Dr. Jennifer Strunk

 Dr. Jennifer Strunk
NBCF 04/685          0234 32 23566       Dr. Jennifer Strunk
  SFB 558 
Photokatalysatoren zur CO2-Reduktion

Entwicklung aktiver und selektiver heterogener Photokatalysatoren für die Reduktion von CO2 zu C1-Basischemikalien 

Ziel des Projekts ist es, einen Weg zur stofflichen Nutzung von CO2 aufzuzeigen, indem es auf chemischen Weg in nützliche Basischemikalien der Industrie umgewandelt wird. Vor allem die Synthese von Methan und Methanol stehen im Vordergrund, da diese Stoffe in großen Mengen nicht nur in der industriellen Produktion, sondern auch als Brennstoffe zur Energiegewinnung Einsatz finden. Anstatt der heutzutage üblichen Hochdruckprozesse, unter Verwendung von Wasserstoff aus fossilen Quellen, soll die chemische Umsetzung von CO2 nur unter Zugabe von Wasser und Bestrahlung mit Sonnenlicht auf photokatalytischem Wege geschehen. Aktive Photokatalysatoren für die gleichzeitige Wasserspaltung und Aktivierung von CO2 sind heutzutage jedoch noch kaum bekannt. Im Rahmen des Projekts sollen aktive und selektive Photokatalysatorsysteme auf der Basis halbleitender Oxide entwickelt und die Reaktionsführung optimiert werden.

Selective alcohol oxidation in the liquid phase

Another aspect of our investigations concerns heterogeneous catalysis in the liquid phase. Therefore we are interested in the selective oxidation of short chain alcohols, particularly ethanol and 2-propanol. To obtain insight into the reaction mechanism it is necessary to know about all products, by-products, and intermediates. This includes different species such as uncharged species and ionic species dissolved in the liquid and adsorbates on the catalyst surface. To get to know all of the present species and their conversion during reaction, different sophisticated characterization methods are used. It is possible to detect uncharged species with Membrane Inlet Mass Spectrometry (MIMS) while ionic species can be detected with Ion Chromatography (IC). IR-spectroscopy in attenuated total reflection (ATR-IR) is used to detect species that are adsorbed on the catalyst surface. Furthermore there will be isotopic exchange experiments (SSITKA, steady state isotopic transient kinetic analysis) to obtain deeper insight into the reaction mechanism and the conversion of the species into each other. The used set-up is shown schematically in Fig. 1.


ATR_IR_set_up
Fig. 1: Schematic representation of the ATR-IR set-up including inlets for gas and liquid, MIMS and ion chromatography

Ausgewählte Publikationen
  1. J. Strunk, W.C. Vining, A.T. Bell, “Synthesis of different CeO2 structures on mesoporous silica and characterization of their reduction properties”, J. Phys. Chem. C. 115 (2011) 4114.
  2. J. Strunk, W.C. Vining, A.T. Bell, “A study of oxygen vacancy formation and annihilation in submonolayer coverages of TiO2 dispersed on MCM-48”, J. Phys. Chem. C. 114 (2010) 16937.
  3. J. Strunk, K. Kähler, X. Xia, M. Comotti, F. Schüth, T. Reinecke, M. Muhler, “Au/ZnO as catalyst for methanol synthesis: The role of oxygen vacancies”, Appl. Catal. A: General 359 (2009) 121.
  4. J. Strunk, K. Kähler, X. Xia, M. Muhler, “The surface chemistry of ZnO nanoparticles applied as heterogeneous catalysts in methanol synthesis”, Surf. Sci. 603(1-2) (2009) 1776.
  5. S. Polarz, J. Strunk, V. Ischenko, M.W.E. van den Berg, O. Hinrichsen, M. Muhler, M. Driess, “On the role of oxygen defects in the catalytic performance of zinc oxide”, Angew. Chem. Int. Ed. 45 (2006) 2965.
  6. J. Strunk, R. Naumann d’Alnoncourt, M. Bergmann, S. Litvinov, X. Xia, O. Hinrichsen, M. Muhler, “Microkinetic modeling of CO TPD spectra using coverage dependent microcalorimetric heats of adsorption”, Phys. Chem. Chem. Phys. 8 (2006) 1556.
  7. M. Kurtz, J. Strunk, O. Hinrichsen, M. Muhler, K. Fink, B. Meyer, C. Wöll, “Active sites on oxide surfaces: ZnO-catalyzed synthesis of methanol from CO and H2”, Angew. Chem. Int. Ed. 44 (2005) 2790.

