Abstract:

The MoS₂/Si-ZrO₂ catalyst was prepared by an equal volume impregnation method, and the catalytic activity stability of CO for sulfur-tolerant methanation was evaluated. The CO conversion of the MoS₂/Si-ZrO₂ catalyst decreased by 11% under the following condition: molar ratio of feed gas composition was 2H₂∶2CO∶1N₂; concentration of H₂S was 0.01%; weight hourly space velocity was 6000 ml/(g·h); reaction temperature was 450℃ and reaction pressure was 2.5 MPa. The catalysts were further characterized by hydrogen temperature programmed reduction (H₂-TPR), X-rays photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), Raman spectra (RS), inductively coupled plasma emission spectra (ICP-OES), thermogravimetric analysis (TGA) and elemental analysis. The results demonstrated that little carbon deposited on the surface of spent catalyst, which did not cause catalyst deactivation. The minor cause was that MoS₂ slabs grew longer and stacked more layers after long-term reaction and then covered the active sites. The root deactivation cause was attributed to parts of catalytic active bridging {\mathrm{S}}_{\mathrm{2}}^{\mathrm{2}-} ^{species converting to less active S2- species and H₂S, which resulted in the loss of active sites and sulfur element.}

Key words: deactivation, catalyst, stability, natural gas, sulfur-resistant methanation, bridging {\mathrm{S}}_{\mathrm{2}}^{\mathrm{2}-} ^species, sulfur loss

摘要：

采用等体积浸渍法制备MoS₂/Si-ZrO₂催化剂，并对其CO耐硫甲烷化的催化活性稳定性进行评估。结果表明在2H₂∶2CO∶1N₂（摩尔比）、反应压力2.5 MPa、反应温度 450℃、硫含量0.01%及质量空速 6000 ml/(g·h)的反应条件下，100 h后CO转化率下降11%。深入进行氢气程序升温还原(H₂-TPR)、X射线光电子能谱(XPS)、拉曼光谱(RS)、等离子体发射光谱(ICP-OES)、高分辨透射电子显微镜(HRTEM)、热重分析(TGA)以及元素分析等表征后，发现反应后催化剂表面无明显积炭，但出现了明显的团聚现象。而催化剂失活的根本原因是硫流失的发生，导致具有催化活性的桥键 {\mathrm{S}}_{\mathrm{2}}^{\mathrm{2}-} 物种转变为S^2-物种和H₂S。

关键词: 失活, 催化剂, 稳定性, 天然气, 耐硫甲烷化, 桥键 {\mathrm{S}}_{\mathrm{2}}^{\mathrm{2}-} 物种, 硫流失