Hitachi, Ltd.

Mitsubishi Petrochemical Company Limited

Babcock-hitachi Kabushiki Kaisha

Babcock-hitachi K.k.

Hitachi Chemical Company, Ltd.

Shimpei Matsuda

Fumito Nakajima

Akira Kato

Masato Takeuchi

Shigeo Uno

Jinichi Imahashi

Seizi Takeuchi

Toshikatsu Mori

Makoto Imanari

Yoshihisa Watanabe

Kohki Tamura

Toshiki Kahara

Hideo Okada

Sigeru Okabe

Kenzo Ishii

Hiroshi Tobita

Teruo Kumagai

Yutaka Fukui

Hisao Yamashita

Ryoichi Sasaki

Yukio Hishinuma

Ryo Hiraga

Akio Honji

Hidetoshi Akimoto

Fumio Hataya

Munehiko Tonami

Hirosi Tobita

Masato Tekeuchi

Teruo Kumagi

A fuel cell provided with an electrolyte retaining plate made of electrical insulating long fibers such as lithium aluminate long fibers which have preferably a length of 100 to 400 .mu.m and a diameter of 1 to 4 .mu.m, are interlocked each other and have vacant spaces for filling an electrolyte can be constructed and operated safely without damaging the electrolyte retaining plate for a long period of time.

Process for producing an electrolyte retaining matrix of electrical

Disclosed is a catalytic reaction process in which a substance in a liquid reaction system is catalytically reacted with a gaseous substance which is hardly soluble in the liquid reaction system in the presence of a solid catalyst of a non-electroconductive, hydrophobic polymeric material, a part of the surface of which is non-compatible with the liquid reaction system or with the liquid reaction system and a product formed by the catalytic reaction. According to this process, mild reaction conditions can be selected and adopted and separation or recovery of the catalyst can be remarkably facilitated. This catalytic reaction process can be applied to various liquid-gas reactions and can be applied especially advantageously to oxidation and reduction of organic substances and inorganic ions for disposal of waste waters and recovery of valuable substances.

Catalytic reaction process

A fuel cell comprising a pair of gas diffusion electrodes, an electrolyte retaining matrix disposed between said gas diffusion electrodes, and a phosphoric acid electrolyte disposed within said matrix, characterized by using as matrix that comprising one or more metal oxides having electronic insulation and insolubility in phosphoric acid and a binder is excellent in phosphoric acid retaining ability and can be used for a long period of time without degradation of the performance of fuel cell.

Fuel cell

A fuel cell electrode being substantially free from cracks on the surface of catalyst layer on the electrode and having a good electrode performance under the atmospheric pressure or under pressure when assembled into a fuel cell, which comprises a gas-diffusing electroconductive substrate with continued pores and a water-repellent catalyst layer comprising electroconductive submicron particles having a catalyst, electroconductive materials each having a volume 10.sup.3 -10.sup.10 as large as the volume of the largest particle of the submicron particles and, if necessary, having a catalyst, and a water-repellent polymer as a binder, the electroconductive submicron particles and the electroconductive materials being provided in a mixing ratio by volume of the former to the latter of 95-50 to 5-50.

Fuel cell electrode

Method of manufacturing catalyst

Fuel cell with improved and stabilized electrode performance having at least one gas diffusion electrode, where the gas diffusion electrode comprises an electronconductive, gas-permeable substrate and an electrode catalyst uniformly distributed on the substrate, the electrode catalyst comprising colonies each consisting of not more than 20 primary particles of noble metal each having a size of 10-30 A and being uniformly distributed and deposited on carrier powder.

A coal or petroleum combustion flue gas containing sulfur oxides and dust is treated by contacting the flue gas with a sulfur dioxide-oxidizing catalyst, thereby converting sulfur dioxide to sulfur trioxide, allowing the resulting sulfur trioxide to react with components of dust, absorbing the trioxide into the dust as a sulfate, and removing the dust. Catalytic oxidation of sulfur dioxide can be efficiently carried out at a low temperature and sulfur oxides can be efficiently removed from the flue gas.

