IMPROVING METHYLCYCLOHEXANE DEHYDROGENATION WITH EX-SITU HYDROGEN SEPARATION IN A REACTOR-INTERSTAGED MEMBRANE SYSTEM

A system of two plug-flow reactors with an interstaged tubular palladium-silver (Pd-Ag) membrane to ex-situ remove H-2 was used to improve the efficiency of methylcyclohexane dehydrogenation. A monometallic noble metal catalyst produced yields of toluene and hydrogen from methylcyclohexane which were much higher than those corresponding to equilibrium at industrially relevant conditions. Experiments in this system at 593-673 K, 1-2 MPa, and overall liquid hourly space velocities of 1-2.6 h(-1) afforded conversions up to 52% greater than those without membrane and 35% greater than the equilibrium values for a conventional reactor. However, the equilibrium conversions for the system itself were never exceeded. The membrane capacity was adequate to remove similar to 90% of the H-2 present in the first reactor product. Results obtained with the two reactors-membrane system were close to those predicted using first reader conversion data.