KINETICS OF METHYLAMINE CONVERSION ON A PD CATALYST IN THE PRESENCE OF H-2

The kinetics of disproportionation of methylamine to dimethylamine and ammonia in the presence of hydrogen have been investigated over a sil ica-supported palladium catalyst. At a fixed partial pressure of methy lamine, the reaction rate generally increases with decreasing hydrogen partial pressure, approaching a limiting or maximum value at sufficie ntly low pressures of hydrogen. The existence of a maximum is supporte d by the observation that the presence of some hydrogen appears to be necessary for the reaction to proceed at a conveniently measurable rat e. At a fixed hydrogen partial pressure, the reaction rate increases w ith increasing methylamine partial pressure. When the methylamine part ial pressure is sufficiently low or the hydrogen partial pressure is s ufficiently high, the reaction order with respect to methylamine can b e somewhat higher than one. At such conditions, a mechanism involving a bimolecular reaction between two partially dehydrogenated methylamin e molecules on the surface appears to make a significant contribution to the overall catalytic reaction.