Reason for the deactivation of SnOx in acetylene hydrochlorination

Abstract

To investigate the deactivation process of Sn-based catalysts and the transformation of their active sites during acetylene hydrochlorination, we synthesized a SnO_x catalyst and subjected it to hydrochloric acid and water-washing treatments. Subsequent characterization showed that the active SnO_x component was transformed into SnCl₄ by hydrochloric acid treatment, and SnCl₄ showed lower catalytic activity compared with SnO_x components. Furthermore, SnO_x reacted with the HCl reactant to form SnCl₄ in the acetylene hydrochlorination, which led to a decline in catalytic performance and a loss of Sn components. Considering the influence of Sn valence states, we used ascorbic acid (C₆H₈O₆) to regulate the valence in SnO_x and found that Sn²⁺ was firstly oxidized to Sn⁴⁺ in the acetylene hydrochlorination, and then secondly Sn⁴⁺ reacted with HCl to form SnCl₄, leading to the deactivation of the SnO_x catalyst.