磷添加方式对NiMo/Al2O3催化剂加氢脱硫性能的影响

采用分步浸渍法制备了不同磷添加方式改性的NiMo/Al₂O₃催化剂,在固定床微反装置上考察了该系列催化剂对焦炉煤气中噻吩加氢脱硫（HDS）性能的影响,采用BET、X射线衍射（XRD）、H₂程序升温还原（H₂-TPR）、NH₃程序升温脱附（NH₃-TPD）、C₄H₄S(H₂)程序升温脱附[C₄H₄S(H₂)-TPD]、X射线光电子能谱（XPS）、高清透射电镜（HRTEM）和拉曼（Raman）等分析手段对催化剂进行表征。结果表明,不同磷添加方式制备NiMo/Al₂O₃催化剂的HDS性能存在较大差异。其中,催化剂PNi-Mo/Al和PMo-Ni/Al表面弱吸附解离活性位增强,对焦炉煤气中噻吩有较好的低温加氢脱硫活性,以含292.5mg/m³噻吩的模拟焦炉煤气为原料时,PNi-Mo/Al在250℃下对噻吩的脱硫率达61%。对于PNi-Mo/Al和PMo-Ni/Al催化剂,先浸渍P、Ni或者P、Mo时,P优先和载体Al₂O₃作用,减弱了活性金属组分Ni、Mo与载体间的相互作用,而又防止Ni或者Mo与载体间相互作用过低而聚集,提高了Ni、Mo在载体表面的均匀分散,生成能够促进硫化形成Ⅱ型活性相Ni-Mo-S的NiMoO₄物种。NiMoO₄和MoO₃之间的协同作用提高了催化剂的硫化度,使HDS活性得以提高。     

Niobium sulfide as a dopant for Mo/TiO2 catalysts

Mo/TiO₂ catalysts were modified with Nb by two different methods, sol–gel and surface deposition, in order to study the effect of Nb incorporation on the thiophene HDS activity. The results show that the formation of Nb–Ti mixed oxides leads to catalysts with poor HDS activity while the deposition of Nb oxide species on the surface of TiO₂ leads to catalysts with activities larger than those of Mo/Al₂O₃ and Mo/TiO₂. This increase in activity was attributed to the formation of a larger population of Mo sulfur anionic vacancies when Nb was surface deposited on the TiO₂.     

双环戊二烯加氢NiMox/γ-Al2O3催化剂耐硫特性的研究

研究了钼元素及其添加量对镍基催化剂在双环戊二烯（DCPD）加氢反应中耐硫特性的影响规律。催化 剂∶DCPD =1∶10,反应温度150℃,压力3.5 MPa,转速600 r/min,噻吩浓度为：500 mg/L时,Ni/γ-Al₂O₃催化剂的双环戊二烯8、9位双键的加氢速率显著降低,3、4位双键的加氢活性完全抑制; 而NiMo_0.2/γ-Al₂O₃催化剂,在4 h内完成加氢反应,四氢双环戊二烯（endo-THDCPD）收率达到98%,抗硫特性显著提高。不同镍钼比的系列催化剂中,NiMo_0.2/γ-Al₂O₃具有最好的加氢活性与耐硫特性。0~2000 mg/L噻吩浓度内,低浓度条件下,NiMo_0.2/γ-Al₂O₃催化剂对双环戊二烯的加氢活性高,选择性好;随着噻吩浓度增加,催化性能有所下降,2000 mg/L时,加氢反应延长至6 h,endo-THDCPD收率降至95%。     

Catalytic activities of Co(Ni)Mo/TiO2–Al2O3 catalysts in gasoil and thiophene HDS and pyridine HDN: effect of the TiO2–Al2O3 composition

