Patent ID: 8258358

Claim:
A process for the production of propylene, the process comprising: contacting a mixed-C 4 stream comprising n-butenes, isobutylene, and paraffins with a metathesis catalyst whereby auto-metathesis occurs including the reaction of isobutylene with n-butenes to form an auto-metathesis product comprising ethylene, propylene, and heavier olefins including unreacted isobutylene and paraffins; fractionating the auto-metathesis product into at least four fractions including an ethylene fraction, a propylene fraction, a C 5+ fraction, and a C 4 fraction containing n-butenes, isobutylene, and paraffins; fractionating the C 4 fraction into at least two fractions including a light C 4 fraction comprising isobutylene and a heavy C 4 fraction comprising n-butenes and paraffins; contacting at least a portion of the heavy C 4 fraction and ethylene with a metathesis catalyst to form a metathesis product comprising ethylene, propylene, C 4+ olefins, and paraffins; feeding the metathesis product to the fractionating the auto-metathesis product; cracking the C 5+ fraction to produce a cracking product comprising ethylene, propylene, and heavier hydrocarbons; and fractionating the cracking product into at least two fractions including a light fraction comprising propylene and a fraction comprising C 5 to C 6 hydrocarbons.