U.J. Etim

Effect of vanadium contamination on the framework and micropore structure of ultra stable Y-zeolite.

Y-zeolites are the main component of fluid catalytic cracking (FCC) catalyst for conversion of crude petroleum to products of high demand including transportation fuel. We investigated effects of vanadium which is present as one of the impurities in FCC feedstock on the framework and micropore structure of ultra-stable (US) Y-zeolite. The zeolite samples were prepared and characterized using standard techniques including: (1) X-ray diffraction, (2) N2 adsorption employing non local density functional theory method, NLDFT, (3) Transmittance and Pyridine FTIR, (4) Transmittance electron microscopy (TEM), and (5) (27)Al and (29)Si MAS-NMR. Results revealed that in the presence of steam, vanadium caused excessive evolution of non inter-crystalline mesopores and structural damage. The evolved mesopore size averaged about 25.0nm at 0.5wt.% vanadium loading, far larger than mesopore size in zeolitic materials with improved hydrothermal stability and performance for FCC catalyst. A mechanism of mesopore formation based on accelerated dealumination has been proposed and discussed. Vanadium immobilization experiments conducted to mitigate vanadium migration into the framework clearly showed vanadium is mobile at reaction conditions. From the results, interaction of vanadium with the passivator limits and decreases mobility and activity of vanadium into inner cavities of the zeolite capable of causing huge structure breakdown and acid sites destruction. This study therefore deepens insight into the causes of alteration in activity and selectivity of vanadium contaminated catalyst and hints on a possible mechanism of passivation in vanadium passivated FCC catalyst.

Process optimization for the application of carbon from plantain peels in dye abstraction

Abstract Activated carbon obtained from plantain peels was applied to the optimization of the adsorption process parameters for abstraction of colour from simulated dye effluent. The activated carbon was prepared and characterized using nitrogen adsorption, X-ray diffractometry (XRD) and Fourier transform infrared spectroscopy (FTIR). Equilibrium isotherms were modelled using the Langmuir, Freundlich, Dubinin–Radushkevich and Temkin models; the Temkin and Dubinin–Radushkevich models provided the best fit for the sorption process, with a correlation coefficient greater than 0.95. The D–R model suggested a chemical process. The pseudo second-order kinetic model agreed well for fitting experimental data with the calculated adsorption capacity, qe, (46.5 mg/g), which was reasonably close to the experimental value (47.3 mg/g). Optimization of the process parameters was achieved using response surface methodology (RSM) – Box–Behnken design, where factors considered are represented on three levels: (−1), (0) and (+1) for high, mean and low levels, respectively. ANOVA fits a quadratic model with prob > F less than 0.05 (<0.0001) at 95% confidence level. From this modelling, significant factors for dye removal have been identified.

A review of the direct oxidation of methane to methanol

This article briefly reviewed the advances in the process of the direct oxidation of methane to methanol (DMTM) with both heterogeneous and homogeneous oxidation. Attention was paid to the conversion of methane by the heterogeneous oxidation process with various transition metal oxides. The most widely studied catalysts are based on molybdenum and iron. For the homogeneous gas phase oxidation, several process control parameters were discussed. Reactor design has the most crucial role in determining its commercialization. Compared to the above two systems, aqueous homogenous oxidation is an efficient route to get a higher yield of methanol. However, the corrosive medium in this method and its serious environmental pollution hinder its widespread use. The key challenge to the industrial application is to find a green medium and highly efficient catalysts.

Nanotechnology Applications in Petroleum Refining

Nanotechnology has successfully gained applications in many areas of life, thereby seen as the modern way of creating products, which results in high efficiency of use. In the petroleum processing industries, this revolution is no exception. The efficiency of a number of conversion processes improves upon application of materials with the nanometer scale dimension, which is caused by improvements and developments of better material properties as the particle size decreases. In this chapter, the applications of nanotechnology through nanocatalysis in petro-refining processes are highlighted. This is exemplified by discussing the applications of nanotechnology in several typical petroleum refining processes, including catalytic cracking, oxidative dehydrogenation of alkanes, and desulfurization. Other processes for the production of clean fuels are also briefly reviewed. The key benefits of “nano-tech” application in catalysis are based on the exposure of a large surface area for reaction, thereby reducing the tendencies to adverse and side reactions. The desire for an improved catalyst with high activity, low deactivation, and low coke formation to meet the growing demand for chemicals and fuels necessitates the increasing exploitation of nanoparticles as catalysts.

Synthesis of monodispersed colloidal particles via a hydrothermally promoted double hydrolysis approach

Monodispersed colloidal particles have received continuously increasing attention due to their unique physicochemical properties for applications in many technological areas, especially in nanotechnology. The size and morphology of the colloid particles produced in a homogeneous solution are very sensitive to the synthesis conditions. Thus, it has been a great challenge to generalize the synthesis of monodispersed colloidal particles. In this work, a hydrothermally promoted double hydrolysis approach (HPDH) was found to be effective in the synthesis of monodispersed colloidal particles of different compositions. Several types of colloids were synthesized to demonstrate the feasibility and versatility of this novel approach. The monodispersity of the colloids was examined by scanning electron microscopy, transmission electron microscopy and particle size distribution analysis. The crystalline structure and porosity of the colloids were investigated by X-ray diffraction, selected area-electron diffraction and N2 adsorption methods. Results show that the HPDH derived colloids have a high monodispersity, which may render these materials highly potential in numerous emerging applications.