To activate a fuel and increase a fuel consumption efficiency by preparing a catalyst obtained by adsorbing noble metals into multiporous ceramics and charging and immersing it into a fuel liquid in a gasoline tank.

Zirconium, hafnium oxide, iron tungustate, etc., are impregnated and adsorbed into a multiporous ceramic cylinder (or spherical body) made of bentonite, zeolite, earthenware, etc., to prepare a catalyst. This catalyst is charged and immersed into a gasoline tank 1 of an automobile in which zirconium and other additive are added, dispersed, and applied into a liquid obtained by dissolving polyester, polyurethane, potassium ferrocyanide, etc., into a solvent. Consequently, it is possible to activate gasoline mixed fuel filled in the tank 1, improve a fuel consumption efficiency, and achieve the removal of NOx. Furthermore, combustion exhaust gas is treated by tungstate, molybdate, triethanol amine, ammonia, etc., and washed to remove NOx and SOx.