Autothermal reactor and method for production of synthesis gas

An autothermal reactor for producing synthesis gas comprising:

• a primary mixing chamber having an orifice to expand a heated oxygen containing stream into said mixing chamber and an inlet located adjacent to said orifice and oriented to introduce a hydrocarbon containing stream into the mixing chamber tangentially to said heated oxygen containing stream such that said hydrocarbon containing stream is entrained in said heated oxygen containing stream to mix oxygen in said heated oxygen containing stream with hydrocarbons contained in said hydrocarbon containing stream at a sufficiently rapid rate so as not to react the oxygen and the hydrocarbons, thereby to produce a reactant stream made up of an unreacted mixture of the heated oxygen containing stream and the hydrocarbon containing stream;
• an initial partial oxidation reaction zone having a supported partial oxidation catalyst on a monolithic support, said initial partial oxidation reaction zone in communication with said mixing chamber and followed by at least two endothermic reforming reaction zones heated by an exothermic reaction of said partial oxidation reaction zone to react the oxygen and the hydrocarbons of said reactant stream and thereby to form said synthesis gas;
• a secondary mixing chamber situated between said partial oxidation reaction zone and said at least two endothermic reforming zones, said secondary mixing chamber having a secondary inlet to receive a recycle stream containing synthesis gas components obtained by separation of hydrogen and carbon monoxide from said synthesis gas;
• and
• the at least two endothermic reforming reaction zones formed of beds of pellets containing a precious metal catalyst supported on supports formed of different materials that provide a greater surface area for a successive of the at least two endothermic reforming reaction zones than an initial of the at least two endothermic reforming reaction zones directly following the partial oxidation reaction zone, the initial and the successive of the at least two endothermic reforming reaction zones configured to operate at ever decreasing operational temperatures such that a material making up a support of the successive of the at least two endothermic reforming reaction zones remains stable.