Extraction Of Organic Substance From Tumuji Oil Sand

Tumuji oil sand from Inner Mongolia was processed to get organic substance with different methods involving hot water extraction, fixed-bed pyrolysis and hydropyrolysis, non-isothermal sub-and supercritical water extraction and isothermal supercritical extraction with supercritical propane and carbon dioxide as solvent.a) With hot water extraction, the effects of experiment conditions on wash yield were investigated including temperature, stirring time, stirring rate, alkali concentration and the weight ratio of water to oil sand. The maximum 90.1% of wash yield could be obtained under the condition of temperature 90°C, alkali concentration 0.3%, water to oil sand 1:1, stirring time 90 min, and stirring rate 200 r/min.b) The pyrolysis characteristics of Tumuji oil sand were studied with thermogravimetric analysis in the stream of N₂. Four kinds of methods, Coats-Redfern, Doyle, Kissinger and Distributed Activation Energy Model (DAEM), were used to determine the kinetic parameters. The results indicated that the kinetic parameters were different with different methods. DAEM is an efficient method to provide more information of the pyrolysis of oil sand.c) Pyrolysis and hydropyrolysis of Tumuji oil sand were carried out in a fixed-bed reactor to investigate the effects of temperature, pressure, gas flowrate and time on liquid yield and product fractions in liquid. A maximum of pyrolysis conversion and liquid yield of 87% and 80%, respectively, can be obtained under the studied experimental conditions, and the maximum of hydropyrolysis conversion and liquid yield is 95% and 90%, respectively. With increase of temperature, conversion, liquid yield and gas yield of pyrolysis all increase, but those of hydropyrolysis firstly increase then decrease little. Pyrolysis time at constant temperature has no evident effect and gas flowrate has an effect on the distribution of organic substance in liquid and gas.d) Tumuji oil sand was extracted with sub- and supercritical water in a semi-continuous apparatus with non-isothermal method at different pressure and different solvent flow rate. The results show that with increase of pressure, liquid yield increases while gas yield decreases. A maximum liquid yield of 83% can be obtained at 30 MPa. The results also show that the formation rates of three fractions (saturates, aromatics, resin) in extract has a maximum with the variation of temperature. The temperature corresponding to the maximum formation rates of saturates and aromatics decrease, while that of resin increases with the increase of pressure.e) Tumuji oil sand was also extracted by using supercritical propane and supercritical carbon dioxide, respectively, on a semi-continuous apparatus with isothermal method. When propane as solvent, the maximum extract yield of 85% is obtained at temperature of 110℃and pressure of 20 MPa. When carbon dioxide as solvent, the maximum extract yield is only 13% at 40℃and 25 MPa. The extract yield increases with the increasing pressure and/or with the decreasing temperature.