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.

The addition of KCl promoted the reducibility of Cu2+ species and increased the proportion of Cu2+ species on PdCl2–CuCl2–KCl/AC catalyst, which further benefited the redox cycle between Pd2+/Pd0 and Cu+/Cu2+ pairs and resulted in the better catalytic performance of PdCl2–CuCl2–KCl/AC catalyst for DMC synthesis from CO and MN.Figure optionsDownload as PowerPoint slide