Ru/TiO2 Nanostructured Catalysts: Synthesis, Characterization and Catalytic Activity Towards Hydrogenation of Ethyl Levulinate.

Pristine TiO2 and x% Ru/TiO2 catalysts with different wt.% of Ru (x%= 1.5%, 2%, 2.5% and 3%) were synthesized using sol-gel and simple impregnation methods. Different characterization techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), High-resolution transmission electron microscope (HR-TEM), Inductively coupled plasma-optical emission spectrometry (ICP-OES) and Thermogravimetry/Differential thermal analysis (TG/DTA) were used to study the physicochemical and morphological properties. The XRD patterns of the as-prepared pristine TiO2 catalyst showed high crystalline nature. The HR-TEM images revealed that the Ru nanoparticles (NPs) were evenly dispersed on the TiO2 surface. The prepared catalysts were evaluated for their catalytic activity towards the liquid phase hydrogenation of ethyl levulinate under mild reaction conditions (ambient H2 pressure). Among the various catalysts, 2.5% Ru/TiO2 catalyst showed the maximum catalytic activity of 79% ethyl levulinate (EL) conversion with 82% selectivity of γ-valerolactone (GVL). The recyclability test revealed that the most active 2.5% Ru/TiO2 also showed the highest stability of the catalyst under optimized experimental conditions.

Degradation of Harmful Organics Using Visible Light Driven N-TiO2/rGO Nanocomposite.

Nitrogen doped titania over reduced form of graphene oxide (N-TiO2/rGO) catalysts were synthesized by adopting single step hydrothermal route. All the prepared photocatalysts were thoroughly characterized by using different analytical tools such as XRD, Raman, UV-DRS, FE-SEM and HRTEM. The photocatalytic activities of bare and composite catalysts were evaluated towards the photocatalytic decolourisation/degradation of Methylene blue dye (MB) and Metronidazole antibiotic (MTZ) under visible electromagnetic radiation. Among all the synthesized catalysts, N-TiO2/rGO composite catalyst showed the highest decolourisation/degradation activity towards both the dye and the antibiotic. The most active catalyst was also tested under UV and solar light irradiations which showed promising results. The stability of the most active catalyst (N-TiO2/rGO) was examined by recyclability test. The possible photocatalytic mechanism was proposed for the composite catalyst.

Liquid Phase Esterification of Levulinic Acid into Ethyl Levulinate Over Sulphobenzylated Nanoporous Al-SBA-15 Catalyst.

Value added chemicals, fuels, and fuel additives can be obtained from cheap bio masses such as levulinic acid. Levulinic acid is the dehydration and hydrolysis products of pentoses and hexoses. The present work deals with the synthesis of sulphobenzylated Al-SBA-15, [SO3H-Bz-Al-SBA-15], characterization by various analytical techniques such as XRD, BET, FT-IR, TGA, DTA, FE-SEM/EDS and HR-TEM/EDX techniques and evaluation of catalytic activity towards esterifi-cation of levulinic acid to ethyl levulinate under mild and non corrosive conditions. Sulphonation of the aromatic ring of the benzyl group has been done in different amounts to get nanoporous x% SO3H-Bz-Al-SBA-15 catalysts where (x ═ 0.02, 0.04, 0.06, 0.08 and 0.10% w/w). Among them 0.08% SO3H-Bz-Al-SBA-15 catalyst showed the highest conversion of levulinic acid (100%) with the highest selectivity towards ethyl levulinate (100%). Esterification of levulinic acid has been carried out with different primary alcohols and all of them yielded 100% selectivity towards alkyl levulinate. However conversion level of levulinic acid was found to be different with different alcohols. Reaction conditions have been optimized. The results were compared with other supported catalysts and discussed.

Synthesis of Nanosized ZSM-5/AlKIT-6 Composite Catalysts for Biofuel Production from Non-edible Jatropha Curcas Oil.

