类水滑石衍生锌基氧化物高温煤气脱硫过程中COS释放行为及其抑制研究

Study on release and inhibition behavior of COS during high-temperature gas desulfurization process using Zn-based oxide derived from hydrotalcite

高温煤气脱硫是煤炭清洁转化过程中的关键技术之一。前期研究表明,锌铝类水滑石基衍生氧化物可高效脱除高温煤气中的H2S,但其脱硫过程中COS释放规律缺乏定性定量研究。探讨了类水滑石衍生锌基氧化物脱硫过程COS释放的可能途径,包括反应热力学分析及实验研究,提出采用镍掺杂策略以抑制脱硫剂脱硫过程中生成COS。研究表明,锌铝类水滑石基衍生氧化物脱除煤气中H_(2)S时产生COS的主要途径是H_(2)S与CO_(2)间的气固相催化反应,该途径所释放COS量占总释放量的78%。通过镍助剂的掺杂使得锌铝类水滑石基衍生氧化物既保持了原有结构形貌,也有效抑制了其脱硫过程中COS的释放;其中最佳镍掺杂量(Zn/Ni摩尔比为30)脱硫剂穿透前的COS释放量减少88%,而硫容仅降低1.5%。

High-temperature coal gas desulfurization is one of the key technologies for coal clean conversion process.Previous studies have shown that Zn-based oxide derived from Zn-Al hydrotalcite(ZnAl-HTO)can efficiently remove H_(2)S from high-temperature gas.However,there is a lack of qualitative and quantitative studies on the law of COS release during the desulfurization process.In this study,the possible pathways of COS release in the desulfurization process of ZnAl-HTO were investigated,the thermodynamic analysis and experimental study were also carried out.A nickel doping strategy was proposed to inhibit the formation of COS during the desulfurization process.It was shown that the main way to generate COS when zinc-aluminum hydrotalcite-based oxides to remove CO_(2) from gas is the gas-solid phase catalytic reaction between H2S and CO_(2),and the amount of COS released by this way accounts for 78%of the total release.The doping of a small amount of nickel additives into the ZnAl-HTO results in no significant change in the morphology.It also effectively inhibits the COS release during desulfurization process.Under the optimal molar ratio of Zn/Ni(30),the overall desulfurization performance of ZnAl-HTO is significantly improved.Compared to sorbents without Ni-doping,the amount of COS released before H2Sbreakthrough reduced by 88%,while the corresponding sulfur capacity declined by only 1.5%.