Process for the alkylation of isobutane with dilute propylene

A process for alkylation of propylene, the process comprising:

• contacting a stream comprising propylene and propane with sulfuric acid in a first reaction zone at a temperature in the range from −28° C. to 7° C. (−20° F. to 45° F.) to form propylene sulfate esters;
• separating the propane from the sulfuric acid and the propylene sulfate esters;
• contacting the propylene sulfate esters with isobutane and sulfuric acid in an alkylation reaction zone at a temperature in the range from −7° C. to 38° C. (20° F. to 100° F.) to react the propylene sulfate esters and the isobutane to form a reactor effluent comprising an acid phase and a hydrocarbon phase comprising unreacted isoparaffin and alkylate product;
• separating the hydrocarbon phase from the sulfuric acid;
• separating the hydrocarbon phase to form a fraction comprising unreacted isoparaffin and a fraction comprising the alkylate product.