ties of ceria (Ce 4 +/Ce H) and the high lability of its lattice oxygen are among the most important factors that contribute to the catalytic reactivity in oxidation reactions [IOJ. Side-chain oxidation of alkyl aromatics using cleaner peroxide oxidants catalyzed by heterogeneous catalysts has been much interesting [11 J, Effective utilization of ethylbcnzene, available in the xylene stream of the petrochemical industry to more value added products is a promising one in chemical industry. The oxidation products of ethylbenzene are widely employed as intermediates in organic, steroid and resin synthesis [12-14]. Zeolite encapsulated Cot llj, Ni(ll) and Cu(Il) complexes gave acetophenone as the only partial oxidation product during ethyl benzene oxidation with H 20 2 [15]. Titanosilicates mainly catalyze ring hydroxylation of arenes with H 202 , whereas vanadium and chromium substituted zeolites and aluminophosphate molecular sieves have been known to favour side-chain oxidation selectively [16]. In the present work. we report the structural characterization of ceria supported vanadia catalysts for various loading of V205 observed using different physico-chemical
Rice husk silica was utilized as the promoter of ceria for preparing supported vanadia catalysts. Effect of vanadium content was investigated with 2-10 wt.% V 2 O 5 loading over the support. Structural characterization of the catalysts was done by various techniques like energy dispersive X-ray (EDX), X-ray diffraction (XRD), BET surface area, thermal analysis (TGA/DTA), FT-infrared spectroscopy (FT-IR), UV-vis diffused reflectance spectroscopy (DR UV-vis), electron paramagnetic spectroscopy (EPR) and solid state magnetic resonance spectroscopies ( 29 Si and 51 V MASNMR). Catalytic activity was studied towards liquid-phase oxidation of benzene. Surface area of ceria enhanced upon rice husk silica promotion, thus makes dispersion of the active sites of vanadia easier. Highly dispersed vanadia was found for low V 2 O 5 loading and formation of cerium orthovanadate (CeVO 4 ) occurs as the loading increases. Spectroscopic investigation clearly confirms the formation of CeVO 4 phase at higher loadings of V 2 O 5 . The oxidation activity increases with vanadia loading up to 8 wt.% V 2 O 5 , and further increase reduces the conversion rate. Selective formation of phenol can be attributed to the presence of highly dispersed active sites of vanadia over the support.
Acetylation of glycerol with acetic acid was carried out over bimetallic silver and copper deposited rice husk silica-alumina like ecofriendly green catalyst. Bioadditive like mono, di and tri acetyl glycerol synthesis from raw glycerol (one of the main product of biodiesel), which are gaining attention as additives for improving petroleum fuel properties towards biofuel additive development applications. Advantage of using bimetallic catalyst for glycerol acetylation due to possible synergistic effect between the metals and it enhances the catalytic conversion and selectivity compared to single metal catalyst. The prepared catalysts were characterised by XRD, FT-IR and TEM. Silver and copper incorporated RHS (rice husk silica)-alumina catalysts are shown higher activity and selectivity towards diacetin (di acetyl glycerol) and triacetins (tri acetyl glycerol) formation by catalytic acetylation of glycerol. Higher conversion (98 %) and good selectivity (51 %) is achieved.
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