Effects of potassium promoter on the performance of PdCl₂-CuCl₂/AC catalysts for the synthesis of dimethyl carbonate from CO and methyl nitrite

The effect of potassium (K) promoter on the catalytic performance of activated carbon (AC) supported Wacker-type catalysts (PdCl₂-CuCl₂/AC) for the synthesis of dimethyl carbonate (DMC) from CO and methyl nitrite (MN) was investigated by means of N₂ adsorption, H₂-temperature-programmed reduction (H₂-TPR), and X-ray photoelectron spectroscopy (XPS). The experimental results showed that the space time yield of DMC on Wacker-type catalysts with different K promoters ranked in the following order: KCl > KOH > CH₃COOK > K₂CO₃. Especially, the addition of KCl significantly improved the catalytic activities of PdCl₂-CuCl₂/AC catalyst for DMC synthesis from CO and MN. N₂ adsorption data indicated that the addition of K promoters did not change the textural properties of Wacker-type catalysts greatly. H₂-TPR and XPS results demonstrated that the existence of KCl promoted the reducibility of Cu²⁺ species and increased the proportion of Cu²⁺ species on catalyst surface, which is favorable for oxidizing Pd⁰ to active Pd²⁺. Further, the addition of KCl benefited the reactivity of PdCl₂-CuCl₂/AC catalyst for DMC synthesis from CO and MN.