水热法制备硫化物催化剂及其加氢脱氧性能研究

关键词：MoS2；加氢脱氧；水热法；对甲基苯酚；生物油
I
Abstract
China's economy is in a stage of rapid development, where needs more and more energy. But the traditional fossil energy reserves is declining, and its utilization has brought many environmental problems. Developing a new renewable green environmental-friendly resource is already in the extremely urgency. Bio-oil is a liquid fuel from the fast pyrolysis of biomass (wood, straw, etc.) under the conditions of isolated from oxygen and medium temperature (500~600 ℃). It has attracted a lot of attentions because of its properties of abundance, easy to transport, renewable and high energy density. However, this lignocellulosic-derived bio-oil contains a considerable amount of oxygenated compounds, resulting in some defects such as thermal instability, corrosion, low-heat value, incompatibility with conventional fuels, and high viscosity, which hinders its wide utilization as fuel. For cost-effective use of bio-oil, it should be refined by hydrodeoxygenation to decrease its oxygen content.
湘潭大学
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二硫化钼（MoS2）具有较好的加氢脱氧（HDO）催化活性，其微观形貌取 决于其制备方法，又决定了其催化活性。本文围绕如何提高 MoS2 的 HDO 催化 活性，展开以下研究：①MoS2 催化剂：采用水热法在 MoS2 催化剂的制备过程中 加入表面活性剂，制备出了具有不同微观形貌和比表面积的 MoS2 催化剂。结果 显示，表面活性剂的加入显著增大了催化剂的比表面积，改变催化剂表面的堆垛 层数，在对甲基苯酚的 HDO 反应中，直接脱氧（DDO）和加氢-脱氧(HYD)的选 择性取决于催化剂的堆垛层数，采用 Rim−Edge 模型能很好地解释 Mo-S 催化剂 的 HDO 活性中心，当加入 DBS 时，堆垛层数减少，增加了甲基环己烷的选择 性，当加入 PVP 时，堆垛层数增大，增加了甲苯的选择性，结合催化剂的微观 形貌，并推导出对甲基苯酚在催化剂表面的催化反应机理。②Co-Mo-S 催化剂： 文献报道助剂 Co 有利于提高 MoS2 催化剂的活性，基于此，采用一步水热法制 备出 Co-Mo-S 催化剂，主要研究 Co-Mo 摩尔比和催化剂制备温度对催化剂 HDO 活性的影响。结果表明最佳的 Co-Mo-S 催化剂制备温度为 200℃，随着助剂 Co 含量的增加，催化剂面的堆垛层数先增加后减少；而堆垛的长度先减少后增加， 当 Co/Mo 摩尔比为 0.5 时，催化剂的 HDO 活性达到最强，在 275℃反应 4h 时后， 对甲苯酚的转化率和脱氧率均达 100%，甲苯选择性达 90%以上。③ Ni-W-Mo-S 催化剂：由于 W-Mo 之间存在协同催化作用，采用一步水热法制备出 Ni-W-Mo-S 催化剂，主要研究了催化剂中 W-Mo 摩尔比对其结构性能及催化活性的影响， 当催化剂中 W-Mo 摩尔比适当时，催化剂的堆垛长度最短，表面活性中心最多， 表现出最佳的 HDO 活性和加氢-脱氧选择性，在 300℃反应 4h 后，对甲苯酚的 转化率和脱氧率分别达 97.9%和 97.6%。
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摘要
中国经济正处于飞速发展的阶段，对能源的需求也逐渐增大，而传统的化石 能源储量在不断下降，且其利用带来了许多环境污染问题，开发可再生绿色环保 的替代能源迫在眉睫。生物质油是指生物质(木材、秸秆等)在高温下加热裂解而 成的液体燃料，因其来源广泛、可再生、环保、能量密度较高等优点备受关注， 但由于其含氧量较高，导致生物油燃烧热值低，热稳定性差等，严重影响了生物 质油作为替代能源的广泛应用，必须对其进行加氢脱氧精制，以降低其含氧量， 提高油品品质。
The unsupported MoS2 nanocatalysts have good HDO catalytic activity. Its morphology depends on their preparation method, which also determine its catalytic activity. This paper focuses on how to improve the HDO catalytic activity of MoS2. The detail researches are showed as followings: ① MoS2 catalyst: The unsupported MoS2 nanocatalysts with the addition of surfactant were prepared by hydrothermal method. The results displayed that adding surfactant significantly increased the specific surface area of the catalyst, changed the stacking layers of the catalyst surface. In the HDO of p-cresol, direct deoxygenation and hydrogenation-deoxygenation depended on the stacking layers. The active sites of the Mo−S catalyst could be explained by the Rim−Edge model. When adding DBS, the stacking layers decreased, increased the selectivity of methylcyclohexane. Adding PVP could increase the stacking layers and then increased the selectivity of toluene. The reaction mechanism on these catalysts’ surface was also deduced. ② Co-Mo-S catalyst: It had reported that adding Co could improve the activity of MoS2 catalyst. Hence, we adopted one step hydrothermal method to prepared Co-Mo-S catalysts and focused on the influence of temperature and the molar ratio of Co-Mo on the catalysts’ HDO activity. The results showed that the optimal reaction temperature for the preparation of Co−Mo−S catalyst was 200 °C. With the increase of Co content, the number of layers in the stack increased first and then decreased, while the slab lengtheased. The conversion of p-cresol on Co−Mo−S was high to 100% with a