Utilizing Shear Factor Model and Adding Viscosity Term in Improving a Two-Dimensional Model of Fluid Flow in Non Uniform Porous Media

In a packed bed catalytic reactor, the fluid flow phenomena are very complicated because the fluid and solid particle interactions dissipate the energy. The governing equations were developed in the forms of specific models. The shear factor model was introduced in the momentum equation for covering the effect of flow and solid interactions in porous media. A two dimensional numerical solution for this kind of flow has been constructed using the finite volume method. The porous media porosity was treated as non-uniform distribution in the radial direction. Experimentally, the axial velocity profiles produce the trend of having global maximum and minimum peaks at distance very close to the wall. This trend is also accurately picked up by the numerical result. A more comprehensive shear factor formulation results a better velocity prediction than other correlations do. Our derivation on the presence of porous media leads to an additional viscosity term. The effect of this additional viscosity term was investigated numerically. It is found that the additional viscosity term improves the velocity prediction for the case of higher ratio between tube and particle diameter

Gamma-Alumina Nanotubes Prepared by Hydrothermal Method as Support of Iron, Cobalt and Nickel for Fischer-Tropsch Catalysts

?-Alumina nanotubes have been synthesized by hydrothermal method from aluminium nitrate nonahydrate, CTAB, urea, and water with a molar ratio of 29:153:1:2028. The alumina has BET surface area of 203.73 m2/g, pore volume of 0.14 ml/g, and average pore diameter of 2.78 nm. The crystallite size calculated by Scherer equation was in the range of 9.8–11 nm. It has been employed as support of iron, cobalt, and nickel for Fischer-Tropsch synthesis catalyst. The three catalysts were prepared by incipient wetness impregnation method. It was found that they showed different catalytic behaviours and activity. The acidity of catalysts increased according to the order: Co/Al2O3<Fe/Al2O3<Ni/Al2O3. The reducibility, amount of active site and catalytic activity increased in the following order: Fe/Al2O3<Co/Al2O3<Ni/Al2O3. Keywords: alumina nanotubes, hydrothermal method, iron, cobalt, nickel, Fischer-Tropsch catalyst