DMAC/DETA复配水溶液两相吸收剂吸收CO_(2)的行为研究

Research on CO_(2) Absorption Behavior by DMAC/DETA Biphasic Absorbent

化学吸收法是现阶段烟气CO_(2)捕集较为成熟的技术路线,但吸收剂再生能耗高影响了该技术广泛工业应用。两相吸收剂具有大幅度降低再生能耗的潜力,受到国内外研究学者广泛的关注。研究N,N-二甲基乙酰胺(dimethylacetamide,DMAC)/二乙烯三胺(diethylenetriamine,DETA)两相吸收剂吸收CO_(2)的行为,测量分析组分分布、吸收和解吸热效应、循环负荷等性能,为DMAC/DETA相变型吸收剂捕集CO_(2)的应用提供关键的基础数据。DMAC/DETA吸收CO_(2)后,发生液液分相,CO_(2)在下层富集。在CO_(2)总负载1.3915mol/mol下,富相占比约45%,组成为35%DETA+6%DMAC水溶液。在120℃解吸条件下,与20%MEA相比,DMAC/DETA单位CO_(2)解吸焓变降低63.3%;与整体解吸相比,富相解吸的单位CO_(2)解吸焓变降低21.4%。DMAC/DETA吸收剂循环稳定性较好,110℃下解吸率维持在约67.5%。

Chemical absorption is currently the most mature technology for CO_(2) capture from flue gas. However, this technology hasn’t been put into commercial application due to the high regeneration energy. Biphasic absorbent is a promising solution as it can significantly reduce the regeneration energy. This paper studied the CO_(2) absorption behavior of the dimethylacetamide(DMAC)/diethylenetriamine(DETA) biphasic absorbent, and measured the composition distribution, absorption and desorption heat, and cyclic loading, which is important for the application of the DMAC/DETA for CO_(2) capture. When DMAC/DETA absorbs CO_(2), liquid-liquid phase separation occurs, and CO_(2) is enriched in the lower phase. Under the total CO_(2) load of 1.3915 mol/mol, the rich phase accounts for about 45%, and the composition is 35% DETA+6% DMAC aqueous solution. Under the condition of 120℃ desorption, compared with 20% MEA, the unit CO_(2) desorption enthalpy change of DMAC/DETA decreased by 63.3%;compared with the overall desorption, the unit CO_(2) desorption enthalpy change of rich phase desorption decreased by 21.4%. The DMAC/DETA absorbent has good cyclic stability, and the desorption rate at 110℃ maintains at about 67.5%.