Combining high-throughput experimentation, advanced data modeling and fundamental knowledge to develop catalysts for the epoxidation of large olefins and fatty esters

摘要

By combining catalyst characterization, molecular descriptors, and high-throughput techniques. two structured titanosilicates, Ti-MCM-41 and Ti-ITQ-2, were successfully optimized for the epoxidation of large olefins and methyl oleate. This new methodology for material science and catalysis can help to identify and partially quantify the roles of the variables involved in catalyst synthesis based on a small number of experiments. Associations among the chemical properties of the silicate used as support (ITQ-2. MCM-41), the dispersion and number of Ti sites grafted onto the surface, the presence of surface modifiers (silylating agents), the nature of the selected alkenes, and the catalytic activity and selectivity are established. We show that the use of surface modifiers increases the activity and selectivity of the catalysts, but that the effectiveness of each silylating agent depends on the surface characteristics of the support. Correlation of the results from the epoxidation of a test molecule, 4-decene with those for the industrially relevant methyl oleate show that the reactivity of the substrate also is significantly influenced by the surface properties of the support. We find that Ti-ITQ-2 modified with SiMe2Bu (dimethylbutylsilane), instead of the more commonly used Ti-MCA-41-SiMe3 system (with trimethylsilane as a silylating agent), represents the best option for carrying out the epoxidation of this fatty ester, leading to a highly active and selective catalyst. (C) 2008 Elsevier Inc. All rights reserved.