342. Development of an active Ga2O3 supported palladium catalyst for the synthesis of methanol fr…

Table 1 Catalytic activitiesa, carbon monoxide uptake, and turnover frequency (TOF) over the various supported palladium catalysts.

Tadahiro Fujitani, et al, Applied Catalysis A: General 125, L199 (1995)
https://doi.org/10.1016/0926-860X(95)00049-6

(1) Pd/Ga2O3 is a super-active catalyst for methanol synthesis, being more active than the Cu/ZnO catalyst.
(2) The hydrogenation of carbon dioxide was carried out at 523 K in a flow reactor by feeding a gas mixture of hydrogen and carbon dioxide with a mole ratio of H2/CO2=3. The reaction products were analyzed using gas chromatographs directly connected to the reactor.
(3) The activities and selectivities at the steady state of the reaction at 523 K and 5.0 MPa were measured after passing the reactants over the catalysts for 2 h.
(4) The effect of the support on the methanol yield and selectivity is found to be significant, with the different support metal oxides in the following order Ga2O3> ZnO > Al2O3> TiO2Cr2O3 > SiO2 ZrO2.
(5) Metallic palladium alone has little catalytic activity for methanol formation.
(6) We postulate that the excellent activity of Pd/Ga2O3 is due to the optimal amount of Pdn+ (0 < n < 2) stabilized by GaxOy, on the surface of palladium.
(7) All catalysts were prepared by a coprecipitation method. A mixed aqueous solution of metal nitrates and an aqueous solution of Na2CO3 were added dropwise to distilled water. Subsequently, the precipitate was filtered out, washed with distilled water, dried in air at 393 K overnight, calcined in air at 623 K for 2 h, and finally screened to size between 60 and 80 mesh.