Argonne National Laboratory

Catalysis

Top: Superior catalyst design via the combination of heterogeneous and homogeneous catalysis. Bottom Left: Isolated single-site metal catalyst on silica for propane dehydrogenation; Bottom right: Supported organotantalum catalyst on porous organic framework (POP) for the selective semi-dehydrogenation of alkynes

Top: Superior catalyst design via the combination of heterogeneous and homogeneous catalysis. Bottom Left: Isolated single-site metal catalyst on silica for propane dehydrogenation; Bottom right: Supported organotantalum catalyst on porous organic framework (POP) for the selective semi-dehydrogenation of alkynes

The scientific achievements of the catalysis science program will help to enable the efficient use of national natural resources, such as light alkanes (i.e., methane, ethane, propane, butane), as precursors of fuels for transportation.

The key parts of our program are: i) synthesis and characterization of new selective catalytic materials; ii) predictive modeling of the single-site metal catalyst structures, kinetics, and reaction mechanisms; iii) experimental mechanistic studies to validate the computational predictions of newly designed catalysts. Achieving these goals requires close collaboration among experts in catalyst synthesis and characterization, catalytic mechanistic analysis, and a high level of theory and modeling.

Since its inception, the catalysis science program has demonstrated that single-site metal catalysts on “hard” supports (oxides) display high activity and selectivity for C-H bond activation of light alkanes, comparable to traditional homogeneous and heterogeneous catalyst systems. These achievements include catalysts that are 1) >98% selective for dehydrogenation of propane to propene and hydrogen and are 2) very long-lived compared to other catalysts. In parallel, we developed molecularly inspired, well-defined single-site catalysts based ontransition metals (e.g., V3+, Mn2+) on “soft” porous polymers (MOFs/POPs) that are active catalysts for the hydrogenation of olefins.

Using these catalysts, along with our knowledge of single-site catalysis, we plan to elucidate the relationship between their structures and the mechanisms of alkane C–H bond activation and C-C bond formation on single-site metal centers. This is expected to provide fundamental information pertinent to the rational design of functional alkane upgrading catalysts. This goal requires the merging of ideas and approaches that bridge heterogeneous and homogeneous catalysis, kinetics, and reaction engineering.

We continue to make progress toward the successful design of single-site catalysts with the objective of manipulating the metal-support (ligand) bonds to control activity and selectivity, understanding how tandem and bifunctional catalysts can be designed to drive multiple reactions at low temperatures with an energetically uphill first step, and discovering descriptors that permit the construction of predictive models for single-site catalysts.

Our work contains computational, catalyst synthesis, characterization, and experimental mechanistic components that take full advantage of our wide-ranging expertise. The single-site catalysts will be synthesized using our new integrated atomic layer deposition synthesis-catalysis tool and the high-throughput robotic synthesis platform. Catalysts are fully characterized by ex-situ, in-situ, and operando techniques. Kinetics and mechanistic studies are conducted at our state-of-the-art high-throughput reactor system.