Mesoporous and macroporous γ‐alumina have been synthesized using the economic source of aluminum pellets. To manipulate the porosity and overall porous characteristics, ammonium bicarbonate was incorporated into the gel and studied to determine its influence on the porous structure of the obtained γ‐alumina. The nanostructure of the synthesized γ‐alumina, characterized by the N2 sorption isotherms and FESEM analysis, indicated that the γ‐alumina of desired pore size distribution could be achieved using such economical source of aluminum when ammonium bicarbonate was considered to tailor its porous structure. The formation of macropores in synthesized γ‐alumina was confirmed by the FESEM images and the crystalline structure of the γ‐alumina of optimal porous structure was revealed via X‐ray diffraction pattern. Before and after being calcinated at 500 °C, TG‐DTA and FT‐IR analyses were also conducted to better assess the impact that thermal processes could have on ultimate γ‐alumina porous characteristics. Considering the embedded ammonium bicarbonate expander, a two‐step mechanism was finally proposed to explain the observed porosity developed through heating stages. Different porosity patterns developed through drying and calcination steps were then contributed to the reactions taking place at each, and N2 sorption isotherms, as well as the FESEM images, were used to evaluate the introduced pore forming mechanisms.

This paper seeks to develop an efficient method for solving natural convection of a non-Newtonian nanofluid flow between two vertical flat plates. Sodium alginate is considered as the non-Newtonian fluid, and then two distinct types of nanoparticles, namely silver and copper, are added to it. To do so, the governing boundary layer and temperature equations are reduced to a set of ordinary differential equations. This approach is based on a global collocation method using Sinc basis functions, and the resulting set of ordinary differential equations are replaced by a system of algebraic equations. It is well known that the Sinc procedure converges to the solution at an exponential rate. Numerical results are included to demonstrate the validity and applicability of the method, and a comparison is made with the existing results. Also, the effect of various parameters such as Prandtl number (Pr), dimensionless non-Newtonian viscosity number () and nanoparticle volume fraction () on non-dimensional velocity and temperature profiles are discussed. It was concluded from this study that velocity and temperature increased with increasing Pr. Moreover, our results indicate that both the velocity and temperature decrease as increases. Finally, the results demonstrated that, when increases, the velocity increases but the temperature values decrease. Keywords Natural convection • Sinc-collocation • Non-Newtonian fluid • Nanoparticles List of symbols 2b Distance between the plates (m) C p Specific heat at constant pressure (J kg K −1) Ec Eckert number k Thermal conductivity (W m −1 K −1) Pr Prandtl number T Temperature (K) Greek symbols Dynamic viscosity (N s m −2) Density (kg m −3) Dimensionless temperature Solid volume fraction Dimensionless non-Newtonian viscosity Subscripts f Pure fluid s Nanoparticle nf Nanofluid