镍基催化剂上甲醇-甘油协同水蒸气重整制氢的应用基础研究

Hydrogen is one of clean energy carriers with very good perspective, and today almost 95% is produced from raw materials based on fossil fuels. It is of great urgency to exploit economical, renewable raw material for H2 production. Crude glycerol, the main byproduct of biodiesel production, contains glycerol concentrations of 40 to 85% and methanol up to 25%. Because of the increasing growing of biodiesel production, the total production of crude glycerol is huge. However, the current utilization of crude glycerol is of less commercial value. It is crucial to search for the value-added utilization of crude glycerol. Using it as a versatile raw material for H2 production is a good choice. Nickel-based catalysts will be used to simultaneously catalyze the steaming reforming of methanol and glycerol to produce hydrogen in this project. Due to the difference of methanol and glycerol in activation style and condition, the synergetic steaming reforming of methanol and glycerol is of high difficulty and complexity. Therefore, many strategies, such as the addition of other active metals and promoters, the use of effective synthesis method and post-treatment process, will be employed to obtain the efficient catalyst to achieve the activation of methanol, glycerol and water at the same time, as well as the efficient hydrogen production. Based on the studies of Ni-based catalysts on activity, reaction dynamics, physicochemical properties, the relationship between synthesis, properties and catalytic performances can be revealed, the modulation of catalytic activity center and the mechanism of synergistic steam reforming of methanol and glycerol would be proposed. In summary, this study not only cuts the costs of hydrogen production by using cheap, renewable raw material, but also favors the value-added utilization of crude glycerol, which is beneficial to the sustainable development of hydrogen and biodiesel, the relief of energy crisis, and also the protection of environment.

氢能是清洁新能源的重要研究方向。目前～95%的氢气来源于化石燃料，廉价可再生原料高效制氢是氢能发展亟需解决的问题。以甘油、甲醇为主要成分的生物柴油副产物-粗甘油产量巨大，现有利用方法商业价值低，不利于生物柴油成本的降低。本项目以粗甘油为原料，通过甲醇-甘油协同水蒸气重整制氢。甲醇、甘油活化方式和条件差异明显，且甲醇-甘油混合醇水蒸气重整体系相对复杂、副反应多，高效催化剂的开发是克服这些困难、提高氢气产率的关键。本项目通过对活性组分、助剂、载体的优化，借助有效的合成方法，制备性能优越的单/双/多金属镍基催化剂，实现甲醇、甘油和水分子的同时活化和协同转化。在催化剂活性评价、物化性质与微观结构表征的基础上，探索催化剂活性中心的调变规律，揭示甲醇-甘油协同水蒸气重整制氢的反应机理。本项目在廉价、可持续制氢的同时，解决了粗甘油高附加值利用的问题，对于氢能和生物柴油的可持续蓬勃发展具有重要的现实意义。

本项目以生物柴油副产物-粗甘油（主要成分为甘油、甲醇）的高值资源化利用为目标，开发高效的镍基催化剂，催化甲醇、甘油水蒸气重整制氢。项目由简到繁逐次推进，先后进行了甲醇水蒸气重整（MSR）、甘油水蒸气重整（GSR）、甲醇-甘油协同水蒸气重整（MGSR）三个制氢体系的研究，考虑到氢气产物中CO对燃料电池电极潜在的毒害，扩展研究了富氢气氛中CO的选择性氧化（CO-PROX）。设计合成了Ni/Al2O3、Ni@Al2O3、Ni/CeO2、CuO/CeO2等催化剂体系，系统考察了镍前躯体、添加剂、载体形貌、核壳结构等因素，及反应温度、甲醇/甘油/水比等条件对醇转化率、氢气产率、产物组成等的影响，细致表征了催化剂形貌、金属-载体相互作用、氧化还原能力、活性组分分布、氧空穴、积碳等物理化学性质，并与催化性能进行关联，研究了反应活性中心和活性中心调变规律，探讨了催化剂失活机制及反应机理。.研究发现，硝酸镍前驱体制备的Ni/Al2O3催化剂对MSR活性较佳，Pr的添加弱化了Ni-Al2O3相互作用，提高了催化性能。针对GSR，设计合成了Ni@Al2O3催化剂，核壳结构有效抑制了Ni核烧结，且Ni-Al2O3相互作用适中，活性Ni0暴露多，积碳生成以丝状炭为主，故600℃下甘油转化率达98%，反应100h仍保持高活性；为降低反应温度，设计合成了Ni/CeO2催化剂，相对于棒状和立方体载体，球状CeO2载体与Ni的作用力更强，更多Ni2+进入CeO2晶格，产生更多表面Ce3+和氧空穴，促进了催化剂还原，抑制了壳状碳的生成，因此500℃实现了甘油的近完全转化，反应30h仍保持高活性。MGSR中，甲醇可与甘油协同作用，促进了反应物活化，提高了甘油转化率和氢气选择性。对于CO-PROX，CuO/CeO2催化剂上Cu+可吸附活化CO，表面活性氧直接参与CO氧化；而Fe和Sn的添加可产生更多的Cu+和表面活性氧，显著提高了CO的选择性氧化。项目研究成果不仅为粗甘油的高值资源化利用和醇类制氢提供了重要的实验数据和理论基础，也丰富了富氢气氛下CO选择性氧化的理论基础。已发表学术论文9篇，其中SCI收录7篇；申请发明专利5项。培养研究生8名。