the steam phase provides heat energy for the feed stock and to promote the hydrolysis reaction in the feedstock that may be in either or both of the steam phase or a liquid phase of the reactor the steam to the reactor 12 may be supplied from a steam source 13 which injects steam directly into the reactor at one or more positions of the reactor 12 and preferably near the feedstock inlet of the reactor the steam may also be injected in the feedstock conveyors 22 24 immediately upstream of the inlet the reactor 12 injection of steam upstream of the inlet to the reactor 12 enhances the mixing of steam and the feedstock before the mixture enters the reactor hydrolysis and particularly pre hydrolysis and auto hydrolysis generally refers to the cooking of the cellulosic biomass feed stock at temperatures of for example between 110 degrees celsius u00b0 c and 160 u00b0 c or 110 u00b0 c to 175 u00b0 c at a gauge pressure of 1 5 bar to 6 bar 150 to 600 kilopascals or 1 5 bar to 10 bar 150 to 1000 kilopascals for approximately ten 10 minutes to sixty 60 minutes min and preferably 20 to 30 minutes to promote hydrolysis and provide pressurization the first pressurized reactor 12 may receive flows of one or more of a mild acid sulfur dioxide gas so 2 oxygen compressed air ammonia water water vapor steam for heating and maintaining temperature and catalyzing agents from sources 30 13 of each of these compounds the received flow s 30 13 may be introduced to the first pressurized reactor 12 proximal to where the feedstock enters the reactor and distal.