(JP11207129-A)      NOVELTY - Adsorption towers (100,200) are connected to auxiliary gas line and isobutane gas line at top and bottom. Zeolite layered with molecular carbon mesh, is provided in each adsorption tower. Several valves (10,11) are provided in the auxiliary gas line to regulate supply of raw material mixing gas to the adsorption towers. A vacuum pump (P) desorbs the impurity in the adsorption towers.    DETAILED DESCRIPTION - A set of valves (1-9) are provided in the gas lines to regulate the supply of raw material mixing gas and isobutane gas.    An INDEPENDENT CLAIM is also included for the purification method of isobutane.    USE -   For refining isobutane used in manufacture of ethylene polymerization reaction solvent, aerosol foaming agent, polystyrene foaming agent, etc.    ADVANTAGE -   Obtains isobutane of very high purity as zeolite and molecular carbon mesh are provided in the adsorption tower.    DESCRIPTION OF DRAWING - The figure shows the process diagram of isobutane refining system. (1-11) Valves; (100,200) Adsorption towers; (P) Vacuum pump.    (US6022398-A)      NOVELTY - Adsorption towers (100,200) are connected to auxiliary gas line and isobutane gas line at top and bottom. Zeolite layered with molecular carbon mesh, is provided in each adsorption tower. Several valves (10,11) are provided in the auxiliary gas line to regulate supply of raw material mixing gas to the adsorption towers. A vacuum pump (P) desorbs the impurity in the adsorption towers.    DETAILED DESCRIPTION - A set of valves (1-9) are provided in the gas lines to regulate the supply of raw material mixing gas and isobutane gas.    An INDEPENDENT CLAIM is also included for the purification method of isobutane.    USE -   For refining isobutane used in manufacture of ethylene polymerization reaction solvent, aerosol foaming agent, polystyrene foaming agent, etc.    ADVANTAGE -   Obtains isobutane of very high purity as zeolite and molecular carbon mesh are provided in the adsorption tower.    DESCRIPTION OF DRAWING - The figure shows the process diagram of isobutane refining system. (1-11) Valves; (100,200) Adsorption towers; (P) Vacuum pump.