载体对负载型过渡金属氮化物催化氨分解性能的影响

采用等体积浸渍法结合NH3程序升温氮化制备出一系列负载型金属Co、Mo氮化物催化剂。并利用XRD、TPD-MS和H2-TPR及氨分解活性测试等手段，考察了载体［Mg(Al)O、MgO和γ-Al₂O₃］对负载型金属氮化物的表面形态及组成的影响。结果表明，（1） 负载催化剂的氨分解速率远远高于非负载的催化剂；（2） 氮的脱附峰可以归为以下三类：a.吸附态的NHx分解；b.氮化物结构转变；c. β-Mo₂N_0.78和Co₂Mo₃Nx 还原成Co和Mo金属；（3） 载体表面的酸碱性和孔结构对其负载的金属氮化物的催化活性和表面形态及化学组成有重要的影响，镁铝复合氧化物MgAlO［n(Al)∶n(Mg)=1∶3］为载体的钴钼双金属氮化物对于氨分解反应具有最好的催化活性。     

过渡金属氮化物催化性能研究进展

过渡金属氮化物具有类似于Pt族贵金属的催化性能得到了广泛的研究.综述了过渡金属氮化钼及助剂促进的氮化钼在加氢脱硫与脱氮、氨合成与分解、芳烃加氢和其他涉氢反应(如炔烃、烯烃加氢、丙酮缩合、肼的分解)中的应用,并介绍了其他金属氮化物(如氮化钒、氮化钴)在催化反应中的应用.     

分散型浆态床渣油加氢双金属催化剂研究进展

浆态床渣油加氢技术的核心和关键是采用了高分散性催化剂,其具有定向催化加氢活性和抑制结焦能力,保证了渣油中沥青质的高效轻质化,维持装置长周期稳定运行。而在分散型催化剂中添加助金属,不仅可以有效降低催化剂的成本,还可以显著提高催化剂的加氢活性。本文全面综述了浆态床渣油加氢裂化技术中分散型双金属催化剂的研究进展,包括钴-钼、镍-钼、铁-镍等双金属催化剂,重点介绍了双金属催化剂的活性和活性相结构,同时分析总结了不同双金属催化剂的优缺点。通过探索双金属催化中金属之间的协同作用,深入认识催化剂活性相结构,展望分散型双金属催化剂的未来发展,对渣油高效转化催化剂的开发具有重要意义。     

采用骨架钴和骨架镍催化剂加氢还原制备糠醇的研究

从钼、铬、铜和铁中筛选金属铬和铁作为助催化剂加入骨架钴或骨架镍催化剂，铬和铁的量分别为催化剂质量的３％和１％。在１００～１２０℃、１０～１２ＭＰａ条件下，用上述骨架钴或骨架镍催化剂在乙醇溶剂中，氢化还原糠醛制备糠醇。用骨架镍催化剂，反应产物含有７８５％的糠醇和１９６％的四氢糠醇；用骨架钴催化剂，反应产物含有９８８％的糠醇和０８％的四氢糠醇，收率９４％。在无乙醇溶剂条件下，反应产物含有９０５％的糠醇、０３％的四氢糠醇和９２％的糠醛。在１８０℃条件下，反应产物含有９０８％的糠醇和８９％的四氢糠醇。     

氨解法制备纳米Ti0.4Cr0.6OxNy粉体

以共沉淀法制备的钛和铬的摩尔比为4：6的TiO2／Cr2O3纳米复合粉体为前驱体,氨气为氮化剂,制备了钛铬双金属氧氮化物纳米粉体。采用Auger电子能谱、X射线衍射、透射电子显微镜、BET比表面积、电子探针等技术对氧化物复合粉体和合成氧氮化物粉体进行了表征。结果表明：前驱体组成均匀、比表面积大、反应活性高,800℃氮化8h可以合成X射线衍射纯立方相钛铬双金属氧氮化物纳米粉体e粉体呈球形,晶粒尺寸在20～35nm,比表面积达35．62m^2／g,基本无团聚。氮化前后粉体的氧含量和氮含量发生了明显变化,粉体的组成可以用Ti0.4Cr0.6OxNy表示。     

钴改性的镍催化甲烷二氧化碳重整反应研究

以CeO_2作为载体,合成了含有更多金属活性位点的钴镍双金属催化剂,并用于催化甲烷二氧化碳重整反应的研究。为了深入探讨双金属催化剂中钴和镍之间的作用机制,通过改变两种活性金属钴和镍的加入顺序,分别合成了Co-Ni/CeO_2、Ni-Co/CeO_2和Ni Co/CeO_2催化剂。与单金属催化剂对比,研究了Co的加入对镍基催化剂的影响,并确认了双金属催化剂中Co与Ni存在的状态和加入顺序对催化剂催化性能的影响。     

