Building Block Approaches to Nanostructured, Single Site, Heterogeneous Catalysts

Abstract

The contributions that catalysts make to almost every facet of our daily lives cannot be overstated. Virtually every natural resource (crude oil, coal, biomass, minerals) and every source of energy (petrochemical fuels, nuclear, natural gas, solar) require the use of many catalysts before finished products (fine chemicals, pharmaceuticals, polymers, composites) arrive in our homes, offices and industries [1]. Catalysts also play increasingly important roles in solving some of the most challenging environmental problems that we currently face (global warming, the greenhouse effect, limited natural resources and pollution) [2]. While the use of heterogeneous catalysts is pervasive in science and technology, it rarely appears in the “credits” that herald the arrival of the next, new high strength material or medicine. Furthermore, the historical development of catalysis, the so-called “art and science” of the discipline has at times led to a picture of incompletely understood chemical systems that accomplish extraordinary chemical transformations [3, 4]. This view of catalysis has changed in the past 50 years as new techniques and instrumentation have been developed to address some of the challenges posed in understanding heterogeneous catalysts. Recently, however, a new opportunity to quicken the pace of this change has presented itself that is having a unifying effect on several disciplines of science and technology involved in catalysis research: nanoscience (Figure 4.1) [5]. While many applications of nanoscience are outside the scope of catalysis (conducting nanowires, devices, electronic and magnetic nanomaterials) the nanometer size regime is located precisely where the disciplines of chemistry, materials science and heterogeneous catalysis meet. The synthesis and tailoring of discrete molecules has long been the goal and focus of the modern chemist [6] while developing strategies to prepare tailored materials is of great current interest in materials science [7]. Chemical engineers now spend much time and effort on understanding exactly what the active catalyst is and in developing methodologies by which more finely tailored catalysts can be prepared. Within the context of