Basavaraju Srinivas

Nano-size effects on CuO/TiO2 catalysts for highly efficient H2 production under solar light irradiation

Solar light induced interfacial charge transfer of electrons from TiO2 to CuO in a water-glycerol mixture produced 99,823 μmol h(-1) g(-1)catalyst of hydrogen gas. The dispersed CuO/TiO2 photocatalyst in solution exhibited uni-directional electron flow and capture at the Schottky barrier facilitating charge separation and electron transfer resulting in enhanced H2 production performance.

Sm3+‐Doped Bi2O3 Photocatalyst Prepared by Hydrothermal Synthesis

Bi2O3 and Sm3+‐doped Bi2O3 visible‐light‐active photocatalysts with different Sm3+ loadings (0.5, 1.0, and 2.0 wt %) were synthesized by a hydrothermal method. The structural properties of the prepared catalysts were studied by X‐ray diffraction (XRD), BET surface area, UV/Vis diffuse reflectance (DRS), FTIR, and X‐ray photoelectron (XPS) spectroscopic techniques. The XRD spectra of the Sm‐doped Bi2O3 catalysts calcined at 550 °C show only the characteristic peaks of Bi2O3. A high red shift in the range 450–600 nm was detected in the DRS band, leading to a large decrease in the band‐gap energy from 2.82 to 2.0 eV. This red shift increased with increasing Sm content. XPS results revealed that Sm interacted with Bi2O3, wherein both Bi and Sm were in the +3 oxidation state. The photocatalytic activities of the catalysts were evaluated for the degradation of methylene blue and phenol under solar irradiation. Of all of the catalysts prepared, the Sm3+‐doped Bi2O3 with a Sm loading of 1 wt % gave the best photocatalytic activity.

Photocatalytic reduction of CO2 over Cu-TiO2 /molecular sieve 5A composite.

TiO2 and different Cu wt% loaded TiO2 (TC0.5–5.0), 10 wt% TC2.0 supported on molecular sieve 5A (10 wt% TC2.0/MS) were prepared by impregnation and solid‐state dispersion methods. The photocatalysts prepared were characterized using XRD, SEM, and UV–Vis DRS, TEM, XPS spectroscopy techniques. Photocatalytic reduction of CO2 in water and alkaline solution are investigated in a batch reactor. The yield of oxalic acid increased notably when TC was supported on molecular sieve. The Cu‐TiO2 supported on molecular sieve catalyst promotes the charge separation that leads to an increase in the selective formation of oxalic acid in addition to methanol, acetic acid and traces of methane. The product formation is due to the high adsorption of CO2, water and product shape selectivity of the composite photocatalyst. The maximum yield of oxalic acid was found to be 65.6 μg h−1 g−1 per cat using 0.2 N NaOH containing solution over 10 wt% TC2.0/MS photocatalyst. The difference in the photocatalytic activity is related to its physicochemical properties.

Correlation of activity and stability of CuO/ZnO/Al2O3 methanol steam reforming catalysts with Cu/Zn composition obtained by SEM–EDAX analysis ☆

Abstract A series of CuO/ZnO/Al 2 O 3 catalysts were prepared and characterized by TPR, surface area, metal area, XRD and SEM–EDAX analysis. These systems were evaluated in the development of a methanol steam reforming catalyst (MSR). A correlation of activity and stability of MSR catalysts with the Cu/Zn ratio derived by SEM–EDAX analysis is observed. The stable activity of these catalysts is also supported by the method of preparation, low temperature reducibility and the presence of reversibly oxidizable Cu species observed by TPR of fresh and used catalysts.

Intermolecular cyclization of ethanolamine to 1,4-diazabicyclo (2.2.2) octane over modified pentasil zeolites ☆

The synthesis of 1,4-diazabicyclo (2.2.2) octane (DABCO) over modified ZSM-5 catalysts was carried out selectively in vapor phase with high conversion and yields. Pb, Zr and Cr-modified HZSM-5 zeolites with medium acidity gave high yields of DABCO. The acid sites of medium strength are found to be active for the selective synthesis of DABCO. The life of the catalyst was significantly improved by tuning various reaction parameters. The optimization of reaction parameters like mole ratio of the feed, weight hour space velocity, time on stream, effect of additives in the feed and the mechanism of selective formation of DABCO are described.

