Abstract: A fuel cell system according to the present invention allows the fuel cell system to realize the higher output. An electrode of a fuel cell includes a gas permeable base material, an anode catalyst layer 92a and a cathode catalyst layer 93a formed on the surface of the base material, on which the catalyst is carried. The anode catalyst layer 92a and the cathode catalyst layer 93a contain carbon aerogels obtained through a process of grinding an organic wet gel material into gel particles, performing a solvent displacement by bringing the gel particle into contact with the water soluble organic solvent, subjecting the gel particle to supercritical drying to obtain dry gel powder, and subjecting the dry gel powder to thermal decomposition.

Abstract: A hydrogen separation filter includes a plurality of hydrogen extraction layers, a plurality of separation layers with hydrogen separation films, and a plurality of reformed gas layers, which are laid one upon another in the sequence of the extraction layer, the separation layer, the reformed gas layer, and the separation layer to form a laminate structure. The respective layers are composed of porous ceramic material to ensure the required strength. The direction of the gas flow in the reformed gas layers and that in the extraction layers are respectively fixed to simplify the gas intake and discharge structure. The hydrogen separation filter is covered with a casing via a cushioning member to ensure the sufficient strength and the required sealing properties. A methanation catalyst that accelerates methanation of carbon monoxide is carried on either the separation layer or the extraction layer.

Abstract: For a reforming device that generates fuel gas for fuel cells by decomposing hydrocarbon compounds such as natural gas and then using a hydrogen separation composite to selectively transmit hydrogen, a hydrogen separation composite having the following structure is used. A porous support medium made of ceramics, etc. is formed, and a hydrogen separation metal is supported in the pores so as to fill the inside of the support medium. It is also possible to support a reforming catalyst. By doing this, it is possible to increase the area at which the hydrogen separation metal contacts gas, so the hydrogen transmission performance is increased. Furthermore, to prevent raw material gas leaks due to pin holes, high pressure gas is supplied to the hydrogen extraction side, and the total pressure is made higher than the pressure on the raw material gas supply side without making the hydrogen partial pressure higher.

Abstract: When the hydrogen separating membrane is in a low temperature condition, a lean bus operation is carried out in a reformer in order to conduct warm-up while suppressing generation of hydrogen. At the timing t1 where the temperature of the hydrogen separator membrane has reached a temperature at which hydrogen embrittlement does not occur, reforming is initiated. In such a condition, oxygen is supplied to hydrogen which is permeated through the hydrogen separator membrane for burning the hydrogen, so as to further facilitate the warm-up. At the timing t2 where the temperature has reached an operation temperature, the supply of oxygen in a purge side is stopped so as to stop the burning of hydrogen, and an operation mode is shifted to a normal operation.

Abstract: A hydrogen-permeable membrane includes a permeable layer which has a function of making hydrogen permeate therethrough, and a catalyst layer which acts as a catalyst for promoting permeation of the hydrogen in the permeable layer. An area of the catalyst layer which contacts gas is larger than an area of the permeable layer.

Abstract: A hydrogen extraction unit has reformed gas flow channel plates, hydrogen separation plates, and purge gas flow channel plates, which are designed as thin metal plate members. The hydrogen extraction unit is constructed by laminating these thin plate members and then bonding them together by diffusion bonding. Each of reformed gas flow channel holes formed in the reformed gas flow channel plates constitutes a flow channel for reformed gas together with a correspondingly adjacent one of the hydrogen separation plates. Each of purge gas flow channel holes formed in the purge gas flow channel plates constitutes, together with a correspondingly adjacent one of the hydrogen separation plates, a flow channel for purge gas with which hydrogen extracted from reformed gas is mixed.

Abstract: The technique of the present invention enhances the separation efficiency and the production efficiency of hydrogen in a hydrogen production system for fuel cells, while reducing the size of the whole fuel gas production system. In the fuel gas production system of the present invention, a hydrocarbon compound is subjected to multi-step chemical processes including a reforming reaction, a shift reaction, and a CO oxidation to give a hydrogen-rich fuel gas. Gaseous hydrogen produced through the reforming reaction is separated by a hydrogen separation membrane having selective permeability to hydrogen. The residual gas after the separation of hydrogen has a low hydrogen partial pressure and undergoes the shift reaction at the accelerated rate. The hydrogen-rich processed gas obtained through the shift reaction and the CO oxidation joins with the separated hydrogen and is supplied to fuel cells.

