MEMBRANE-ASSISTED 2-STEP PROCESS FOR METHANE CONVERSION INTO HYDROGENAND HIGHER HYDROCARBONS

In this work, methane conversion was carried out over a group VIII met al in a Pd-Ag membrane reactor to produce hydrogen and higher hydrocar bons in a nonoxidative atmosphere. A two-step reaction sequence operat ed at two different temperatures was adopted to pass around the thermo dynamic barrier of low-temperature methane conversion. Methane was fir st activated as a result of the dissociative deposition over a Ru cata lyst, followed by rehydrogenation to form higher hydrocarbons. The use of the Pd-Ag membrane reactor significantly enhanced the methane conv ersion into hydrogen and carbonaceous species in the first step and th e yield of higher hydrocarbons upon rehydrogenation in the second step . The repartition of different carbonaceous species was monitored by t emperature-programed surface reaction(TPSR). The effective methane con version at low temperatures in the membrane reactor favored the format ion of C-alpha species which were selective to produce higher hydrocar bons. A C-2+ yield of about 16% was obtained by conducting methane dec omposition at 300 degrees C and rehydrogenation at 100-120 degrees C i n the Pd-Ag membrane reactor.