Nanosized ZSM-5/AlKIT-6 composite catalyst which comprises of both mesoporous large pore 3D KIT-6 and coke resistant microporous ZSM-5 was synthesized using simple in-situ overgrowth method. AlKIT-6 were coated over nano ZSM-5 with different coating ratios (5%, 10% and 15%) and utilized for biofuel production from non-edible Jatropha curcas oil using catalytic cracking technology. The morphology, porosity, acidity and Si/Al ratio of the synthesized catalysts were characterized using analytical techniques like SEM, TEM, XRD, BET, FTIR, ICP-AES and TPD. SEM and TEM images clearly confirm that the composite catalyst is not a physical mixture but a core-shell architected arrangement. Fixed-bed reactor was used for conducting the cracking reaction at the optimized temperature of 400 °C with WHSV of 4.6 h-1 and at atmospheric pressure. The composite catalyst with 10% coating gave the highest conversion (98%) and high yield of gasoline (69%). The biofuel properties were similar to that of conventional fuel. The characterization results and the catalytic results are correlated and discussed thoroughly.

Facile Synthesis, Characterization and Enhanced Photocatalytic Activities of NiWO4/Nitrogen Doped Reduced Graphene Oxide Nanocomposites.

In this study, we report the synthesis of NiWO4/nitrogen doped reduced graphene oxide nano composite by one-pot hydrothermal method. The NiWO4 nano particles were dispersed uniformly on graphene sheets. The as prepared NiWO4, NiWO4/5% rGO and NiWO4/N-5% rGO composites were analytically characterized by Powder X-ray diffraction (XRD), Raman spectroscopy, Diffuse reflectance spectroscopy (DRS-UV), Scanning electron microscopy (SEM) and N2 adsorption-desorption isotherm. The photocatalytic performances of the synthesized composites were evaluated towards the photo degradation of congo red (CR) under visible light radiation. The synthesized catalysts showed remarkable photocatalytic activity in the degradation of CR. Among the catalysts NiWO4/N-5% rGO showed the highest decolourization of congo red (92%) under visible light irradiation. This high activity is attributed to its high e- transport property. Our results provide an invaluable methodology for designing high-performance photo-catalysts for new energy applications.

Solvent Free Transesterification of Glycerol Into Glycerol Carbonate Over Nanostructured CaAl Hydrotalcite Catalyst.

Drastic increase in green house gases due to fossil fuels usage urges the mankind to look for alternative fuel resources. Biodiesel is one of the alternative fuels which attracted the attention of many researchers. In recent years, bio-diesel drags much attention as an alternative clean fuel. Glycerol is an unavoidable byproduct in the transesterification process of vegetable oils into bio diesel and therefore market is flooded with glycerol. So it is high time to find ways of utilizing the abundant glycerol into value added products. Herein we report the catalytic transesterification of glycerol using dimethyl carbonate over MgAl-hydrotalcite (MgAl-HT), CaAl-hydrotalcite (CaAl-HT) and nano structured CaAl-HT catalysts. All the catalysts were characterized by XRD, FT-IR, TPD-CO2, BET, SEM and HR-TEM techniques. Among them Ca4Al-HT was found to be best in terms of conversion of glycerol (82.4%) and selectivity (95.9%) towards glycerol carbonate. The effect of CTAB template concentration in the nano synthesis of Ca4Al-HT on conversion and selectivity was studied and Ca4Al-HT synthesized with 0.4 moles of CTAB showed the best conversion of glycerol (98.7%) and the highest selectivity towards glycerol carbonate (97.9%). The recyclability test performed with the best catalyst showed that the catalyst was recyclable even after 5 cycles. Valorization of glycerol yields glycerol carbonate (GC) which is a very good polar solvent with high boiling point, building block in several organic syntheses and used in the production of surfactants, poly urethanes etc.

Non-Metal Doped Titania Photocatalysts for the Degradation of Neonicotinoid Insecticides Under Visible Light Irradiation.

Recombination of e-/h+ pair, the major issue of any titania based photocatalytic material, is addressed here by doping non-metals such as C, N, B, F into the lattice of nano TiO2. The as-synthesised catalysts were characterized by using various instrumental techniques such as X-ray diffraction (XRD), UV-Diffuse reflectance spectroscopy (UV-DRS), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Nanosize of titania was confirmed by both XRD and TEM studies. Visible light inactivity of TiO2 is overcome by C, N, B, F doped titania catalysts in the degradation of neonicotinoid type insecticides namely imidacloprid (IMI) and thiamethoxam (TMX). The degradation efficiencies of the catalysts under different irradiations namely UV, visible and solar were compared. Among the catalysts, CNBF/TiO2 degraded IMI completely at 150, 240 and 330 min whereas TMX has been degraded completely at 210, 270 and 420 min under UV, solar and visible irradiations respectively. The recyclability test of CNBF/TiO2 confirmed its stability towards photocatalytic reaction.

