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氮掺杂介孔碳的制备及其室温催化氧化脱除H_2S性能
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摘要
H_2S是工业生产过程中主要含硫污染物之一,脱硫工艺始终是生产的关键环节。在低温有氧条件下,将H_2S选择性催化氧化为硫单质,是一种环境友好的脱硫方法。但固体硫的生成对脱硫催化剂的结构提出了要求,具有较大尺寸孔道结构的介孔碳材料有利于对该反应实现高硫容。模板法是合成均一孔径MCs最主要的方法。本文采用纳米二氧化硅模板辅助的共炭化方法,以煤焦油为碳源、三聚氰胺为氮源,制备出高氮元素掺杂、发达介孔结构的氮掺杂介孔碳(NMCs)。对比考察了不同合成条件对所得样品组成、结构及室温催化脱硫性能的影响。结果表明,当二氧化硅与前驱物质量比为1:1、煤焦油与三聚氰胺(C/M)质量比为1:2、碳化温度700℃时,所得样品NMC-1-700-1/2显示出高效的催化脱硫性能,穿透硫容高达4.74 g H_2S/g催化剂。结合元素分析、扫描/透射电镜观察及低温氮气吸附-脱附测试分析表明,NMC-1-700-1/2具有较高的氮掺杂量、较大的孔径、孔容及介孔结构,为H_2S的扩散、吸附、表面催化反应及产物单质硫的贮存提供了便利条件。
Nnitrogen-doped mesoporous carbon(NMCs) with high N doping level and developed mesoporous structure were prepared by a SiO_2 template-assisted blend carbonization process, using coal-tar(C) as carbon source and melamine(M) as nitrogen source. The effects of different synthetic process on the chemical composition, pore structure of the NMCs and the catalytic performance for H_2S at room temperature have been investigated. The results showed that the NMC-1-700-1/2 sample, obtained at carbonization temperature 700℃ with the mass ratio of SiO_2/precursor and C/M is 1:1 and 1:2 respectively, showed the efficient activity for H_2S oxidation, the achieved breakthrough sulfur capacity could be up to 4.74 g H_2S/g catalyst. Combined with the characterization of elemental analysis, FESEM/TEM observation and low-temperature N_2 adsorption-desorption, it can be revealed that the higher N doping level, large pore size, high pore volume and 3D mesoporosity of NMC-1-700-1/2 could provide benefits for the diffusion and adsorption of H_2S, surface catalytic reaction, and serve as a storehouse for the product sulfur.
引文

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