro-3,3,3-trifluoropropene (1233zd(Z)), cis-1,2,3,3,3-pentafluoropropene (1225ye(E)). |