Preparation of extruded alumina with suitable crushing strength and good stability

The extruded alumina was prepared by the extrusion of a paste that contains boehmie, -alumina, polyethylene glycol 400 as an additive, and nitric acid as a peptizing agent. Porosity and crushing strength of the samples were carried out by means of N2 adsorption-desorption isotherm and mechanical strength instrument, respectively. The calcined extruded alumina has the specic surface area of 168-240 m2/g, pore volume of 0.37-0.5 cm3/g, and pore diameter of 8.2-8.8 nm. More than 36% of pore volume belonged to the pore diameters larger than 10 nm. The lateral crushing strength was found to be 232- 476 N/cm2. The highest crushing strength of the prepared samples was 30% higher than that reported in the literature. The addition of aluminum nitrate to the paste increased 50% in the lateral crushing strength; hence, it reached the value of 622 N/cm2. This was mainly the result of the binder functionality of aluminum nitrate that led to stronger connections between the particles. The extruded alumina did not show any deformation when introduced to the impregnation solution. This extruded alumina can be used as the catalyst support