Influence of copper on nickel-based catalysts in the conversion of glycerol

Abstract

The catalytic transformation of glycerol to value-added compounds was investigated over bimetallic Ni-Cu/y-Al2 O3 catalysts with Ni/Cu atomic ratios of 8/1, 4/1, 2/1, 1/1, 1/2, 1/4, and 1/8. XPS analysis revealed that the surface composition of the catalyst exhibited progressive enrichment of Cu as its content in the catalyst increased. H2 -chemisorption indicated that the total number of exposed Ni atoms decreased as the Cu content increased. As a result, deep hydrogenolysis to produce CH4 was inhibited by the addition of Cu to the Ni catalyst, yielding higher selectivity toward the dehydration products of glycerol such as hydroxyacetone.FTIR spectra of adsorbed CO reveal that Cu asserts both geometric and electronic effects on the adsorption properties of Ni. The geometrical effect is visualized by the progressive disappearance of the bridge-bound adsorbed CO on metallic Ni by the incorporation of Cu. This suggests that the deep hydrogenolysis of glycerol to CH4 formation requires an ensemble of adjacent active Ni atoms. The electronic effect of Cu on Ni is indicated by the red shift of the IR peak of adsorbed CO as the Cu content increases. The electronic interaction between Cu and Ni species was also substantiated by XANES results. HTREM revealed metal particles very well distributed on the support with particle size of 1.5 to 5 nm. The Ni-Cu samples were not a total intermetallic alloys..

Recent Advances in the Catalytic Production of Platform Chemicals from Holocellulosic Biomass

“…Glycerol can be used as a fuel additive, animal feed, food acrolein, in chemical and pharmaceutical products; and methanol, ethanol and biogas can be also produced. Miranda et al . published a research on the effects of bimetallic Ni−Cu systems on the conversion of glycerol into different value‐added compounds (methane, hydroxyacetone, pyruvaldehyde).…”

Phase‐Contact Engineering in Mono‐ and Bimetallic Cu‐Ni Co‐catalysts for Hydrogen Photocatalytic Materials

“…TheX ANES spectra corresponding to the pure chemical species (Cu 0 and Cu II ) expand the differences between the samples.A sc an be seen in Figure 3s ubtle differences are presented in the Cu II state but more acute ones are visible in the Cu 0 state.T he typical shape of the Cu foil is reasonable followed by the Cu sample. [8,9] Note however that this would occur with arather limited quantity of Ni (Cu-rich alloy) as the Ni K-edge does not show asignificant reduction of Ni. View of the sample and experimental conditions.…”

xNi–yCu–ZrO2 catalysts for the hydrogenation of levulinic acid to gamma valorlactone

“…The most active catalyst (45Ni-5Cu-ZrO 2 ) has both the highest BET surface area and a high specific adsorption of N 2 O with small metal particle sizes, indicating high metal dispersion in this material. The high dispersion coupled with low Cu content may also lead to more regions of exposed Ni metal available to catalyse hydrogenation [26,41].…”