A Revised Physical Theory for Adsorption of Metal Complexes at Oxide Surfaces

Influence of pH and ionic strength on the metal profile of impregnation catalysts

“…2-5 show the variation of surface properties of the alumina support (surface charge, surface potential and surface coverage), the ionic strength and the adsorption equilibrium constant K eq as a function of the pH of the liquid solution for di erent concentrations of the electrolyte background, which is varied from 10 to 1000 mol=m 3 . Since several experimental studies reported pH-values of the PZC close to 8 for this particular support, in the calculations this value was used (see for example Agashe and Regalbuto, 1997;Spieker and Regalbuto, 2001). Fig.…”

“…The most common relationship to describe metal adsorption is the Langmuir isotherm, which ÿts experiments within a limited range of conditions (Morbidelli et al, 2001). However, numerous experimental studies have shown that acids and salts can a ect the metal adsorption during the impregnation and drying stages (Agashe and Regalbuto, 1997;Contescu and Vass, 1987;Heise and Schwarz, 1988;Chu et al, 1989;Ruckenstein and Karpe, 1989;Shah and Regalbuto, 1994;Spieker and Regalbuto, 2001). Thus, since adsorption of metal ions greatly depends on the pH and ionic strength, the description of the adsorption using Langmuir isotherms is unsatisfactory.…”

“…This mechanism is adopted in this work to describe the metal-support interaction during drying. It has been experimentally veriÿed for several supported catalyst systems (Agashe and Regalbuto, 1997;Spieker and Regalbuto, 2001;Regalbuto et al, 1999).…”

“…In many cases, ÿtting of experimental results leads to large chemical terms, such that the resulting model can predict an unphysical adsorption of large amounts of cations onto positively charged surfaces. In order to minimize the need for adjustable parameters, Agashe and Regalbuto (1997) used a more rigorous derivation of the solvation term. In their model, the solid surface potential was estimated by a non-Nernstian type equation, commonly used in the colloid science literature for amphoteric oxide supports.…”

Template-Assisted Electrochemical Growth of Hydrous Ruthenium Oxide Nanotubes

“…26 A number of articles have reported that ions can be adsorbed on the surface of alumina. [27][28][29][30] Ru is a typical multivalent noble metal, with oxidation states ranging from −2 to +8. In this work, the most common precursor compound was RuCl 3 , which has an oxidation state of +3.…”