UPGRADING AGBABU BITUMEN USING HYDROUS AND ANHYDROUS PYROLYSIS

Abstract

ABSTRACT With the increasing scarcity of conventional crude oil, a consequence of depletion and decline in production due to the fact that petroleum is extracted much faster than its rate of formation, there is need to source for crude oil from the unconventional sources such as oil sand, oil shale and bitumen. However, heavy oils cannot be transported easily without first upgrading. This thesis was undertaken to evaluate Agbabu bitumen as feedstock for synthetic crude oil production via pyrolysis. Initial characterization tests were carried out on the bitumen including Thermogravimetric Analysis (TGA), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM) and Gas Chromatography Mass Spectrometry (GC-MS) to determine the thermal behaviour, functional groups, elemental composition and nature of the Saturates, Aromatics, Resins and Asphaltenes (SARA) composition of the bitumen. Bitumen pyrolysis (Anhydrous pyrolysis) and Bitumen-water mixture pyrolysis (Hydrous pyrolysis) were carried out using a horizontal tube furnace at different temperatures from 200 oC to 500 oC and time from 30 minutes to 60 minutes. Design Expert was used to obtain the optimum condition for the pyrolysis experiments with temperature and time set as variables. The synthetic crude oil obtained from both processes were subjected to further test to determine the viscosity, density, specific gravity, determination of the API gravity and GC-MS analysis. The bitumen was found to have high viscosity of 28 cSt and low API gravity of 8.6 oAPI which corresponds to standard for heavy oil. The bitumen SARA components determined are 35 % saturates, 37 % aromatics, 26 % resins and 2 % asphaltenes. At the end of the study, it was established that the yield of synthetic crude oil from hydrous pyrolysis has a greater API gravity of 29.20, lower viscosity 3.04 cSt and a higher concentration of saturates 65 % than the synthetic crude obtained from anhydrous pyrolysis which respectively had 23.99, 0.16 %, 3.28 cSt and 50 %. Kinetic studies were carried out from the TGA for both hydrous and anhydrous pyrolysis using Coats-Redfern Method. The activation energy for anhydrous pyrolysis was 291.796 kJmol-1 which was higher than that of hydrous pyrolysis 224.04 kJmol-1. Hence hydrous pyrolysis proceeds at a much faster rate and it requires less energy input than anhydrous pyrolysis.