Study of the adsorption of phenolics and furanics on the surface of Ni-Cu catalysts

Abstract

Paper provides a comprehensive study of Ni-Cu catalysts on alumina, focusing on the effects of metal loading, reduction temperatures, and bimetallic interactions on catalyst properties and adsorption behaviour of model organic molecules. Introduction of metal reduces catalyst surface area. Low Cu loadings promote formation of isolated Cu sites, higher result in large CuO clusters. Ni catalysts have composition consisting of a mixture of NiO, NiO-like, and spinel species and the surface is primarily covered by NiO. Bimetallic Ni-Cu catalysts reveal Cu enhanced hydrogenation ability and reducibility. Acidity, primarily originating from alumina, decreases with increasing metal loading, however increasing nickel loading induces new type of sites capable of decomposing NH₃. Reduced acidity limits anisole and guaiacol adsorption, while the presence of Cu provides additional adsorption sites for furfuryl alcohol. Organics exhibit distinct adsorption modes with following desorption and/or decomposition during thermal heating influenced by metal loading, catalyst composition and organics type. Incorporating Ni and Cu affects coke deposits: the most deposits are formed on alumina after guaiacol adsorption, while anisole leaves no carbonaceous residues. The study highlights the importance of reduction conditions on catalytic performance, advocating further research on adsorption under reaction-like conditions to understand the catalysts’ behaviour in practical applications.