Sonochemical synthesis of heterostructured ZnO/Bi2O3 for photocatalytic desulfurization.

In this study, metal oxides nanoparticles heterogeneous photocatalysts prepared by coprecipitation and ultrasonic techniques were used for diesel desulfurization. They were characterized by scanning electron microscope, powder X-ray diffraction, energy dispersive analysis, diffused reflectance spectra, photoluminescence analysis and BET surface area. The surface area of catalyst B is larger than catalyst A confirming its higher reactivity. X-ray reflectance spectroscopy was used to analyze the sulfur contents in feed. Thiophene was used as a model fuel to evaluate the photocatalytic activity of catalysts A and B. Using the Scherrer equation, sharp and intense signals suggesting their higher degrees of crystallinity, with average crystal sizes for ZnO, Bi2O3, catalysts A and B, respectively; of 18, 14.3, 29.7, and 23.8 nm. The operational parameters of the desulfurization process were optimized and have been studied and the maximum sulfur removal was achieved via a further solvent extraction step. A diesel fuel with a 24 and 19 ppm sulfur content and hence a total sulfur removal of 94.6% and 95.7% was acquired for catalysts A and B, respectively (sulfur compounds concentration in diesel fuel feedstock was 450 ppm). These findings demonstrated that photocatalysts A and B are good and effective catalysts for desulfurization of diesel fuel.

Synthesis and characterization of iron-alumina composites as novel efficient photocatalysts for removal of DBT.

The content of sulfur compounds in diesel fuels is one of the main encountered drawbacks during the production process. Such compounds are generally of substantial, hazardous, and negative environmental impacts. Thus, the massive reduction of their content is recommended. Among these compounds, DBT is one of the most challenging compounds to be disposed of industrially via the HDS method. Therefore, this study presents the removal of such compounds using the oxidative-photocatalytic desulfurization technique. Three iron oxide doped alumina composites containing different weight percentages of iron (10-30%) were synthesized as novel photocatalysts. Structural characteristics of these composites were verified via X-ray diffraction (XRD) by detecting the indicative peaks for Fe2O3 and Al2O3. These composites' surface and optical properties could reveal their mesoporous nature and suitability as effective visible-light photocatalysts. These structures were next introduced to the process of DBT removal from a model diesel oil with a content of 1500 ppm at different operating conditions. The composite, which contains 20% iron oxide, was the most effective photocatalyst of DBT elimination. Specifically, 97% removal of sulfur content in the model diesel oil was successfully attained under visible-light irradiation source with a power of 500 W at a reaction time equals to 30 min, 1 g/L as photocatalyst dose and H2O2 to feed ratio of 1.5.

Elevated CO-free hydrogen productivity through ethanol steam reforming using cubic Co-Nanoparticles based MgO catalyst.

Hydrogen production through the processes of ethanol catalytic steam reforming (SR) is one of the promising routes due to its extensive yield that can be gained. However, catalyst deactivation (as a result of coke formation) is a major drawback in such a process. Therefore, this research work introduces efficient MgO supported Cubic cobalt oxide catalyst for the process of ethanol SR. This catalyst was successfully able to produce gases that have high contents of CO-free hydrogen was produced (above 78%) at 500°C and various flow rates of feed. This catalyst had also avoided coke formation at that temperature while attaining capture of the in-situ produced CO2 gas. The employment of an operating temperature beyond 500°C, during the SR process, could reduce the percentages of hydrogen (in products) to less than 55%. Such increases in the operational temperature could leave behind the detection of coke deposits onto the catalyst surface. The presence of these deposits was confirmed visually as well as via Raman spectroscopy.

Increased production of hydrogen with in situ CO2 capture through the process of water splitting using magnetic core/shell structures as novel photocatalysts.

One of the chief challenges in hydrogen production through the photocatalytic splitting of water is to employ an efficient photocatalyst that has an absorption edge at the range of long wavelengths. In this study, composite structures made of different Ag-based shells over the core of Fe2O3 nanoparticles were utilized as novel magnetic photocatalysts for hydrogen generation from water. Specifically, Ag nanoparticles, Ag/(3-aminopropyl) triethoxysilane (APTS), and Ag/polyethyleneimine (PEI) were capped on the surface of the hematite core to produce three visible light-effective photocatalysts. Structural and textural properties of the synthesized photocatalysts were confirmed by Fourier transform infrared (FTIR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Additionally, their thermal stability and optical properties were respectively studied using thermogravimetric analysis (TGA) and UV reflectance. Photocatalytic activities of the presented core/shells were planned either as a function of the magnetic force or composition of the shell layer. It could be noted that the incorporation of organic or polymer layer could significantly increase the electronic density at the metal centers. Thus, the ability of iron oxide to catalyze the water-splitting process could be enhanced. Hence, the variation of shell structure could show a key-role in the photocatalytic potential of the presented structures in terms of manipulating the composition of produced gases. On the other hand, the magnetic nature of hematite could also positively affect the photocatalytic activity of these structures by minimizing the scattering of light irradiation during the splitting process. Particularly, shifting the way of photocatalysts dispersion from magnetic to mechanical (during water splitting) had in turn reduced hydrogen productivity from 540 to 485 mmol h-1 g-1. This obviously confirms the relationship between the level of hydrogen production by the presented photocatalysts and their magnetic nature which results in quenching of irradiation scattering.