NiCo双金属磷化物纳米片的制备及其电催化性能

以硝酸镍为镍源、硝酸钴为钴源,通过钼酸根和二甲基咪唑改变活性位点和结构,制备层状双金属氢氧化物,并以次磷酸钠为磷源制备了磷化镍钴双金属催化剂。利用电化学工作站对催化剂的析氢反应和析氧反应性能进行了测试,并使用电子显微镜对催化剂的显微结构进行表征。通过改变镍钴加入量探究双金属比例对催化剂电催化性能的影响。结果表明,当Ni、Co比例为1∶1时性能最好。     

液化气加氢脱烯烃脱硫催化剂的研究

考察了浸渍液的配制方法、钼含量、钴镍加入量、以及助剂镧对液化气脱烯烃脱硫催化剂活性的影响。实验表明,低温配制的浸渍液制备的催化剂低温低压活性好;钴镍加入量影响双功能;钼含量影响转化活性;镧的加入可提高催化剂加氢转化的活性稳定性。     

采用骨加钴和骨架镍催化剂加氢还原制备糠醇的研究

从钼、铬、铜和铁中筛选金属和铁作为助催化剂加入骨架钴或骨架镍催化剂,铬和铁的量分别为催化剂质量的３％和１％。在１００￣１２０℃、１．０￣１．２ＭＰａ条件下,用上述骨架钴或骨架醇和１９．６％的四氯糠醇;用骨架钴催化剂,反应产物含有７８．５％的糖醇和１９．６％的四氢糠醇;用骨架钴催化剂,反应产物含有９８．８％的糠醇和０．８％的四氢糖醇,收率９４％。在乙醇溶剂条件下,反应产物含有９０．５％的糠醇、０．３     

Mo-Ni纳米自组装催化剂的表征与活性评价

以二次纳米自组装氧化铝为载体,浸渍以氨为溶剂、双金属活性组分配比不同的钼镍铵溶液,制备一种新型加氢催化剂,并对制得的催化剂进行表征和评价。结果表明,钼镍催化剂的孔性质稳定,孔径大小集中在3~10 nm和30~100 nm,其中在30~100 nm的孔道占33.70%~39.47%。以劣质催化裂化柴油为原料,对催化剂进行加氢活性评价,催化剂的脱硫率为81%~93%,脱氮率为87%~97%,芳烃饱和率为56%~67%,在催化剂运行时间内无明显结焦现象且活性较好。结合钼镍催化剂的表征数据及加氢活性评价结果发现钼镍质量比为7∶1时催化剂的性质最适宜,并且催化剂活性最优。     

Effect of cobalt (nickel) content on the catalytic performance of molybdenum carbides in dry-methane reforming

The dry-methane reforming (DMR) behavior of Co-Mo and Ni-Mo carbide catalysts has been studied in order to establish the effect of the cobalt or nickel content of molybdenum carbide DMR catalysts. The results indicate that incorporating cobalt into the Mo₂C structure at a Co/Mo ratio of 0.4, i.e. a Co_0.4Mo₁C_x catalyst, gives a DMR activity and stability that are markedly higher than those of Mo₂C catalysts. With respect to the Ni-Mo carbide catalysts, a Ni/Mo atom ratio of 0.2 (i.e. an Ni_0.2Mo₁C_x catalyst), gives the maximum synergistic interaction between Ni and Mo. However, higher molar ratios decrease the promoting effect and facilitate the phase separation of the promoter. These results are proved by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy and N₂-adsorption studies, and are also reflected in the poor catalytic stability of both the Co-Mo and the Ni-Mo carbide catalysts.     

The modification of molybdenum nitrides: the effect of the second metal component

A set of Mo2N-based bimetallic catalysts with high surface area around 140 m 2 /g have been successfully prepared from precursors obtained using the coprecipitation method. Both the precursors and the end-catalysts were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The nitriding processes were monitored by differential thermal analysis (TDA). The catalytic properties of Co-Mo bimetallic catalyst under mediumpressure (3.0 MPa) are much better for the hydrodenitrogenation of pyridine than those of pure γ-Mo2N and a commercially used sulfided CoMo/Al2O3 catalyst. The introduction of the second metal component has been shown to disrupt the morphology of the nitride phase with a greater concentration of (111) planes being present compared to (200) planes, a situation that is reversed compared to γ-Mo2N. This revised version was published online in July 2006 with corrections to the Cover Date.     

