Method for oxidizing hydrocarbons with oxygen
A method for oxidizing saturated hydrocarbons with oxygen, preferably saturated cyclic hydrocarbons such as cyclohexane, to produce alkyl hydroperoxide is described. A method for oxidizing saturated hydrocarbons with oxygen in a plurality of consecutive steps to control the rate of the reaction and obtain a high degree of alkyl hydroperoxide selectivity is also described. The described methods can relate to methods for condensing oxidation gases recovered in an oxidation reactor and recycling thereof.
1. A process for producing alkyl hydroperoxide, the process comprising oxidizing a saturated hydrocarbon in a liquid phase with an oxygen-containing gas, and conducting the oxidation in a plurality of successive steps, comprising supplying hydrocarbon at least to a first step at a temperature of from 100° C. to 250° C., further comprising cooling in, at least a last step of the reaction to maintain and control temperature at a level which is less than or equal to a temperature used in the first step, wherein each step of the reaction comprises a liquid phase and a gaseous phase and comprises forming a gaseous overhead extracting and evacuating the gaseous phase forming the overhead to be at least partially condensed, and recovering at least one condensate from the gaseous phase of one step and recycling the condensate directly into one of the oxidation steps, wherein a resulting concentration of oxidized products in the supplied reaction medium is at least equal to a concentration of oxidized products in the condensate or condensates to be recycled.
2. The process as defined by claim 1 , wherein the condensate recycled to one step is obtained by mixing condensates or gaseous phases deriving from at least two oxidation steps.
3. The process as defined by claim 1 , wherein the gaseous phase recovered at a head of one reaction step is partially condensed and the condensate obtained is recycled to a supply to the preceding step.
4. The process as defined by claim 1 , wherein the gaseous phase recovered at a head of the last reaction step is partially condensed and the condensate obtained is recycled to a supply to the preceding step.
5. The process as defined by claim 1 , wherein the saturated hydrocarbon is a cyclic hydrocarbon.
6. The process as defined by claim 5 , wherein the saturated hydrocarbon is selected from the group consisting of cyclohexane, cyclooctane, cyclododecane and decalin.
7. The process as defined by claim 6 , wherein the saturated hydrocarbon is cyclohexane.
8. The process as defined by claim 1 , wherein after partial condensation of the gaseous phases forming the overhead of each step, the process further comprises completely condensing any uncondensed fraction, then flashing a condensate obtained in order to obtain an aqueous liquid fraction and an organic fraction, and recycling said organic fraction to the first oxidation step.
9. The process as defined by claim 1 , wherein the oxidation is carried out in a plant comprising a plurality of oxidation reactors mounted in series or as a cascade, each reactor forming an oxidation step.
10. The process as defined by claim 9 , wherein the reactors are of a bubble column type.
11. The process as defined by claim 1 , wherein oxidation is carried out in a plant comprising as an oxidation reactor a partitioned bubble column, each compartment forming an oxidation step.