1. A continuous flow method for generation of hydrogen from formic acid Artur Majewski [a], David J. Morris [b], Kevin Kendall [a], and Martin Wills [b] [a] Department of Chemical Engineering, The University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK. fax: (+44) 121 414 2739, e-mail: K.kendall@bham.ac.uk [b] Department of Chemistry, The University of Warwick, Coventry, CV4 7AL, UK. fax: (+44) 24 7652 4112, e-mail: M. wills@warwick.ac.uk Introduction A method is described for the continuous-flow generation of hydrogen from the ruthenium-catalysed decomposition of formic acid (FA) in the presence of an amine base. The rate of addition of formic acid may be mediated by either a temperature feedback mechanism or through the use of impedence measurements. Procedure Results on the use of ruthenium complexes for hydrogen generation from FA/amine systems at around 120 o C are disclosed. In order to establish which amines were worthy of further examination as a base in hydrogen production, a series (1-6) were screened for compatibility with formic acid. The best result, was achieved using N,N- dimethyloctylamine 3, which gave a smooth increase and then decrease of gas generation over time. For larger scale continuous flow reactions a test rig was constructed containing a 2L reaction flask mounted on a stirrer/hotplate. The reaction vessel was fitted with an inlet tube into which formic acid could be replenished using a peristaltic pump. The reaction temperature (or resistance) was monitored using the LabVIEW programme. The reactor was charged with ca. 100 mL of a 5:2 (molar) mixture of FA and the amine, together with a ruthenium(II) complex. Results and Discussion A continuous flow addition reaction was carried out each day for between 1 and 6 days and measurements of the gas flow rate were taken using the flow meter. Selected results are illustrated in Figure below. Since the control of the reaction using a temperature feedback mechanism had proved to be difficult due to a delay in the response time, the use of impedence as a feedback response mechanism was investigated. Because the formate salt is a strong electrolyte and amines are dielectric, we tested impedence measurement to control the reaction. Replenishment was programmed for when the impedence rose above 80Ω. Using RuCl 2 (DMSO) 4 the reaction was very effective on the first day, with an average gas production of over 1.5L/min. This rate reduced each day, in line with the temperature-controlled reaction. Conclusions and Acknowledgements We have demonstrated that efficient continuous generation of hydrogen and CO 2 can be achieved from a formic acid/tertiary amine base mixture using either a temperature or impedence-based feedback system. We thank the EPSRC for funding through a feasibility grant and via the SUPERGEN 14 H-Delivery grant. Impedance meter Refrigerator circulator Peristaltic pump Computer - pump controlling and data recording Fuel cell Reactor Condensers Flow meter References 1.Artur Majewski, David J. Morris, Kevin Kendall, and Martin Wills, ChemSusChem 2010, 3, 431-434. 2.a) T. C. Johnson, D. J. Morris, M. Wills, Chem. Soc. Rev. 2010, 39, 81-88; b) F. Joó, ChemSusChem 2008, 1, 805-808; c) S. Enthaler, ChemSusChem 2008, 1, 801-804. 3.D. J. Morris, G. J. Clarkson, M. Wills, Organometallics 2009, 28, 4133-4140. HDelivery