Kondakindi Rajender Reddy

Alkylation of phenol with methanol over molybdenum oxide supported on NaY zeolite

A series of MoO3/NaY catalysts were prepared with Mo loadings ranging from 2 to 16 wt% and characterized by X-ray diffraction (XRD), BET specific surface area and temperature-programmed desorption (TPD) of ammonia. XRD results revealed that the crystallinity of NaY zeolite was found to decrease with increase in Mo loading in the catalysts. The total acidity measured by ammonia TPD of the catalysts was found to decrease with increase in Mo loading. The catalytic properties were evaluated for the vapor phase alkylation of phenol with methanol and the results were correlated with results obtained from different characterization techniques. The conversion of phenol decreases as Mo loading increases in the catalyst. With increase in Mo loading on NaY zeolite the selectivity for the formation of C-alkylated compounds was decreased. However, the selectivity towards the formation of O-alkylated products was increased.

Vapour phase ammoxidation of toluene over vanadium oxide supported on Nb2O5-TiO2

Vanadium oxide catalysts with V2O5 loadings ranging 1 to 9% (w/w) supported on 1∶1 wt% Nb2O5–TiO2 mixed oxide have been prepared by the wet impregnation method. The calcined samples were characterized by X-ray diffraction (XRD), pulse oxygen chemisorption and temperature programmed desorption (TPD) of NH3. Dispersion of vanadia was determined by oxygen chemisorption at 643 K in a dynamic method. At low V2O5 loadings, vanadia is found to be present in a highly dispersed state. X-Ray diffraction results also suggest that vanadium oxide exists in a highly dispersed state at lower loadings and in a crystalline V2O5 phase at higher vanadia loadings (5 wt% and above). The dispersion of vanadia was found to decrease with V2O5 loading due to the formation of V2O5 crystallites. The catalytic properties were evaluated for the vapor phase ammoxidation of toluene to benzonitrile and correlated with characterization results.

Characterization and catalytic properties of MoO3–V2O5/Nb2O5 catalysts

Abstract The influence of molybdenum oxide on the dispersion of vanadium oxide supported on niobia was investigated. A series of MoO3–V2O5/Nb2O5 catalysts with varying MoO3 content ranging from 1% to 5% (w/w) with fixed V2O5 content were prepared by impregnation of previously prepared 5 wt% V2O5/Nb2O5 with requisite amounts of ammonium molybdate solution. X-ray diffraction patterns indicate the presence of β-(Nb,V)2O5 phase with the addition of MoO3 up to a loading of 3 wt%. Temperature-programmed reduction (TPR) results suggest that the reducibility is decreasing with MoO3 loading. The results of temperature programmed desorption (TPD) of ammonia suggest that the acidity of the catalysts increased with the addition of MoO3. The catalytic properties of the catalysts in the ammoxidation of 3-picoline were correlated with the characterization data.

Dispersion and reactivity of molybdenum oxide catalysts supported on titania

Abstract A series of MoO 3 catalysts with Mo loadings ranging from 2 to 10 w/w% supported on TiO 2 were prepared and investigated by X-ray diffraction (XRD), temperature programmed reduction (TPR) and oxygen chemisorption measurements. Dispersion of molybdena was determined by the oxygen chemisorption at 623 K and by static method on the samples prereduced at the same temperature. At low Mo loadings, i.e. below 6% Mo, molybdenum oxide was found to present in a highly dispersed amorphous state. TPR profiles of MoO 3 /TiO 2 samples suggest that the reduction of MoO 3 to Mo proceeds in two stages and the reducibility of MoO 3 increases with Mo loading in the catalysts. The catalytic properties were evaluated for the vapor-phase ammoxidation of toluene to benzonitrile and are related to the oxygen chemisorption sites.

Dispersion and reactivity of Mo/Nb2O5 catalysts in the ammoxidation of toluene to benzonitrile

A series of Mo/Nb2O5 catalysts were prepared with Mo loadings ranging from 2.5–15 wt% of Mo and characterized by X-ray diffraction (XRD), pulse oxygen chemisorption, temperature-programmed desoprtion of ammonia. Dispersion of molybdena was determined by oxygen chemisorption at 623 K in a dynamic method. At low Mo loadings molybdenum oxide is found to be present in a highly dispersed state. XRD results show the presence of crystalline MoO3 at higher Mo loadings (from 10 wt%). The dispersion of molybdena was found to decrease with increased Mo loading due to formation of MoO3. The catalytic properties were evaluated for the vapour phase ammoxidation of toluene to benzonitrile and are related to different characterization results.