GB716770A - Method of purifying a cuprous salt catalyst in the synthesis of acrylonitrile - Google Patents

Abstract

<PICT:0716770/IV (b)/1> In the synthesis of acrylonitrile from hydrocyanic acid and acetylene using a cuprous salt catalyst at 70-100 DEG C., polymerization products dissolved in the hot catalyst are separated by cooling at least part of the catalyst to a temperature below 70 DEG C. and at which the catalyst is still substantially liquid; the separated polymerization products are removed and the purified catalyst reheated for further use in the synthesis. Preferably the catalyst is cooled to about 40 DEG C. and then reheated in two stages, firstly to 50-55 DEG C. to coagulate the polymerization products, and then to reaction temperature. The whole of the catalyst may be treated at once, or a portion (e.g. one-tenth) may be withdrawn continuously or periodically for purification. As shown, hydrocyanic acid enters at 1 into reaction vessel R containing a catalyst composed of water, cuprous chloride, ammonium chloride, copper powder, and concentrated hydrochloric acid; acetylene introduced at 2 circulates through pipes 4 and acrylonitrile is dissolved out with water in tower W; a portion of the catalyst passes continuously through pipes 6 to vessel D1 maintained at 40 DEG C. and then to vessel D2 maintained at 50-55 DEG C., from which precipitated polymerization products are removed.ALSO:<PICT:0716770/III/1> In the synthesis of acrylonitrile from hydrocyanic acid and acetylene using a cuprous salt catalyst at 70-100 DEG C polymerization products dissolved in the hot catalyst are separated by cooling at least part of the catalyst to a temperature below 70 DEG C. and at which the catalyst is still substantially liquid; the separated polymerization products are removed and the purified catalyst reheated for further use in the synthesis. Preferably the catalyst is cooled to about 40 DEG C. and then reheated in two stages, firstly to 50-55 DEG C. to coagulate the polymerization products, and then to reaction temperature. The whole of the catalyst may be treated at once, or a portion (e.g. one-tenth) may be withdrawn continuously or periodically for purification. As shown, hydrocyanic acid enters at 1 into reaction vessel R containing a catalyst composed of water, cuprous chloride, ammonium chloride, copper powder, and concentrated hydrochloric acid; acetylene introduced at 2 circulates through pipes 4 and acrylonitrile is dissolved out with water in tower W; a portion of the catalyst passes continuously through pipes 6 to vessel D1 maintained at 40 DEG C. and then to vessel D2 maintained at 50-55 DEG C., from which precipitated polymerization products are removed.