Influence of Synthesis Conditions on the Performance of Palladium-Copper Ethanol-to-Butanol Conversion Catalysts

The influence of the synthesis conditions on the performance of Pd-Cu ethanol-to-butanol conversion catalysts was studied. The optimum conditions for forming the most active system 0.2%Cu/0.3%Pd/Al2O3 are as follows: sample synthesis by Al2O3 impregnation from aqueous solutions of Pd and Cu nitrates; deposition of the metal precursors in succession; total content of Pd and Cu in the sample 0.5 wt %; Pd : Cu molar ratio 1 : 1; catalyst reduction temperature 200 degrees C. As shown by TEM, XPS, TPD-NH3, TPR-H-2, XRD, and N-2 adsorption, the surface of the most active catalyst contains (PdCu0)-Cu-0 particles with the mean size of 4 +/- 2 nm. The bimetallic particles are an alloy with the fcc structure and Pd : Cu ratio of 40 : 60. At 275 degrees C, the performance of 0.2%Cu/0.3%Pd/Al2O3 is 182 x 10(-4) mol h(-1) g(-1). The value obtained is higher by several orders of magnitude than the performance of the reference catalysts M1/Al2O3 (M-1 = Fe, Ni, Co) and by an order of magnitude than that of the reference catalysts M-2/Al2O3 (M-2 = Ru, Rh, Pt, Pd, Pt-Re, Ni-Mo).