Producing propylene from abundant and cheap propane via catalytic dehydrogenation has been considered as a profitable strategy to close the growing “propylene gap” and has thus attracted extensive research interests. The prevalent commercial catalysts are the Pt and Cr based alloys. The desire of new catalysts, however, is driven by the current drawbacks of low propane conversion, poor propylene selectivity and fast deactivation of Pt and Cr based catalysts. With density functional theory (DFT) calculations, we show that the construction of “confined” active sites surrounded by “H diffusion channels” is the key for the designing of new catalysts for the semi-dehydrogenation of propane. The semi-hydrogenation of propyne to propylene is also an important industrial reaction. With DFT calculations, we demonstrate that the successful catalysts in this reaction should exhibit the moderate binding energies of propylene. In particular, the single metal atoms are outstanding candidates for catalyzing the semi-hydrogenation of propyne.