A fixed bed, radial flow reforming reactor having an inner catalyst zone between an inlet fluid zone and an outlet fluid zone. The catalyst zone is separated into two concentric, annular zones, a first annular zone having a first solid particle material having a first catalytic activity for reforming hydrocarbons into the catalyst zone, and, a second annular zone having a second solid particle material having a second catalytic activity for reforming hydrocarbons into the catalyst zone, wherein the second catalytic activity is different. One of the materials may be inert. A divider may be used to separate the two annular zones.

A liquid/gas reactor comprises: a primary catalyst bed having an inlet and outlet end; means for supplying a primary feed stream to the inlet end; a secondary catalyst bed having an inlet and outlet end; means for supplying a secondary feed stream to the inlet end; means for collecting at least partially converted liquid product from the outlet end of the primary catalyst bed and recycling at least a portion of the liquid product to the inlet end of the primary catalyst bed and secondary catalyst bed; a separating wall between the primary catalyst bed and secondary catalyst bed; means for supplying a primary gas stream only to the inlet end of the primary catalyst bed; and means for supplying a secondary gas stream only to the inlet end of the secondary catalyst bed. A process for carrying out a gas/liquid reaction using the reactor is also disclosed.

Disclosed is a combined reformer including two or more catalyst tubes reacting at different temperatures, having different reforming reactions continuously performed as a combustion gas sequentially supplies heat to two or more catalyst tubes, and capable of easily replacing a catalyst, and a catalyst replacement method thereof.