Modification of the acid-base and catalytic properties of CuCl2-KCl-LaCl3/gamma-Al2O3 by MgAl2O4 in ethane oxychlorination

Effect of MgAl2O4 on the structure, acidity as well as catalytic activity of CuCl2-KCl-LaCl3/gamma-Al2O3 catalystin ethane oxychlorination was studied. Impregnation of gamma-Al2O3 with Mg and Al nitrates formed magnesium aluminate spinel on the support. TPR results showed that Cu species were located on both gamma-Al2O3 and MgAl2O4 phases. With modification of gamma-Al2O3 by MgAl2O4, the interaction between Cu species and support weakened and the surface active species CuCl2 increased. Formation of MgAl2O4 leads to a decrease of strong acid sites and an increase of weak acid sites. Much larger quantities of coke were deposited on the CuCl2-KCl-LaCl3/gamma-Al2O3 than on the modified catalyst, which was attributed to its more strong acid sites. Based on these factors CuCl2-KCl-LaCl3/MgAl2O4-Al2O3 catalyst exhibits better catalytic activity and stability than gamma-Al2O3 supported catalyst, and the highest vinyl chloride selectivity reached 46.8% and was still 40.6% after 210 h reaction.