Abstract: The present invention relates to a chemical reaction system for efficiently excluding nitrogen oxides with low power consumption when excess oxygen is present in exhaust gas, to a method of use therefor, to an activation method therefor, and to a reaction method for oxidizing or reducing by the use of an oxidation-reduction reactor with high selectivity without the need to supply or exchange a reducing agent or oxidizing agent.

Abstract: The present invention provides a chemical reactor with which nitrogen oxide emission control can be performed very efficiently at a low applied voltage when an excess of oxygen is present in a combustion exhaust gas. The present invention is a chemical reactor in which the upper cathode, lower cathode, and anode that make the chemical reactor are a mixture of an electron-conductive substance and an ion-conductive substance, and the electron-conductive substance and ion-conductive substance of the upper cathode are mixed in a specific ratio, which makes it possible to lower the applied voltage and reduce the power consumption of the chemical reactor, and is also a method for the emission control of nitrogen oxides in which this chemical reactor is used.

Abstract: An adsorbent for exhaust gas purification is composed of a molecular sieve having high acidic hydrothermal resistance obtained by substituting part or the whole of the Al constituting the framework of crystalline aluminosilicate molecular sieve, with the ion of at least one element selected from elements M for framework element substitution, i.e. Mg, P, Ti, Cr, Ge, Zr, In, Sn, Hf, W, V, Co, Ni, Cu, Zn, Ag and B. The adsorbent for exhaust gas purification can be suitably used in the applications requiring high heat resistance and high hydrothermal resistance, such as the exhaust gas purification system for internal combustion engine or combustion furnace. The adsorbent can be used particularly preferably for the purification of automobile exhaust gas containing hydrocarbons, nitrogen oxides, etc.

Abstract: A highly heat-resistant and hydrothermal-resistant &bgr;-zeolite having a SiO2/Al2O3 ratio of 80 or more, which is constituted by primary particles having an average particle diameter of 30 nm or more or by primary particles having such a particle size distribution that the 10% particle diameter is 20 nm or more; and an adsorbent for automobile exhaust gas purification, using said &bgr;-zeolite. The &bgr;-zeolite and the adsorbent can be produced reliably so as to have guaranteed properties.

Abstract: A highly heat-resistant and hydrothermal-resistant &bgr;-zeolite having a SiO2/Al2O3 ratio of 80 or more, which is constituted by primary particles having an average particle diameter of 30 nm or more or by primary particles having such a particle size distribution that the 10% particle diameter is 20 nm or more; and an adsorbent for automobile exhaust gas purification, using said &bgr;-zeolite. The &bgr;-zeolite and the adsorbent can be produced reliably so as to have quaranteed properties.

Abstract: The present invention provies an adsorbent which, as compared with an adsorbent comprising a zeolite (an aluminosilicate) of at least about equal Si/(Fe+Al) molar ratio (Fe is substantially absent), has high heat resistance and high hydrothermal resistance and can maintain adsorption capability even when exposed to high temperatures. This adsorbent comprises a &bgr;-silicate molecular sieve containing at least Fe besides H, O and Si and, when Al is contained, containing Fe in a molar amount at least equal to that of Al.

Abstract: A system for exhaust gas purification disposed in the exhaust pipe of an internal combustion engine, which includes a zeolite as adsorbent component capable of adsorbing the hydrocarbons present in the exhaust gas emitted from the engine and a catalyst capable of reducing the harmful substances present in the exhaust gas; the system satisfies the following conditions: a/c=3 to 50 cc/g, wherein a is the total volume of the pores of diameters of 10 Å or smaller possessed by the zeolite as measured using N2, and c is the total amount of the hydrocarbons emitted from the engine during the period of 140 seconds from the start of the engine when the engine is operated in accordance with the LA-4 mode of FTP, thereby the adsorption capacity of the zeolite used as a HC adsorbent is optimized against the amount of the HC discharged from an engine during a certain period of the cold start so as to adsorb and purify the HC effectively.

Abstract: A process for synthesizing a high-silica aluminosilicate molecular sieve, includes: subjecting, to hydrothermal synthesis, a raw material containing Al, H, O and Si and, as other elements, at least Fe and having a Si/Al molar ratio of 50 or more and a Si/Fe molar ratio of 80 or less (45 or less when a high-silica aluminosilicate molecular sieve having a .beta. type zeolite structure is produced) and then subjecting the resulting material to heat treatment in an oxidizing atmosphere at 300.degree. C. or more. The above process can synthesize a high-silica zeolite low in Al content directly without dealumination operation, and can provide process simplification and a higher yield.