The effect of the TiO₂–Al₂O₃ mixed oxide support composition on the hydrodesulfurization (HDS) of gasoil and the simultaneous HDS and hydrodenitrogenation (HDN) of gasoil+pyridine was studied over two series of CoMo and NiMo catalysts. The intrinsic activities for gasoil HDS and pyridine HDN were significantly increased by increasing the amount of TiO₂ into the support, and particularly over rich- and pure-TiO₂-based catalysts. It is suggested that the increase in activity be due to an improvement in reducing and sulfiding of molybdena over TiO₂. The inhibiting effect of pyridine on gasoil HDS was found to be similar for all the catalysts, i.e., was independent of the support composition. The ranking of the catalysts for the gasoil HDS test differed from that obtained for the thiophene test at different hydrogen pressures. In the case of gasoil HDS, the activity increases with TiO₂ content and large differences are observed between the catalysts supported on pure Al₂O₃ and pure TiO₂. In contrast, in the case of the thiophene test, the pure Al₂O₃-based catalyst appeared relatively more active than the catalysts supported on mixed oxides. Also, in the thiophene test the difference in intrinsic activity between the pure Al₂O₃-based catalyst appeared relatively more active than the catalysts supported on mixed oxides. Also in the thiophene test, the difference in intrinsic activity between the pure Al₂O₃- and pure TiO₂-based catalysts is relatively small and dependent on the H₂ pressure used. Such differences in activity trend among the gasoil and the thiophene tests are due to a different sensitivity of the catalysts (by different support or promoter) to the experimental conditions used. The results of the effect of the H₂ partial pressure on the thiophene HDS, and on the effect of H₂S concentration on gasoil HDS demonstrate the importance of these parameters, in addition to the nature of the reactant, to perform an adequate catalyst ranking.     

Ni---Mo/Al2O3 catalysts promoted with phosphorus and fluoride

Ni---Mo/Al₂O₃ catalysts containing two promoters, fluoride and phosphorus, were studied to learn whether the benefits of both promoters could be combined to produce a superior catalyst. Initially, two series of catalysts differing in the sequence of impregnation of the additives were prepared and tested in the hydrocracking of cumene and the hydrodesulfurization of thiophene. Catalysts impregnated in the sequence phosphorus—metals (Ni and Mo)—fluoride were clearly superior to those prepared by adding first phosphorus, then fluoride and finally metals. The more effective series of catalysts was tested in the hydroprocessing of a gas oil feedstock; to determine the resistance of these surfaces to poisoning, tests were also carried out with the same feedstock spiked with quinoline. The bi-promoted catalysts retained fluoride well, and were quite effective in hydrogenation and hydrodesulfurization. They were even more effective than phoshorous-only promoted catalysts in quinoline hydrodenitrogenation.     

Hydrodenitrogenation of pyridine over alumina-supported iridium catalysts

The catalytic properties of alumina-supported Ir catalysts (≈1 wt% Ir) were studied in the hydrodenitrogenation (HDN) of pyridine at 320°C and 20 bar of pressure in the absence as well as presence of parallel hydrodesulfurization (HDS) of thiophene. The effects of Ir precursor (Ir(AcAc)₃, Ir₄(CO)₁₂, H₂IrCl₆, (NH₄)₂IrCl₆), metal dispersion and sulfur addition were investigated. Ir₄(CO)₁₂ gave the most active catalyst which was ascribed to a lower amount of contaminants originated from the starting Ir compounds rather than to a better Ir dispersion. The decrease of Ir dispersion by sintering in air led to much higher decrease of the rate of C–N bond hydrogenolysis than that of pyridine hydrogenation. The Ir dispersion determined partly the HDN selectivity; a better dispersed Ir phase gave a lower amount of intermediate piperidine. Presulfidation of the reduced catalyst led to 20% decline of the rates of both consecutive HDN steps. An additional and much larger activity decline was caused by the simultaneous execution of HDS. The competitive adsorption of thiophene (or H₂S) was selectively affecting C–N bond hydrogenolysis more than pyridine hydrogenation. The alumina-supported Ir catalysts possessed much higher HDN activity and HDN/HDS selectivity than a conventional NiMo system.     

Aromatic reduction properties of molybdenum sulfide clusters in HY zeolite

Molybdenum sulfide catalysts supported on an HY zeolite at various Mo contents were studied. Catalysts were prepared by incipient wetness impregnation with ammonium heptamolybdate solution and calcined without drying. Their reactivity has been evaluated in toluene hydrogenation under typical hydrotreating conditions. Compared to alumina supported catalysts, zeolite supported Mo catalysts are extremely active for aromatics hydrogenation. At low molybdenum loading, molybdenum sulfide phases inside the zeolite show a particularly high intrinsic activity. This activity can be attributed to molybdenum sulfide clusters differing from MoS₂ slabs.     

Effects of small MoO3 additions on the properties of nickel catalysts for the steam reforming of hydrocarbons III. Reduction of Ni-Mo/Al2O3 catalysts

Ni/Al₂O₃ catalyst modified by small amounts of Mo show unusual properties in the steam reforming of hydrocarbons. There are no data about the effect of small amounts of molybdenum on reduction of the Ni-Mo supported catalysts. The properties of these very complex systems depend on the conditions of successive preparation stages (calcination, reduction) or the process conditions.

