The catalytic action of copper. Part VII.—A study of the effect of pressure on the rate of dehydrogenation of alcohols

The assumption that reaction occurs in a uni-molecular film covering the surface of the copper can be tested by studying the effect of pressure on the change. If all the adsorbed molecules can react, then increasing the pressure should increase the thickness of the film, and therefore the reaction velocity. If the molecules only react in the uni-molecular film next to the catalyst surface, then varying the pressure only effects the change in so far as affects the life of a molecule in the surface layer. This effect is known to be small. Hence the reaction velocity should be practically independent of the pressure, provided the catalyst is completely covered with the adsorbed alcohol film. At low pressures the velocity would be expected to fall with pressure, since the surface is not completely covered. However, since the aldehydes are known to poison the bare copper surface, it is desirable to avoid very low pressures in the experimental work.