煤基高能量密度燃料的合成及表征

高能量密度燃料是为新型高性能飞行器提供动力保障的关键,其合成及应用研究具有重要的前瞻性和重大战略意义。煤炭是我国的主体能源和重要原料,通过煤直接转化获取的煤基油,充分保留了煤中特有的环状分子化学结构,具有良好的热安定性和较高的能量密度,被认为是高超音速飞行器的优选燃料。以煤直接液化工艺生产的煤液化石脑油馏分为起始原料,通过富集轻质芳烃、化学合成、催化加氢稳定和产物分离提纯等方法制备煤基高能量密度燃料,并对其产物进行分子结构表征和性能评价。结果表明,煤直接液化生产的石脑油馏分是一种优异的催化重整原料,经催化重整富集轻质芳烃后,其轻质芳烃质量分数高达71.05%。Diels-Alder化学合成主产物是由多个封闭环平面组成且具有空间立体构型的二环或三环烃类物质,质量分数为46.18%,因分子内存在较大的张力能,结构紧凑,其拥有更大的密度和体积热值。煤基高能量密度燃料的密度和体积热值分别为0.8990 g/cm3与38.06 MJ/L,均大大超过现行的国内石油基喷气燃料(RP-3和RP-6)、煤基大比重喷气燃料、美国和俄罗斯军用标准。与单一纯物质合成高能量密度燃料(JP-10和T-10)比较,其密度与体积热值偏小。究其原因主要是轻质芳烃的富集度仅为71.05%,需进一步提高其轻质芳烃质量分数。另外,制备的煤基高能量密度燃料种类复杂,其主产物质量分数仅46.18%,下一步可重点调控合成产物的分子构型和纯化分离。     

Detailed microkinetic modelling of syngas to hydrocarbons via Fischer Tropsch synthesis over cobalt catalyst

Fuels production from syngas via Fischer Tropsch synthesis (FTs) is an alternative technology for clean energy production. The microkinetic model is a promising approach for gaining insight into FTs activity. In this study, a systematic microkinetic model was proposed to develop a process for cobalt-catalyzed FTs. All possible elementary reactions based on the carbide mechanism and characteristics of catalyst sites were considered in the kinetic model. The effects of the reaction rate constant, reaction pathways, and H₂ to CO ratio were represented by a kinetic parameter, reaction path, and operating parameter, respectively. The model could accurately predict product distribution trends, with an R² value and mean absolute relative residuals percentage of 0.91–0.93 and 5–43%, respectively, in comparison with experimental data. Hydrogen utilization was predicted and analyzed. High model accuracy was achieved, with a 10^?10–10^?3% error in the material balance.     

Remarkable hydrogen properties of MgH2 via combination of an in-situ formed amorphous carbon

Carbon-based materials have been proposed as an ideal medium to reduce the reaction energy barriers and improve the (de)hydrogenation kinetics of magnesium-based hydrogen storage material (MgH₂) in term of their excellent dispersion. However, tedious preparation process and uneven distribution of carbon restrict the application. Therefore, in this paper, we cover MgH₂ by in-situ formed amorphous carbon via a facile approach of co-sintering Mg with fluorene followed by hydriding combustion and ball milling processes, named as MgH₂-carbonization product of fluorene (MgH₂-CPF). As a result, the MgH₂-CPF composite prepared at 823 K initially dehydrogenates at 557 K, 94 K lower than the as-milled MgH₂ (651 K). Meanwhile, the composite can release 5.67 wt% H₂ within 1000 s at 623 K. Even at a lower temperature of 423 K, the MgH₂-CPF composite still reabsorbs 5.62 wt% H₂ within 3600 s, while the as-milled Mg can hardly absorb hydrogen under a same condition. Furthermore, by addition of CPF, the apparent activation energy of the system is decreased from 161.2 kJ/mol to 87.2 kJ/mol. Our finding suggests that the carbon layer can keep the MgH₂ from aggregation, promote hydrogen transport and improve the efficiency of hydrogen absorption and desorption.     

