Chemical Engineering Science 65 (2010) 372--379 Contents lists available at ScienceDirect Chemical Engineering Science journal homepage: www.elsevier.com/locate/ces Microreactor numbering-up in multi-scale networks for industrial-scale applications: Impact of flow maldistribution on the reactor performances M. Saber, J.M. Commenge ∗ , L. Falk Laboratoire des Sciences du Génie Chimique, LSGC-CNRS, Nancy Université, 1, rue Grandville, 54001 Nancy, France ARTICLE INFO ABSTRACT Article history: Received 7 July 2008 Received in revised form 27 May 2009 Accepted 2 June 2009 Available online 10 June 2009 Keywords: Microreactor Multi-scale networks Hydrodynamic Selectivity Robustness The performances of multi-scale networks are investigated considering the selectivity of consecutive catalytic reactions occurring at the coated walls of the parallel microchannels. The impact of the channel arrangement on the global performance of the network is analysed. It is shown that controlling the flow uniformity through the parallel channels can result in the improvement of the overall reaction selectivity, while reducing simultaneously the overall pressure drop through the network. The robustness of such networks is also analysed through a channel clogging simulation. © 2009 Elsevier Ltd. All rights reserved. 1. Introduction The main features of interest of microstructured reactors reside in the enhanced mass and heat transfer offered by their small dimen- sions, as well as the large surface-to-volume ratios of the volumes where the chemical transformation takes place (Hessel et al., 2004; Charpentier, 2007). Catalytic microstructured reactors have been investigated for various applications in the laboratory scale and in- dustrial scale. The operating conditions that can be reached in mi- croreactors (high pressure, uniform temperature, etc.), which are hardly achievable in conventional reactors, make them particularly interesting for kinetic studies. In addition, catalyst testing within mi- croreactors requires reduced quantities of active components com- pared to conventional reactors and many catalysts formulations can be rapidly tested (Senkan and Ozturk, 1999; Senkan et al., 1999). Finally, their heat-transfer characteristics enable to study highly exothermic or even potentially explosive reactions. The reactors can be made from the catalytic metal itself or im- pregnated with the catalytic material after fabrication (Mills et al., 2007). Many catalysts and catalytic reactions have been tested in microstructured reactors (Aartun et al., 2004; Chen et al., 2007; Giornelli et al., 2007; Schwarz et al., 2008) and results indicate sig- nificant improvements in selectivity for various reaction systems. Pfeifer et al. (2004) investigated Pd/Zn catalysts prepared by the ∗ Corresponding author. E-mail address: commenge@ensic.inpl-nancy.fr (J.M. Commenge). 0009-2509/$ - see front matter © 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.ces.2009.06.010 washcoating technology with nanoparticles for methanol steam ap- plication. High conversion and selectivity are achieved using catalytic dehydration of bioethanol to ethylene over microchannel reactors coated by TiO 2 /-Al 2 O 3 catalysts (Chen et al., 2007). Kiwi-Minsker et al. (2002) investigated the non-oxidative propane dehydrogena- tion in a microstructured membrane reactor with microchannels formed by the space between closely packed catalytic filaments. They found that propene selectivities exceeding 97% can be achieved at propane conversions exceeding the equilibrium value. Cao and Gavriilidis (2005) investigated the catalytic oxidative dehydrogena- tion of methanol to formaldehyde over silicon microreactors and ob- tained high selectivities and isothermal reaction conditions even at high oxygen concentrations, compared to those obtained in a small fixed-bed reactor. The highly exothermic oxidation of hydrogen from an explosive mixture of gases has also been safely performed using a microstructured reactor coupled with a heat exchanger and Pt/Al 2 O 3 catalyst microreactors (Janicke et al., 2000). To maximize the performances of catalytic microstructured reac- tors used for kinetics measurements of catalyst screening at the lab- oratory scale, geometrical parameters must be precisely controlled, to ensure the same flow of reactant through the coated microchan- nels of a test plate (Mies et al., 2007). Actually, the flow distribution between the channels should be uniform to avoid measurement biases due to non-uniform operating conditions. Several studies investigated the design methodology of microstructured devices in order to get optimum reactor performances and proposed design strategies (Commenge et al., 2002; Amador et al., 2004; Aoki et al., 2005). In addition, particular attention must be paid to the fabrica- tion of the reactor and the coating of the catalytic layers inside an