Photocatalytic Degradation of Textile Reactive Dyes-A Comparative Study Using Nano Silver Decorated Titania-Silica Composite Photocatalysts.

Photocatalytic degradation of commercial textile azo dyes such as Reactive Red 120 (RR 120), Acid Orange 20 (AO 20), Reactive Orange 16 (RO 16) and Congo Red (CR) was studied under UV light and visible light irradiations of wave length 365 nm and 420 nm respectively over bare and modified titania catalysts such as TiO2, 1% Ag/TiO2, 30% TiO2/SiO2 and 1% Ag/30% TiO2/SiO2. On comparison of the catalytic activity of all the synthesized catalysts under UV and Visible irradiations, it was found that the composite catalysts showed higher photocatalytic activity than bare TiO2. Among the catalysts 1% Ag/30% TiO2/SiO2 composite catalyst was the best catalyst for the decolourization of the chosen dyes. Results obtained showed that the time taken for the complete decolourization of dyes was found to be significantly different for different dyes under both UV and visible light irradiations. Among the four dyes, AO 20 decolourised completely (100%) in 2 hrs, whereas Congo Red (CR) decolourised to the least extent (35%) over 1% Ag/30% TiO2/SiO2 under UV light irradiation. Experiments carried out under dark condition in the presence of catalyst revealed very high adsorption of CR (≈60%) over titania catalysts and hence this could be reason for suppressed catalytic activity of 1% Ag/30% TiO2/SiO2. Various optimization studies such as effects of substrate concentration, weight of catalyst and substrate pH were carried out. TOC analysis revealed a very high mineralization of all the dyes.

BiVO4 /N-rGO nano composites as highly efficient visible active photocatalyst for the degradation of dyes and antibiotics in eco system.

Herein, we report the synthesis of novel nitrogen doped reduced graphene oxide/ BiVO4 photo catalyst by single step hydrothermal method. The physicochemical properties of the catalysts were characterized using XRD, N2 adsorption-desorption, Raman, XPS, SEM TEM, DRS-UV and EIS techniques. The synthesized catalysts were tested for their catalytic activity in the photo degradation of some harmful textile dyes (methylene blue & congo red) and antibiotics (metronidazole and chloramphenicol) under visible light irradiation. Reduced charge recombination and enhanced photocatalytic activity were observed due to the concerted effect between BiVO4 and nitrogen-rGO. The degradation efficiency of BiVO4/N-rGO in the degradation of CR and MB was remarkably high i.e 95% and 98% under visible light irradiation. Similarly 95% of MTZ and 93% of CAP were degraded under visible light irradiation. HPLC studies implied that both the dyes and antibiotics were degraded to the maximum extent. The plausible photocatalytic mechanism on the basis of experimental results was suggested.

Photocatalytic Degradation of Congored on Silica Supported Ag Impregnated TiO2.

Advanced oxidation process using nano sized silver impregnated titania-silica composite catalysts for the degradation of carcinogenic dye has been investigated. x% Silver/y% Titania/Silica. (x = 1%, 4%, 7% and 10%; and y = 10%, 15%, 20% and 25%), composite photocatalysts were synthesized by a three step process and characterized by using various physicochemical analytical techniques and evaluated for their photocatalytic activities towards decolourization/degradation of Congo red. The photodecolourisation and the photodegradation were monitored by using UV-Visible spectrophotometer and Total Organic Carbon analyzer respectively. The effects of various operating variables such as percentage loading of titania and silver on the decolourization/degradation of Congo red dye were studied, optimized and compared. Impregnation of silver increased the photocatalytic activity. 1% Silver/Titania/Silica composite catalyst showed better photocatalytic activity than titania-silica composite catalysts. However further increase of silver to 4%, 7% and 10% did not show any significant improvement in photocatalytic activity. Among the catalysts synthesized 1% silver/25% titania/silica composite catalyst was found to show the best decolourization and degradation of Congo red.