Sn(II)/PN@AC catalysts: synthesis, physical-chemical characterization, and applications

In this study, the novel tin-based catalysts (Sn(II)/PN@AC) were prepared using the phosphorus and nitrogen dual-modified activated carbon as support and SnCl₂ as active compounds, as well as then evaluated in acetylene hydrochlorination. Under the reaction temperature of 180 °C and an acetylene gas hourly space velocity (GHSV-C₂H₂) of 30 h^-1, the 15%Sn(II)/PN@AC-550 showed the initial acetylene conversion of 100% and vinyl chloride selectivity over 98.5%. Additionally, the deactivation rate of 15%Sn(II)/PN@AC-550 reached 0.47% h^-1, which was lower than that of 15%Sn(II)/AC-550 (1.02% h^-1), suggesting that PN@AC-550 as novel support can retarded the deactivation of Sn(II)/AC-550 catalysts during acetylene hydrochlorination. Based on the catalytic tests and characterization results (XRD, Raman, BET surface area, TEM, C₂H₂-TPD, H₂-TPR, XPS, FT-IR, TGA, and ICP), it demonstrated that PN@AC-550 as support could effectively improve the dispersion of tin species, retard the formation of coke deposition, lessen the oxidation of SnCl₂ during the preparation process, as well as relatively inhibit the leach of tin species during the reaction. By combing the FTIR results and Rideal-Eley mechanism, we proposed that that HSnCl₃ was transition state of SnCl₂ in catalysis acetylene hydrochlorination and then adsorbed the acetylene to produce the vinyl chloride.