Preparation Of Modified SO₄^2-/ZrO₂-TiO₂ Solid Superacid And Their Catalytic Performance In Heavy Oil Reduction

In last decades, with the rapid increasing consumption of conventional oil and gas resources, much attentions have been paid to heavy oil and other low-grade mining resources as the major petroleum supplementary energy. The poor liquidity and high viscosity of heavy oil have threw many difficulties to to oil the exploitation of reservoir and the subsequent treating process. While the key technology of heavy oil recovery lies in reducing the oil viscosity and increasing the liquidity. Hydrothermal catalytic pyrolysis is a kind of very potential way to reduce the viscosity in exploiting heavy oil. It can make irreversible change to reduce viscosity of heavy oil, increase the hydrogen/carbon ratio and improve the quality of heavy oil. Among numerous catalysts in heavy oil recovery, the solid superacid catalyst is a Triton of the minnows due to its strong acidity and strong oxidicability in heavy oil hydrothermal catalysis. In this paper, Ti Cl4 and Zr OCl2·8H2O as chosen to synthesize a series of modification of solid superacid catalyst by different preparation methods. And preferable efficiency were obtained when the catalyst were applied to heavy oil catalytic viscosity recovery. The main research contents and results are as follows:1. Synthesis of solid superacid catalyst through the different methods and its application in heavy oil catalytic reduction experiment.Herein, ZrO₂-TiO₂ was selected as the fundamental catalysts because of its superior solid superacid properties, and a series of SO₄^2-/ZrO₂-TiO₂ catalysts were prepared by different synthetic routes. The as-prepared catalysts were characterized systematically by TEM, XRD, FTIR and N2 adsorption-desorption isotherms measurement. The reduction efficiency of the heavy oil viscosity achieved as high as 61.2% at 180 ?when catalyst content was 1%, indicating that catalyst SO₄^2-/ZrO₂-TiO₂ obtain from hydrothermal process showed a good activity for reducing viscosity and improving the quality of the heavy crude oil.2. Preparation of the surfactant coated SO₄^2-/ZrO₂-TiO₂ catalyst and its catalytic activity researchTo improve the dispersion of catalyst in the heavy oil, different kind of surfactant were selected as the surfactant package coat to help enhance catalytic activity. Comparing the heavy oil reduction efficiency, it is easy to find that catalyst modified by cetyl trimethyl ammonium bromide showed the best catalytic activity. The reduction efficiency of the heavy oil viscosity achieved as high as 66.3% at 180?, heavy oil viscosity decreased from 80500 m Pa·s to 27310 m Pa·s. In addition, the portion of asphaltenes and resins slipped down 4.93% and 3.78%, respectively, while saturated and aromatic hydrocarbon component enhanced 5.37%, and 3.26%, respectively. Part of big molecules in resins and asphaltenes disintegrated into relatively small fragments dissolving into saturated and aromatic hydrocarbons, turning out a lower viscosity.Experiment was designed to ascertain the optimal dosage of cetyl trimethyl ammonium bromide, the dosage of 10% showed the best effect of viscosity reduction. When tetralin was adding hydrogen donor, heavy oil catalytic recovery efficiency was up to 76.2% after 24 h under 180?. At the same time, the saturated and aromatic hydrocarbon increased, while the asphaltene content decreased by 10.02%, and resins increased by 5.17%. The main reaction process is a restructuring decomposition of asphaltene, meanwhile, smaller fragments dissolved into saturated and aromatic hydrocarbon, larger molecules aggregate into resins again.3. Preparation of different transition element modified SO₄^2-/ZrO₂-TiO₂ and its catalytic role in heavy oil catalytic recovery.For further analysis of reaction mechanism and improving the efficiency of catalytic reduction sticky, different transition element ions were used to modify the solid superacid catalysts. Fe3+ and Ni2+, Cu2+, Co2+ as common metal ions were chosen to decorate the solid super acid. catalytic reduction results displayed that solid acid catalyst modified by Fe3+ and Ni2+ possessed a better catalytic activity. During the catalytic process, saturated hydrocarbon and aromatic hydrocarbon increased, the Fe3+ was more advantageous to saturated hydrocarbon, while Ni2+ was more beneficial to the increase of aromatic hydrocarbon.