Abstract Ammonia-based CO2 capture is a promising option for suppressing CO2 emissions from thermal power plants. However, the regeneration of a CO2-loaded ammonia solution requires a large heat duty, hindering its industrial application. Herein, we investigated the regeneration of a CO2-loaded ammonia solution with the aid of solid acid catalysts, i.e., protonated Zeolite Socony Mobil-5 (HZSM-5), γ-Al2O3, and TiO2. The results demonstrate that all the catalysts can effectively promote the regeneration and the catalytic performance follows the trend: HZSM-5 > TiO2 > γ-Al2O3. Especially, the presence of HZSM-5 can reduce the energy consumption by 23.9% compared to the non-catalytic regeneration. The catalysts were also characterized to reveal their various acid and textural properties. The characterization shows HZSM-5 possesses the most Bronsted acid sites amounting to 3143.8 μmol/g; while γ-Al2O3 has the most Lewis acid sites amounting to 3554.1 μmol/g. Furthermore, the relationships between the catalytic performance and catalyst properties were analyzed. Unlike amine-based regeneration, the CO2 desorption rate increases linearly with the BET surface area × Bronsted acid sites. This is attributed to two factors: (1) smaller molecular volume of NH2COO−, and (2) a large proportion of HCO3− in the CO2-loaded solution. Finally, a plausible catalytic mechanism was proposed. It suggested that Bronsted acid sites can provide accessible free protons to promote CO2 released from HCO3− and CO32−. However, the Bronsted acid sites and Lewis acid sites played a synergistic effect on the breakdown of NH2COO−.

中文翻译：

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用固体酸催化剂再生载有 CO2 的氨溶液的研究：降低再生能量的有前途的替代方案

摘要 基于氨的 CO2 捕获是抑制热电厂 CO2 排放的一种有前景的选择。然而，载有 CO2 的氨溶液的再生需要很大的热负荷，阻碍了其工业应用。在此，我们研究了在固体酸催化剂，即质子化沸石 Socony Mobil-5 (HZSM-5)、γ-Al2O3 和 TiO2 的帮助下，负载 CO2 的氨溶液的再生。结果表明，所有催化剂均能有效促进再生，催化性能遵循以下趋势：HZSM-5 > TiO2 > γ-Al2O3。尤其是HZSM-5的存在，与非催化再生相比，能耗降低了23.9%。还表征了催化剂以揭示它们的各种酸和质地特性。表征表明，HZSM-5 具有最多的布朗斯台德酸位点，达到 3143.8 μmol/g；而γ-Al2O3 的路易斯酸位点最多，达到 3554.1 μmol/g。此外，还分析了催化性能与催化剂性能之间的关系。与基于胺的再生不同，CO2 解吸速率随 BET 表面积 × 布朗斯台德酸位点线性增加。这归因于两个因素：(1) NH2COO− 的分子体积较小，以及 (2) 负载 CO2 的溶液中 HCO3− 的比例较大。最后，提出了一种合理的催化机制。这表明布朗斯台德酸位点可以提供可接近的游离质子以促进从 HCO3- 和 CO32- 释放 CO2。然而，布朗斯台德酸位和路易斯酸位对 NH2COO− 的分解起到了协同作用。