according to fig1 and 2 , a purification unit 20 according to the invention is usually accommodated in a housing 22 . the gas to be purified , preferably pressurized air , is supplied via a supply pipe 24 and discharged via an outlet pipe 26 . a purification unit 20 according to the invention is usually installed downstream from compressors ( not shown ); however , a use as a terminal device directly in the area of use of the purified pressurized air is also possible . the purification unit 20 can be installed and operated downstream from compressors of any constructional type ( piston compressors , screw compressors , etc .) provided the respective operating conditions are observed . for high energetic efficiency , heat exchanging systems are used which enable the return of escaping thermal energy . the proportion of energy that is to be supplied additionally is reduced accordingly following an initial heating - up phase . thus , the supply pipe 24 first conducts the gas to be purified through a heat exchanger 28 , preferably configured as a plate heat exchanger . it then arrives in a converter 30 filled with catalyst material , which is not depicted . in the exemplary embodiment shown , the converter 30 comprises a cylindrical converter housing 32 through which the gas to be purified flows in the longitudinal direction . hopcalite , for example , which is preferably used in the form of pellets with a diameter of approximately 1 to 5 mm , can be used as the catalyst material for separating hydrocarbons . however , any other form is also conceivable in principle . according to the invention , the converter housing 32 and thus the catalyst material is heated from the outside by means of a heat source or heating system 34 until the required operating temperature is reached . in principle , the type of heating system 34 can be chosen freely , however , the use of a strip heating which is wound around the converter housing 32 has proven to be very suitable . such a strip heating comprises metal strips which are enclosed by a textile or plastic material and heat up when an electric current flows through them . thus , the generated heat is given off directly to the entire outer surface of the converter housing 32 and then to the catalyst material . temperature sensors 36 , which are preferably located in the inflow and outflow areas of the converter housing 32 , and optionally in the center of the converter housing 32 , are provided for monitoring the temperature in the interior of the converter housing ( see in particular fig2 ). appropriate displays 38 can be provided on the outside of the housing 22 of the purification unit 20 for visualizing the measurement result . if a temperature is reached that is too high , the purification unit 20 can either be switched off immediately , or an alarm signal can be issued . furthermore , the purification unit 20 comprises a temperature control unit 40 which is also accessible from the outside and through which the purification unit 20 can be set and controlled . according to the invention , an enrichment of the catalyst material with pure hopcalite can be provided . either the converter housing 32 contains layers of pure hopcalite , or the pure hopcalite is admixed to the catalyst material and distributed substantially uniformly in the converter housing 32 . if there is an increase in the amount of hydrocarbons , the pure hopcalite leads to a sharp temperature increase which is registered by the temperature sensors 36 . the purification unit according to the invention operates with a catalytic system which was specifically developed and optimized for the total oxidation of hydrocarbons ( lubricants , oils , anthropogenic substances contained in the air , among others sulfur dioxide , carbon monoxide , nitrogenous gases ) in pressurized gas , in particular pressurized air . the substances contained in the air may be present in the form of gases , vapors and aerosols and are converted in the purification unit into carbon dioxide and water . the oil - charged air entering from the compressor usually has a temperature of approximately 10 degrees above ambient temperature . in the heat exchanger 28 , this is pre - heated by the hot air from the converter housing 32 to temperatures of 100 to 130 ° c . it then flows into the converter housing 32 and there flows through the catalyst material at a set operating temperature of approximately 150 ° c . in the converter housing , the hydrocarbons contained in the air are then oxidized catalytically by means of atmospheric oxygen . the resulting reaction heat is negligibly small given the hydrocarbon concentration common in pressurized air . the purified pressurized air is subsequently cooled off in the heat exchanger 28 to a temperature of approximately 10 to 15 ° c . above entry . the invention is not limited to the exemplary embodiment described but also comprises further embodiments that have the same effects or result directly from the invention .