Description and aim:

In recent years, experiments and theory on the atomic and molecular mechanisms underlying catalytic reactions have been on the move from (ultra)-high vacuum and low temperatures to the high-pressure, high-temperature conditions of practical catalysis. The ORCA workshop aimed to bring together the different communities involved in this emerging field of operando research in catalysis, namely surface scientists – physics and chemistry, experiment and theory – developers of new instrumentation, and researchers from the chemical industry.

ORCA has been a much appreciated, very useful, lively and timely workshop. What has been new and refreshing, with respect to the multitude of meetings in which catalysis is central, was:

1. The combination of the focus on operando conditions and the firm link to the fundamental physics and chemistry on the atomic and molecular scale.

2. The attention to new techniques, both experimental and theoretical, and including open discussion on both the opportunities and the drawbacks.

3. The mixture of attendants, from academia (chemistry and physics), from the instrumentation manufacturers and from the chemical industry.

Format:

The open format – a limited number of talks with ample room for discussion, dedicated discussion sessions fuelled through an introduction by a moderator, flash presentations by poster presenters and short contributions, in part put on the schedule during the week itself – was perceived as excellent and matching well to the purpose of the workshop. The open hours in the program have been used efficiently for in-depth discussions, in many cases in small circles of collaborating research teams.

Outcome:

Even though it is not appropriate to summarize the outcome of the workshop in a brief list of trivia, a few general statements can be made:

1. Experiment and theory are now both paying attention to the multi-scale aspect of catalysis, combining the atomic- and molecular aspects of the basic steps in the chemical transformations with the fluid dynamics of the flowing gas phase and the resulting inhomogeneities in the gas composition and the temperature and their interplay with the local surface structure and the local reaction mechanisms.

2. Much of the work discussed at the workshop was devoted to the ‘fruit fly’ of catalysis, namely the oxidation of CO. Even though we now know much more about this catalytic reaction, also about how it proceeds under operando conditions, there is still discussion / debate about fundamental issues, such as the chemical state of the surface (metallic or surface oxide?). Nevertheless, it is generally perceived that “there is a world out there” of other chemical reactions that are demanding to be investigated (chemical industry!). First steps in this direction are now visible.

3. Impressive progress is being made in the investigation of ensembles of catalytic nanoparticles in addition to the more traditional ‘surface-science’ setting of flat, low-index, single-crystal surfaces.

4. The industry is really interested in this emerging research field. In bridging the pressure gap and our first steps to bridge the complexity gap, this community is also bridging the valorization gap between academia and application.

Organizational aspects:

There are three relevant elements that should be mentioned here:

1. The combination of organizers from different backgrounds, namely theory (Reuter), experiment (Frenken) and industry (Helveg), proved to be very useful in setting up a well-balanced program and in attracting an interesting mixture of speakers and discussion moderators.

2. ORCA was timed to coincide with the final stage of the SmartMix research consortium NIMIC (Nano-Imaging under Industrial Conditions), which had the development and application of new instruments for operando catalysis studies as one of its prime foci. This has generated a platform of expertise and experts. Two of these experts, Helveg and Frenken, were among the organizers, while the NIMIC community served as a natural, local nucleus of participants in the workshop. NIMIC has also provided a substantial financial contribution to ORCA.

3. Last but not least, the support by the Lorentz Center has been of crucial importance for the professional and smooth organization and operation of ORCA. The facilities are truly excellent and they optimally support the special workshop character. A special word of gratitude goes to Ikram Cakir, Henriette Jensenius, and Mieke Schutte for guiding us in all aspects of the organization of the workshop’s program and taking over all other organizational tasks. They have been instrumental in making ORCA a success!

Future:

Finally, the choice of theme and audience was experienced as so useful and fruitful that there was immediate talk of ORCA serving as the potential start of a series of workshops. Probably these will not be linked automatically to the Lorentz Center. But “ORCA-1” certainly has set the standard!

Joost Frenken (Leiden, The Netherlands)

Stig Helveg (Lyngby, Denmark)

Karsten Reuter (Garching, Germany)