The invention relates to a method and an apparatus for purifying gas, wherein the gas which includes at least tars and/or undesired hydrocarbons is supplied to a catalytic treatment reactor which has at least one catalyst zone including at least one catalyst element with a catalyst, oxygen gas is fed into the catalyst element of the catalyst zone in the catalytic treatment reactor and is supplied through the catalyst element, the gas is arranged to flow to the catalyst zone and arranged to contact with the oxygen gas and the catalyst, and a purified gas is discharged from the catalytic treatment reactor. Further, the invention relates to the use of the method.

A process for synthesising hydrocarbons is described comprising the steps of (a) making a synthesis gas comprising hydrogen, carbon monoxide and carbon dioxide from a feedstock in a synthesis gas generation unit, (b) removing carbon dioxide to produce a carbon dioxide stream and purified synthesis gas comprising hydrogen and carbon monoxide for synthesis in a Fischer-Tropsch hydrocarbon synthesis unit wherein (i) at least a portion of the FT water stream is fed to an electrolysis unit to provide an oxygen stream, which is fed to the synthesis gas generation unit. Carbon dioxide stream recovered from the carbon dioxide removal unit and a portion of the hydrogen stream produced by the electrolysis unit are fed to a reverse water-gas shift unit to produce a carbon monoxide stream, with carbon monoxide stream from the reverse water-gas shift unit is fed to the Fischer-Tropsch hydrocarbon synthesis unit.