Oxyhydrochlorination processes wherein ethylene, hydrogen chloride, and molecular oxygen are reacted in the presence of oxychlorination catalyst to form 1,2-dichloroethane [CAS 107-06-2], are themselves well known; see U.S. Pat. Nos. 3,256,352; 3,288,868; 3,345,422; 3,378,597; 3,679,373; 4,151,212; and 4,172,052. The process is usually conducted either in a fluidized bed of oxychlorination catalyst particles at elevated temperatures in the range of from 190.degree. C. to 350.degree. C., or in a fixed bed of oxychlorination catalyst particles at elevated temperatures in the range of from 200.degree. C. to 450.degree. C. When ethylene is so oxyhydrochlorinated, satisfactorily high yields of 1,2-dichloroethane may be obtained under moderate reaction conditions. However, the product typically contains objectionable amounts of chloral, i.e., amounts in excess of about 0.2 percent by weight. In addition to being classified as a pollutant, the normal boiling point of chloral is quite close to that of 1,2-dichloroethane. Chloral is therefore both difficult and costly to remove by distillation to produce high purity 1,2-dichloroethane.
Oxychlorination catalysts have been manufactured in the past by milling attapulgus clay with water, extruding the milled clay into pellets, drying the pellets, calcining the dried pellets, grinding the dried pellets and screening to form particles of appropriate size, adding a hot aqueous solution of cupric chloride and potassium chloride to the particles, and drying to remove water and thereby form substantially dry catalyst particles. The addition of the hot aqueous solution of cupric chloride and potassium chloride to the particles is usually accomplished either by spraying the hot solution onto heated clay particles in a tumbling vessel or by spraying the hot solution into a heated fluidized bed of the particles. Rescreening may be performed to verify the correct particle size distribution.
Oxychlorination catalysts have also been made by mixing attapulgus clay, water, an aqueous solution containing cupric chloride and potassium chloride to form a slurry, drying the slurry at 160.degree. C. for 48 hours in a forced draft oven to form a dried cake, breaking up the cake, and grinding the broken cake to -70 to +200 mesh; See, for example, U.S. Pat. No. 4,151,212. See also U.S. Pat. No. 4,172,052 which discloses drying slurries at 105.degree. C. and grinding the resulting cakes.
USPTO Backgrounds
USPTO Backgrounds