Highly Efficient Visible-Light-Induced Photocatalytic Hydrogen Production via Water Splitting using FeCl3 -Based Ionic Liquids as Homogeneous Photocatalysts.

The ionic liquid (IL) 1-octyl-3-methylimidazolium bromide/FeCl3 [OMIM]Br/FeCl3 was prepared with three molar ratios of [OMIM]Br/FeCl3 (0.5 : 1, 1 : 1, and 2 : 1), and fully characterized through 1 H and 13 C NMR, Fourier-transform IR, and Raman spectroscopic techniques. The optical properties of the prepared [OMIM]Br/FeCl3 ILs were revealed via diffuse reflectance and photoluminescence spectra. The photocatalytic activity of [OMIM]Br/FeCl3 ILs as homogenous photocatalysts were investigated towards hydrogen generation from methanol/water mixtures under visible light irradiation. The FeCl3 -based IL with [OMIM]Br/FeCl3 molar ratio of 1 : 1 exhibited the highest visible light photocatalytic activity with a hydrogen productivity of 243.2 mmol h-1 g-1 and a hydrogen purity of 95.5 %; such a high hydrogen yield and purity was reported for the first time. It was proposed that [OMIM] Br acted as an electron acceptor, which delayed the electron-hole pair recombination of FeCl3 . Also, [OMIM] Br could capture the produced carbon dioxide that is released with hydrogen gas. Additionally, [OMIM] Br/FeCl3 could be reused six times with nearly the same photocatalytic activity. These outstanding credits in terms of hydrogen generation rate and purity plus the economic feasibility, through several cycles of reuse, could certify such an IL as a promising photocatalyst for employment in water splitting. This paper suggests ways forward for research to develop the use of ILs as efficient and effective photocatalysts for hydrogen generation via water splitting.

Novel Calcium Carbonate-titania nanocomposites for enhanced sun light photo catalytic desulfurization process.

Preparation of active photocatalytic nanostructures to harvest the abundant sunlight energy is a recent worldwide direction for clean energy production and environmental management. Following this target, different calcium carbonate-titania nanostructures were prepared by three different pathways using available raw materials such as limestone as calcium precursor. After characterization of the prepared materials with X-ray diffraction (XRD), X-ray fluorescence (XRF) patterns, Fourier transmission infrared (FT-IR), high resolution transmission electron microscope (TEM), N2 adsorption-desorption isotherm, UV-vis diffuse reflectance and photoluminance (PL), the materials were applied as novel photocatalysts for desulfurization of dibenzothiophene (DBT) and gas oil using different radiation sources at room temperature. It has been obtained that, 95% desulfurization of DBT was possible under 1 h visible light irradiation with linear halogen lamp (LHL) at catalyst/DBT-solution = 10 g/L, while ultra-clean diesel production (99% removal, 3.47 ppm) could be obtained via normal sunlight photochemical desulfurization of diesel fuel by calcium carbonate titania photocatalyst in presence of H2O2 and acetic acid as oxidizing agents and acetonitrile as a solvent. Here, the followed preparation pathway produced highly active calcium titanate photocatalysts with tunable band gap energy (2.05 eV), reduced electrons/hole pairs recombination and stable photocatalytic activity with enhanced visible light removal of organosulfur compounds for economic ultra-clean fuel production, pollution control, and environmental management.

Anti-hepatitis B virus activity of new 1,2,4-triazol-2-yl- and 1,3,4-oxadiazol-2-yl-2-pyridinone derivatives.

A number of 1,3,4-oxadiazole, 3-9, and 1,2,4-triazole derivatives, 13-15, were synthesized starting form the acid hydrazide 1. The 1,3,4-thiadiazole derivative 12 was prepared from the substituted phenylthiosemicarbazide derivative 11 by treatment with sulfuric acid. The aryl hydrazone derivatives 10a-c were synthesized by reaction of the hydrazide 1 with the corresponding ketones. The thioalkyl derivatives 16a-e were prepared by akylation of the thiol derivatives 3 and 13 with different alkylating agents. The newly synthesized compounds were tested for their anti-HBV activity and some of these compounds showed high antiviral activity.