负载型碳氧化钼催化剂的制备及其二苯并噻吩的HDS活性

通过XRD物相分析和利用小型在线质谱仪,对负载的或体相的氧化钼利用正己烷作为碳源,进行程序升温碳化考察,对所制备的负载型催化剂进行了二苯并噻吩（DBT）加氢脱硫（HDS）活性评价。实验发现,与采用甲烷相比,采用正己烷作为碳源进行碳化可以适当降低碳化所需要的温度,但对于HDS反应来说,并不是碳化越完全催化效果越好。对30%MoO3/γ-Al2O3进行碳化时,碳化原料组成为正己烷/氢气＝0.025（摩尔比）,在620℃碳化1ｈ所得催化剂具有比较好的DBT HDS活性。讨论了制备因素对HDS活性的影响。     

States of Carbon Nanotube Supported Mo-Based HDS Catalysts

The dispersion of the active phase and loading capacity of the Mo species on carbon nanotube (CNT) was studied by the XRD technique. The reducibility properties of Co-Mo catalysts in the oxide state over CNTs were investigated by TPR, while the sulfided Co-Mo/CNT catalysts were characterized by means of the XRD and LRS techniques. The activity and selectivity with respect to the hydrodesulfurization (HDS) performances on carbon nanotube supported Co-Mo catalysts were evaluated. It was found that the main active molybdenum species in the oxide state MoO3/CNT catalysts were MoO2, but not MoO3, as generally expected. The maximum loading before the formation of the bulk phase was lower than 6% (percent by mass, based on MoO3). TPR studies revealed that the active species in the oxide state Co-Mo/CNT catalysts were reduced more easily at relatively lower temperatures in comparison to those of the Co-Mo/γ-Al2O3 catalysts, indicating that the CNT support promoted or favored the reduction of the active species. The active species of a Co-Mo-0.7/CNT catalyst were more easily reduced than those of the Co-Mo/CNT catalysts with Co/Mo atomic ratios of 0.2, 0.35, and 0.5, respectively, suggesting that the Co/Mo atomic ratio has a great effect on the reducibility of the active species. It was found that the incorporation of cobalt improved the dispersion of the molybdenum species on the support, and a phenomenon of mobilization and re-dispersion had occurred during the sulfurization process, resulting in low valence state Mo3S4 and Co-MoS2.17 active phases. HDS measurements showed that the Co-Mo/CNT catalysts were more active than the Co-Mo/γ-Al2O3 ones for the desulfurization of DBT, and the hydrogenolysis/hydrogenation selectivity of the Co-Mo/CNT catalysts was also much higher than those of the Co-Mo/γ-Al2O3. The Co-Mo/CNT catalyst with a Co/Mo atomic ratio of 0.7 showed the highest activity, whereas the catalyst with a Co/Mo atomic ratio of 0.35 had the highest selectivity.     

硫化态三组元NiMoP/γ-Al2O3催化剂的TPR表征及噻吩HDS活性的研究

A series of sulfided tertiary NiMoP/γ-Al2O3 catalysts with different contents of MoO3 were prepared by using molybdophosphoric acid of Keggin structure(H3PMo12O40) and nickel nitrate as origins of active phase components of molybdenum, phosphorus and nickel, and characterized by TPR technique, with their HDS activity being investigated with thiophene as a model substrate. For the sulfided Mo-0 catalyst containing no nickel as promoter, the only hydrogen sulfide evolution peak Ⅰ　is observed at 462 K and attributed to the hydrogenation of the so-called edge sulfur atoms chemisorbed on coordinatively unsaturated(cus) Mox+ sites on the MoS2 phase(MoS2 slab). With the introduction of nickel into the active phase of the sulfided Mo-0 catalyst and with the increase of the molybdenum loading, a new hydrogen sulfide evolution peak Ⅱ gradually develops at the low temperature side of the peak Ⅰ, at the same time accompanied by both the increase of the area ratio of the peak Ⅱ to the peak Ⅰ and the shift of the hydrogen sulfide evolution maximum rate to lower temperatures, which may imply the existence of two kinds of active centers related to molybdenum and nickel respectively and the synergic action between the two centers above. It should be noted that for the sulfided NiMoP/γ-Al2O3 catalysts, the thiophene HDS rate and the quantity of hydrogen sulfide evolved during TPR process increase monotonously with the atomic ratio of molybdenum to nickel in the form of ［n(Ni)+n(Mo)］/n(Ni). On the basis of the results here, the conclusion may be reached that the two kinds of vacancies can be formed on the edge of Ni-Mo-S slab due to the loss of S during TPR process and vacancies or sites related to the H2S evolution peak II should be regarded as the mainly active reaction centers of thiophene HDS.     

