First crystal structure studies of CaAlH5

A new member of the aluminum hydride family, CaAlH5, is formed during the decomposition of Ca(AlH4)2. The crystal structure of this new compound was calculated by density functional theory band-structure calculations and confirmed by X-ray powder diffraction analysis. The structure crystallizes in space group P21/n (No. 14), with a = 8.3797(9) Å, b = 6.9293(8) Å, c = 9.8138(11) Å, β = 93.78(1)°, and Z = 8

One Pot Cooperation of Single Atom Rh and Ru Solid Catalysts for a Selective Tandem Olefin Isomerization - Hydrosilylation Process

[EN] Realizing the full potential of oxide-supported single-atom metal catalysts (SACs) is key to successfully bridge the gap between the fields of homogeneous and heterogeneous catalysis. Here we show that the one-pot combination of Ru-1/CeO2 and Rh-1/CeO2 SACs enables a highly selective olefin isomerization-hydrosilylation tandem process, hitherto restricted to molecular catalysts in solution. Individually, monoatomic Ru and Rh sites show a remarkable reaction specificity for olefin double-bond migration and anti-Markovnikov alpha-olefin hydrosilylation, respectively. First-principles DFT calculations ascribe such selectivity to differences in the binding strength of the olefin substrate to the monoatomic metal centers. The single-pot cooperation of the two SACs allows the production of terminal organosilane compounds with high regio-selectivity (>95 %) even from industrially-relevant complex mixtures of terminal and internal olefins, alongside a straightforward catalyst recycling and reuse. These results demonstrate the significance of oxide-supported single-atom metal catalysts in tandem catalytic reactions, which are central for the intensification of chemical processes.X-ray absorption experiments were performed at the ALBA Synchrotron Light Source (Spain), experiments 2018082961 and 2019023278. L. Simonelli and C. Marini (CLAESSALBA beamline) are thanked for beamline setup. E. Andres, M. E. Martinez, M. Garcia, and I. Lopez (ITQ), are acknowledged for their assistance with XAS experiments. J. Buscher, J. Ternedien, B. Spliethoff, and C. Wirtz (MPI-KOFO) are acknowledged for the performance of XPS, XRD, BF-TEM and 2H NMR experiments, respectively. I. C. de Freitas (MPIKOFO) is thanked for assistance with Raman spectroscopy. J. M. Salas (ITQ) is gratefully acknowledged for his contribution to CO-FTIR experiments. J. J. Barnes and Shell (Amsterdam) are acknowledged for kindly providing an industrial olefin mixture as feed. Authors are thankful to F. Schuth for the provision of lab space and continued support. Part of the HRSTEM and EDX-STEM studies were conducted at the Laboratorio de Microscopias Avanzadas, Instituto de Nanociencia de Aragon, Universidad de Zaragoza, Spain. R.A. gratefully acknowledges the support from the Spanish Ministry of Economy and Competitiveness (MINECO) through project grant MAT2016-79776-P (AEI/FEDER, UE) and from the European Union H2020 programs "ESTEEM3" (823717). The authors acknowledge support by the state of Baden-Wurttemberg through bwHPC (bwUnicluster and JUSTUS, RV bw17D01), by the GRK 2450 and by the