Reactor for the catalytic treatment of a gas stream

A reactor for catalytic treatment of residual gas for reducing a content of nitrogen oxides in processes for producing nitric acid by the Ostwald process, comprising:

• a catalyst bed for catalytic treatment of a gas stream, wherein the catalyst bed extends substantially over a cross section of the reactor and the catalyst bed is axially flown through by gas to be treated;
• and
• a carrier structure for the catalyst bed that is at least partly floatingly mounted in the reactor, wherein the carrier structure comprises:
• a sieve element,
• radially outwardly, carrier elements fixedly joined to a reactor wall below the sieve element, wherein the sieve element provides a resting surface for the catalyst bed, wherein the sieve element terminates, radially outwardly, at a distance from the reactor wall, and
• support elements for the sieve element that are floatingly mounted in the reactor;
• wherein the carrier elements fixedly joined to the reactor wall include brackets on which the support elements displaceably rest;
• wherein the sieve element rests on the displaceable support elements.