Abstract: A hydrogen-permeable membrane includes a permeable layer which has a function of making hydrogen permeate therethrough, and a catalyst layer which acts as a catalyst for promoting permeation of the hydrogen in the permeable layer. An area of the catalyst layer which contacts gas is larger than an area of the permeable layer.

Abstract: When the hydrogen separating membrane is in a low temperature condition, a lean bus operation is carried out in a reformer in order to conduct warm-up while suppressing generation of hydrogen. At the timing t1 where the temperature of the hydrogen separator membrane has reached a temperature at which hydrogen embrittlement does not occur, reforming is initiated. In such a condition, oxygen is supplied to hydrogen which is permeated through the hydrogen separator membrane for burning the hydrogen, so as to further facilitate the warm-up. At the timing t2 where the temperature has reached an operation temperature, the supply of oxygen in a purge side is stopped so as to stop the burning of hydrogen, and an operation mode is shifted to a normal operation.

Abstract: A hydrogen extraction unit has reformed gas flow channel plates, hydrogen separation plates, and purge gas flow channel plates, which are designed as thin metal plate members. The hydrogen extraction unit is constructed by laminating these thin plate members and then bonding them together by diffusion bonding. Each of reformed gas flow channel holes formed in the reformed gas flow channel plates constitutes a flow channel for reformed gas together with a correspondingly adjacent one of the hydrogen separation plates. Each of purge gas flow channel holes formed in the purge gas flow channel plates constitutes, together with a correspondingly adjacent one of the hydrogen separation plates, a flow channel for purge gas with which hydrogen extracted from reformed gas is mixed.

Abstract: A CO gas sensor is equipped with a detecting unit in which a solid electrolyte membrane is held between a detection electrode and a counter electrode, and a voltage applying unit which applies voltage between the detection electrode and the counter electrode and changes the voltage. The detection electrode includes an electrochemically active first catalyst in an electrically conductive porous body, a reaction layer having a density of 1 ng/cm2-100 &mgr;g/cm2 and having a thickness of 0.3 nm-15 &mgr;m, and the counter electrode includes an electrochemically active second catalyst carried on an electrically conductive porous body.

Abstract: A hydrogen separation filter includes a plurality of hydrogen extraction layers, a plurality of separation layers with hydrogen separation films, and a plurality of reformed gas layers, which are laid one upon another in the sequence of the extraction layer, the separation layer, the reformed gas layer, and the separation layer to form a laminate structure. The respective layers are composed of porous ceramic material to ensure the required strength. The direction of the gas flow in the reformed gas layers and that in the extraction layers are respectively fixed to simplify the gas intake and discharge structure. The hydrogen separation filter is covered with a casing via a cushioning member to ensure the sufficient strength and the required sealing properties. A methanation catalyst that accelerates methanation of carbon monoxide is carried on either the separation layer or the extraction layer.

Abstract: The technique of the present invention enhances the separation efficiency and the production efficiency of hydrogen in a hydrogen production system for fuel cells, while reducing the size of the whole fuel gas production system. In the fuel gas production system of the present invention, a hydrocarbon compound is subjected to multi-step chemical processes including a reforming reaction, a shift reaction, and a CO oxidation to give a hydrogen-rich fuel gas. Gaseous hydrogen produced through the reforming reaction is separated by a hydrogen separation membrane having selective permeability to hydrogen. The residual gas after the separation of hydrogen has a low hydrogen partial pressure and undergoes the shift reaction at the accelerated rate. The hydrogen-rich processed gas obtained through the shift reaction and the CO oxidation joins with the separated hydrogen and is supplied to fuel cells.

Abstract: There is provided a concentration sensor for measurement of concentrations of one or plural target substances in a system, with a detection electrode of conductive diamond. The measuring method with the concentration sensor involves measuring the reaction potentials of plural target substances in a sample containing and determining the concentrations of the plural substances by use of the difference between the resulting reaction potentials of the respective substances. The measuring method can also determine the concentration of a single substance in a sample containing one kind of target substance.