Unravelling the potential of confinement effects in catalysts and adsorbents

The majority (> 90 %) of chemical and pharmaceutical industry processes are based on catalysis. In a society where sustainability becomes increasingly important, it is essential to develop catalysts that enable formation of the target product under mild conditions, without byproduct formation. During the last decade, improved characterization tools have enabled chemists and physisists to elucidate which atom arrangement in solid catalysts that constitutes the active catalytic site for some reactions. Furthermore, systematic studies of catalytic materials with pores of molecular dimensions (0.4 - 1.2 nm) have demonstrated the effect of the immediate surrounding of the active site, and furthermore, the effect of confinement, on the rate and selectivity of a few, complex reactions. In this project, the goal is to study the effect of confinement for a wider class of reactions, and furthermore to study the effect of co-functional groups in the immediate surroundings of the active site. The study will be carried out by comparing the rate of reaction over homogeneous metal complex catalysts, as well as over their heterogeneous analogues, i.e. when the active site (and possible co-functional groups) is built into a 3-dimensional network, so-called metal-organic framework (MOF) materials. The fundamental knowledge gained in this project will contribute to the development of design principles for single-site heterogeneous catalysts. A first break-through was obtained in 2019, when we found that the pores in a zeolite-based catalyst solvates the active catalyst complex in an ethene dimerization catalyst in a manner similar to the role of the solvent for homogeneous complex catalysts. The solvatisation leads to reduced activation energy and to enhanced selectivity towards linear butenes. This result was obtained by a combination of catalyst synthesis, characterization, testing and DFT-based molecular dynamics simulations. Another break-through was obtained in 2020 when we revealed how open Zr-sites in the Zr-node of UiO-67 type MOFs stabilize the important formate intermediate for methanol production from CO2 and hydrogen, thereby enhancing the selectivity to methanol. Based on this and other results obtained in CONFINE, we are currently able to design improved catalysts for this reaction. Overall, the expertise developed in CONFINE, by combining organic and inorganic synthesis, advanced catalytic testing, ex-situ and in-operando spectroscopy as well as computational tools, fulfills the vision of CONFINE, i.e. to enable design of single-site heterogeneous catalysts where confinement is a major parameter for catalyst selectivity.

- An ERC Synergy Grant project (CUBE) that builds on the achievements of CONFINE, has been awarded (2019), with the CONFINE project leader as Corresponding PI - Among 5 PhD candidates, 3 have graduated, while 2 are currently in the final stage of PhD thesis writing. All graduated PhD and postdoc candidates have found relevant positions. - 16 scientific papers (2 in JACS) and 27 conference contributions have been published - CONFINE Postdoc candidate Andrea Lazzarini recently received the Grazelli young researcher award - The vision of the CONFINE project, i.e. "to enable design of single-site heterogeneous catalysts where confinement is a major parameter for catalyst selectivity" has been accomplished - A potential long-term effect of CONFINE is the development of cleaner, more efficient industrial processes for production of commodity products. Hence, CONFINE is highly relevant for the "Green Deal" policy

The ultimate purpose of the CONFINE project is to enable design of, and understand the fundamental principles of, single-site heterogeneous catalysts where confinement is a major parameter for catalyst selectivity. The project defines activities that will embrace all expertise in the Catalysis research group at UiO in a joint effort directed at the rational design of similar catalytic systems in "open" and confined settings. The Catalysis group at UiO is quite unique in that it possesses all the required expertise to undertake this task: organic, metal-organic and inorganic synthesis, organocatalysis, metal-organic homogeneous catalysis, synthesis of hybrid MOF materials, advanced catalytic testing, kinetic modeling, relevant computational expertise, and advanced spectroscopic characterization of interaction of molecules with surfaces and/or active sites in catalysts. The CONFINE project will benefit the research group as a whole in its ambition to be at the forefront of contemporary catalysis research. Three types of catalytic reactions have been selected for this endeavor, representing areas where group members have considerable experience with catalysis in "open" or non-confined catalytic environments. The selected reactions are (1) oxidation of C-H bonds to C-OH catalyzed by copper complexes, (2) C-C and C-heteroatom coupling reactions catalyzed by gold complexes, and (3) C-C coupling reactions catalyzed by chiral organocatalysts. Pertinent homogeneous catalytic systems are already available. Confinement will be achieved by anchoring the catalytic sites inside highly porous metal-organic frameworks, MOFs. The highly tunable UiO series of MOFs, discovered in the UiO catalysis group, is the most versatile MOF scaffold available today, and the UiO group has a leadership role in its exploration.