Study on Unconventional Process for Production of Clean Diesel Fuel

Abstract

Mesoporous alumina with narrow pore size distribution was synthesized using sol-gel method. The effect of various synthesis parameters, including reactants molar ratio, type of co-surfactant, aging time and the presence of source of power (conventional process - under ambient conditions (C) and microwave irradiation (MW)) on the structural properties of the resultant alumina samples were examined. The texture and crystalline phase of the prepared samples were characterized using XRD, TG-DTA, FT-IR, N2 adsorption-desorption, pyridine adsorption, and TEM. The adsorption activity of the prepared samples was examined towards thiophene and dibenzothiophene species and the resulted materials have the following characteristics: - All of the prepared alumina samples using different preparation conditions show similar XRD patterns with the reflections of γ-alumina appeared after calcination at temperature 600ºC and at 400ºC in case of conventional process (under ambient conditions) and microwave irradiation process successively. - The TEM photographs of all prepared alumina samples illustrated that the alumina particles was build as cylindrical shapes have diameter ranged from 68 to 73 nm and length ranged from 326 to 518 nm under conventional process but when using the microwave irradiation the diameter ranged from 41 to 102 nm and length ranged from 172 to 489 nm. - All isotherms of the prepared alumina samples by conventional process could be classified as type IV for mesoporous materials and H3 hysteresis loop due to the presence of non-rigid aggregates of plate-like particles giving rise to slit-shaped pores. - Microwave irradiation give also alumina samples with type IV isotherm and H2 hysteresis loop. Such loops are characteristics of many inorganic oxide gels. These materials have complex pore structures like as interconnected pore networks of various sizes and shapes. - In case of using propanol as co-surfactant at metal precursor/ surfactant/ co-surfactant molar ratio 2/1/1 and aging time 4h at 25 ºC by conventional process give alumina sample with surface area 262 m2/gm, total pore volume 0.520 cm3/gm, micropore volume 0.067 cm3/gm and average pore diameter 4.42 nm. That increases in surface area give increasing in pyridine adsorption capacity 1302 µmol pyridine/gm. - By using iso-propanol at molar ratio 2/1/1 metal precursor/ surfactant/ co-surfactant and after exposure to microwave irradiation for 8 min at 300 watt, Lewis acid sites increased and accordingly the pyridine adsorption capacity increased to 2189 µmol pyridine/gm that due to increasing the surface area to 334.2 m2/gm and the average pore diameter to 5.80 nm. - Increasing of the surface area of the alumina samples corresponded with an increasing in the pyridine and thiophene adsorption capacity due to increasing the Lewis acid sites.