Process for the preparation of practically formic acid-free acetic acid

Claim 2

In a process for the preparation of acetic acid substantially free of formic acid by oxidation of acetaldehyde with oxygen in the liquid phase in the presence of a catalyst at a temperature of from 40° C. to 120° C., the improvement which comprises oxidizing liquid acetaldehyde in the presence of a catalytic mixture of cobalt, nickel, and manganese compounds, one of said compounds being present in an amount up to five times the sum of the amounts of the other compounds.

Claim 3

The process as defined in claim 1, wherein said compounds are selected from the group consisting of halides, sulfates, nitrates and carboxylates.

Claim 4

The process as defined in claim 2, wherein said compounds are acetates.

Claim 5

The process as defined in claim 1, wherein said temperature is from 50° C. to 80° C.

Claim 6

The process as defined in claim 1, wherein each compound is present in an amount of from 0.05 to 0.5 weight % based on the acetaldehyde.

Claim 7

The process as defined in claim 1, wherein the product mixture, that is crude acetic acid and the catalytic mixture contained therein, is distilled to obtain a distillate containing acetic acid and the catalytic mixture-containing residue is recycled to the oxidation zone.

Claim 8

In a process for the preparation of acetic acid substantially free of formic acid by oxidation of acetaldehyde with oxygen in the liquid phase in the presence of a catalyst at a temperature of from 40° C. to 120° C., the improvement which comprises oxidizing liquid acetaldehyde in the presence of a catalytic mixture of cobalt, nickel and manganese compounds, one of said compounds being present in an amount up to five times the sum of the amounts of the other compounds; separating crude acetic acid containing catalytic mixture; distilling said crude acetic acid to obtain a distillate of low-boiling substances and acetic acid; distilling the distillate of said second distillation and further distilling the distillate of the third distillation; and returning to the oxidation zone the bottom product of said fourth distillation.

Claim 9

In a process for the preparation of acetic acid substantially free of formic acid by oxidation of acetaldehyde with oxygen in the liquid phase in the presence of a catalyst at a temperature of from 40° C. to 120° C., the improvement which comprises oxidizing liquid acetaldehyde in the presence of a catalytic mixture of cobalt, nickel and manganese compounds, one of said compounds being present in an amount up to five times the sum of the amounts of the other compounds; separating crude acetic acid containing catalytic mixture; distilling said crude acetic acid to obtain a distillate of low-boiling substances and acetic acid; distilling the distillate of said second distillation and further distilling the distillate of the third distillation; and returning to the oxidation zone the bottom product of said fourth distillation.