Process for separating isobutylene from C.sub.4 hydrocarbon mixtures
AssigneeChemische Werke Huls Aktiengesellschaft
InventorWilly Zerrweck
Life of this patent
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Abstract
An improvement in the process for separating isobutylene from a mixture of C.sub.4 hydrocarbon by extracting with sulfuric acid, characterized in that the C.sub.4 hydrocarbon mixture is extracted at a temperature between about 30.degree. and 45.degree.C by means of about 40 - 55 percent by weight sulfuric acid in a first stage, whereupon the extract thus obtained is converted into isobutylene and into sulfuric acid, the residual mixture of C.sub.4 hydrocarbons after separating the entrained tertiary butyl alcohol is extracted in a second stage at a temperature between about 10.degree. and 25.degree.C by means of about 60 - 70 percent by weight sulfuric acid, the extract thus obtained being separated into sulfuric acid and into hydrocarbons (dimers and trimers).
Claims9
In the process of selectively extracting isobutylene from a hydrocarbon mixture of C.sub.4 hydrocarbons comprising olefins and paraffins in addition to said isobutylene by reacting said hydrocarbon mixture with a first aqueous solution of sulfuric acid to convert said isobutylene to tertiary butyl alcohol soluble in said first aqueous solution, separating said first aqueous solution from a raffinate comprising the remaining hydrocarbon mixture and entrained tertiary butyl alcohol and regenerating said tertiary butyl alcohol in said first aqueous solution to isobutylene, the improvement comprising:
- a. extracting said hydrocarbon mixture in a first stage at a temperature between about 30.degree. and 45.degree.C with said first aqueous solution having about 40 - 55 percent by weight sulfuric acid and separating a first raffinate and a first extract comprising tertiary butyl alcohol;
- and
- b. extracting said first raffinate after separating the entrained tertiary butyl alcohol by washing with aqueous sulfuric acid at a temperature between 20.degree. and 40.degree.C in a second stage at a temperature between 10.degree. and 25.degree.C with a second aqueous solution having about 60 - 70 percent by weight sulfuric acid and separating a second raffinate comprising remaining hydrocarbon substantially free of isobutylene and a second extract which is regenerated to recover dimers and trimers of isobutylene.
In the process of selectively extracting isobutylene from a hydrocarbon mixture of C.sub.4 hydrocarbons comprising olefins and paraffins in addition to said isobutylene by reacting said hydrocarbon mixture with a first aqueous solution of sulfuric acid to convert said isobutylene to tertiary butyl alcohol soluble in said aqueous solution, separating said first aqueous solution from a raffinate comprising the remaining hydrocarbon mixture and entrained tertiary butyl alcohol and regenerating said tertiary butyl alcohol in said first aqueous solution to isobutylene, the improvement comprising:
- a. extracting said hydrocarbon mixture in a first stage at a temperature between about 30.degree. and 45.degree.C with said first aqueous solution having about 40 - 55 percent by weight sulfuric acid and separating a first raffinate and a first extract comprising tertiary butyl alcohol;
- b. washing said first raffinate continuously with aqueous sulfuric acid at a temperature between 20.degree. and 40.degree.C to remove entrained tertiary butyl alcohol in a wash extract and produce a washed first raffinate;
- and
- c. extracting said washed first raffinate in a second stage at a temperature between about 10.degree. and 25.degree.C with a second aqueous solution having about 60 - 70 percent by weight sulfuric acid and separating a second raffinate comprising remaining hydrocarbons substantially free of isobutylene and a second extract which is regenerated to recover dimers and trimers of isobutylene.
Dependencies are inferred from the claim text.