Catalytic performances of NiMo/Zr-SBA-15 catalysts for the hydrotreating of bitumen derived heavy gas oil

Gas-oil obtained from bitumen contains a significant amount of impurities, which are difficult to remove using a conventional alumina supported hydrotreating catalyst. Innumerable studies have been carried out to develop a highly effective hydrotreating catalyst, and among all utilizing more advanced support is considered as a better alternative. Recently, SBA-15, which is an ordered mesoporous silica support, has received importance as a catalyst support because of its excellent textural properties. However, SBA-15 lacks surface acidity and provides very low metal-support interaction. By modifying SBA-15 with zirconia, an optimum level of surface acidity and Si-Mo interaction can be achieved. Also, by doping zirconia with SBA-15, the textural properties of zirconia can be improved. Hence, a synergistic effect can be obtained while incorporating zirconia onto SBA-15 and the resulting material Zr-SBA-15 can be used as an effective support for hydrotreating catalyst. In the present study, Zr-SBA-15 supports were prepared by the post synthesis and the direct synthesis method with different zirconia loading. Zr-SBA-15 supported NiMo catalysts were prepared by incipient wetness impregnation technique. Catalysts and supports were characterized by small angle X-ray scattering (SAXS), nitrogen adsorption/desorption (BET), powder X-ray diffraction (XRD), transmission electron spectroscopy (TEM), scanning electron microscopy (SEM), and Raman spectroscopy methods. Characterization of support confirmed that the zirconia was successfully incorporated in a mesoporous SBA-15 structure without significantly changing the textural properties of SBA-15. The performance of the Zr-SBA-15 supported NiMo catalysts was evaluated based on hydrodesulfurization and hydrodenitrogenation activities exhibited during hydrotreating of heavy gas oil derived from Athabasca bitumen at industrial operating condition (temperature 375-395 °C, pressure 8.9 MPa, LHSV 1.0 hr-1 and gas/oil ratio 600 Nm3/m3). The comparison of catalytic activities showed that the NiMo catalysts supported on Zr-SBA-15, prepared by direct and post synthesis method exhibited higher hydrotreating activity compared to SBA-15 supported catalyst. NiMo catalyst supported on Zr-SBA-15 with 23 wt% of ZrO2 loading, prepared by post synthesis method showed the highest activity among all the catalysts. After determining the best support, the optimum catalyst metal loadings on the Zr-SBA-15 support was found to be 17 wt% of Mo and 3.4 wt% of Ni. This catalyst also showed higher activity in mass basis for the hydrotreating of heavy gas oil compared to that of commercial hydrotreating catalyst. A kinetic study was performed on the optimum NiMo/Zr-SBA-15 catalyst to predict its HDS and HDN activities while varying the parameters of temperature, liquid hourly space velocity (LHSV), pressure and gas-to-oil ratio. Rate expressions were developed using Power Law and Langmuir-Hinshelwood model to predict the behavior of both the HDS and HDN reactions. Power law models were best fit with reaction orders of 1.8 and 1.3, and activation energies of 115 kJ/mol and 121 kJ/mol, for HDS and HDN reactions, respectively. The activation energies calculated using Langmuir-Hinshelwood model considering H2S inhibition were found to be 122 kJ/mol and 138 kJ/mol, for HDS and HDN reactions, respectively

Adverse effects of the toxic industrial dye malachite green on the antioxidant and antimicrobial properties of Allium cepa L.

The therapeutic importance of Allium cepa L. has been well established through ethnobotanical studies. Malachite Green is a highly toxic dye that finds extensive use in the textile industry as a fabric colorant. A. cepa was treated with malachite green solutions (20mg/l and 40mg/l) for 45 days. The roots actively take up malachite green and impede the plant's growth in root length, shoot length and fresh weight. A. cepa is rich in bioactive compounds, which have superior antioxidant and antimicrobial properties. We observe that the antimicrobial activities decrease by 36% for Staphylococcus aureus and 31% for Escherichia coli on the treatment of A. cepa bulbs with 40 mg/l malachite green. Antioxidant activity was similarly lowered by 61% under the toxic effects of the dye. Reduction in the efficacy of A. cepa in terms of the critical medicinal properties and general retardation in growth is a cause of concern. This article reports a previously unknown aspect of malachite green toxicity and presents the effect of any dye on the medicinal properties of A. cepa for the first time

Activating ZnO nanorods photoanodes in visible light by CdS surface sensitiser

Thin films of c-axis aligned uniform ZnO nanorods (NRs) were fabricated on to fluorine-doped tin oxide-coated soda lime glass substrate by a two-step chemical route. Thereafter ZnO NRs/CdS core shell structures were successfully synthesised by depositing CdS layer on top of vertically aligned ZnO NRs using less hazardous nanocrystal layer deposition technique. The presence of CdS in ZnO NRs/CdS core shell structures was confirmed by energy dispersive X-ray analysis. Examination of structure and morphology of the fabricated films by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) revealed that both films have one-dimensional hexagonal wurtzite structure. Optical properties evaluated from ultraviolet-visible and photoluminescence spectra demonstrated better photo response of ZnO NRs/CdS core shell structure with respect to bare ZnO NR structure. Optical to chemical conversion efficiency of ZnO NRs/CdS photoanode was found to be similar to 1.75 times higher than bare ZnO NRs photoanode in photo electrochemical water splitting under visible light

Attitude of Tribal Parents Towards the Higher Education of Girls in India

The paper focuses on the attitude of tribal parents regarding the education of girls. This review paper intends to understand the attitudes of tribal parents towards the education of girls in India and West Bengal, according to their gender, educational level, and socioeconomic position. We determined that tribal parents have a positive mindset for their daughters’ education. They realize the importance of education, however they cannot control certain situations, such as migration and the negligence of the girls towards their coeducation. The essential point in all these instances is that tribal parents in India desire to educate their daughters; the majority of them face severe challenges due to a lack of schools or lack of basic infrastructure within the area’s current schools

Nanostructured ZnO thin film with improved optical and electrochemical properties prepared by hydrothermal electrochemical deposition technique

Zinc oxide (ZnO) thin films were grown on fluorine-doped tin oxide coated glass substrate by the hydrothermal electrochemical deposition (HTED) route using slightly acidic aqueous zinc acetate solution at 80°C and were characterised by various techniques. The deposited films showed n-type behaviour with improved carrier concentration. The steady state photocurrent densities were found to be 0.4 mA/cm2(under UV irradiation) and 8 μA/cm 2(under visible light illumination) at zero bias potential. Significant improvement of optical, electrochemical and photoelectrochemical properties of deposited films could be achieved using HTED technique