KMS Chongqing Institute of Green and Intelligent Technology, CAS
| New insight into subcritical and supercritical water reactivity during non-catalytic hydrothermal upgrading of heavy oil | |
Chen, Zhong1,2 
| |
| 2024-06-15 | |
| 摘要 | Hydrothermal treatment is a green and sustainable technology to upgrade heavy oil with water acting both as a solvent and a reactant. However, water reactivity under subcritical and supercritical conditions is still not fully understood. To address this, a comprehensive deuterium isotopic tracing study is conducted under various temperatures ( T , 300 -450 degrees C), pressures ( P , 8.6 -42.9 MPa), liquid (deuterium oxide) to oil ratios (L/O, 2 and 20), and residence times ( t , 30 and 120 min). Results indicate that the water reactivity is highly correlated with both operating T and water ionic product ( K W ). Then, a new insight is proposed: water reactivity is the sum of ionic and free -radical reactions. The ionic reaction is the dominant reaction under subcritical conditions, where water has a high K W . When T is increased, the free -radical reaction shows accelerated growth. However, K W first gradually decreases and then drops dramatically approaching phase -transition temperatures. Under supercritical conditions, the free -radical reaction dominates. Moreover, the K W can be improved by increasing P . As a result, the apparent total water reactivity shows various curves with the changes of both T and P . In conclusion, water under subcritical and supercritical conditions indeed acts as a hydrogen donor during hydrothermal upgrading of heavy oil. However, its capacity is still insufficient to meet the demands of heavy -oil upgrading, especially under supercritical conditions. This study expands the current understanding of water reactivity in the hydrothermal upgrading of heavy oil under both subcritical and supercritical conditions and clarifies the contrasting results reported previously. |
| 关键词 | Deuterium tracing Hydrogen -donating capacity Aquathermolysis Thermal cracking Ionic reaction Free -radical reaction |
| DOI | 10.1016/j.fuel.2024.131380 |
| 发表期刊 | FUEL
 |
| ISSN | 0016-2361 |
| 卷号 | 366页码:12 |
| 通讯作者 | Chen, Zhong(chenzhong@cigit.ac.cn) |
| 收录类别 | SCI |
| WOS记录号 | WOS:001218703000001 |
| 语种 | 英语 |
