title: Effect of surface acidity and basicity of aluminas on asphaltene adsorption and oxidation.
abstract: This study investigates the effect of surface acidity and basicity of aluminas on asphaltene adsorption followed by air oxidation. Equilibrium batch adsorption experiments were conducted at 25°C with solutions of asphaltenes in toluene at concentrations ranging from 100 to 3000 g/L using three conventional alumina adsorbents with different surface acidity. Data were found to better fit to the Freundlich isotherm model showing a multilayer adsorption. Results showed that asphaltene adsorption is strongly affected by the surface acidity, and the adsorption capacities of asphaltenes onto the three aluminas followed the order acidic>basic and neutral. Asphaltenes adsorbed over aluminas were subjected to oxidation in air up to 600°C in a thermogravimetric analyzer to study the catalytic effect of aluminas with different surface acidity. A correlation was found between Freundlich affinity constant (1/n) and the catalytic activity. Basic alumina that has the lowest 1/n value, depicting strongest interactions, has the highest catalytic activity, followed by neutral and acidic aluminas, respectively.
authors.affiliation: Department of Chemical & Petroleum Engineering, Alberta Ingenuity Centre for In-Situ Energy, University of Calgary, Calgary, Alberta, Canada. nassar@ucalgary.ca
authors.forename: Nashaat N
authors.initials: NN
authors.lastname: Nassar
authors.forename: Azfar
authors.initials: A
authors.lastname: Hassan
authors.forename: Pedro
authors.initials: P
authors.lastname: Pereira-Almao