| 摘要: |
| 原料天然气中二氧化碳（CO2）、羰基硫（COS）、硫化氢（H2S）和甲硫醇（CH3SH）等酸性气体需要采用碱性溶剂予以脱除，在吸收过程中，以瞬时质子机理反应的H2S脱除速率远远大于COS和CO2，故尽管原料气中COS含量通常远低于H2S，但用于脱除H2S的常规技术不能完全有效地脱除COS。COS与CO2化学结构相似，但CO2吸收速率远大于COS，因此，要深度脱除COS且保留部分CO2难度较高。目前，对COS和CO2吸收机理差异性的研究较少，导致在大量CO2和COS共存的条件下，COS选择性吸收溶剂的设计缺乏理论依据。因此，需深入研究COS的吸收机理。对有机胺法吸收CO2及COS的机理研究进展进行了总结，并提出以下认识：①在机理研究方面，普遍认为COS在伯胺和仲胺中的吸收机理与CO2吸收机理相同；②醇胺吸收CO2的机理通常认为是通过形成氨基甲酸盐而脱除CO2，进一步的加热分解即是CO2的释放与吸收液的循环使用；③ COS与CO2均为线性分子，物理化学性质也非常接近，使得在二者共存的条件下，COS选择性吸收的难度较大。 |
| 关键词: 羰基硫 二氧化碳 天然气净化 吸收机理 醇胺 |
| DOI：10.3969/j.issn.1007-3426.2024.05.018 |
| 分类号: |
| 基金项目:中国石油西南油气田公司科技项目“羰基硫选择性脱除溶剂的开发研究”（20230306-02） |
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| Research progress on the removal mechanism of carbon dioxide and carbonyl sulfide in natural gas |
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Jingwen XUE1,2,3, Wenzhao ZHU1,2,3, Feng GAO1,2,3, Longchao RAN4, Weimao PENG5, Yun HE4, Wei ZHANG4, Shuanglong LI6, Guochuan YIN6
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1.Research Institute of Natural Gas Technology, PetroChina Southwest Oil & Gasfield Company, Chengdu, Sichuan, China;2.National Energy R & D Center of High Sulfur Gas Exploitation, Chengdu, Sichuan, China;3.Key Laboratory of Natural Gas Quality Control and Energy Measurement, State Administration for Market Regulation, Chengdu, Sichuan, China;4.Natural Gas Purification Plant General, PetroChina Southwest Oil & Gasfield Company, Chongqing, China;5.Southwest Oil & Gas Field CDB Operating Company, Dazhou, Sichuan, China;6.Huazhong University of Science and Technology, Wuhan, Hubei, China
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| Abstract: |
| Acidic gases such as carbon dioxide (CO2), carbonyl sulfide (COS), hydrogen sulfide (H2S), methyl mercaptan(CH3SH), etc. in feed natural gas need to be removed through alkaline solvent treatment. During the absorption process, the removal rate of H2S through instantaneous proton mechanism reaction is much faster than that of COS and CO2. Therefore, although COS content is usually less abundant than H2S content in the feed gas, conventional techniques for removing H2S cannot completely and effectively remove COS. Because the chemical structure of COS is similar to that of CO2, but the absorption rate of CO2 is much higher than that of COS, it is difficult to retain part of CO2 and deeply remove COS. At Present, there is a lack of research on the differences between COS and CO2 absorption mechanisms, which leads to the lack of a theoretical basis for the design of COS selective absorption solvent under the coexistence of a large amount of CO2. Therefore, the absorption mechanism of COS needs to be further studied. The research progress on the mechanism of CO2 and COS absorption in organic amine solutions was summarized, and the following understandings are put forward. Firstly, in the aspect of mechanism research, it is generally believed that the absorption mechanism of COS in primary and secondary alkanolamines is the same as that of CO2 absorption. Secondly, the mechanism of CO2 absorption by alkanolamine is generally considered to be the removal of CO2 by the formation of carbaminate, and further thermal decomposition is the release of CO2 and the recycling of the absorption solution. Thirdly, both COS and CO2 are linear molecules with very similar physical and chemical properties, making it difficult to selectively absorb COS under the coexistence of COS and CO2. |
| Key words: carbonyl sulfide carbon dioxide natural gas purification absorption mechanism alkanolamine |