Photocatalysts for CO2 reduction

  1. B. Mei, D. Heeskens, J. Strunk, M. Muhler, “CO2 adsorption on potential photocatalysts for CO2 reduction“, Poster presentation, EuropaCat X, Glasgow, UK, Aug. 28-Sept. 2, 2011.
  2. W. Busser, B. Mei, J. Strunk, M. Muhler, „Development of titania-based photocatalysts – Towards visible light driven water splitting and CO2 reduction”, Poster Presentation, 1st International Symposium on Chemistry of Energy Conversion and Storage, Berlin, Germany, Feb. 27 – March 2, 2011.
  3. M. Bledowski, L. Wang, A. Ramakrishnan, O.V. Khavryuchenko, V.D. Khavryuchenko, P.C. Ricci, J. Strunk, T. Cremer, C. Kolbeck, R. Beranek, “Visible-light photocurrent response of TiO2–polyheptazine hybrids: evidence for interfacial charge-transfer absorption” Phys. Chem. Chem. Phys. accepted (2011).

In situ Infrared spectroscopy

  1. J. Strunk, K. Kähler, X. Xia, M. Muhler, “The surface chemistry of ZnO nanoparticles applied as heterogeneous catalysts in methanol synthesis”, Surf. Sci. 603(1-2) (2009) 1776.
  2. K. Kähler, M.C. Holz, M. Rohe, J. Strunk, M. Muhler, „Probing the reactivity of ZnO and Au/ZnO nanoparticles by methanol adsorption: A TPD and DRIFTS study”, ChemPhysChem 11 (2010) 2521.

(Sub)Monolayers of metal oxides on mesoporous silica

  1. W.C. Vining, J. Strunk, A.T. Bell, “Investigation of Structure and Activity of VOx/ZrOx/SiO2 catalysts for methanol oxidation to formaldehyde”, J. Catal. 281 (2011) 222.
  2. J. Strunk, W.C. Vining, A.T. Bell, “Synthesis of different CeO2 structures on mesoporous silica and characterization of their reduction properties”, J. Phys. Chem. C. 115 (2011) 4114.
  3. J. Strunk, W.C. Vining, A.T. Bell, “A study of oxygen vacancy formation and annihilation in submonolayer coverages of TiO2 dispersed on MCM-48”, J. Phys. Chem. C. 114 (2010) 16937.
  4. W.C. Vining, A. Goodrow, J. Strunk, A.T. Bell, “An experimental and theoretical investigation of the structure and reactivity of bilayered VOx/TiOx/SiO2 catalysts for methanol oxidation”, J. Catal. 270 (2010) 163.

Influence of structural defects on catalytic activity

  1. J. Strunk, K. Kähler, X. Xia, M. Comotti, F. Schüth, T. Reinecke, M. Muhler, “Au/ZnO as catalyst for methanol synthesis: The role of oxygen vacancies”, Appl. Catal. A: General 359 (2009) 121.
  2. S. Polarz, J. Strunk, V. Ischenko, M.W.E. van den Berg, O. Hinrichsen, M. Muhler, M. Driess, “On the role of oxygen defects in the catalytic performance of zinc oxide”, Angew. Chem. Int. Ed. 45 (2006) 2965.
  3. M. Kurtz, J. Strunk, O. Hinrichsen, M. Muhler, K. Fink, B. Meyer, C. Wöll, “Active sites on oxide surfaces: ZnO-catalyzed synthesis of methanol from CO and H2”, Angew. Chem. Int. Ed. 44 (2005) 2790.