The study aimed to investigate the partial upgrading of bitumen in the absence of water (non-water) and the presence of supercritical water (SCW). Partial upgrading experiments were conducted at the target temperature of 420 °C, with the reaction time varying from zero to 60 min in a batch reactor. The liquid products were analyzed for density, viscosity, composition, total acid number (TAN), olefin content, and elemental analysis. The gas composition and morphology of solid products were also studied. The experimental results revealed that while partial upgrading of bitumen with SCW could accelerate improvement in oil quality, particularly in terms of API and viscosity, it concurrently led to elevated gas and coke formation levels. Moreover, the difference in the distribution of oil fractions between the two environments (absence and presence of SCW) tends to diminish with an extended residence time. Additionally, as the residence time increases, the efficiency of TAN reduction under SCW conditions is less pronounced compared to the non-water conditions. Liquid products obtained in an SCW environment exhibited higher olefin content (between 3 and 4 wt %) compared to non-water conditions (between 1.8 and 2.7 wt %). In both environments, the olefin content was initially increased up to a residence time of 20 min and then decreased. Regarding heteroatoms, the sulphur (S) and nitrogen (N) contents decreased up to 36 % and 72 %, respectively, while a greater reduction was observed in the presence of SCW. More non-hydrocarbon gases (HS, CO and CO) were produced in the presence of SCW. SEM images showed that an extended residence time led to a shift in coke morphology towards a more uniform and compact structure, regardless of the upgrading environment. However, the porous structures of coke samples obtained under SCW are distinguished from those formed without water, which is attributed to the phase inversion of precursors. The findings of this study confirm that SCW plays a beneficial role as a solvent in the partial upgrading of bitumen, expediting the process. However, the increased level of coke formation and olefin contents suggest that it may not function effectively as a hydrogen donor in the process.

中文翻译：

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超临界水沥青部分改质——液体产品特性、气体组成和焦炭形态


该研究旨在研究在没有水（非水）和存在超临界水（SCW）的情况下沥青的部分升级。部分升级实验在420℃的目标温度下进行，反应时间在间歇式反应器中从0到60分钟变化。分析液体产品的密度、粘度、组成、总酸值（TAN）、烯烃含量和元素分析。还研究了固体产物的气体组成和形态。实验结果表明，虽然用超临界水对沥青进行部分升级可以加速油品质量的改善，特别是 API 和粘度方面，但它同时会导致气体和焦炭形成水平升高。此外，两种环境（存在和不存在超临界水）之间的油馏分分布差异往往会随着停留时间的延长而减小。此外，随着停留时间的增加，与无水条件相比，SCW 条件下 TAN 降低的效率不太明显。与无水条件（1.8 至 2.7wt% 之间）相比，在 SCW 环境中获得的液体产品表现出更高的烯烃含量（3 至 4wt% 之间）。在这两种环境中，烯烃含量最初增加至 20 分钟的停留时间，然后减少。对于杂原子，硫 (S) 和氮 (N) 含量分别降低了 36% 和 72%，而在 SCW 存在下观察到更大的降低。超临界水存在时会产生更多的非碳氢化合物气体（H2S、CO 和 CO）。 SEM 图像显示，无论升级环境如何，延长的停留时间都会导致焦炭形态向更均匀和致密的结构转变。 然而，超临界水下获得的焦炭样品的多孔结构与无水形成的焦炭样品的多孔结构不同，这归因于前体的相转化。这项研究的结果证实，SCW 作为溶剂在沥青的部分升级中发挥着有益的作用，加速了这一过程。然而，焦炭形成和烯烃含量的增加表明它可能无法在该过程中有效地发挥氢供体的作用。