Helmholtz Association. This research received funding from the Max Planck Society, and the Fonds der Chemische Industrie of Germany. Funding from the Spanish Ministry of Science, Innovation and Universities (Severo Ochoa program SEV-2016-0683 and grant RTI2018096399-A-I00) is also acknowledged. B.B.S. acknowledges the Alexander von Humboldt Foundation for a postdoctoral scholarship. Open Access funding is provided by the Max Planck Society.Sarma, BB.; Kim, J.; Amsler, J.; Agostini, G.; Weidenthaler, C.; Pfaender, N.; Arenal, R.... (2020). One Pot Cooperation of Single Atom Rh and Ru Solid Catalysts for a Selective Tandem Olefin Isomerization - Hydrosilylation Process. Angewandte Chemie International Edition. 59(14):5806-5815. https://doi.org/10.1002/anie.201915255S580658155914Liang, S., Hao, C., & Shi, Y. (2015). The Power of Single-Atom Catalysis. ChemCatChem, 7(17), 2559-2567. doi:10.1002/cctc.201500363Liu, J. (2016). Catalysis by Supported Single Metal Atoms. ACS Catalysis, 7(1), 34-59. doi:10.1021/acscatal.6b01534Gates, B. C., Flytzani-Stephanopoulos, M., Dixon, D. A., & Katz, A. (2017). Atomically dispersed supported metal catalysts: perspectives and suggestions for future research. Catalysis Science & Technology, 7(19), 4259-4275. doi:10.1039/c7cy00881cLiu, L., & Corma, A. (2018). Metal Catalysts for Heterogeneous Catalysis: From Single Atoms to Nanoclusters and Nanoparticles. Chemical Reviews, 118(10), 4981-5079. doi:10.1021/acs.chemrev.7b00776Wang, A., Li, J., & Zhang, T. (2018). Heterogeneous single-atom catalysis. Nature Reviews Chemistry, 2(6), 65-81. doi:10.1038/s41570-018-0010-1Parkinson, G. S. (2019). Single-Atom Catalysis: How Structure Influences Catalytic Performance. Catalysis Letters, 149(5), 1137-1146. doi:10.1007/s10562-019-02709-7Babucci, M., Sarac Oztuna, F. E., Debefve, L. M., Boubnov, A., Bare, S. R., Gates, B. C., … Uzun, A. (2019). Atomically Dispersed Reduced Graphene Aerogel-Supported Iridium Catalyst with an Iridium Loading of 14.8 wt %. ACS Catalysis, 9(11), 9905-9913. doi:10.1021/acscatal.9b02231Qiao, B., Wang, A., Yang, X., Allard, L. F., Jiang, Z., Cui, Y., … Zhang, T. (2011). Single-atom catalysis of CO oxidation using Pt1/FeOx. Nature Chemistry, 3(8), 634-641. doi:10.1038/nchem.1095Duan, S., Wang, R., & Liu, J. (2018). Stability investigation of a high number density Pt1/Fe2O3 single-atom catalyst under different gas environments by HAADF-STEM. Nanotechnology, 29(20), 204002. doi:10.1088/1361-6528/aab1d2Pinto, H., Haapasilta, V., Lokhandwala, M., Öberg, S., & Foster, A. S. (2017). Adsorption and migration of single metal atoms on the calcite (10.4) surface. Journal of Physics: Condensed Matter, 29(13), 135001. doi:10.1088/1361-648x/aa5bd9Parkinson, G. S., Novotny, Z., Argentero, G., Schmid, M., Pavelec, J., Kosak, R., … Diebold, U. (2013). Carbon monoxide-induced adatom sintering in a Pd–Fe3O4 model catalyst. Nature Materials, 12(8), 724-728. doi:10.1038/nmat3667Yang, X.