CO esterification to methyl formate: from Pd nanoparticles to single atom catalysts

Abstract

CO esterification involves processes using CO as the starting material and ester chemicals as products. Methyl formate, dimethyl oxalate and dimethyl carbonate are the main products. Traditional Pd nanoparticle (Pd_NP) catalysts have excellent catalytic performance for the CO esterification reaction. However, Pd_NP catalysts have problems such as high metal loading, low metal utilization and high cost. In recent years, single atom catalysts have developed rapidly due to their high atomic utilization and low loading. In this work, Pd₁/(ZnMn₂O₄@MnO₂) (Pd₁/ZMO) was synthesized via a sol–gel method followed by a redispersion strategy-assisted calcination process. This Pd₁/ZMO catalyst exhibits exceptional catalytic performance for CO esterification to methyl formate. Compared to the Pd_NP/α-Al₂O₃ catalyst, Pd single atom catalysts significantly reduce noble metal loading from 1 wt% to 0.25 wt%, while increasing the catalyst's mass activity by 4 times. More importantly, the Pd₁/ZMO catalyst is quite stable at least for 150 hours under reaction conditions. And we have demonstrated the high dispersibility of the Pd single atom through AC-TEM, in situ DRIFTS and XPS. This work adopts the strategy of single atom catalyst, which controls the cost of the catalyst while achieving a 4-fold increase in metal utilization, providing important reference significance for the efficient utilization of noble metal and catalyst cost control.