3855 www.MaterialsViews.com wileyonlinelibrary.com IntroductionMetal-organic frameworks (MOFs) are innovative materials built out of metal nodes and organic ligands forming extended, crystalline porous structures. They exhibit remarkable properties (high surface area, defi ned metal sites, and accessible porous structure), which remain unmatched for prospective applications in gas sorption, separation, catalysis and biomedicine. [1][2][3][4][5][6] Nevertheless, up to date their industrial scope has barely breached scaled-up syntheses of a handful of structures. As a result of the characteristic ionic and fl exible nature of their framework, the most signifi cant barrier for MOF application has been their hydrothermal stability, [ 7 ] which directly impacts the fi nal stage of their life cycle. While the stability of some MOF structures can reach temperatures up to 500 °C (e.g., Al-benzenedicarboxylate [ 8 ] and ZIF-8), [ 9 ] extensive research has been focused on delaying their so-far inevitable degradation, with special interest on water-related effects. Explored approaches include use of mixed linkers, [ 10 ] hydrophobization of the linker, [ 11 ] variation of the framework through functionalization, [12][13][14] encapsulation of polyoxometalates, [ 15 ] isolation of crystals from humidity by carbon layers, [ 16 ] generation of interpenetrated structures [ 17 ] and theoretical work on the effect of solvent coordination. [ 18 ] Unfortunately most of these routes raise the operational cost or they are not amenable for industrial application. Thus, a general optimization for any selected application by removing water or just fi nding a compromise between the present of water and a certain degradation degree of the MOF material remains as the only viable route for fi ghting or minimizing its deterioration by humidity.In spite of some reports presenting a rather integral approach for MOF application, [ 19 ] the fi nal and critical step of MOF lifetime has been largely ignored. While porous aluminosilicate materials such as zeolites do not present practically any hazard after their lifetime is exhausted, spent MOF materials would result in a potentially problematic mixture of metallic and aromatic compounds, which would require expensive solvent extraction and work-up. This poses fi nancial and ecological issues deterring their adoption into industrial applications and underlines the urgent need for material recovery strategies after their degradation.A general mechanistic picture of MOF degradation by water has been known for quite some time. [ 7 ] Basically, water molecules gradually coordinate the metal nodes, structurally weakening the framework with increasing coordination and ligand displacement. [ 20 ] Finally, this results in the complete hydrolysis of the metal-linker bond followed by the collapse of the framework, resulting in a material containing the protonated (carboxylic) linker and the metal hydroxide. [ 7,[21][22][23] Such a degradation path has also been verifi ed for HKUST-1 (Cu 3 (BTC) 2 , BTC = 1,...

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A highly active Cu‐based Deacon catalyst with an enhanced lifetime was developed by combining two corrosion‐resistant high‐throughput reactor setups in this combinatorial study. Catalyst activities were studied in a sequential 10‐fold reactor equipped with online MS. For accelerated catalyst ageing studies, a parallel 10‐fold reactor was used. The starting point was a CuTi mixed‐metal oxide found in former discovery investigations. As development criteria, catalyst stability and HCl conversion were selected. The amount of Cu in the CuTi catalysts were analyzed before and after the ageing process by X‐ray fluorescence spectroscopy. Dopant elements were selected that are reported to form oxides with a high corrosion resistance against gaseous HCl. Our study revealed that doping with 1 mol % Nb reduced the Cu leaching during the reaction. Furthermore, the activation energy was decreased by Nb, which enhanced the chlorine production.

Two ten‐channel fixed‐bed reactor systems were developed for high‐throughput screening of new Deacon catalysts. The sequential ten‐channel reactor allows the determination of the activity of up to ten catalysts per day. With a ten‐channel ageing reactor the long‐time stability of catalytic activity can be tested in parallel. Both systems are robust, quite resistant against corrosion, and use the identical reaction tubes which enable the direct transfer of a catalyst from one to the other system. A mass‐spectrometric pulse method has been developed and applied successfully for the analysis of the corrosive product gas mixture of the Deacon reaction.