Isomerization of α-Pinene Oxide to Campholenic Aldehyde Over Fe-and Al-containing Zeotype Materials
Nowadays, considerable attention is focused on the development of new solid Lewis catalysts, which can be applied at industrial level. The main goal of the design of solid Lewis acids is the substitution of the traditional homogeneous acid catalysts, such as ZnCl2, AlCl3, FeCl3 etc. Zeolites and zeotype materials containing transition metal ions are the promising systems as Lewis acids. These materials can be used as catalysts for processes of isomerization of terpenes, for example, isomerization of terpene oxides, which is one of the important reactions for synthesis of intermediates for production of drugs, vitamins and fragrances.
α-Pinene oxide (PO) is one of the important product in industry, which isomerizes rapidly in the presence of acids, thereby forming many products.
The aim of this study is to investigate the dependence of activity and selectivity of the rearrangement of PO to campholenic aldehyde (CA) on the textural and acid-base properties of new Fe-containing materials, such as Fe-containing mesoporous mesophase silica materials (Fe-MMM-2), microporous Fe-containing nickel phosphate molecular sieves (Fe-VSB-5) , and Al-containing porous metal-benzenetricarboxylates (Al-BTCs), such as MIL-X(Al) (X = 96, 100 and 110) and isostructural family MIL-100(М) (М – Al, Fe and Cr) . The catalytic performance of these materials was investigated with a combination of physicochemical and catalytic approaches. The investigation of Lewis acidity was done by EPR and IR spectroscopy using 2,2',6,6'-tetramethyl-1-piperidinyoxyl radical (TEMPO) and benzonitrile/pyridine as the probe molecules, respectively.