Source: {"pile_set_name": "USPTO Backgrounds"}

Catalysts for oxychlorination of ethylene to 1,2-DCE that comprise a copper compound, generally cupric chloride, and promoters based on salts of alkali and/or alkaline-earth metals and rare earth metals are well-known in the literature.
The copper content of these catalysts is generally not higher than 6-8% by weight.
Catalysts with a copper content that can reach 12-14% by weight are also known. Examples of these catalysts are disclosed in patent GB 1,189,815.
The catalysts are prepared by coprecipitation of hydrogels of alumina and copper, followed by aging of the precipitate at 10 to 40° C. for at least 10 hours, drying and washing and finally calcining at temperatures between 300 and 600° C. for a time sufficient to convert the alumina hydrogel into gamma alumina.
The catalysts are preferably used in a fluidized bed.
Differently from catalysts that have a high copper content (12% by weight) obtained by impregnation of alumina with a solution of a copper salt, which according to the patent cited above provide low conversions of hydrochloric acid and considerable combustion of the ethylene to CO and CO2, catalysts prepared by coprecipitation allow to obtain, in the operating conditions cited in the patent, a good performance in terms of conversion and selectivity and in terms of stability of the fluidized bed.
However, the drawback of these catalysts is due to the fact that it is necessary to work with high spatial velocities, i.e., with short contact times and accordingly with a considerable recycling of the unconverted ethylene.
Commercial catalysts with a high copper content (12-13% by weight) are known which are probably prepared by means of the coprecipitation method and which cause a considerable combustion of the ethylene even when operating at relatively low temperatures (210° C.).