-F., Wang, A., Qiao, B., Li, J., Liu, J., & Zhang, T. (2013). Single-Atom Catalysts: A New Frontier in Heterogeneous Catalysis. Accounts of Chemical Research, 46(8), 1740-1748. doi:10.1021/ar300361mCui, X., Li, W., Ryabchuk, P., Junge, K., & Beller, M. (2018). Bridging homogeneous and heterogeneous catalysis by heterogeneous single-metal-site catalysts. Nature Catalysis, 1(6), 385-397. doi:10.1038/s41929-018-0090-9Mitchell, S., Vorobyeva, E., & Pérez‐Ramírez, J. (2018). The Multifaceted Reactivity of Single‐Atom Heterogeneous Catalysts. Angewandte Chemie International Edition, 57(47), 15316-15329. doi:10.1002/anie.201806936Mitchell, S., Vorobyeva, E., & Pérez‐Ramírez, J. (2018). Die facettenreiche Reaktivität heterogener Einzelatom‐Katalysatoren. Angewandte Chemie, 130(47), 15538-15552. doi:10.1002/ange.201806936Kumar, A., Bhatti, T. M., & Goldman, A. S. (2017). Dehydrogenation of Alkanes and Aliphatic Groups by Pincer-Ligated Metal Complexes. Chemical Reviews, 117(19), 12357-12384. doi:10.1021/acs.chemrev.7b00247Lang, R., Li, T., Matsumura, D., Miao, S., Ren, Y., Cui, Y.-T., … Zhang, T. (2016). Hydroformylation of Olefins by a Rhodium Single-Atom Catalyst with Activity Comparable to RhCl(PPh3)3. Angewandte Chemie International Edition, 55(52), 16054-16058. doi:10.1002/anie.201607885Lang, R., Li, T., Matsumura, D., Miao, S., Ren, Y., Cui, Y.-T., … Zhang, T. (2016). Hydroformylation of Olefins by a Rhodium Single-Atom Catalyst with Activity Comparable to RhCl(PPh3)3. Angewandte Chemie, 128(52), 16288-16292. doi:10.1002/ange.201607885Cui, X., Junge, K., Dai, X., Kreyenschulte, C., Pohl, M.-M., Wohlrab, S., … Beller, M. (2017). Synthesis of Single Atom Based Heterogeneous Platinum Catalysts: High Selectivity and Activity for Hydrosilylation Reactions. ACS Central Science, 3(6), 580-585. doi:10.1021/acscentsci.7b00105Chen, Y., Ji, S., Sun, W., Chen, W., Dong, J., Wen, J., … Li, Y. (2018). Discovering Partially Charged Single-Atom Pt for Enhanced Anti-Markovnikov Alkene Hydrosilylation. Journal of the American Chemical Society, 140(24), 7407-7410. doi:10.1021/jacs.8b03121Malta, G., Kondrat, S. A., Freakley, S. J., Davies, C. J., Lu, L., Dawson, S., … Hutchings, G. J. (2017). Identification of single-site gold catalysis in acetylene hydrochlorination. Science, 355(6332), 1399-1403. doi:10.1126/science.aal3439Ye, L., Duan, X., Wu, S., Wu, T.-S., Zhao, Y., Robertson, A. W., … Tsang, S. C. E. (2019). Self- regeneration of Au/CeO2 based catalysts with enhanced activity and ultra-stability for acetylene hydrochlorination. Nature Communications, 10(1). doi:10.1038/s41467-019-08827-5Zhang, X., Sun, Z., Wang, B., Tang, Y., Nguyen, L., Li, Y., & Tao, F. F. (2018). C–C Coupling on Single-Atom-Based Heterogeneous Catalyst. Journal of the American Chemical Society, 140(3), 954-962. doi:10.1021/jacs.7b09314Chen, Z., Vorobyeva, E., Mitchell, S., Fako, E., Ortuño, M. A., López, N., … Pérez-Ramírez, J. (2018). A heterogeneous single-atom palladium catalyst surpassing homogeneous systems for Suzuki coupling. Nature Nanotechnology, 13(8), 702-707. doi:10.1038/s41565-018-0167-2Wasilke, J.