Patent ID: 7348466

Claim:
In a process for the solvent extraction of butadiene from a mixture of C 4 compounds that boil close to butadiene and the recovery of butadiene as a product of the process, wherein at least one solvent extraction step is employed using at least one lean solvent that preferentially extracts butadiene from said mixture of C 4 'S to form a solvent extract stream that carries butadiene and tars that form during said butadiene extraction process, said extract being subjected to a stripping operation to separate butadiene from said solvent and tars, the butadiene separated from said solvent and tars being recovered as a product of the process, a separate primary mixture of solvent and tars being recovered for reuse in said at least one solvent extraction step, and wherein a secondary portion of said primary mixture of solvent and tars is separated from said primary mixture and subjected to a reclamation step in which substantial quantities of tars are removed from said secondary portion and from said extraction process thereby forming a secondary lean solvent stream that is essentially depleted in its content of tars, and reintroducing said secondary lean solvent stream into said extraction process to absorb additional butadiene, the improvement comprising operating said extraction process in a manner such that sufficient tars are removed from said extraction process to maintain the amount of tars present in said extraction process at a level no greater than about 1.6 wt. %, based on the total weight of solvent and tars in said extraction process.