Autorefrigerated isomerization process

In an isomerization process which comprises reacting a hydrocarbon feed stock which comprises a saturated acyclic hydrocarbon having at least 4 carbon atoms, a saturated alicyclic hydrocarbon having at least 6 carbon atoms or mixtures thereof, with hydrogen in a reaction zone comprising at least one reactor having therein at least one temperature zone and with a catalyst comprising tantalum pentafluoride, niobium pentafluoride or mixtures thereof and hydrogen fluoride, the molar ratio of hydrogen fluoride to metal fluoride present in the reaction zone being at least 2:1, at least a portion of said metal fluoride being dissolved in said hydrogen fluoride, said reaction zone being maintained at substantially liquid phase catalyst isomerization conditions including a temperature ranging from about 0.degree. C. to the critical temperature of the hydrogen fluoride, and a hydrogen partial pressure varying from about 5 to about 2000 psig, thereby forming a reaction product of enhanced octane, the improvement which comprises controlling the temperature in said at least, one temperature zone by vaporizing at least a portion of said hydrogen fluoride.

In an isomerization process which comprises reacting a hydrocarbon feed stock which comprises a saturated acyclic hydrocarbon having at least four carbon atoms, a saturated alicyclic hydrocarbon having at least 6 carbon atoms and mixtures thereof, with hydrogen in a reaction zone comprising at least one reactor having therein at least two temperature zones, the isomerization temperature of the first temperature zone being greater than the isomerization temperature of the second temperature zone, and with a catalyst comprising a metal halide selected from the group consisting of the bromides and chlorides of aluminum and gallium and the chlorides, bromides and flourides of niobium, tantalum, molybdenum or tungsten and at least an equal molar amount, based on the metal halide, of a hydrogen halide selected from the group consisting of hydrogen fluoride, hydrogen chloride and hydrogen bromide, at least a portion of said metal halide being dissolved in said hydrogen halide, said reaction zone being maintained at isomerization conditions which include at least a portion of the catalyst and the hydrocarbon feed stock being in the liquid phase, the improvement which comprises forming an isomerate of enhanced octane by controlling the temperature in at least one of said temperature zones by vaporizing a portion of said hydrogen halide.

In an isomerization process which comprises reacting a hydrocarbon feed stock which comprises a saturated acyclic hydrocarbon having at least four carbon atoms, a saturated alicyclic hydrocarbon having at least six carbon atoms or mixtures thereof, with hydrogen in a reaction zone comprising at least one reactor having therein at least two temperature zones, the isomerization temperature of the first temperature zone being greater than the isomerization temperature of the second temperature zone, and with a catalyst comprising tantalum pentafluoride, niobium pentafluoride or mixtures thereof and hydrogen fluoride, the molar ratio of hydrogen fluoride to metal fluoride present in the reaction zone being at least 2:1, at least a portion of said metal fluoride being dissolved in said hydrogen fluoride, said reaction zone being maintained at substantially liquid phase catalyst isomerization conditions including a temperature ranging from about 0.degree. C. to the critical temperature of the hydrogen fluoride and a hydrogen partial pressure varying from about 5 to about 2000 psig, the improvement which comprises forming an isomerate of enhanced octane by controlling the temperature in at least one of said temperature zones by vaporizing at least a portion of said hydrogen fluoride.