高炉煤气脱硫是实现钢铁行业多工序全流程超低排放的关键。高炉煤气中主要含硫组分是羰基硫(COS),常用γ?Al2O3基催化剂水解脱除,但是其水解活性及抗氧能力有待提高。本工作采用浸渍法制备了添加Fe和La活性组分的催化剂,通过ICP, XRD和TPD等手段表征了催化剂的理化性质,并在固定床-气相色谱联用装置考察了空速、粒径对催化剂催化水解COS过程的扩散效应,研究了催化剂的理化性质与COS水解活性的构效关系以及O2的作用机制。结果表明,催化剂在80℃, 160000 h-1条件下,活性组分Fe和La的添加可明显提高γ?Al2O3基催化剂的碱性位点;同时,丰富的孔隙结构降低了内扩散阻力,增强了H2S从催化剂表面到气相的传质。Fe/Al2O3催化剂在保持较高的水解活性的同时能够协同脱除H2S,但是O2的存在增强了H2S的吸附及其与Fe的硫化反应;而La/Al2O3催化剂的COS水解活性及稳定性较好,活性组分La可明显提高H2S从催化剂表面到气相的脱附,进而提高抗氧中毒能力。
Desulfurization for blast furnace gas is one of the keys to achieve ultra-low emissions for the multi-process in the iron and steel industry. The sulfur component in blast furnace gas is mainly organic sulfur-carbonyl sulfur (COS), which is usually removed by the catalytic hydrolysis method with γ-Al2O3 based catalyst, but its hydrolysis activity and antioxidant capacity need to be improved. In this work, three kinds of catalysts with Fe or La as an active component were prepared by the impregnation method. The physical and chemical properties of the catalysts were characterized by ICP, XRD and TPD. The diffusion effect of gas hourly space velocity (GHSV) and particle size on the catalytic hydrolysis of COS were investigated on a fixed bed-gas chromatography combined device. The structure-activity relationship between the physicochemical properties of the catalysts and the hydrolysis activity of COS and the action mechanism of O2 were also analyzed. The results showed that the addition of Fe or La as active components can obviously improve the COS hydrolysis activity on the catalyst, due to the much more alkaline sites on the surface of the γ-Al2O3 based catalyst at conditions of 80℃ and 160000 h-1. The abundant pore structure and suitable pore size can also reduce the internal diffusion resistance of COS and H2S, enhance the mass transfer process of H2S from the catalyst surface to the gas phase. Fe/Al2O3 catalyst can collaboratively remove H2S and simultaneously maintain a high hydrolytic activity. But the presence of O2 enhanced the adsorption of H2S on the catalyst surface and the sulfidation reaction between H2S and metal Fe. While La/Al2O3 catalyst had better activity and stability for COS hydrolysis, and the active component La can significantly improve the desorption of H2S from the catalyst surface to the gas phase, and then improve the anti-oxygen toxicity ability of the catalyst.