|
|
Heterogeneous catalysis of terpenoid redox reactions
Kurucová, Svetlana ; Přech, Jan (advisor) ; Bulánek, Roman (referee)
Heterogeneous catalysts for Meerwein-Ponndorf-Verley (MPV) reduction of ketones and aldehydes are investigated due to issues connected with water sensitivity and separation problems of homogeneous catalysts. During MPV reduction, a hydrogen atom is transferred from the sacrificial alcohol onto the carbonyl group of the ketone/aldehyde forming corresponding alcohol. Tin and zirconium containing zeolites are active catalysts in this hydrogen transfer reaction. However, when using conventional 3D zeolites in the reduction of bulky molecules, e.g., terpenoid compounds, problems with active site accessibility for these bulky reactants may arise. The use of 2D pillared zeolites may represent a solution to the diffusion problem. Silica metal-oxide pillars increase the distance between individual layers of a 2D (lamellar) zeolite and thus improve the active site accessibility. 2D catalysts were prepared by pillaring a parent lamellar pure-Si MFI with a mixture of tetraethyl orthosilicate and Zr (IV) isopropoxide or Sn (IV) isopropoxide, while conventional 3D zeolites were synthesised hydrothermally. The activity of Sn and Zr containing pillared catalysts was compared with the activity of the 3D MFI and beta zeolites in MPV reduction of furfural and citronellal. The 2D zeolites, however, did not facilitate...
|
guest ::
