Dr. Jennifer Strunk

 Dr. Jennifer Strunk

NBCF 04/685          0234 32 23566       Dr. Jennifer Strunk

SFB 558    
Photocatalysts for CO2 Reduction

Development of active and selective heterogeneous photocatalysts for the reduction of CO2 to C1 building block chemicals 

The aim of this project is the identification of a feasible way to reduce carbon emissions by chemical recycling of CO2 to important building block chemicals for industrial production. In particular, it focuses on the synthesis of methane and methanol, as these chemicals are needed in large quantities, not only for chemical production, but also as fuels for energy production. Instead of high-pressure processes with the consumption of hydrogen from fossile resources used today, the aim is the chemical conversion of CO2 only by the addition of water and the illumination with sun light in a photocatalytic reaction. However, active photocatalysts for the concomitant water splitting and activation of CO2 are hardly known yet. Within the scope of this project, active and selective photocatalyst systems based on semiconducting oxides are to be developed, and an optimization of the reaction parameters is desired.

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.