The Primary Exploration On The Chemical Structure And Refining Properties Of Different Types Of Petroleum Molecules

In recent years, significant changes of the world energy structure are taking place, the low growth of oil demand, decrease of oil price and higher quality standards on petroleum products, which also raised higher requirements on the petroleum refining technologies. The R & D mode of current petroleum refining technologies are mainly conducted from mixture to mixture, which focused on the trial and error exploration and accumulation of experience rules, rather than pay attention to the research on molecular structure characteristics. To satisfy the requirements of the new molecular level of petroleum products, new petroleum refining technology research mode needs to be explored to change the petroleum refining technology from running after to take the lead. Based on this, the molecular simulation method and quantum mechanics were adopted, started from the atoms composition of petroleum, and studied the electronic structural characteristics of C, H, O, N and S atoms as well as the structural characteristics of the chemical bonds formed by these atoms. Then, based on these findings, the paper takes advantage of the characterization information of the molecular level, studied the structural characteristics of different types of petroleum hydrocarbon molecules, oxygenated compounds, sulfur-contained compounds and nitrogenous compounds revealed the refining behavior characteristics of the petroleum molecules with different structures, and provided new ideas for the research of molecular level petroleum refining technology.Based on the studies on structural characteristics of different structures of petroleum hydrocarbon molecules, such as the chemical bond energy, frontier orbital distribution, orbital energy, charge distribution and Fukui index, the structural characteristic rules of different structures of petroleum molecules were obtained, the refining behavior characteristics according to the structural characteristic rules of the petroleum molecules was studied, and then draw the conclusion as following:C-H and C-C bonds are strong at the two ends of n-alkanes and weak at the middle, n-alkanes produces ethylene easily in pyrolysis processing, while produces much more propylene in acid catalyst processing; due to the impact of substituent, the cracking activity of i-alkanes are stronger than that of n-alkanes; because of the special annular structure of the cycloalkanes, the ring opening reactions of the rupture C-C bonds on the ring are difficult, while the hydrogen donating ability is strong, and cycloalkanes are easier to produce aromatics when mixed and cracked with other hydrocarbon molecules; As for aromatics, when in pyrolysis processing, the β position C-C bonds of aromatic ring will easily crack to produce short side chain and easy-to-condense small molecules; cycloalkylaromatics have strong hydrogen donating ability but weak ring opening capability; separate processing can promote ring opening reactions. In oxygenated compounds oil acid, it is difficult to realize decarboxylation in pyrolysis, while it can be achieved under acid catalysis. In addition, the structural characteristics of thiophene and pyrrole have also been studied, revealed the higher polarity of C-N bond and lower polarity of C-S bond is the main cause about why nitrogen in pyrrole is more difficult to be removed than sulfur in thiophene, and proposed new ideas to promoting the nitrogen removal by introducing acid center. The research of this paper laid a theoretical basis for the new R & D mode, and also verified the feasibility of the new R & D mode.