Mechanism of carbon-nitrogen bond cleavage during amylamine hydrodenitrogenation over a sulphided NiMo/Al2O3 catalyst

By comparison of the hydrodenitrogenation rate of amylamine with those of neopentylamine and tert-amylamine over a conventional catalyst, it was evidenced that the hydrogen atoms of the carbon in the position with respect to the nitrogen atom participate in the C-N bond cleavage. A detailed mechanism including the interaction with the catalyst is proposed for this reaction.     

Experimental and Kinetics Studies of Aromatic Hydrogenation in a Two‐Stage Hydrotreating Process using NiMo/Al2O3 and NiW/Al2O3 Catalysts

In this work, hydrogenation of aromatic compounds in light gas oil derived from Athabasca bitumen was carried out using a single‐ and two‐stage hydrotreating processes. Experiments were performed in a trickle‐bed reactor using two catalysts namely NiMo/Al₂O₃ and NiW/Al₂O₃. NiMo/Al₂O₃ was used in the first stage for nitrogen and sulphur containing heteroatoms removal whereas NiW/Al₂O₃ was used in the second stage for saturation of the aromatic rings in the hydrocarbon species. Temperature and liquid hourly space velocity (LHSV) were varied from 350‐390°C and 1.0‐1.5 h^?1, respectively, while pressure was maintained constant at 11.0 MPa for all experiments. Results from single‐stage were compared with those from two‐stage process on the basis of reaction time. Kinetic analysis of the single‐stage hydrotreating process showed that HDA and HDS activities were retarded by the presence of hydrogen sulphide that is produced as a by‐product of the HDS process. However, with inter‐stage removal of hydrogen sulphide in the two‐stage process, significant improvement of the HDA and HDS activities were observed.     

煤焦油加氢脱氮动力学

在小型固定床加氢装置上,选取加氢脱氮催化剂中期缓慢失活阶段,研究煤焦油加氢脱氮动力学。依据加氢装置大量实验数据,运用Levenberg-Marquardt法拟合出各动力学参数,建立了煤焦油加氢脱氮动力学模型和催化剂失活函数表达式。该模型不仅能较为准确地预测不同工艺条件下加氢产品的氮含量,而且可以根据加氢工艺条件和产品指标的要求,预测催化剂的使用寿命。     

加氢裂化预处理催化剂功能分区研究

探究加氢裂化预处理过程中催化剂功能分区以及区域的反应规律,考察了在反应压力15.7 MPa、反应温度370℃、液态空速1.0 h-1、氢油体积比800的条件下,不同预处理催化剂功能区域脱氮率、脱硫率、芳烃转化率以及产品油的油品性质的差异.实验结果表明,原料油经过各反应区后油品性质不断提高,其中第一反应区影响最大,第一反...     

Magnesia-Supported Mo, CoMo and NiMo Sulfide Catalysts Prepared by Nonaqueous Impregnation: Parallel HDS/HDN of Thiophene and Pyridine and TEM Microstructure

MgO-supported Mo, CoMo and NiMo sulfide catalysts were prepared by impregnation using slurry MoO₃/methanol and solutions of Ni and Co nitrates in methanol. The catalysts exhibited very high hydrodesulfurization activity and low hydrodenitrogenation activity in competitive reactions of thiophene and pyridine. The promotion effect for HDS of Ni and Co was higher for our MgO-supported MoS₂ catalysts than for conventional Al₂O₃-supported catalysts. The specific features in the TEM images of MgO-supported catalysts as compared to conventional Al₂O₃-supported catalysts were fairly broad MoS₂ slab length distribution and the presence of unusually long MoS₂ slabs.     

磷助剂对负载型磷化钼催化剂性能的影响

以γ- Al2O3为载体,采用程序升温还原法合成了不同P含量的负载型磷化钼催化剂,并对所合成的催化剂进行了XRD,BET,NH3-TPD,TG表征。在反应压力3MPa、反应温度370℃的条件下,以噻吩、吡啶、环己烯的混合物为模型化合物,通过高压微反装置对催化剂的加氢活性进行了测定。结果表明,P的加入对催化剂的活性组分分散、表面酸性及表面酸量有一定的影响,适量P的加入可以提高MoP/γ- Al2O3的加氢活性,P含量为1.4%时,P-MoP/γ- Al2O3催化剂对噻吩、环己烯和吡啶的转化率分别为74.04%,88.50%,79.04%。     

