RESPONSE SURFACE METHODOLOGY OPTIMIZATION AND UPGRADING OF AGBABU BITUMEN IN THE PRESENCE OF RICE HUSKS

With the current global trend in energy demand due to the increase in human population and technological inclination in carrying out day to day activities, the conventional crude oil is fast depleting and thus an alternative source of energy is needed for sustainability for the fuel/energy supply. Natural bitumen upgrading could serve as an alternative source for the future fuel supply but the process of upgrading the bitumen needs to be optimized to obtain the best conditions at which the bitumen upgrading process would effectively take place which brought about this study. In this study research work, optimization of Agbabu bitumen in the presence of rice husks using response surface methodology (RSM) was carried out to determine the optimal conditions at which the bitumen could be upgraded. Box-Behnken Designed experiment (BBD) was used as the template to design the experiment where the chosen variable factors were temperature, residence time and rice husks at a range or level of (300 – 350 o C), (30 – 180 min) and (0.6 – 1.0 wt.%) for each of the variable factor respectively and the chosen responses were viscosity, API gravity, residue yield and light oil yield. The Agbabu bitumen was characterized by viscosity at 70 o C to be 86.78 Pa.s, density at 60 o C to be 1.0153 Kg/L, H/C ratio 1.19:1 and API gravity of 7.87 o etc. The optimum conditions at which the Agbabu bitumen could be upgraded for maximum yield of light oil was found to be (temperature 345.716 o C, residence time 30.0 min, and rice husks 1.0 wt.%) at response value of viscosity 8.340 Pa.s, API gravity 24.520 o , residue yield 22.39 w/w% and light oil yield 50.064 w/w%. The light oil yield for the upgraded Agbabu bitumen at the optimum conditions had a desirability of 0.688989, amounting to 68.4% yield. The overall desirability for the whole upgrading process was 0.909415 at the optimum conditions. Thus, indicating an acceptable optimization and upgrading process for Agbabu bitumen.