FCC汽油选择性HDS催化剂的原位红外光谱研究

采用器外预硫化法制备了碳纳米管(CNT)负载的硫化态Co-Mo-S选择性加氢脱硫催化剂.应用原位红外技术(in-situ IR)对选择性加氢脱硫催化剂(Co-Mo-S/CNT)的表面吸附烯烃特性和HDS过程进行了动态研究.原位红外光谱数据表明:1-辛烯在Co-Mo-S/CNT催化剂表面很容易发生加氢饱和,150℃时完全反应;二异丁烯较难加氢,340℃下归属于=C-H伸缩振动吸收峰的3081cm-1特征峰依然很明显;噻吩的特征峰在280℃左右完全消失,Co-Mo-S/CNT催化剂对二异丁烯和噻吩具有很高的选择性HDS活性,噻吩和二异丁烯在Co-Mo-S/CNT催化剂上的吸附发生在不同的活性位上,不存在相互影响.     

碳纳米管负载Co-Mo催化剂在孤岛减压渣油加氢裂化反应中的应用

采用等体积浸渍法制备了一系列不同Co/Mo原子比的碳纳米管（CNT）负载Co Mo催化剂。将该系列催化剂用于孤岛减压渣油加氢裂化反应,评价其催化效果,并在相同反应条件下与 γAl2O3负载Co-Mo催化剂的催化性能进行比较。结果表明,Co-Mo/CNT催化剂的催化效果略低于Co-Mo/γAl2O3催化剂。Co/Mo原子比对Co-Mo/CNT催化剂的催化效果有较大的影响。与相同载体的催化剂相比,当Co/Mo原子比为0.50时,Co-Mo/CNT催化剂具有最佳的催化效果,而Co-Mo/γAl2O3催化剂在Co/Mo原子比为0.35时具有最佳的催化效果。     

碳纳米管负载金属Pt催化剂的制备和机理研究

本文报道了高温裂解法沉积铂纳米颗粒于碳纳米管壁的新方法。利用红外光谱技术考察了碳纳米管壁的官能团衍生化以及这些官能团与铂颗粒沉积间的关系。利用透射电镜(TEM)、X-射线粉末衍射(XRD)以及光电子能谱技术(XPS)对碳纳米管壁上负载的铂纳米颗粒进行了表征。结果表明，大小约为5 nm的铂纳米颗粒以金属Pt(0)的形式均匀分散在纳米管表面，主要晶面定向为(111)面。同时，考察了甲醇在碳纳米管负载铂纳米颗粒复合材料电极上的电催化氧化。     

MCM-41分子筛负载钼钴系催化剂的噻吩HDS研究

通过氧吸附量、噻吩吸附热及反应速率常数的测定，研究了MoO3/MCM-41、MoO3-CoO(NiO)/MCM-41系列催化剂，发现，对于MoO3/MCM-41催化剂，当MoO3的质量分数（以MCM－41为底数，即MCM－41＝1g时，MoO3含量为0．15g，下同）从15％增加到20％时，其噻吩的加氢硫（HDS）活性增大，至25％时活性下降，所对应的氧吸附量（mL/g催化剂）也是先增大后减少，并且两者有很好的线性对应关系，而且噻吩吸附热则基本保持不变，采用不同的MoO3-CoO(NiO)浸渍顺序制备的MoO3-CoO(NiO)/MCM-41催化剂中，先浸渍CoO(NiO）再浸渍MoO3的催化剂，其噻吩HDS活性明显优于对其它浸渍顺序制备的催化剂，同时催化剂的氧吸附量和噻吩吸附热也最大。     

单壁碳纳米管自还原法制备负载Pt催化剂及其催化性能

金属Pt是良好的催化加氢、脱氢催化剂, 利用单壁碳纳米管(SWNTs)自身的还原性, 将K2PtCl6溶液中的Pt直接还原并负载在SWNTs表面上, 制备了具有良好催化性能的SWNTs/Pt负载型催化剂. 通过TEM, XPS和TG对材料进行了表征, 研究了K2PtCl6浓度及溶剂对Pt负载量、粒径的影响, 并测试了SWNTs/Pt的催化性能. 实验结果表明, SWNTs负载的Pt颗粒小, 分散均匀, 负载量高, 与SWNTs结合紧密, 催化性能好, 是催化加氢和脱氢反应的良好催化剂.     