-C., Obrey, S. J., Baker, R. T., & Bazan, G. C. (2005). Concurrent Tandem Catalysis. Chemical Reviews, 105(3), 1001-1020. doi:10.1021/cr020018nLohr, T. L., & Marks, T. J. (2015). Orthogonal tandem catalysis. Nature Chemistry, 7(6), 477-482. doi:10.1038/nchem.2262Reuben, B., & Wittcoff, H. (1988). The SHOP process: An example of industrial creativity. Journal of Chemical Education, 65(7), 605. doi:10.1021/ed065p605Fogg, D. E., & dos Santos, E. N. (2004). Tandem catalysis: a taxonomy and illustrative review. Coordination Chemistry Reviews, 248(21-24), 2365-2379. doi:10.1016/j.ccr.2004.05.012Poe, S. L., Kobašlija, M., & McQuade, D. T. (2006). Microcapsule Enabled Multicatalyst System. Journal of the American Chemical Society, 128(49), 15586-15587. doi:10.1021/ja066476lLu, J., Dimroth, J., & Weck, M. (2015). Compartmentalization of Incompatible Catalytic Transformations for Tandem Catalysis. Journal of the American Chemical Society, 137(40), 12984-12989. doi:10.1021/jacs.5b07257Abel, M.-L. (2011). Organosilanes: Adhesion Promoters and Primers. Handbook of Adhesion Technology, 237-258. doi:10.1007/978-3-642-01169-6_11Semenov, V. V. (2011). Preparation, properties and applications of oligomeric and polymeric organosilanes. Russian Chemical Reviews, 80(4), 313-339. doi:10.1070/rc2011v080n04abeh004110Obligacion, J. V., & Chirik, P. J. (2018). Earth-abundant transition metal catalysts for alkene hydrosilylation and hydroboration. Nature Reviews Chemistry, 2(5), 15-34. doi:10.1038/s41570-018-0001-2Jones, J., Xiong, H., DeLaRiva, A. T., Peterson, E. J., Pham, H., Challa, S. R., … Datye, A. K. (2016). Thermally stable single-atom platinum-on-ceria catalysts via atom trapping. Science, 353(6295), 150-154. doi:10.1126/science.aaf8800Pereira-Hernández, X. I., DeLaRiva, A., Muravev, V., Kunwar, D., Xiong, H., Sudduth, B., … Datye, A. K. (2019). Tuning Pt-CeO2 interactions by high-temperature vapor-phase synthesis for improved reducibility of lattice oxygen. Nature Communications, 10(1). doi:10.1038/s41467-019-09308-5Speier, J. L., Zimmerman, R., & Webster, J. (1956). The Addition of Silicon Hydrides to Olefinic Double Bonds. Part I. The Use of Phenylsilane, Diphenylsilane, Phenylmethylsilane, Amylsilane and Tribromosilane. Journal of the American Chemical Society, 78(10), 2278-2281. doi:10.1021/ja01591a068Nakajima, Y., & Shimada, S. (2015). Hydrosilylation reaction of olefins: recent advances and perspectives. RSC Advances, 5(26), 20603-20616. doi:10.1039/c4ra17281gMeister, T. K., Riener, K., Gigler, P., Stohrer, J., Herrmann, W. A., & Kühn, F. E. (2016). Platinum Catalysis Revisited—Unraveling Principles of Catalytic Olefin Hydrosilylation. ACS Catalysis, 6(2), 1274-1284. doi:10.1021/acscatal.5b02624Morgan, K., Goguet, A., & Hardacre, C. (2015). Metal Redispersion Strategies for Recycling of Supported Metal Catalysts: A Perspective. ACS Catalysis, 5(6), 3430-3445. doi:10.1021/acscatal.5b00535Ono, L. K., Yuan, B., Heinrich, H., & Cuenya, B. R. (2010). Formation and Thermal Stability of Platinum Oxides on Size-Selected Platinum Nanoparticles: Support Effects. The Journal of Physical Chemistry C, 114(50), 22119-22133. doi:10.1021/jp1086703Stein, J., Lewis, L. N., Gao, Y., & Scott, R. A. (1999). In Situ Determination of the Active Catalyst in Hydrosilylation Reactions Using Highly Reactive Pt(0) Catalyst Precursors. Journal of the American Chemical Society, 121(15), 3693-3703. doi:10.1021/ja9825377Sadeghmoghaddam, E., Gu, H., & Shon, Y.