Membrane reactor advantages for methanol reforming and similar reactions

Membrane reactors achieve efficiencies by combining in one unit a reactor that generates a product with a semipermeable membrane that extracts it. One well-known benefit of this is greater conversion, as removal of a product drives reactions toward completion, but there are several potentially larger advantages that have been largely ignored. Because a membrane reactor tends to limit the partial pressure of the extracted product, it fundamentally changes the way that total pressure in the reactor affects equilibrium conversion. Thus, many gas-phase reactions that are preferentially performed at low pressures in a conventional reactor are found to have maximum conversion at high pressures in a membrane reactor. These higher pressures and reaction conversions allow greatly enhanced product extraction as well. Further, membrane reactors provide unique opportunities for temperature management which have not been discussed previously. These benefits are illustrated for methanol reforming to hydrogen for use with PEM (polymer electrolyte membrane) fuel cells.