Ni2P/SiO2/堇青石整体式催化剂的制备及加氢脱硫性能

以硝酸镍为镍源、磷酸为磷源,与硅溶胶按一定比例混合,制成混合物浆料,然后采用浸渍法将混合物浆料负载于处理好的堇青石蜂窝陶瓷载体上,经过干燥、焙烧后制得含磷化镍前驱体的整体式催化剂,再经氢气气氛下程序升温还原,制得一系列不同镍含量的磷化镍/SiO2/堇青石整体式催化剂.采用XRD、N2吸脱附和SEM等现代分析测试手段对催化剂的结构进行了表征.以二苯并噻吩为模型含硫化合物,对催化剂的加氢脱硫活性进行了评价.结果表明,磷化镍/SiO2/堇青石整体式催化剂中,Ni含量小于3.2wt%时,磷化镍在堇青石表面高度分散,Ni含量大于6.4wt%时,催化剂的活性相是Ni2P,催化剂的平均孔径在3.6nm左右.催化活性层平均厚度约为20μm.在液时空速(LHSV)为1.9 h-1时,Ni含量为12.8wt%的催化剂具有最高的加氢脱硫活性,在360℃时二苯并噻吩的转化率为92.0%,联苯的选择性为69.8%,环己基苯的选择性为30.2%,反应主要按直接脱硫机理进行.     

利用程序升温还原方法研究钴,钌,钼加氢脱硫催化剂氧化态的还原过程

钴或镍在加氢脱硫(HDS)催化剂中的助剂作用文献已有很多的讨论。近年来,研究结果发现,少量的钌加入到Mo/Al_2O_3和Co-Mo/Al_2O_3催化剂上可以显著地提高其加氢脱硫活性,可是关于钌的助剂作用前人研究的较少。因此对比研究钴和钌的的助剂作用有助于认识各种不同类型的助剂在加氢脱硫催化剂中的功能。本文应用程序升温还原方法对钴和钌在加氢脱硫催化剂的前身态氧化物还原过程中的助剂作用进行了考察。     

Effect of Acidic and Basic Species on the Hydrodesulfurization of Methyl-Substituted Dibenzothiophenes

Acidic components when added to Mo-based catalysts enhance the activity of the catalysts for the hydrodesulfurization (HDS) of methyl-substituted dibenzothiophenes (DBTs), the major refractory compounds included in gas oil. However, the enhancing effect of the acidic species is frequently retarded by impurities present in the gas oil, particularly by basic nitrogen compounds. Accordingly, evaluations of the performance of such acid-modified catalysts in HDS should take into account the combined effects of acidic and basic components. The performance is strongly dependent on the types of DBT compounds, acidic and basic species involved in the reaction, and promoters of the Mo-based catalysts.     

Ni含量及预硫化对NiW/γ-Al2O3催化剂上噻吩加氢脱硫反应活性的影响

 采用连续流动微反装置考察了活性组分Ni／（Ni＋W）原子比及\r\n预硫化条件对NiW／γ－Al2O3催化剂噻吩加氢脱硫（HDS）反应活性的\r\n影响．用X射线光电子能谱和电镜微区元素分析方法对硫化态催化剂进\r\n行了表征．结果表明，催化剂的组成、硫化方法、硫化度和反应条件等\r\n都能影响NiW／γ－Al2O3催化剂的HDS反应活性．对于在较低温度（30\r\n0℃）下硫化的催化剂，当反应温度较低（260～290℃）时，最佳Ni／\r\n（Ni＋W）原子比为0．50，而当反应温度较高（330～360℃）时，最佳\r\nNi／（Ni＋W）原子比为0．23．当催化剂在300～450℃下硫化时，其噻\r\n吩HDS反应活性随硫化温度升高而增大，表明硫化度较高的催化剂具有\r\n较高的HDS反应活性．     

Surface fine structure of hydrodesulfurization catalysts. New aspects of promoting effects of Co and Ni

By using the highpressure DRIFT, EXAFS, and TPDDRIFT methods, it is shown that the wellknown effects concerning Co–Mo/Al₂O₃ (i.e., promoting effect of Co or Ni, activating effect of catalyst presulfiding, and inhibiting effect of H₂S) are closely connected to each other. Some direct evidence of the interactions between Mo and Co on sulfided Co–Mo/Al₂O₃ is also shown.     

ZnO/θ-Al2O3催化剂上全馏分FCC汽油的选择性加氢脱硫

研究了三种氧化铝载体和一种ZnO/θ-Al2O3催化剂对全馏分FCC汽油的选择性加氢脱硫性能.结果表明,θ-Al2O3对于全馏分FCC汽油的加氢脱硫选择性因子高于γ-Al2O3和在900℃下焙烧过的γ-Al2O3.负载ZnO能进一步提高θ-Al2O3的加氢脱硫活性和选择性.通过吡啶吸附傅里叶变换红外光谱、氢气程序升温还原和X射线衍射表征发现,θ-Al2O3表面只有微弱的L酸性,其吡啶吸附红外光谱明显不同于其他氧化铝.负载ZnO导致θ-Al2O3载体中出现了尖晶石结构,并且使催化剂的高温H2还原峰位向低温方向移动.     