碳纳米管负载镍基催化剂对甘油水蒸气重整的性能研究

以硝酸盐为前驱体，CNTs为载体，采用简单浸渍法制备了一系列不同NiO含量的催化剂3Ni-CNTs、 5Ni-CNTs、 10Ni-CNTs和15Ni-CNTs（NiO含量分别为3.0%、 5.0%、 10.0%和15.0%），通过X-射线衍射（XRD）、氢气程序升温还原（H₂TPR）、氢气程序升温脱附（H₂TPD）、 X-射线光电子能谱（XPS）和透射电镜（TEM）对其物理化学性质进行了分析，并考察其对甘油水蒸气重整反应的影响。结果表明：15Ni-CNTs的催化性能最好，在375 ℃条件下，甘油转化率和氢气选择性分别为100%和72.9%。     

碳纳米管负载铑催化剂上丙烯氢甲酰化

Effect of carbon nanotubes, as a novel support material, on the performance of Rh-catalyst supported by them was studied. Catalysts based on carbon nanotubes, SiO2, carbon molecular sieves, active carbon, and GDX-l02(a copolymer of styrene with divinylbenzene),were prepared, and their catalytic behaviors for propene hydroformylation were investigated and compared. The results showed that, over the carbon nanotubes-supported Rh-catalyst, C3H6 conversion and regioselectivity of butyric aldehyde (represented by n/i, a ratio of n-butyric aldehyde to its isomer, i-butyric aldehyde, in the products) were pronouncedly improved: the average turnover frequency(TOF) for the catalytic hydroformylation of propene was 0.079 s-1 at 393K, which was 2.1 times faster than that over the Rh catalyst based on SiO2, and the n/i ratio of the aldehyde products reached to 11.6, which was 1.9 times higher than that over the catalyst based on SiO2. The roles of six-membered C-ring at the surface of the carbon-nanotubes on the stability of the catalytically active Rh-complexes and of the tubular nano-channel on the spatiospecific seletivity of reaction intermediate state and butyric aldehyde produced were discussed.     

FT-IR Study of Carbon Nanotube Supported Co-Mo Catalysts

In this paper, adsorption properties of dibenzothiophene (DBT) on carbon nanotube, carbonnanotube supported oxide state and sulfide state CoMo catalysts are studied by using thermal gravi-metric analysis (TGA) technique and FT-IR spectroscopy. Activated carbon support, 7-A1203 supportand supported CoMo catalysts are also subjected to studies for comparison. It was found that sulfidestate CoMoS/MWCNT, CoMoS/AC and CoMoS/γ-A12O3 catalysts adsorbed much more DBT moleculesthan their corresponding oxide state catalysts, as well as their corresponding supports. The chemicallyadsorbed DBT aromatic molecules did not undergo decomposition on the surface of supports, supportedoxide state CoMo catalysts and sulfide state CoMo catalysts when out-gassing at 373 K. FT-IR results indicated that DBT molecules mainly stand upright on the active sites (acid sites and/or transition active phases) of CoMoS/MWCNT catalyst. However, DBT aromatic molecules mainly lie flat on MWCNT and CoMoO/MWCNT.     

Study of Carbon Nanotube Supported Co-Mo Selective Hydrodesulphurization Catalysts for Fluid Catalytic Cracking Gasoline

In this paper, carbon nanotube supported Co-Mo catalysts for selective hydrodesulphurization （HDS） of fluid catalytic cracking （FCC） gasoline were studied, using di-isobutylene, cyclohexene, 1-octene and thiophene as model compounds to simulate FCC gasoline. The results show that the Co-Mo/CNT has very high HDS activity and HDS/hydrogenation selectivity comparing with the Co-Mo/γ-Al2O3 and Co-Mo/AC catalyst systems. The saturation ratio of cyclohexene was lower than 50%, and the saturation ratio of 1,3-di-isobutylene lower than 60% for the Co-Mo/CNT catalysts. Co/Mo atomic ratio was found to be one of the most important key factors in influencing the hydrogenation selectivity and HDS activity, and the most suitable Co/Mo atomic ratio was 0.4. Co/CNT and Mo/CNT mono-metallic catalysts showed lower HDS activity and selectivity than the Co-Mo/CNT bi-metallic catalysts.     

