The Isothermal Methanol Converter, or IMC, is a quasi-isothermal converter in which the reaction heat is continuously removed by means of special heat exchanging plates directly embedded in the catalyst.

The converter typically includes only single isothermal bed, with the gas flowing through the catalyst outside the plates, in an axial or axial radial flow path. The cooling medium circulating inside the heat exchanging plates is the incoming reactor feed gas. The plates are designed in such a way to insure that the coolant inside the plates and the reacting gas outside the plates flow co-currently.