Catalytic Processes for Clean Energy

Research interests

 

1) Application of the monometallic (Pd/C, Pd/SiO2) and bimetallic catalysts based on palladium (Pd/Au, Pd/Ir/ Pd/Ru) for liquid phase hydrogenations of the organic molecules containing the C=O and C=C bonds, including cinnamaldehyde, furfural and 5-hydroxymethylfurfural.  The catalysis are synthesized using the inverse microemulsion method, making it possible to produce nanoparticles of uniform and controlled size.  For the bimetallic systems, this method makes it possible to control the surface-related properties of nanoparticles like Pd-Ir of various iridium content.

2)  Investigation of systems containing nanoparticles of palladium distributed in the MoO3 and WO3 oxide matrices, focused on finding of a role of hydrogen bronzes formed in situ during hydrogenations in the reaction kinetics, including its activity and selectivity.  These effects are investigated for the hydrogenations of cinnamaldehyde furfural and 5-hydroxymethylfurfural.  The research also includes the kinetics and thermochemical aspects of the hydrogen bronze formation using the gas flow-through microcalorimetry.

3) Study of nonlinear dynamics of oscillations accompanying the reaction of hydrogen with the metallic palladium.  The nonlinear kinetics of the sorption of molecular hydrogen in palladium manifests itself by the oscillatory rate of heat evolution accompanying the reaction, e.g., the thermokinetic oscillations, which are recorded microcalorimetrically.  The concurrent fluctuations of pressure in the gas phase, as well as the oscillations of electric conductivity of the palladium powder, both correlated with the thermokinetic oscillations, are also measured in situ.

4) Synthesis and characterization of physicochemical and electrochemical properties of carbon-based materials doped with nitrogen, in view of their application for the oxygen electroreduction reaction.  The non-noble metal nanoparticles are formed and embedded in carbon support in-situ during carbon material synthesis, whereas the noble metal nanoparticles are deposited onto carbon support ex-situ.

Research methods

  • catalytic hydrogenation in batch type reactor,
  • product analysis GC-MS and HPLC methods,
  • characterization of Pd-polymer systems (XRD, XPS, FTIR, Raman, UV-Vis, SEM, TEM, TPD, TPR)
  • thermal effects of solid-gas interactions measured with gas flow-through microcalorimeter
  • electrochemical measurements using cyclic voltammetry method

Main achievements

  • The successful synthesis of the catalysts containing both mono- and bi-metallic nanoparticles of controlled size and surface properties
  • Finding of a relation between the surface properties of the Pd-Ir nanoparticles and the selectivity of the hydrogenation of furfural
  • Detection of a reactivity of hydrogen species contained in the host lattices of Mo- and W-oxide bronzes in selective hydrogenation of the unsaturated C=C bonds in cinnamaldehyde and furfural
  • Formulation of reaction mechanism for the oscillatory heat evolution in the Pd/H systems
  • Mathematical proof of a relation useful for distinguishing between deterministic chaos and randomness in non-periodic time series
  • For the case of Ni/C composites, it has been shown that from among the Ni sites, that can be either loosely attached, or strongly anchored in the C-matrix, the more active in the electrochemical oxidation of methanol are actually the anchored ones, because of electron interaction between the Ni site and the carbon nanotube.
  • For the case of the C-composites containing the metallic Co nanoparticles, it has been shown that activity of the acid-treated composites in the electrochemical reduction of oxygen is due to the carbon sites related to both the structural defects and to the functional groups containing nitrogen.  Moreover, the carbon sites are promoted by the cobalt nanoparticles located inside the carbon nanotubes, close enough for the sites to interact with.