制备条件对碳化钼催化剂加氢脱硫性能的影响

以MoO3为前驱体,在CH4/H2气氛中程序升温还原碳化反应制备了Mo2C催化剂,用XRD和BET进行了表征. 以二苯并噻吩/环己烷溶液为模型反应物,评价了制备条件对碳化钼催化剂加氢脱硫性能的影响. 结果表明,在还原碳化温度为675 ℃,恒温保持150 min的合成条件下可制得高纯度的a-Mo2C催化剂,该催化剂表现出了较高的加氢脱硫活性,用质量分数为0.6%的二苯并噻吩/环己烷溶液为反应物,反应压力3.0 MPa,反应空速8 h-1,反应温度330 ℃实验条件下的二苯并噻吩加氢脱硫转化率达到了73.29%. 随还原碳化温度的升高和恒温保持时间的延长,制备的碳化钼催化剂的比表面积下降,表面积炭增多,引起其二苯并噻吩加氢脱硫活性的下降. 适当增大制备过程中还原碳化气体空速,有利于还原碳化反应过程中C、 O之间局部规整反应的进行,并对其二苯并噻吩加氢脱硫活性有明显的促进作用. 实验确定的还原碳化气体空速以1.8×104h-1为宜.     

NiMoS/γ-Al2O3上二苯并噻吩加氢脱硫和喹啉加氢脱氮反应的相互影响

在固定床高压微反装置上,考察了预硫化型NiMoS/γ-Al2O3催化剂上二苯并噻吩(DBT)加氢脱硫(HDS)反应和喹啉加氢脱氮(HDN)反应之间的相互影响.结果表明,喹啉对DBT的HDS反应具有强烈的抑制作用,其中对加氢路径比氢解路径的抑制作用更强,这是由喹啉及其HDN反应的中间产物与DBT在活性位上的竞争吸附造成的.在300和340℃时,喹啉对DBT的HDS反应中氢解路径的抑制程度与其HDN中间产物的相对含量紧密相关.而DBT能够提高喹啉的脱氮能力,这源于其HDS产物H2S.H2S促进了催化剂表面硫阴离子空穴向B酸位的转化,从而提高了喹啉HDN中间产物分子的C(sp3)-N键的断裂能力.HDN活性相的保持不需要过多的硫原子.     

尿素反应法制备介孔Ni-Mo复合氧化物

采用尿素反应法合成出具有介孔结构的Ni-Mo复合氧化物。用XRD、低温氮气吸附-脱附表征、HRTEM、TG-DTA、FTIR等分析手段对所合成的Ni-Mo复合氧化物及其前躯体进行了表征,并确定了制备Ni-Mo复合氧化物适宜的焙烧温度。以2%二苯并噻吩(DBT)溶液为模型化合物,在固定床连续高压微反装置上考察了介孔Ni-Mo复合氧化物作为催化剂的加氢脱硫(HDS)性能。尿素反应法合成的Ni-Mo复合氧化物具有较高的比表面积,达到124 m²·g^-1,适宜的孔容0.22 mL·g^-1,和理想的孔径分布,平均孔径为5.8 nm。HDS活性评价表明,这种催化剂具有较高的脱硫率和加氢活性,在反应温度为280 ℃时脱硫率可达100％,远高于对比催化剂Ni-Mo/Al₂O₃。     

In situ FT-IR spectroscopy investigations of carbon nanotubes supported Co-Mo catalysts for selective hydrodesulfurization of FCC gasoline

To better understand the nature of carbon nanotubes supported Co-Mo catalysts （Co-Mo/CNTs） for selective hydrodesulfurization （HDS） of fluid catalytic cracking （FCC） gasoline, studies are carried out using in situ Fourier transform infrared spectroscopy （FT-IR）. The catalytic performances of Co-Mo/CNTs catalysts were evaluated with a mixture of cyclohexane, diisobutylene, cyclohexene, 1-octene （60 ： 30 ： 5 ： 5, volume ratio） and thiophene （0.5%, ratio of total weight） as model compounds to simulate FCC gasoline. The HDS experimental results suggested that the HDS activity and selectivity of Co-Mo/CNTs catalysts were affected by Co/Mo ratio; the optimal Co/Mo atomic ratio is about 0.4, and the optimum reaction temperature is 260 ℃. The in situ FT-IR studies revealed that 1-octene can be completely saturated at 200 ℃. In the FT-IR spectra of diisobutylene, the characteristic absorption peak around 3081 cm^-1 for the stretching vibration peak of =C-H bond was still clear at 320 ℃ indicating that diisobutylene is difficult to be hydrogenated. As for the thiophene, no characteristic absorption peak could be found around 3092 cm^-1 and 835 cm^-1 when the reaction temperature was raised to 280 ℃, indicating that thiophene had been completely hydrodesulfurized. On the basis of FT-IR results, it can be deduced that thiophene HDS reaction occurred mainly through direct hydrogenolysis route, whereas thiophene HDS and diisobutylene hydrogenation reaction over Co-Mo/CNTs catalysts might occur on two different kinds of active sites.