opened the discussion of the introductory lecture by Avelino Corma: The metal nanoparticles inside the zeolites are in a different environment from those outside. Is there any difference in their chemistry and their catalytic behaviour?Avelino Corma answered: We were not able to determine the differences in reactivity, other than the accessibility of reactants with different sizes. It should be said that we did not use molecules specically suited for showing potential electronic-entropic differences. I agree that this is an important point to be considered. What we clearly observed is that the clusters inside the channels were stable towards sintering.Cynthia Friend asked: Have you considered the possible effect of ligands bound to your clusters? Have van der Waals' interactions been explicitly included?Avelino Corma replied: The theoretical calculation of the interactions of nitrobenzene with the nanoparticles includes the interactions with the support and van der Waals' interactions. In the case of clusters, H 2 dissociation has been carried out on isolated Pt, Au and Au-Pt clusters and van der Waals' interactions were not considered.Graham Hutchings continued: You rightly point out in your design strategy that the adsorption of the reactant is the key factor, and that adsorption occurs This journal is preferentially via the nitro group when reacting substituted nitrobenzenes. What happens if you add an additional nitro group? Will this inevitably lead to oligomers being formed?Avelino Corma responded: If the molecule has two nitro groups to be reduced, instead of one, it is not a problem.On the contrary, for the coupling of the corresponding amino groups derived from nitrobenzene to form the azo compounds, we did not see the formation of trimers or tetramers.The consecutive steps are slow and the higher molecular weight products would be difficult to desorb at the lower reaction temperatures.Bruce Gates remarked: A valuable goal with metal cluster catalysts is to control the cluster nuclearity. With a zeolite as a support, the clusters may be stabilized. What confers that stability? Is it a connement effect associated with the structure of the zeolite? Are there other issues at play? Avelino Corma answered: Indeed I believe that besides a connement effect, which should be more important in small pore zeolites, the zeolite framework with the electric elds associated and interactions with the framework oxygen atoms can also stabilize charged metal clusters.Parasuraman Selvam asked: Where do you draw a line to distinguish between the clusters and nanoparticles in terms of the size and shape? Are these clusters amorphous or crystalline? What do we understand about these aspects in terms of their activity towards a chosen reaction?In general, the driving force for the adsorption is the coordinative unsaturation of the active sites. In this context, the nanoclusters/nanoparticles have denite sizes and shapes, viz., the corners, edges and faces, and predominantly the sites at the faces are utilized for the react...

Hans-Joachim Freund opened the discussion of the paper by Alberto Roldan: How is the atomic hydrogen produced on the greigite surface? In the paper (DOI: 10.1039/C5FD00186B) there is no comment whether you studied dissociate hydrogen adsorption.Alberto Roldan answered: We agree with Prof. Freund that we have not studied the hydrogen dissociation on the surface. However, the experiments are carried out on small nanoparticles exposing different surfaces and edges where H 2 molecules dissociate, as DRIFTS tests (not published) have suggested by the formation of reduced carbonated species.Rutger van Santen remarked: According to Wachterhauser, the reactive phase is Mackinawite. This is a layered FeS phase. The S may also have a higher reactivity than that of Greigite. How does the activation of H 2 on Greigite compare with that of Mackinawite, and would the reactivity of S be such that SO groups form in the surface that helps to generate CO? The SO group can have a subsequent reaction with H 2 S to give S 2 , which would help to transform the Mackinawite to pyrite.

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opened discussion of the introductory lecture by Bruce Gates: As you have shown, EXAFS plays a crucial role in determining the structure and the nuclearity of nanoparticles (NPs). For each shell, the accuracy of this deter-mination depends on the error bar associated to the coordination number, that strongly correlates with the corresponding Debye-Waller (DW) parameter. This becomes even more important when in situ operando experiments are performed at reaction temperature. Based on your experience, what suggestions can you give to reduce this correlation and increase the potentiality of the technique? Do you believe it is possible to x or to determine, in a reliable way, DW parameters from independent experimental or computational works? Do you believe that in temperature-dependent experiments it is reliable to adopt the Debye or the Ein-stein model 1,2 to parametrize the evolution of DW parameters? 1 G. Dalba, P. Fornasini, R. Grisenti and J.

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