In one embodiment, a method of heating an exhaust treatment device can comprise: generating reformate in a reformer, wherein the reformate comprises hydrogen; introducing oxygen to the reformate prior to combining the reformate with another stream; combusting a portion of the reformate and generating an exotherm to form heated reformate; and introducing the heated reformate to the exhaust treatment device. In one embodiment the exhaust system can comprise: a reformer; a reformate conduit disposed in physical communication with a reformate outlet of the reformer; an exhaust treatment device disposed in fluid communication with the reformer; and an oxygen supply disposed in fluid communication with the reformate conduit such that oxygen can be introduced into the reformate conduit upstream of a reformate conduit outlet, wherein the reformate conduit outlet is disposed in physical communication with an exhaust conduit and/or the exhaust treatment device.