TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Component: The outlet of primary reactor is an annular space defined by an insulation liner provided between the heat exchanger and the primary reactor. The insulating liner minimizes heat transfer from hot synthesizing hydrogen gas exiting the primary reactor to cooled synthesizing hydrogen gas exiting the heat exchanger. The primary reactor further comprises a honeycomb ceramic, metallic monolith or porous foam carrier, and/or inorganic refractory oxide particles, to add support to the catalyst. The apparatus further comprises a mixing chamber positioned before an inlet of a fuel processor (11). The mixing chamber is configured to provide for the even mixing of the fuel stream with the oxygen-containing stream. The inlet and outlet conduits are formed between an inner shell and an outer shell of the heat exchanger, or formed by a prime surface provided between the outer and inner shells. The primary reactor is situated within an interior diameter of the inner shell, or enclosed within the inner shell. The inlet or outlet conduits are a group of tubes situated between the inner shell and the outer shell of the heat exchanger. The tubes extend in an axial direction to a longitudinal length of the primary reactor.The prime surface comprises a single corrugated sheet metal or corrugated sheet metals. It has a first corrugation width for the outlet conduit and a second corrugation width for the inlet conduit, where a ratio of the first corrugation width to the second corrugation width is 1.3-1.6. The first corrugation width is larger than the second corrugation width. The prime surface comprises a straight flow pattern, a ruffled pattern and/or fin surfaces. A porous structure is in fluid connection with the inlet conduits for flowing the oxygen-containing steam annularly into the mixing chamber. The heat exchanger further comprises a liner situated around an interior of the inner shell, an annular duct having an inlet for receiving the oxygen-containing stream, and a central outlet in fluid communication with the outlet conduit. The liner minimizes heat transfer from hot synthesizing hydrogen gas exiting the primary reactor to cool synthesizing hydrogen gas exiting the heat exchanger. The annular duct is in fluid communication with the inlet conduits. The central outlet is partially surrounded by the annular duct.Preferred Property: The apparatus has a length (L) to diameter (D) ratio of 0.5-2.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Component: The catalyst comprises nickel, cobalt, platinum, palladium, rhodium, ruthenium, iridium, magnesia, magnesium aluminate, alumina, silica, zirconia and/or potassium.