-S. (2012). Pd Nanoparticle-Catalyzed Isomerization vs Hydrogenation of Allyl Alcohol: Solvent-Dependent Regioselectivity. ACS Catalysis, 2(9), 1838-1845. doi:10.1021/cs300270dGaleandro-Diamant, T., Zanota, M.-L., Sayah, R., Veyre, L., Nikitine, C., de Bellefon, C., … Thieuleux, C. (2015). Platinum nanoparticles in suspension are as efficient as Karstedt’s complex for alkene hydrosilylation. Chemical Communications, 51(90), 16194-16196. doi:10.1039/c5cc05675fROTH, J. F., ABELL, J. B., FANNIN, L. W., & SCHAEFER, A. R. (1970). Catalytic Dehydrogenation of Higher Normal Paraffins to Linear Olefins. Advances in Chemistry, 193-203. doi:10.1021/ba-1970-0097.ch011Dry, M. E. (1990). The fischer-tropsch process - commercial aspects. Catalysis Today, 6(3), 183-206. doi:10.1016/0920-5861(90)85002-6Bukur, D. B., Lang, X., Akgerman, A., & Feng, Z. (1997). Effect of Process Conditions on Olefin Selectivity during Conventional and Supercritical Fischer−Tropsch Synthesis. Industrial & Engineering Chemistry Research, 36(7), 2580-2587. doi:10.1021/ie960507bPrieto, G., De Mello, M. I. S., Concepción, P., Murciano, R., Pergher, S. B. C., & Martı́nez, A. (2015). Cobalt-Catalyzed Fischer–Tropsch Synthesis: Chemical Nature of the Oxide Support as a Performance Descriptor. ACS Catalysis, 5(6), 3323-3335. doi:10.1021/acscatal.5b00057Keim, W. (2013). Oligomerization of Ethylene to α-Olefins: Discovery and Development of the Shell Higher Olefin Process (SHOP). Angewandte Chemie International Edition, 52(48), 12492-12496. doi:10.1002/anie.201305308Keim, W. (2013). Oligomerisierung von Ethen zu α-Olefinen: Erfindung und Entwicklung des Shell-Higher-Olefin-Prozesses (SHOP). Angewandte Chemie, 125(48), 12722-12726. doi:10.1002/ange.201305308Chalk, A. J., & Harrod, J. F. (1965). Homogeneous Catalysis. II. The Mechanism of the Hydrosilation of Olefins Catalyzed by Group VIII Metal Complexes1. Journal of the American Chemical Society, 87(1), 16-21. doi:10.1021/ja01079a004Jia, X., & Huang, Z. (2015). Conversion of alkanes to linear alkylsilanes using an iridium–iron-catalysed tandem dehydrogenation–isomerization–hydrosilylation. Nature Chemistry, 8(2), 157-161. doi:10.1038/nchem.2417Dvořák, F., Farnesi Camellone, M., Tovt, A., Tran, N.-D., Negreiros, F. R., Vorokhta, M., … Fabris, S. (2016). Creating single-atom Pt-ceria catalysts by surface step decoration. Nature Communications, 7(1). doi:10.1038/ncomms10801Kozlov, S. M., Viñes, F., Nilius, N., Shaikhutdinov, S., & Neyman, K. M. (2012). Absolute Surface Step Energies: Accurate Theoretical Methods Applied to Ceria Nanoislands. The Journal of Physical Chemistry Letters, 3(15), 1956-1961. doi:10.1021/jz3006942Wodrich, M. D., Busch, M., & Corminboeuf, C. (2016). Accessing and predicting the kinetic profiles of homogeneous catalysts from volcano plots. Chemical Science, 7(9), 5723-5735. doi:10.1039/c6sc01660jGutiérrez-Tarriño, S., Concepción, P., & Oña-Burgos, P. (2018). Cobalt Catalysts for Alkene Hydrosilylation under Aerobic Conditions without Dry Solvents or Additives. European Journal of Inorganic Chemistry, 2018(45), 4867-4874. doi:10.1002/ejic.20180106