Methane reforming reaction with carbon dioxide over SBA-15 supported Ni-Mo bimetallic catalysts

A series of mesoporous molecular sieves SBA-15 supported Ni-Mo bimetallic catalysts (xMo1Ni, Ni = 12 wt.%, Mo/Ni atomic ratio = x, x = 0, 0.3, 0.5, 0.7) were prepared using co-impregnation method for carbon dioxide reforming of methane. The catalytic performance of these catalysts was investigated at 800 °C, atmospheric pressure, GHSV of 4000 ml·g_cat^− 1·h^− 1 and a V(CH₄)/(CO₂) ratio of 1 without dilute gas. The result indicated that the Ni-Mo bimetallic catalysts had a little lower initial activity compared with Ni monometallic catalyst, but it kept very stable performance under the reaction conditions. In addition, the Ni-Mo bimetallic catalyst with Mo/Ni atomic ratio of 0.5 showed high activity, superior stability and the lowest carbon deposition rate (0.00073g_c·g_cat^− 1·h^− 1) in 600-h time on stream. The catalysts were characterized by power X-ray diffraction, N₂-physisorption, H₂-TPR, CO₂-TPD, TG and TEM. The results indicate that the Ni-Mo bimetallic catalysts have smaller metal particle, higher metal dispersion, stronger basicity, metal-support interaction and Mo₂C species. It is concluded that Mo species in the Ni-Mo bimetallic catalysts play important roles in reducing effectively the amount of carbon deposition, especially the amount of shell-like carbon deposition.     

Upgrading Siberian (Russia) crude oil by hydrodesulfurization in a slurry reactor: A kinetic study

Hydrodesulfurization (HDS) of sour crude oil is an effective way to address the corrosion problems in refineries, and is an economic way to process sour crude oil in an existing refinery built for sweet oil. In the current study, the HDS of Siberian crude oil was carried out in a slurry reactor. The Co-Mo, Ni-Mo, and Ni-W catalysts supported on γ-Al₂O₃ were compared at the temperature of 340℃ and the pressure of 4.5 MPa. The HDS activity follows the order of Co-Mo > Ni-Mo > Ni-W at a high concentration of H₂S, and the difference between Co-Mo and Ni-Mo becomes insignificant at a low concentration of H₂S. The influence of reaction temperature 320-360℃ and reaction pressure 3-5.5 MPa was investigated, and both play a positive role in the HDS reaction. A kinetic model over Ni-Mo/Al₂O₃ in the slurry reactor was established. The activation energy is estimated as 60.34 kJ·mol^-1; the orders of sulfur components and hydrogen partial pressure are 1.43 and 1.30, respectively. The kinetic parameters are compared with those in a trickle-bed reactor, implying that the mass transfer is greatly enhanced in the slurry reactor. The back mixing effect is present in the slurry reactor and can be reduced by a multi-stage design, which would lead to higher reactor efficiency in industrial application.     

Studies of the batch hydrotreatment of Rundle shale oil

Studies of the batch hydrotreatment of shale oil from the Rundle (Queensland, Australia) deposit were carried out, and the suitabilities of three commercial catalysts based on Ni-Mo, Co-Mo and Ni-W were evaluated in terms of nitrogen removal and hydrocracking ability. All catalyst systems were effective for olefin saturation and removal of labile N and O compounds (nitriles and ketones). Both the Ni-Mo and Co-Mo systems removed significant amounts of pyridines and quinolines, but failed to convert the less basic pyrrolic material. The Ni-Mo system gave the most satisfactory performance in this area. The Ni-W catalyst behaved poorly. Only limited hydrocracking was observed, and this was confined to cracking of n-paraffins and alkyl side chains of aromatics. Polyaromatic structures were not cracked.     

Kinetic correlations in codeposition of coatings of molybdenum-iron group metal alloys

Electrodeposition of Ni-Mo and Fe-Mo alloy coatings from acid citrate electrolyte was investigated over a wide range of cathode potentials and under various hydrodynamic conditions. Such alloys had been found to be deposited with substantial depolarization against iron group metals. With the same electrodeposition conditions, the molybdenum percentage in Fe-Mo coatings is much higher than in Ni-Mo. The molybdenum presence results in a lower overvoltage of hydrogen evolution, so that these alloys are deposited with a current efficiency much lower than that in the separate reduction of iron group metals. For a Ni-Mo system, the Mo percentage in the coating is increased together with increase of the transport rate of ions towards the cathode and with decrease of the cathode potential value being reduced; while for Fe-Mo alloy an inverse relation is observed. When passing from the Ni-Mo to the Fe-Mo system, the control of the molybdenum reduction reaction is changed. In codeposition with nickel it shows a diffusion control, while in discharging with iron its control is of the activation type. The Ni-Mo coatings obtained contained from 1.5–6% molybdenum whereas Fe-Mo deposits contained from 12–40% depending on electrolysis conditions. The quality of the coatings containing more than 20% Mo deteriorated and in these deposits some nonmetallic inclusions were present.     

