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煤直接液化油加氢制高能量密度燃料

Direct coal liquefaction oil hydrogenation to produce high energy density fuel

  • 摘要: 超音速飞行器的不断发展,对燃料性能的要求也不断提高,传统的石油基燃料难以完全满足需求。煤炭直接液化油富含多环芳烃(部分饱和芳烃),是高能量密度燃料的理想原料,通过加氢可获得环烷烃,具有高热值、热氧化安定性好等优势。目前对煤直接液化油加氢的研究多采用模型化合物,鲜有通过煤直接液化馏分油加氢制高能量密度燃料的研究。为了研究煤直接液化油制备高能量密度燃料的可行性,以Al−SBA15修饰的USY负载Pt为催化剂(Pt/ASU)对煤直接液化油(220~350 ℃)进行加氢处理,首先采用固定床反应器探究最佳加氢温度、压力与空速,通过梯度实验对产物分布与碳数分布进行研究。结果表明,温度较高时不利于加氢反应的进行,且存在裂化反应与烷基化反应,最佳的反应温度为360 ℃,较高的压力有利于加氢反应的进行,空速较小时,反应物与催化剂接触时间短,仅接触外表面,无法进行完全反应,当空速增大时,反应物增多,此时催化剂的量难以将反应物完全转化,最佳的反应空速为6 h−1。采用高压反应釜对其完全加氢制备高能量密度燃料,通过全二维气相色谱−质谱联用仪对加氢产物分析可知其主要组分为环烷烃,其中双环环烷烃及三环环烷烃占比约80%。对加氢产物进行燃料性能测定,其密度为0.88 g/cm3,热值为45.26 MJ/kg,闪点为67.00 ℃,凝点为−42.00 ℃,芳烃质量分数为0.5%,硫体积分数低于3×10−4%,符合国标要求,热氧化安定性通过JFTOT法5 h/355 ℃测定,最大压降为0,管路等级评级< 1,最低点火温度为271 ℃,点火延迟时间为1 402 ms,是优异的高能量密度燃料。

     

    Abstract: With the continuous development of supersonic aircraft, the demand for energy performance is also increasing. Traditional petroleum-based fuels are difficult to meet the requirements. Direct coal liquefaction oil is rich in polycyclic aromatic hydrocarbons (partially saturated aromatic hydrocarbons) and is an ideal candidate for high-energy-density fuels. Through hydrogenation, cycloalkanes can be obtained, which have advantages such as high calorific value and good thermal oxidation stability. Currently, most studies on the hydrogenation of direct coal liquefaction oil use model compounds. There are few studies on the production of high-energy-density fuels through the hydrogenation of direct coal liquefaction distillate oil. To investigate the feasibility of preparing high-energy-density fuels from direct coal liquefaction oil, Al-SBA15-modified USY-supported Pt was used as the catalyst to hydrogenate direct coal liquefaction oil (220−350 ℃). A fixed-bed reactor was first used to explore the optimal hydrogenation temperature, pressure, and space velocity. The product distribution and carbon number distribution were studied through gradient experiments. The results showed that higher temperatures were not conducive to the hydrogenation reaction and cracking and alkylation reactions occurred. The optimal reaction temperature was 360 ℃. Higher pressure was beneficial to the hydrogenation reaction. When the space velocity was low, the contact time between the reactants and the catalyst was short. Only the outer surface was contacted, which could not complete the reaction. When the space velocity increased, the amount of reactants increased, and the amount of catalyst was insufficient to completely convert the reactants. Therefore, the optimal reaction space velocity was 6 h−1. A high-pressure autoclave was used to prepare high-energy-density fuels. The analysis of the hydrogenation products by comprehensive two-dimensional gas chromatography coupled with mass spectrometry showed that the main components were cycloalkanes, among which bicyclic and tricyclic cycloalkanes accounted for about 80%. The fuel properties of the hydrogenation products were determined. The density was 0.88 g/cm3, the calorific value was 45.26 MJ/kg, the flash point was 67.00 ℃, the pour point was −42.00 ℃, the aromatic hydrocarbon mass fraction was 0.5%, and the sulfur volume fraction was less than 3 ppm, meeting the national standard requirements. The thermal oxidation stability was determined by the JFTOT method at 355 ℃ for 5 hours, with a maximum pressure drop of 0 Pa, a pipeline grade rating of < 1, a minimum ignition temperature of 271 ℃, and an ignition delay time of 1 402 ms. These results show that the prepared fuel is an excellent high energy density fuel.

     

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