Abstract: Methods to produce propylene oxide are described. One method can include providing a propene feedstream, an oxygen feed stream and, optionally, a hydrogen feed stream to a reaction zone, and maintaining, in a reaction zone during the reaction, at least 50 vol. % propene and 1 to 15 vol. % O2 by gradually introducing a feed stream that includes the O2 over the length of the catalytic bed or the length of the reaction zone and/or a feed stream that includes the H2 over the length of the catalytic bed or the length of the reaction zone.