Synthesis of liquid hydrocarbons

Claim 1

IN THE SYNTHESIS OF LIQUID HYDROCARBONS OF THE MOTOR FUEL TYPE BY THE PROCESS INVOLVING THE STEPS OF GENERATING SYNTHESIS GAS CONSISTING OF AT LEAST ABOUT 95% BY VOLUME OF HYDROGEN AND CARBON MONOXIDE IN A MOLAR RATION HYDROGEN TO CARBON MONOXIDE OF ABOUT 1.8:1 TO 2.1:1 BY THE PARTIAL COMBUSTION OF A CARBONACEOUS FUEL WITH OXYGEN AND OF REDUCING SAID CARBON MONOXIDE BY SAID HYDROGEN IN THE PRESENCE OF AN IRON CATALYST AT AN ELEVATED PRESSURE AND TEMPERATURE TO SYNTHESIZE SAID LIQUID HYDROCARBONS, THE IMPROVEMENT OF SIMULTANEOUSLY EFFECTING A HIGH YIELD OF SAID LIQUID HYDROCARBONS AND MAINTAINING A LONG LIFE IN SAID IRON CATALYST, WHICH COMPRISES MAINTAINING A HYDROGEN CONTENT IN THE RANGE OF ABOUT 35% TO 55% BY VOLUME IN THE TOTAL GAS FEED CHARGED INTO THE CATALYTIC SYNTHESIS REACTION ZONE, WITHDRAWING THE REACTION GASES FROM SAID SYNTHESIS ZONE AFTER THE CARBON MONOXIDE CONTENT THEREOF HAS FALLEN TO ABOUT 1.5% TO 4% BY VOLUME BUT BEFORE THE HYDROGEN CONTANT THEREOF HAS FALLEN BELOW ABOUT 20% BY VOLUME, RECOVERING FROM THE WITHDRAWN GASES A TAIL GAS SUBSTANTIALLY FREE OF C3 AND HIGHER HYDROCARBONS, AND RECYCLING TO SAID STEP OF GENERATING SYNTHESIS GAS AND TO SAID SYNTHESIS ZONE A TOTAL OF ABOUT 0.7 TO 1.6 VOLUMES OF SAID TAIL GAS FOR EACH VOLUME OF SYNTHESIS GAS THAT WOULD BE GENERATED IN THE ABSENCE OF RECYCLING, SAID RECYCLING BEING DIVIDED SO THAT ABOUT 1% TO 15% BY VOLUME OF THE RECYCLED TAIL GAS IS TURNED TO SAID STEP OF GENERATING SYNTHESIS GAS AND THE REMAINDER OF THE RECYCLED TAIL GAS IS TURNED TO SAID SYNTHESIS ZONE.