(US4849187-A)      An endothermic gas reactor comprises a cylindrical vessel with annular coaxial fuel gas supply, flue gas and reaction passages. A wall (300) has a combustion catalyst holding layer (400) facing the flue gas passage (500), and a prod. gas passage is in countercurrent heat-exchange with the reaction passage (818) and is connected to it at one end. A mixt. of fuel and O-contg. gases passes through the catalyst wall into the flue passage, burning to provide heat for the reaction passage, through which raw gas passes for discharge through the prod. passage. The catalyst holding wall is pref. of insulating ceramic and is 0.5-20mm thick, while the catalyst holding layer is 1-40mm thick.    USE/ADVANTAGE -   Partic. for steam reforming, has small internal vol. but large capacity.    (16pp)    (JP94042940-B2)      An arrangement for the endothermic reaction of a gas includes a vertical cylindrical vessel coaxial with which is a circular endothermic reaction chamber with two cylindrical walls. Other components include a gas-permeable cylindrical combustion-catalyser holding wall which is coaxial with the vessel and which has, on the side facing the reaction chamber, a catalyser holding bed. A mixt. of a fuel gas and an oxygen-contg. gas is burned by the catalyser to become a combustion gas and produce heat. An initial- or raw-material gas flows through the reaction chamber, where it reacts endothermically and becomes a prod. gas which gives up heat before it leaves the reactor.    The example shown is intended for converting hydrocarbons into a gaseous mixt. contg. large amts. of hydrogen and carbon monoxide as active constituents, by the transformation of the hydrocarbons with steam at high temps. in the presence of a steam re-forming catalyst. The cylindrical reaction vessel includes a gas-permeable wall surrounding a charging duct for oxygen-contg. gas.    USE/ADVANTAGE -   A typical use is for steam re-forming. The reactor has high efficiency combined with min. bulk.