Role of ZrO₂ on Cu/ZnO/Al₂O₃/ZrO₂ in Methanol Synthesis

Abstract

Cu/ ZnO / Al 2 O 3 / ZrO 2 ( CZAZr ) catalysts were prepared by a coprecipitation method. CO 2 was introduced into aging solution to get CZAZr precusors with malachite phase. The x value in CZAZr ( x ) is the metallic ratio of the Zr component at a fixed metallic ratio of Cu:Zn:Al of 6:3:1. TOF MeOH of CZAZr (0) was 0.56 µmol/ m 2 Cu /s at 250 °C, 50 atm and a gas hourly space velocity ( GHSV ) of 12 000 mL /g cat /h. TOF MeOH s of CZAZr (1), CZAZr (2), CZAZr (3), and CZAZr (4) were 0.64, 0.90, 0.99, and 1.08 µmol/ m 2 Cu /s at the same reaction condition, respectively. TOF MeOH s of CZAZr catalysts increased with increasing ZrO 2 content, indicating that high TOF MeOH of CZAZr catalysts came from ZrO 2 as compared with CZAZr (0) catalysts. These kinetic data on CZAZr catalysts in the practical reaction condition proved the suggestion from previous infrared ( IR ) study on Cu/Zr catalysts. ZrO 2 afforded the adsorption sites for CO and CO 2 insertion into Zr– OH and Cu supplied active hydrogen to ZrO 2 for hydrogenating formate and hydroxycarbonate to methanol on ZrO 2 in addition to methanol synthesis on Cu/ ZnO / Al 2 O 3 .