n "II HYDROGENOI.YSIS CF HYDROCARBONS ON IRON CATALYSTS By

In the hydrogenolysis of hydrocarbons, iron is unique among the transi tion metal s since it breaks molecules extensivel y and produces large quantIties of methane even at low conversion. Hydrogenolysis of opropane, isopentane and · n-hexadecane were stUdied at 325 and 355 Cover reduced Fe and carbided Fe catalysts prepared from a commercial NIl 3 synthesis catalyst. Reaction network analysis applied to the selectivity data yielded a quantitative estimate of the relative importance;9T ' an adsorbed species, of desorbing or undergoing C-C bond spl1ttfng; this method indicated that procfuct desorption is the slow step in the reaction mechanism. Power rate expressions were obtained for hydrogenolysis of propane and isopentane at 3250 C. Used catalysts, characteri zed by!t)ssbauer spectroscopy, contained a-Fe at high feed ratios of H2 to,hydrocarbon, and Fe 3 C, at low ratios. The formation of bulk iron carbides led to changes in selectivity, yielding less methane and more-intermediate hydrocarbons. In hydrogenolysis of n-hexadecane, the anal,ysis of ·the c 7-e 15 products by gas chromatography-ma.ss spectrometry showed the presence of alkylbenzenes, alkenes and branched alkanes, which account altogether [or as much as 20 mole S of the o I heav ier hydrocarbons. The data also suggest that the breaking of paraffins on iron poS'sibly occurs by rapid demethYlation. Hydro-genolysis of hydrocarbons is completelY inhibited when carbon monoxide is added to the feed, even at concentration as low as 4 mole S; CO. i