Nissan Motor Company Limited

Agency of Industrial Science and Technology

Junichi Mine

Fujio Mizukami

Kazuyuki Maeda

Shuichi Niwa

Koji Masuda

Makoto Toba

Yoshiyuki Eto

Tetsuhiko Yoneshige

Keiichi Sawamura

Akio Iizuka

Hidefumi Ito

A process includes a step of melting aluminium alkoxide in hexylene glycol (2-methyl 2,4-pentonediol). Then, the solution is subject hydrolysis. During this, hydrolysis and dehydrating condensation of hexylene glycol is controlled by alkoxide. This is found effective for obtaining alumina having uniform porous structure with high specific surface area.

Process for producing alumina with high specific surface area

A process of production of alumina includes method for controlling specific surface area of alumina. Control of specific surface area is performed by controlling porous structure of alumina. In the process, aluminum alkoxide is subject hydrolysis for forming alumina sol. During hydrolysis process, polyether is used as organic solvent in order to control the porous structure of produced alumina.

Method for controlling specific surface area of alumina

A method of producing a monolithic three-way catalyst for the purification of exhaust gases of internal combustion engines. First, a mixed oxide coating is provided to a monolithic carrier by treating the carrier with a coating slip in which an active alumina powder containing cerium in oxide form is dispersed together with a ceria powder and then baking the treated carrier. Next, Pt, Rh and/or Pd are deposited on the oxide coating by a known thermal decomposition process. The addition of the ceria powder to the coating slip is effective in enhancing the CO, HC and NO.sub.x conversions and durability of the produced catalyst at high temperatures. Preferably the content of Ce in the active alumina powder is 1-5 wt %, and, in the coating after baking, Ce of the ceria powder amounts to 5-50 wt % of the coating. Optionally a zirconia powder too may be added to the coating slip such that Zr of the zirconia powder amounts to 1-10 wt % of the coating.

Method of producing monolithic catalyst for purification of exhaust gas

A catalyst, which consists essentially of a catalytic metal, or metals, of the platinum group distributed on a carrier of active alumina and exhibits high conversion ability for CO and HC and good durability but exhibits a relatively low activity on the oxidation of SO.sub.2, is produced by impregnating the carrier with an aqueous solution containing, dissolved therein, a complex of a salt of EDTA and the catalytic metal and baking the impregnated carrier in a stream of steam at temperatures between 300 and 700.degree. C.

Method of producing catalyst for conversion of carbon monoxide and

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Kanagawa, Japan

Junichi Mine