XPS Characterization of Carbon Nanotube Supported CoMo Hydrodesulfurization Catalysts

In this paper, the effect of catalytic support and sulfiding method on the chemical state of supported Co-Mo catalysts is studied by XPS. After sulfidation with in-situ method, the majority of molybdenum in CNT supported CoMo catalyst is transferred to a species with a formal chemical state Mo(Ⅳ) in MoS2 phase, and the rest to Mo(Ⅴ) which consists of Mo coordinated both to O and S, such as MoO2S2^2- and MoO3S^2-. In case of CoMo/γ-Al2O3 catalyst sulfided with in-situ method, a fraction of molybdenum is transferred to formal state Mo(Ⅳ) in the form of MoS2, but there is still a mount of unreduced Mo(VI) phase which is difficult to be sulfided. In CoMo/CNT catalyric system sulfided with ex-situ method, Mo(IV) in the form of MoS2 is detected along with a portion of unreduced Mo(VI) phase, suggesting that not all the Mo phases are reduced and sulfided by ex-situ method. As for CoMo/γ-Al2O3, a portion of molybdenum is sulfided to intermediate reduced state Mo(V) which consists of Mo coordinated both to O and S, such as MoO2S2^2- and MoO3S^2-, in addition, there is still a fraction of unreduced Mo(Ⅵ)phase. XPS analyses results suggest that CNT support facilitates the reduction and sulfidation of active species to a large extent, and that alumina support strongly interacts with active species, hereby producing a fraction of phase which resists complete sulfiding. Catalytic measurements of catalysts in the HDS of dibenzothiophene (DBT) show that CoMo/CNT catalysts are of higher HDS activity and selectivity than CoMo/γ-Al2O3 catalyst, which is in good relation with the sulfiding behavior of the corresponding catalyst.     

Study of Dibenzothiophene Adsorption Over Carbon Nanotube Supported CoMo HDS Catalysts

Adsorption properties of dibenzothiophene (DBT) on a CNT (carbon nanotube) support as well as on CoMoS/CNT and CoMoO/CNT catalysts have been studied. Consecutive desorption of adsorbates was measured by TGA. The commonly used carriers AC (activated carbon), γ-Al2O3, and their supported catalysts (CoMoO/AC, CoMoS/AC, CoMoO/γ-Al2O3, CoMoS/γ-Al2O3) were also subjected to analysis for comparison. The acidic properties of the samples were characterized using the NH3-TPD technique.Correlation between the adsorption of DBT and the acidic properties of the catalysts has been established.It was found that the Co-Mo catalysts in the sulfide state adsorbed much more DBT molecules than the corresponding Co-Mo catalysts in the oxide state. The CoMoS/CNT catalyst exhibited very high HDS activity and selectivity, as compared with the CoMoS/γ-Al2O3 catalysts. Based on the BET data and the high hydrogenolysis/hydrogenation selectivity of the CoMoS/CNT, it was deduced that more than 90% of the DBT molecules adsorbed on the CoMoS/CNT with an end-on mode, and the surface of the CoMoS/CNT catalyst was almost fully covered with DBT molecules. Although the AC support had very high surface area and high loading ability, the AC supported CoMoS catalyst showed lower HDS activity,as compared with the CoMoS/γ-Al2O3 catalyst.     

堇青石负载La-Mn-O复合氧化物催化剂的甲苯催化燃烧性能

以堇青石蜂窝陶瓷为载体,以La2O3,Mn(NO3)2为基本原料,掺杂一些稀土等非贵重金属元素,采用浸渍法制备了系列负载La-Mn-O复合氧化物催化剂.考察了焙烧温度等对甲苯催化燃烧性能的影响,并对催化剂进行了XRD,TPR表征.结果表明,800 ℃焙烧的LaMn/Cord催化剂具有较高的甲苯催化燃烧性能;Ce取代催化剂中部分La后能改善催化剂的氧化活性,当Ce∶La=1∶1(摩尔比)时催化性能最佳,在260 ℃的反应温度下甲苯转化率达到90%以上.     

碳纳米管激光等离子体的质谱研究

The time-of-flight mass spectra of carbon nanotube plasma produced by laser was first investigated in this paper. We found the hemi-spherical tips of carbon nanotube were easily fragmentated and aggregated into fullerenes between Coo arid C_(174) in high laser fluence.     

介孔碳担载的 Co-Mo 和 Ni-Mo 加氢脱硫催化剂

 自制介孔碳 (CMC) 具有比传统活性碳 (AC) 更大的比表面积、孔径和孔体积, 以其为载体, 在浸渍液中加入螯合剂, 采用等量浸渍法制备了 Co-Mo/CMC 和 Ni-Mo/CMC 催化剂, 分别用于模型汽油和柴油加氢脱硫反应. 结果表明, Co-Mo/CMC 和 Ni-Mo/CMC 催化剂具有比 Co-Mo/AC 催化剂更好的织构性质和加氢脱硫活性. 在模型汽油的加氢脱硫反应中, Co-Mo/CMC 催化剂活性比工业催化剂 Co-Mo/Al2O3 高得多; 而在模型柴油的加氢脱硫反应中, Ni-Mo/CMC 催化剂活性也比工业催化剂 FH-98 高得多.