An integrated approach of solar photocatalytic and biological treatment of N-containing organic compounds in wastewater

In the present study the integration of TiO2-assisted solar photocatalysis and biological treatment for the degradation of organic nitrogen containing pyrazinamide (antituberculosis drug) synthesis process effluent is investigated. The experimental results showed that a considerable increase in the degradation efficiency of N-containing compounds is obtained by integration of photocatalysis and biological treatment when compared to either biological or photocatalysis treatment alone. The optimization parameter like amount of photocatalyst (TiO2 Degussa-P-25) was performed for photocatalytic treatment under solar irradiation. Furthermore BOD5/COD ratios were also evaluated. The optimum catalyst (wt.%) of 0.35 TiO2, and 40 times dilution are found to be optimum for achieving a maximum of 76, 83, 80% of COD, color and TOC removals respectively and an improved BOD5/COD ratio of 0.3 to 0.7 in a duration of 24 h. Also the formation of increased from 10 to 44 mg L−1 within 20 h of photocatalytic treatment. The effluent subjected to biological treatment for five days (120 h) has resulted 43% COD removal only, whereas the treatment method using integrated approach resulted a 91% COD removal in a duration of 44 h.

REACTION OF N-(2-HYDROXYETHYL)ETHYLENEDIAMINE OVER ZEOLITE AND CHROMITE CATALYSTS +

N-(2-hydroxyethyl) ethylenediamine reaction was observed over zeolite catalysts giving rise to only dehydrocyclization and over chromite catalysts showing dehydrocyclization together with dehydrogenation. The major product changes from the cyclized compound piperazine to pyrazine when the reactant is switched from zeolite to chromite catalyst. This process stands as a model reaction for characterizing lone acid sites and adjacent acid-base sites over zeolite and chromite catalysts, respectively.

Solar photocatalytic degradation of the herbicide isoproturon on a Bi–TiO2/zeolite photocatalyst

The photocatalytic degradation of the herbicide isoproturon under solar light was investigated in aqueous solution containing a Bi–TiO2/zeolite photocatalyst. The catalysts were characterized using X-ray diffraction, UV-Vis diffuse reflectance spectroscopy, Fourier transform-infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. The effect of Bi–TiO2 loading onto the zeolite support and influence of the parameters such as catalyst amount, pH, and initial concentration of isoproturon on the degradation rate were evaluated. The recycling ability of the catalyst was found to be sustainable for elongated periods. The high activity of the Bi–TiO2/zeolite was attributed to its absorptivity of visible light and its high adsorption capacity for the pollutant molecules.

A novel one step photocatalytic synthesis of dihydropyrazine from ethylenediamine and propylene glycol

Dihydropyrazine (DHP), the intermediate for pyrazine, is synthesized from ethylenediamine and propylene glycol; it is assumed that the reaction proceeds by photooxidation of propylene glycol and cyclization with ethylenediamine to give dihydromethylpyrazine, which by subsequent oxidative demethylation via the corresponding acid, forms dihydropyrazine; molecular oxygen, light and TiO2/zeolite promote the reaction.

Steam Reforming of Glycerol for Hydrogen Production over Catalyst

The performance of catalyst for glycerol reforming has been investigated in fixed-bed reactor using careful tailoring of the operational conditions. In this paper, a commercial Engelhard catalyst has been sized and compared to gas product distribution versus catalyst size, water-to-carbon ratio, and stability of the catalyst system. catalysts of three sizes (, , and mm) are evaluated using glycerol: water mixture at to produce 2 L H2 g−1 cat h−1. The results indicate that mm size pellet is showing minimum coking and maintaining same level of conversion even after several hours of reforming activity. Whereas studies on and mm pellets indicate that carbon formation is affecting the reforming activity. Under accelerated aging studies, with 1 : 9 molar ratio of glycerol to water, 3 mg carbon g−1 cat h−1 was generated in 20 cycles, whereas 1 : 18 feed produced only 1.5 mg carbon g−1 cat h−1 during the same cycles of operation. The catalysts were characterized before and after evaluation by X-ray diffraction (XRD), BET surface area, scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDAX), CHNS analysis, transmission electron microscopy (TEM), and X-ray photo electron spectroscopy (XPS).