Abstract: A method is disclosed for the concentration of an aqueous acrylamide solution prepared by hydration of acrylonitrile or an aqueous acrylamide solution substantially free of acrylonitrile. The method makes use of a concentration apparatus at least a part of whose solution-contacting section is made of a copper-containing material. The concentration is conducted while introducing an oxygen-containing gas into the apparatus. Use of this method can prevent formation, adhering, accumulation and the like of popcorn polymers inside the concentration apparatus upon concentration of the aqueous acrylamide solution, and can also produce high-quality acrylamide.

Abstract: A process for preparing acrylamide is disclosed herein which comprises subjecting acrylonitrile to a hydration reaction in the presence of a copper-based catalyst, said process comprising the step of allowing a compound having an active methylene group and an acidic group in one molecule or a salt of the compound, for example, malonic acid, cyanoacetic acid or its salt to be present in a reaction system. According to the hydration reaction, it is possible to inhibit the secondary formation of impurities which cannot be heretofore removed, without any deterioration of a catalyst activity, and acrylamide can be obtained which is useful as a material for the manufacture of a high-molecular weight flocculant having a sufficiently large molecular weight and a good water solubility.

Abstract: A molten Raney copper alloy containing copper and a metal selected from Al, Si and Zn as major components and, if necessary, specific metals as minor components is solidified at a cooling rate of not less than 1.times.10.sup.2 K/sec by a rotary water atomizing process, water or gas atomizing process, single roll process or similar process. The Raney copper alloy thus obtained is leached to obtain a Raney copper catalyst. The resultant catalyst exhibits activity several times higher than that of conventional Raney copper catalysts in the reaction of acrylonitrile with water to give acrylamide.