Prototyping of catalyst pore-systems by a combined synthetic, analytical and computational approach: Application to mesoporous TiO 2 Vladimír Novák a , Erik Ortel b , Benjamin Winter c , Benjamin Butz c , Benjamin Paul b , Petr Koc ˇí a,⇑ , Miloš Marek a , Erdmann Spiecker c,⇑ , Ralph Kraehnert b,⇑ a Institute of Chemical Technology, Prague, Department of Chemical Engineering, Technická 5, CZ 16628 Prague, Czech Republic b Technical University Berlin, Department of Chemistry, Straße des 17. Juni 124, 10623 Berlin, Germany c Center for Nanoanalysis and Electron Microscopy, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany highlights  Mesoporous TiO 2 layer synthesized using nanocasting techniques.  3D morphology of pore-space analyzed by electron tomography.  Pore size distribution observed in reconstructed tomograms matches experimental sorption data.  Anisotropic diffusion coefficients evaluated by diffusion flux simulation in 3D medium.  Parametric study revealed effects of templated pore size on model reactor performance. article info Article history: Received 13 December 2013 Received in revised form 30 January 2014 Accepted 3 February 2014 Available online 8 February 2014 Keywords: Catalyst Nanocasting Synthesis Electron tomography Multi-scale mathematical modeling Diffusion abstract During the last decade, quantum-chemical calculations of surface reactions have become well established for the design of catalytic sites. However, the corresponding methods allowing optimization of adequate pore structures for catalyst supports have so far not reached the same level of sophistication. This holds in particular for realistic pore systems that can be practically synthesized with a reasonable effort. We propose a strategy that enables virtual prototyping and computational optimization of the pore system of a solid catalyst. The method combines template-assisted synthesis of porous metal oxides with tunable pore-space morphology, 3D imaging of the catalysts nanostructure by the state-of-the-art electron tomography in HAADF STEM mode, and multi-scale mathematical modeling that provides com- putational evaluation of the pore size distribution, effective diffusivity and tortuosity in the reconstructed system as well as macroscopic performance of the catalytic layer in terms of reactant conversion. This general approach is demonstrated on mesoporous TiO 2 layers. Ó 2014 Elsevier B.V. All rights reserved. 1. Introduction Approximately 80% of the processes in the chemical industry re- quire the use of catalysts, and catalysis contributes directly or indi- rectly to approximately 35% of the world’s GDP [1], involving petroleum, chemical, energy, environmental and renewable sources industry [2]. Solid catalysts come in the form of powders, pellets or wires as well as layers coated on plates or honeycomb monoliths. Their performance is determined by two main factors: intrinsic catalytic properties and mass-transport phenomena. The properties of catalytically active sites located on the surface of metal nanoparticles can be controlled by composition, size and shape of the particles as well as by metal-support interactions. The transport of molecules to the active centers occurs via diffu- sion through the catalysts pore system, which is determined by porosity and pore-space morphology of the support material. Here, small pores provide a large surface area where active particles can be dispersed and anchored, thus enabling high reaction rates per catalyst volume. However, the small pores provide only low diffu- sion rates of the reactants to the active sites due to an increased number of collisions between gas molecules and pore walls. A balanced compromise of high surface area and fast pore diffusion can be realized in hierarchical pore systems, where large pores facilitate fast transport while the small pores provide a high surface for supporting active metal sites [80]. In consequence, http://dx.doi.org/10.1016/j.cej.2014.02.004 1385-8947/Ó 2014 Elsevier B.V. All rights reserved. ⇑ Corresponding authors. Tel.: +420 22044 3293; fax: +420 22044 4320. E-mail addresses: petr.koci@vscht.cz (P. Koc ˇí), erdmann.spiecker@ww. uni-erlangen.de (E. Spiecker), ralph.kraehnert@tu-berlin.de (R. Kraehnert). URL: http://www.vscht.cz/monolith (P. Koc ˇí). Chemical Engineering Journal 248 (2014) 49–62 Contents lists available at ScienceDirect Chemical Engineering Journal journal homepage: www.elsevier.com/locate/cej