Simultaneous hydrodesulfurization of thiophene and hydrogenation of cyclohexene over dimolybdenum nitride catalysts

A series of unsupported dimolybdenum nitride (γ-Mo₂N) catalysts differing in surface area were prepared by temperature programmed reduction of MoO₃ with a mixture of NH₃:N₂ (90:10). Characterization of catalysts by BET, XRD, TPR and XPS techniques was carried out. The samples were used as catalysts in hydrotreating reactions (simultaneous hydrodesulfurization of thiophene and hydrogenation of cyclohexene). Low surface area γ-Mo₂N materials show much higher specific conversions than those with higher surface area. These results indicate that HDS and HYD reactions over γ-Mo₂N seem to be structure-sensitive. The relative exposure extent of crystalline planes (1 1 1) and (2 0 0) over the different catalysts can be associated with their hydrogen adsorption capacities and with their catalytic performances. The catalytic activities are significantly affected by the catalyst pretreatment conditions.     

双组分金属类型对四氢萘加氢裂化反应性能的影响

以Beta分子筛为载体,采用等体积浸渍法制备不同双组分金属类型(Ni-Mo、Ni-W和Co-Mo)加氢裂化催化剂,利用XRD、BET、NH3-TPD、Py-IR和H2-TPR等对催化剂进行表征。在固定床连续加氢反应器上考察催化剂对四氢萘加氢裂化性能的影响,结果表明,催化剂CAT-a(Ni-Mo/Beta)有较适宜的比表面积和孔体积,酸量和酸强度最大,四氢萘转化率和BTX选择性最高。以Ni-Mo/Beta催化剂为研究对象,考察不同金属负载量对催化剂物化性质及四氢萘反应性能的影响,结果表明,Beta分子筛载体上金属负载质量分数18%的催化剂最适宜四氢萘加氢裂化多产BTX类物质。     

Hydrodesulfurization over intrazeolite molybdenum nitride clusters prepared by using hexacarbonyl molybdenum as a precursor

Metal nitride catalysts have received extensive attention because of their potential high performance for hydrodesulfurization (HDS). In the present study, highly dispersed Mo nitride clusters having a composition of Mo₂N are synthesized in zeolite pores by means of a CVD method using Mo(CO)₆ as a precursor. The catalytic properties of the molybdenum nitride catalysts for the HDS of thiophene are compared with that of an intrazeolite molybdenum sulfide catalyst. The molybdenum nitride catalyst shows a more stable thiophene HDS activity than the molybdenum sulfide catalyst. Molybdenum nitride clusters are only partially sulfided even after a prolonged HDS reaction.     

负载型钴铜双金属氮化物催化氨分解研究

Co and Mo bimetallic nitrides supported on Mg（Al）O, MgO and γ-Al2O3 were prepared in temperatureprogrammed reactions with NH3. The surface morphology, chemical composition and catalytic activity for NH3 decomposition on the supported Co and Mo bimetallic nitrides were studied by X-ray diffractometer （XRD）, NH3 temperature-programmed desorption and mass spectrometer （NH3-TPD-MS）, temperature-programmed desorption and mass spectrometer （TPD-MS）, H2 temperature-programmed surface reaction （H2-TPSR） and activity test. The phases of Co3Mo3N and MoN could be formed on Mg（Al）O, MgO and Al2O3 during the nitridation, and they might be more uniformly dispersed on Mg（Al）O and MgO than on γ-Al2O3. Transition metallic nitrides are generally considered as potential catalysts for hydrogen-involving reactions due to the entrance of hydrogen atoms into subsurface and the lattice of metallic nitrides. The diffusion of nitrogen in the bulk and the structure transformation of Co and Mo nitride compounds occur during NH3-TPD, but the supported Co and Mo bimetallic nitrides are not easily reduced at H2 atmosphere. Co3Mo3N/Mg（Al）O catalyst exhibits the highest activity, while Co3Mo3N/Al2O3 exhibits the lowest activity for NH3 decomposition. Furthermore, the catalytic activity of Co and Mo bimetallic nitrides is not only much higher than that of supported single metallic nitride, but also highly dependent upon the surface acidity and BET surface area of support.