Nanocrystalline aluminosilicate F-type zeolite (K-F, EDI-type structure) was synthesized in an organic template-free system
using rice husk ash (RHA) silica source and microwave energy. The morphology, crystallite size, chemical composition,
crystallographic and basicity properties of the nanocrystals were studied by using various characterization techniques.
The results showed that fully crystalline K-F zeolite (Si/Al ratio = 1.26) with flattened cuboid-like shaped could be
obtained within 2 min of crystallization which was considerably very fast. In addition, K-F zeolite nanocrystals was also
tested as a solid base catalyst in the microwave-enhanced Aldol condensation reaction of heptanal with benzaldehyde
and the six catalytic parameters were studied and optimized. The nanosized K-F zeolite crystals showed good catalytic
performance in the studied reaction with 77.1% heptanal conversion and 69.5% jasminaldehyde selectivity under optimum
reaction condition. The nanocatalyst was reusable and no significant loss in its catalytic reactivity was observed even
after five consecutive reaction cycles.
Mohammad Anwar Mohamed Iqbal, Muhammad Zulhelmi Nazri, Mohammad Norazmi Ahmad, Erna Normaya Abdullah, Umie Fatihah Mohamad Haziz, Mohd Rizal Razali, et al.
Silver (I) dicyanonitrosomethanide, Ag[ONC(CN)2] represent a 3D interwoven coordination polymer organization in which all the donor atoms of the functional groups of ONC(CN)2- are coordinated to the Ag(I). Oxidation of styrene utilizing H2O2 as an oxidant in acetonitrile (CH3CN) was used as a model reaction to investigate the catalytic potential of the Ag (I) complex. The CH3CN was chosen as the solvent based on the data collected from Conductor like Screening Model for Real Solvents (COSMO-RS) study. The data indicate that the Ag [ONC(CN)2] complex was compatible and soluble in CH3CN. Different parameters such as styrene:H2O2 molar ratio, reaction time, catalyst mass, and reaction temperature were studied. Highest styrene conversion (36%) with 100% selectivity towards benzaldehyde (BZ) was achieved when 25 mg catalyst, 1:1 styrene to H2O2 molar ratio were used. The reaction was carried out at 303 K for 3 h. The catalytic conversion of styrene to BZ is proposed to take place via [Ag-H2O2] adduct with styrene oxide (StO) as an intermediate. Molecular Electrostatic Potential (MEP) shows that the Ag atom has the highest probability to coordinate with the oxygen atom of H2O2. The MEP data confirms the proposed mechanism.