Strontium doping in mullite-type bismuth aluminate: A vacancy investigation using neutrons, photons and electrons

We report on strontium doped dibismuth-nonaoxoaluminate(III) produced at 1023 K. Partial substitution of bismuth by strontium in the structure yields oxygen vacancies for charge balance. Introducing oxygen vacancies rearranged the associated Al2O7 double-tetrahedra forming “Al3O10” tri-clusters which were identified by multi-quantum 27Al MAS NMR. Both STEM-EDX and XPS showed homogeneous distribution of strontium in the bulk and on the surface, respectively. Moreover, XPS confirms the valence state of bismuth after doping. The orientations of bismuth 6s2 lone electron pairs were calculated using DFT methods. The amount of strontium in the crystal structure was further confirmed from the decomposition product SrAl12O19 formed during the temperature-dependent X-ray powder diffraction. The structural proof was carried out by refining the structure of (Bi0.94Sr0.06)2Al4O8.94 from powder neutron and X-ray diffraction data. Rietveld refinements clearly showed the under occupation of one oxygen site and the shift of two aluminum atoms from the double-tetrahedra to two tri-cluster sites

Synthetic ferripyrophyllite: preparation, characterization and catalytic application

[EN] Sheet silicates, also known as phyllosilicates, contain parallel sheets of tetrahedral silicate built up by [Si2O5](2-) entities connected through intermediate metal-oxygen octahedral layers. The well-known minerals talc and pyrophyllite are belonging to this group based on magnesium and aluminium, respectively. Surprisingly, the ferric analogue rarely occurs in nature and is found in mixtures and conglomerates with other materials only. While partial incorporation of iron into pyrophyllites has been achieved, no synthetic protocol for purely iron-based pyrophyllite has been published yet. Here we report about the first artificial synthesis of ferripyrophyllite under exceptional mild conditions. A similar ultrathin two-dimensional (2D) nanosheet morphology is obtained as in talc or pyrophyllite but with iron(iii) as a central metal. The high surface material exhibits a remarkably high thermostability. It shows some catalytic activity in ammonia synthesis and can serve as catalyst support material for noble metal nanoparticles.The authors gratefully acknowledge the following people for support with analytical measurements and data analysis: Hans-Josef Bongard (SEM-EDX), Silvia Palm (EDX bulk), Adrian Schluter (TEM), Norbert Pfander (STEM), Jan Ternieden and Jan Nicolas Buscher (XRD and XPS), Prof. Dr Osamu Terasaki and Dr Yanghang Ma (3D electron diffraction tomography: failed due to the poor crystallinity and stability under strong beam irradiation), Dr Nicolas Duyckaerts (NH3-TPD measurements), Kai Jeske (GC gas analysis), Dr Yuxiao Ding (ATR-IR) and Dr Zhengwen Cao (titration). The authors also would like to thank Prof. Dr Robert Schlogl, Dr Thomas Lunkenbein, Fabian Pienkoss and Dr Gaetano Calvaruso for helpful and enthusiastic discussions, as well as Niklas Fuhrmann and Lars Winkel for technical support. The studies were carried out as part of our activities in the Cluster of Excellence "Tailor-Made Fuels from Biomass" (EXC 236) and "The Fuel Science Center" funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy -Exzellenzcluster 2186 "The Fuel Science Center" ID: 390919832. Open Access funding provided by the Max Planck Society.Qiao, Y.; Theyssen, N.; Spliethoff, B.; Folke, J.; Weidenthaler, C.; Schmidt, W.; Prieto González, G.... (2021). Synthetic ferripyrophyllite: preparation, characterization and catalytic application. Dalton Transactions. 50(3):850-857. https://doi.org/10.1039/d0dt03125aS85085750

Hydrogen storage in liquid hydrogen carriers: recent activities and new trends

Efficient storage of hydrogen is one of the biggest challenges towards a potential hydrogen economy. Hydrogen storage in liquid carriers is an attractive alternative to compression or liquefaction at low temperatures. Liquid carriers can be stored cost-effectively and transportation and distribution can be integrated into existing infrastructures. The development of efficient liquid carriers is part of the work of the International Energy Agency Task 40: Hydrogen-Based Energy Storage. Here, we report the state-of-the-art for ammonia and closed CO2-cycle methanol-based storage options as well for liquid organic hydrogen carriers

Materials for hydrogen-based energy storage - past, recent progress and future outlook

Globally, the accelerating use of renewable energy sources, enabled by increased efficiencies and reduced costs, and driven by the need to mitigate the effects of climate change, has significantly increased research in the areas of renewable energy production, storage, distribution and end-use. Central to this discussion is the use of hydrogen, as a clean, efficient energy vector for energy storage. This review, by experts of Task 32, “Hydrogen-based Energy Storage” of the International Energy Agency, Hydrogen TCP, reports on the development over the last 6 years of hydrogen storage materials, methods and techniques, including electrochemical and thermal storage systems. An overview is given on the background to the various methods, the current state of development and the future prospects. The following areas are covered; porous materials, liquid hydrogen carriers, complex hydrides, intermetallic hydrides, electrochemical storage of energy, thermal energy storage, hydrogen energy systems and an outlook is presented for future prospects and research on hydrogen-based energy storage

Field application of a tailored catalyst for hydrodechlorinating chlorinated hydrocarbon contaminants in groundwater

Catalytic hydrodechlorination via Pd catalysts is an efficient way to destroy chlorinated hydrocarbon compounds (CHCs) in aqueous systems. However, its application in groundwater suffers from rapid catalyst deactivation, e.g. by sulfur poisoning and interference with biological processes, such as growth of sulfate-reducing bacteria. In this paper we describe the application of a tailored catalyst for groundwater remediation in a full-scale field installation. The catalyst (Pd on a hydrophobic zeolite Y) was operated in a flow-through mode over 2 years and showed sustained removal efficiencies. Typical half-lives for CHC reduction were between 1.5 and 3min. As the addition of the reductant hydrogen results in favorable conditions for sulfate-reducing bacteria, the system was periodically flushed with a dilute H2O2solution to prevent the growth of this type of bacteria. With this it could be shown, that a catalytic method with noble metals for the direct reductive destruction of chlorinated contaminants in groundwater can be operated over extended periods of time with sustained efficiencies. © 2004 Elsevier B.V. All rights reserved