Process for treating flue gas

There is provided a method for converting sulfur dioxide in an exhaust gas to sulfur, which comprises the reduction step of reducing sulfur dioxide in an exhaust gas containing water vapor to hydrogen sulfide in the presence of carbon, a part of the exhaust gas is caused to bypass the reduction step and the remainder of the exhaust gas is fed to the reduction step to convert sulfur dioxide in the exhaust gas to hydrogen sulfide; the gas from the reduction step is mixed with the exhaust gas bypassing the reduction step while controlling the amount of the bypassing exhaust gas so that the ratio of hydrogen sulfide to sulfur dioxide in the mixed gas is maintained at 2; the mixed gas is fed to the Claus reaction step; and the Claus reaction step of reacting hydrogen sulfide formed at the reduction step with sulfur dioxide to convert hydrogen sulfide to sulfur.

Method and apparatus for converting sulfur dioxide in gas to sulfur

A waste gas containing sulfur oxides is contacted with an adsorbent comprising an intimate mixture of an iron oxide and/or a copper oxide and a titanium oxide at a temperature of 250.degree.-500.degree. C. The sulfur oxides thus adsorbed are desorbed with a reducing gas and recovered as sulfur material. The efficiency of the adsorbent is not reduced even after many repetitions of the adsorption-desorption cycle. Since the adsorbent exhibits a high resistance to sulfuric acid mist (SO.sub.3) contained in the waste gas.

Process for treating a waste gas containing sulfur oxides

A process for treating an exhaust gas containing nitrogen oxides, oxygen and ammonia gas with a catalyst consisting essentially of titanium oxide, copper oxide in an amount of 0.02 to 0.3 mole and molybdenum oxide or tungsten oxide in an amount of 0.01 to 0.5 mole per one mole of the titanium oxide. Because the catalyst exhibits good properties for decomposition of ammonia as well as for decomposition of nitrogen oxides it is possible to avoid secondary pollution due to unreacted ammonia.

Process for catalytically treating exhaust gas containing NO.sub.x in

A catalyst compositions for reducing nitrogen oxide comprising, as its chief ingredient, an intimate mixture of

Catalytic process for reducing nitrogen oxides to nitrogen

A process for treating an exhaust gas containing substantially only ammonia gas and oxygen gas as reactants to decompose catalytically the ammonia gas to nitrogen and water, which comprises contacting at an elevated temperature the exhaust gas with a catalyst consisting essentially of the oxides of titanium, copper and a member selected from the group consisting of molybdenum, tungsten, vanadium, cerium, iron and mixtures thereof. The ammonia gas is catalytically decomposed in accord with the following chemical reaction:

Process for catalytically treating an exhaust gas containing ammonia gas

A catalyst layer is formed on the metallic surface of a structure constructing a reactor by diffusing a developable metal into the structure by the pack cementation method and developing the diffused metal. The catalyst layer is metallurgically combined with the structure, so that it has excellent mechanical strength and heat conductivity. Thus, by using the structure having the catalyst layer as a heat exchanger type methanation reactor it is possible to obtain a methanation reactor enabling an extremely enhanced rate of reaction to be obtained with superior operability and at great savings.

Method of producing thin layer methanation reaction catalyst

An ammonia gas to be determined, and an oxidative gas containing nitrogen oxides in moles more than those of the ammonia are brought into contact with an analytical catalyst capable of forming nitrogen and water from ammonia and nitrogen oxides. Concentrations of nitrogen oxides of the gas before and after the contact with the analytical catalyst are determined, and an ammonia concentration of the gas is determined by converting the difference between the concentrations of nitrogen oxides to the ammonia concentration by calculation.

Method and apparatus for determining ammonia concentration of gas

A catalyst composition for reducing nitrogen oxides, which is characterized in that the same contains, as its chief ingredient,

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Ibaraki, Japan

Shimpei Matsuda