I have a reactor which contains dry gaseous hydrogen chloride (hydrochloric acid) at 450°C. which kinds of materials including ceramics, metals, polymers or coating can withstand such a corrosive environment?
Refractory material lining like dolomite or magnesia should serve the purpose. Thermally stable polymers containg aromatic nuclei in its parent chain can withstand high temperature. Special alloys can also come to your rescue.
Please check my answer at similar query ― the materials I have suggested for 400 ºC can also be considered for 450 ºC: https://www.researchgate.net/post/Is_anhydrous_hydrogen_chloride_a_corrosive_gas