Washcoating and chemical testing of a commercial Cu/ZnO/Al2O3 catalyst for the methanol synthesis over copper open-cell foams

We herein present the preparation of washcoated copper open-cell foam prototypes by dip-blowing a ball-milled aqueous slurry made of commercial powdered Cu/ZnO/Al2O3 methanol catalyst, deionized water and methylhydroxyethylcellulose. We then show the results of the chemical testing of such prototypes in the low temperature-low pressure methanol synthesis at relevant industrial conditions (i.e. T = 505 K, P = 50 bara, H2/CO/CO2/CH4/N2 feed molar ratio = 73.2/8.3/2.6/5.1/11.2). Three levels of temperature (485, 505 and 525 K) were investigated, keeping constant all the other operating conditions. The performances were compared to those of the original powder. We found that washcoated copper foams coated with a 75 μm thick catalytic layer were active in the methanol synthesis, but showed lower COx conversion and MeOH productivity than the original powder. Slurried powders (i.e. slurry dried and calcined) showed the same chemical activity as the washcoated foams, therefore ruling out any effect related to the deposition step and singling out the slurry preparation and/or calcination procedure as responsible for a change in the catalytic performances. We also tested the same catalytic systems in the reverse-water–gas-shift (RWGS) reaction at P = 1 bara, T = 505 K and with H2/CO2 = 20. The campaign of low pressure tests confirmed the lower activity of slurried powders with respect to the original catalytic powder and leads us to the conclusion that the RWGS reaction can be considered as a representative probe reaction for ranking the intrinsic activity of Cu/ZnO/Al2O3 methanol catalysts without requiring testing under the high pressures typical of the commercial methanol synthesis process.