Chapter 3 - Titanium-Based Nanoporous Materials

Abstract

This chapter presents a brief overview of titanium-based nanoporous materials. Titanium as an integral compound is found in many different nanoporous materials. During the past decades, micro- and mesoporous titanosilicates became very prominent, especially with regard to their catalytic activity. The properties of these materials strongly depend on the coordination of the titanium. They include natural and synthetic zeolites as well as amorphous silica materials with defined porosity. Partial substitution of silicon by titanium in zeolites results in titanosilicates with titanium with the same coordination as the silicon in the silica, that is, tetrahedral coordination. The types of materials range from titanosilicates to pure titania and the types of pores found in these materials cover the whole range of pore types, from micropores (<2nm) over mesoporous (2–50 nm) to macropores (>50 nm). However, applications of nanoporous Ti-based materials on larger scale are rather limited at present. The application of the titanosilicate TS-1 as epoxidation catalyst is presently probably the most prominent industrial process, which makes use of such materials. The degree of control on the materials properties, which is already achieved in the preparation of nanoporous titanium-containing solids, is already impressive, but it can be expected that knowledge and skills will further increase. Research has been focused mainly on classical fields of applications, especially of zeolitic materials, but there seems to exist no reason why these should be the only areas where such materials can be successfully applied. Meanwhile, the creation of novel Ti-based materials is a fascinating venture which surely will keep the scientific community rather busy during the years to come.