Oxidative Decomposition of Cellulosic Materials

In commercial applications, the decomposition of cellulose is accomplished using an acid hydrolysis step which leads to a significant volume of waste generation during the neutralization step. This project will look at selective oxidation as a means of breaking down cellulose.

Sub-nanoscale, catalytically active phases, particularly metal nanoparticles and metal oxide clusters, supported on high surface area oxides are one of the most important classes of heterogeneous catalysts. The overall objective of the proposed research is to improve our fundamental understanding of these supported heterogeneous catalysts and catalytic chemistry. The goals of this integrated experimental/theoretical research program are:

• Synthesize new materials based on the chemistry of atomic layer deposition (ALD) and direct size-selected metal and metal oxide catalyst deposition, for producing atomically uniform, catalytic metal oxide clusters and monolayers, supported on high-surface-area and flat substrates.
• Evaluate the catalytic activity and selectivity patterns and the reaction kinetics and mechanisms.
• Characterize the chemical and structural properties of these uniform supported catalysts at each stage of their life cycle.
• Computational-model the new catalysts to understand the relationships between the atomic composition/structure details of the clusters/nanoparticles and their catalytic chemistry including reaction mechanisms and kinetics.

Existing methods for preparing supported catalysts typically fall into one of three categories: impregnation, homogeneous deposition-precipitation, and ion exchange. While these preparation methods are simple and can produce catalytic material with high surface area, they do not provide a high degree of control over the initial size, atomic structure, and composition of the active phases nor over their spatial distribution across the support material. The “green” catalytic materials are inherently inhomogeneous with a distribution of cluster sizes and compositions. The initial clusters or nanoparticles are determined by nucleation and growth processes that are statistically governed. In most cases the initial inhomogeneity is not removed by the subsequent catalyst treatments. Two important consequences of this inhomogeneity for both fundamental and practical catalysis science are an inability to “pin down” the active and selective catalytic sites and a lack of control over the synthesis of specific, desirable sites at the expense of others. As a result of these limitations in current techniques, it is very desirable to develop synthetic approaches to fabricate uniform high-surface area, practical catalysts using chemical procedures that have atomic control of structure and composition and avoid the statistics of nucleation as a determining factor in catalyst structure. Moreover, synthesis should be coupled to a combination of characterization tools to achieve an understanding of their catalytic properties at the atomic level. In this research project, we are combining novel synthesis methods with testing, characterization, and modeling in an integrated approach.