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

Abstract

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 : Сu molar ratio 1 : 1; catalyst reduction temperature 200○С. As shown by TEM, XPS, TPD-NH3, TPR-H2, XRD, and N2 adsorption, the surface of the most active catalyst contains Pd0Cu0 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○C, the performance of 0.2%Cu/0.3%Pd/Al2O3 is 182 × 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 (M1 = Fe, Ni, Co) and by an order of magnitude than that of the reference catalysts M2/Al2O3 (M2 = Ru, Rh, Pt, Pd, Pt–Re, Ni–Mo).