Determination of the Surface Energetics and Acid-Base Properties of Copper Modified MCM-41 Mesoporous Molecular Sieve Catalysts

F. Thielmann, M. Naderi, N. Kumar, T. Salmi and D.Y. Murzin
Surface Measurement Systems Ltd, UK

Keywords: Catalysts, Molecular Sieve, Energetics

Abstract:
The MCM-41 mesoporous molecular sieve material has attracted attention of researchers in academia and industry because of large pore, high surface area, thermal stability and mild acidic properties. Development of proton and metal modified mesoporous molecular sieve catalysts is important in order to meet the increasing demand for processing of heavy oil fractions to value added products and to synthesize fine chemicals using heterogeneous catalysts. Cu modified MCM-41 is a potential catalyst for the synthesis of fine chemicals, hydrocarbon transformations, and environmental catalysis. In order to understand the role of Cu, acidic-base property and structure of MCM-41 in catalytic reactions mentioned above several characterization methods have been reported. Dynamic vapor phase techniques are interesting tools for the determination of the surface energetic and acid-base properties. When compared to standard wettability experiments, they provide two main benefits. They can easily and reproducibly be applied to powders and a wide variety of probe molecules can be selected. In the current study Inverse Gas Chromatography (IGC) has been used to characterize the energetic and acid-base properties of different kinds of a Cu-MCM-41 catalysts as well as the corresponding H-MCM-41 and Na-MCM-41. Cu-MCM41 catalysts show a significantly increased surface energy and acid-base interaction compared to H-MCM-41. The acid-base chemistry changes at the same time from slightly acidic or neutral for the H-MCM-41 to significantly basic for the Cu-MCM-41. Studies with different Cu contents and Cs exchanged metals in MCM-41 will be discussed in detail.

Nanotech 2004 Conference Technical Program Abstract