Adsorption and conductivity studies in oxychlorination catalysis. Part 3.—The ethene–transition-metal chloride interaction

Abstract

Gas adsorption chromatography (g.a.c.) has been used to obtain isotherms and isosteric heats of adsorption of C2H4 at temperatures < 150 °C on VCl3, CrCl3, CrCl2, MnCl2, FeCl2, CoCl2, NiCl2, CuCl2 and CuCl. Physical adsorption is indicated for CrCl2, MnCl2 and CuCl and chemisorption for NiCl2 and CuCl2; the others occupy an intermediate position. The results are discussed in terms of d-electron configuration and ion charge/(radius)2 ratio. G.a.c. studies of C2H4 on PdCl2, PtCl2 and PtCl4 indicate that chemical reaction occurs at room temperature. For those adsorbents for which heats of adsorption had been obtained, further reaction was initiated by increasing the temperature above 150 °C. Reaction products, e.g. HCl, vinyl chloride, dichloroethane and polymers, were identified, where possible, by mass spectrometry or chromatography. The capabilities of a microreactor to study the copper chloride–C2H4 system have been evaluated.