The invention disclosed is a method for improving the selectivity of a desired chemical reaction over an undesired chemical reaction utilizing a reactor having at least one channel having a catalyst positioned thereon and a presenting a reactant flow stream at a known flow rate and inlet temperature over the catalyst at a velocity such that a boundary layer formed thereby relative to said catalytic surface defines a thickness that is sufficiently less than the thickness of a fully developed boundary layer over said catalytic surface whereby the desired chemical reaction occurs preferentially over the undesired chemical reaction.