Solid catalytic materials

The great majority of catalytic reactions which have been applied technically as industrial processes are those where solid catalytic material acts on gaseous material. They, therefore, represent one type of hetcro-qeneous catalvsis. In such cases, theoretical considerations, especially those based upon the laws of mass action, do not apply in the same way as in cases where the system is homogeneous, i.e. where the catalyst together with all of the components of the reaction are in the same state of aggregation as, for example, when all are either liquids or gases. 

Combinatorial approach in heterogeneous catalysis means search for optimal combinations between chemical composition and structure of solid catalytic materials which are related to a diversity of preparation parameters (type of precursors, calcination temperature, calcination media, etc.) and operating conditions (temperature, contact time, reeictant concentrations). 

Solid catalytic materials can be divided into two main groups ... 

The characteristics of sol-gel processing allow the application of different strategies for the preparation of solid catalytic materials. A schematic representation is shown in Figure 5.2. The gelation of colloidal solution followed by desolvation of the obtained gel can be applied for the preparation of three types of materials ... 

Combinatorial methodology and its experimental validation by parallel synthesis, testing and characterization of solid catalytic materials, in Principles and Methods for Accelerated Catalyst Design and Testing (eds E.G. Derouane et al.), Kluwer Academic Publishers, Dordrecht, pp. 85-100. 

For high-throughput preparation of solid catalytic materials, automated robots equipped with synthesis control protocols are used. These robots carry out the various synthesis steps at high speed and in parallel or consecutively. The steps require high accuracy and reproducibiUty, without which no reliable data on optimal catalyst composition and best performance can be obtained. Moreover, the steps have to be performed in such a way, which is transferable to pilot- and technical-scale plant operation. For illustration, an automated sjmthesis robot is presented in Figure 2.3. 

For optimisation of empirical functions in the development of solid catalytic materials, it is unfortunately impossible to employ methods using partial derivatives, that is — methods from groups 2 and 3. The reasons for this impossibility are connected with the character of catalytic experiments, and can be summarised as set out below ... 

Rodemerck, U., Baerns, M., Helena, M. and Wolf, D. (2004). Application of a genetic algorithm and a neural network for the discovery and optimization of new solid catalytic materials, Appl. Surf. Sci., 223,168-174. 

---