Electrodeposited NiMoP catalysts on carbon felt for hydrogenation of indigo during electrocatalytically splitting water

Electrochemical hydrogenation is an environmentally favorable alternative to chemical reduction of indigo because it performs under ambient conditions using water as the donor of hydrogen. The purpose of this work is to fabricate electrocatalysts with high activity and durability for electrocatalytic hydrogenation of indigo. This work compares the performances of a series of Ni based catalysts (Ni, NiMo, NiP and NiMoP) on the substrate of carbon felt (CF) for electrolyzing water. Both the overpotential and Tafel slop are decreased as a function of the components as Ni > NiMo > NiP > NiMoP. Hence, NiMoP/CF shows the excellent performance based on the thermodynamics (η₁₀ = 239 mV) and kinetics (Tafel slope = 89.7 mV·dec^?1) for splitting water. Further, the electrode of NiMoP/CF was used for the electrocatalytic hydrogenation of indigo. The conversion efficiency and Faradic efficiency can be improved as 26.2% and 10.7% respectively. Furthermore, the dyeing behavior of the electrohydrogenated indigo is similar to that of conventional reduction methods. Thus, the present work offers foundational results and paves the way for the design of new catalytic materials for the reduction of vat dyes.     

Robust optimal operation of continuous catalytic reforming process under feedstock uncertainty

The continuous catalytic regenerative (CCR) reforming process is one of the most significant sources of hydrogen production in the petroleum refining process. However, the fluctuations in feedstock composition and flow rate could significantly affect both product distribution and energy consumption. In this study, a robust deviation criterion based multi-objective optimization approach is proposed to perform the optimal operation of CCR reformer under feedstock uncertainty, with simultaneous maximization of product yields and minimization of energy consumption. Minimax approach is adopted to handle these uncertain objectives, and the Latin hypercube sampling method is then used to calculate these robust deviation criteria. Multi-objective surrogate-based optimization methods are next introduced to effectively solve the robust operational problem with high computational cost. The level diagram method is finally utilized to assist in multi-criteria decision-making. Two robust operational optimization problems with different objectives are solved to demonstrate the effectiveness of the proposed method for robust optimal operation of the CCR reforming process under feedstock uncertainty.     

煤直接液化循环溶剂供氢性影响因素研究

在煤直接液化生产中,循环溶剂供氢性能的强弱对煤炭转化及油品收率发挥着关键作用,通过试验研究发现,在液化混合重油加工循环溶剂过程中,调整反应压力、反应温度、反应空速、催化剂活性等参数对循环溶剂供氢性能均有较大影响,尤其是反应压力、反应空速的影响更为显著。此次试验研究结果可有效指导工业生产,最大化地提高循环溶剂的供氢性能,从而间接提高煤直接液化的油收率,增加煤制油的经济效益。     

海泡石的改性及应用研究现状

海泡石是一种纤维状的硅酸盐粘土矿物，具有巨大的比表面和独特的孔结构及良好的吸附性、流变性、催化性等。本文介绍了海泡石的改性方法及海泡石在不同领域的广泛应用。     

煤加氢热解高效转化及过程脱硫脱氮效应

系统考察了煤非催化加氢热解反应特性及过程脱硫脱氮效应，通过调整工艺条件，煤加氢热解的焦油收率视煤种不同可高达５０％￣７０％，占煤热解总转化率的７０％￣８０％，表现出很高的选择性，而不同煤种热解过程的氢利用效率对氢压的变化均存在一个峰值压力。煤热解的过程总脱硫率可高达７０％以上，煤中几乎所有硫铁矿硫被脱除殆尽，残留在热解半焦中的微量硫的形态分布主要表现为硫酸盐硫，热解半焦为洁净固体燃料，而热解焦油的     

煤气化焦油加氢过程中脱氮及结焦的研究

在对气化焦油加氢过程中脱氨和预热器的结焦难题的研究中发现，原料油中的多环芳香烃因具有碱性，是影响脱氮反应的主要因素，采用缓和条件下的预饱和加氢反应，能除去多环芳香烃，使原料油一次加氢精制达到符合加氢裂解原料的要求．在加氢催化剂和氢压的存在下，完成原料油的升温过程，破坏了原料油结焦的外部条件，有效地解决了预热过程的结焦难题．