Showing papers by "Shankar Narayanan published in 1988"
TL;DR: The influence of modifiers such as barium and lanthanum on the physical properties of γ-alumina has been studied in this paper, where it is assumed that the oxide layers over the surface of alumina prevent the interaction between nickel and γAl2O3, making more nickel available on the surface.
Abstract: The influence of modifiers such as barium and lanthanum on the physical properties of γ-alumina has been studied. Calcination of the modified alumina at 723 K for 5 h does not result in any compound formation as evidenced from X.r.d. Ca. 8–9 wt% nickel was prepared by impregnation method using this modified alumina. Ba and La modifiers improve the reducibility of nickel and the metal area measured by hydrogen adsorption. It is presumed that the oxide layers over the surface of alumina prevent the interaction between nickel and γ-Al2O3, making more nickel available on the surface. The activity and turnover number (TON) for benzene hydrogenation vary directly with the available metal area, irrespective of the modifier.
15 citations
TL;DR: In this article, a reduction of Ti4+ to Ti3+ can be brought about by hydrogen spillover or by lattice oxygen deficiency in the oxide surface, or by both.
Abstract: Reduction of Ti4+ to Ti3+, a primary step in the origin of strong metal–support interaction, can be brought about by hydrogen spillover or by lattice oxygen deficiency in the oxide surface, or by both.
5 citations
TL;DR: The influence of modifiers such as barium and lanthanum on the physical properties of γ-alumina has been studied in this paper, where it is assumed that the oxide layers over the surface of alumina prevent the interaction between nickel and γAl2O3, making more nickel available on the surface.
Abstract: The influence of modifiers such as barium and lanthanum on the physical properties of γ-alumina has been studied. Calcination of the modified alumina at 723 K for 5 h does not result in any compound formation as evidenced from X.r.d. Ca. 8–9 wt% nickel was prepared by impregnation method using this modified alumina. Ba and La modifiers improve the reducibility of nickel and the metal area measured by hydrogen adsorption. It is presumed that the oxide layers over the surface of alumina prevent the interaction between nickel and γ-Al2O3, making more nickel available on the surface. The activity and turnover number (TON) for benzene hydrogenation vary directly with the available metal area, irrespective of the modifier.