No abstract

No abstract

No abstract

No abstract

Silica nanosphere was synthesized using homogeneous and heterogeneous systems, respectively. In homogeneous system, silica spheres were synthesized without cetyltrimethylammonium bromide (CTABr), which gave bimodal particle size and lower yield (77%). To improve the yield, CTABr was added and found that the yield was very high (100%). The particle was in nm range, but the particle sizes are bimodal. To avoid it, reaction in heterogeneous system using CTABr was carried out. Nanosized silica sphere with uniform size (yield, 94%) was observed. Homogeneous system contains a mixture of ethanol, water, aqueous ammonia and tetraethylorthosilicate (TEOS). In the case of heterogeneous system, only ethanol was absent.

No abstract

No abstract

Mn-MCM-41 was synthesized by the hydrothermal method. The synthesized material was characterized by various physicochemical techniques such as small angle X-ray diffraction, elemental analysis, Fourier transform infrared spectroscopy and diffuse reflectance ultraviolet-visible spectroscopy. The gas-phase cyclohexanol and air reaction over Mn-MCM-41 molecular sieve was studied for the first time. The conversion is almost constant even up to 5 h, and follows a parabolic behavior with respect to temperature. The conversion reaches a maximum at 350°C and selectivity towards cyclohexene is increased with temperature. The conversion and cyclohexene selectivity were increased with flow rate.