Abstract:

Diesel production with low/no sulfur content is a major trend in world-wide development of clean fuels. Among many alternative technologies, hydrogenation desulfurization (HDS) is most effective to produce clean diesel at industrial scale, which development of highly active catalysts is the key. In this study, a series of Mo/Al₂O₃-MgO catalysts were prepared by metal oxide composites of MgAl-hydrotalcite and alumina as carriers with incipient-wetness impregnation method. Their catalytic performance was evaluated on dibenzothiophene (DBT) solution in n-heptane as raw material in a fixed-bed reactor. The results showed that Mg/Al molar ratio, calcination temperature, and additive amount all affected acidity, reduction and sulfidation of the catalysts and stacking degree of MoS₂ crystallites. When Mg/Al molar ratio was 3, calcination temperature was 800℃, and hydrotalcite was 10% (mass), the obtained catalyst has the highest HDS activity with up to 96.2% desulfurization rate. Appropriate catalyst acidity and suitable interaction between active component and carrier make it easier to sulfide the active component, which is beneficial to improve stacking degree of MoS₂ crystallites and enhance catalytic performance.

Key words: MgAl-hydrotalcite, Mo/Al₂O₃-MgO, catalyst, hydrogenation desulfurization, reactivity

摘要：

生产低硫或无硫柴油是当今世界范围内清洁燃料发展的趋势，加氢脱硫（HDS）是大规模生产清洁柴油最为有效的技术之一，而研制高活性的HDS催化剂成为该技术的关键。以镁铝水滑石与氧化铝的复合氧化物为载体，通过等体积浸渍法制备了一系列Mo/Al₂O₃-MgO催化剂，以二苯并噻吩（DBT）的正庚烷溶液为原料，在固定床反应器上评价所得催化剂的HDS活性，考察了不同镁铝比的水滑石、焙烧温度和添加量对催化剂物化性质和催化性能的影响。研究结果表明，镁铝比、焙烧温度和添加量均影响催化剂的酸性、金属还原性、硫化性能和MoS₂片晶的堆垛度等，当镁铝摩尔比为3、焙烧温度为800℃、成型时水滑石加入量为10%（质量分数）时，所制备催化剂的HDS活性最高，其脱硫率可达96.2%。这是由于该催化剂的酸性较适宜，活性组分与载体间的相互作用力适中，活性组分更易硫化，有助于提高MoS₂片晶的堆垛度进而改善催化剂的HDS性能。

关键词: 镁铝水滑石, Mo/Al₂O₃-MgO, 催化剂, 加氢脱硫, 活性