乙二醇对Ni-W/Al2O3催化剂的加氢性能影响

以Ni、W为活性组分,Al2O3为载体,制备催化剂Ni-W/Al2O3,并采用乙二醇后处理未焙烧的催化剂Ni-W/Al2O3,得到催化剂Ni-W/Al2O3-AT。通过X射线衍射（XRD）、氢气程序升温还原（H2-TPR）、紫外拉曼光谱（LRS）、透射扫描电子显微镜（TEM）、XPS等表征方法研究催化剂的物化性质。结果表明：催化剂Ni-W/Al2O3经乙二醇后处理后,改善了载体氧化铝表面的羟基基团的分布,促使W物种以八面体配位多核聚钨酸的形态存在;并有效削弱了载体与活性金属之间的强相互作用,提高了W物种的分散度与硫化度,最终使得催化剂形成更多“Ni-W-S”加氢活性相,提高了催化剂Ni-W/Al2O3-AT的加氢活性。与催化剂Ni-W/Al2O3相比,催化剂Ni-W/Al2O3-AT对舟山石化焦化轻蜡油具有更高的加氢脱硫、脱氮与芳烃饱和性能,硫质量分数可从6 850 μg/g降至10 μg/g,氮质量分数由3 720 μg/g降至12 μg/g,双环以上芳烃质量分数可从25.8%降至3.2%。     

磷改性对TiO2-SiO2复合氧化物性质的影响

 采用溶胶-凝胶法制备了H₃PO₄改性的TiO₂-SiO₂复合氧化物载体,采用BET、XRD、NH₃-TPD和Py-FTIR等方法研究了P对TiO₂-SiO₂复合氧化物载体性质的影响。结果表明,在溶胶-凝胶制备TiO₂-SiO₂复合氧化物的过程中加入H₃PO₄,使TiO₂晶粒的尺寸减小,载体的孔容和孔径增大;P与缺电子Ti原子的结合,使L酸中心的数量减少,B酸中心数量增加。P的加入既改变了载体的酸量和不同酸类型的比例,又提高了中强酸的比例,保留较高L酸比例。中强酸比例较高的低含量P改性的TiO₂-SiO₂复合氧化物载体制备的催化剂具有较好的加氢脱硫和脱氮性能。     

NiMoP/Al2O3催化剂上柠檬酸促进喹啉加氢脱氮性能研究

在NiMoP浸渍液中添加不同量的柠檬酸,负载在氧化铝载体上制备了系列NiMoP-C(x)（x表示浸渍液中羧酸与Ni的摩尔比）加氢催化剂。将该类催化剂应用于喹啉加氢脱氮反应中,表现出了较高的催化活性,其中NiMoP-C(4)催化剂的加氢脱氮活性最高。用XRD,H2-TPR,HRTEM,XPS技术对系列催化剂进行了表征,XRD结果表明柠檬酸未影响活性组分在载体表面的分散,H2-TPR结果表明柠檬酸使得催化剂的低温还原峰向低温方向迁移,HRTEM结果表明柠檬酸的加入使MoS2颗粒的堆积层数增加,活性组分进入载体体相的比例降低,进一步优化了活性组分与载体的表面相互作用,XPS结果表明柠檬酸的加入降低了Ni与载体间的相互作用,提高了Ni的硫化程度和有效利用率,延缓了Ni的硫化,促进了边缘镶嵌Ni原子的MoS2颗粒的形成,增加了催化剂表面的活性位数量,提高了催化剂的活性。     

乙二醇对NiMoP/Al2O3催化剂上喹啉加氢脱氮反应的影响

燃料油中的含氮化合物是空气中NOx的主要来源,为了降低NOx排放,满足日益严格的排放标准,需要降低燃料油中含氮化合物含量,开发研制高效的加氢精制催化剂是达到这一目标的有效手段。通过在NiMoP浸渍液中添加不同含量乙二醇,制备一系列NiMoP/Al₂O₃催化剂,以喹啉为模型化合物,对催化剂进行加氢脱氮活性评价,分析表征各类脱氮产物。结果表明,乙二醇的加入能够大幅提高喹啉脱氮率,尤其是喹啉全加氢产物中C-N键的直接断键能力得到较大提高。