A series of Ni/Al₂O₃ catalysts modified by Mo were prepared in order to investigate the influence of promoter amounts and preparation sequence on their properties. Temperature programmed reduction (TPR) has been employed to study the reducibility of Ni-Mo/Al₂O₃ catalysts. Catalysts were further characterized by BET area, H₂ chemisorption and X-ray diffraction measurements.

The TPR curves of Ni-Mo/Al₂O₃ catalysts are very complex. Mo addition leads to the decrease of catalysts reducibility. However, complete reduction of NiO and MoO₃ can be achieved at 800 °C. The reduction course depends on the sequence of nickel and molybdenum addition into the support. Precise measurements of Ni peaks positions in the XRD pattern of Ni/Al₂O₃ and Ni-Mo/Al₂O₃ samples show the possibility of Ni-Mo solid solution formation.     

重芳烃轻质化催化剂n（Ni）/n（Ni+Mo）的优化与分析

以β分子筛为载体,在保持金属总负载量不变的情况下,采用等体积浸渍法制备了4种不同n（Ni）/n（Ni+Mo）的催化剂。分别采用X射线衍射（XRD）、比表面积测试（BET）、氨程序升温脱附（NH₃-TPD）、氢程序升温还原（H₂-TPR）、氢程序升温脱附（H₂-TPD）和热重-差热分析（TG-DTG）等方法对催化剂进行了表征。结果表明,4种催化剂的酸量和酸强度相近,在n（Ni）/n（Ni+Mo）等于基准+0.2时,Mo与载体之间的相互作用最弱,其氢气吸附量最多且积炭量最少;采用某炼厂重整C₁₀⁺ 重芳烃对4种催化剂进行评价,结果表明n（Ni）/n（Ni+Mo）等于基准+0.2催化剂具有最优的催化活性和稳定性。上述结果表明,影响重芳烃轻质化催化剂活性和稳定性的关键因素是催化剂氢气吸附量的多少,氢气吸附量越多金属表面的溢流氢效应越明显,积炭前驱体被溢流氢及时消除,从而保护了催化剂的加氢活性中心不被积炭覆盖,有助于催化剂在较高活性下保持稳定。     

Investigation of CoNiMo/Al2O3 catalysts: Relationship between H2S adsorption and HDS activity

Sulfidation of trimetallic CoNiMo/Al₂O₃ catalysts was studied by thermogravimetry at 400 °C under flow and pressure conditions. Results were compared with those obtained on prepared and industrial CoMo/Al₂O₃ and NiMo/Al₂O₃ catalysts. The amount of sorbed H₂S on the sulfided solids was measured at 300 °C in the H₂S pressure range 0–3.5 MPa at constant H₂ pressure (3.8 MPa). The adsorption isotherms were simulated using a model featuring dissociated adsorption of H₂S on supported metal sulfides and bare alumina. The amount of sulfur-vacancy sites could thus be determined under conditions close to industrial practice. A relationship with activity results for thiophene HDS and benzene hydrogenation was sought for.     

Catalytic synthesis of methanethiol from hydrogen sulfide and carbon monoxide over vanadium-based catalysts

The direct synthesis of methanethiol, CH₃SH, from CO and H₂S was investigated using sulfided vanadium catalysts based on TiO₂ and Al₂O₃. These catalysts yield high activity and selectivity to methanethiol at an optimized temperature of 615 K. Carbonyl sulfide and hydrogen are predominant products below 615 K, whereas above this temperature methane becomes the preferred product. Methanethiol is formed by hydrogenation of COS, via surface thioformic acid and methylthiolate intermediates. Water produced in this reaction step is rapidly converted into CO₂ and H₂S by COS hydrolysis.

Titania was found to be a good catalyst for methanethiol formation. The effect of vanadium addition was to increase CO and H₂S conversion at the expense of methanethiol selectivity. High activities and selectivities to methanethiol were obtained using a sulfided vanadium catalyst supported on Al₂O₃. The TiO₂, V₂O₅/TiO₂ and V₂O₅/Al₂O₃ catalysts have been characterized by temperature programmed sulfidation (TPS). TPS profiles suggest a role of V₂O₅ in the sulfur exchange reactions taking place in the reaction network of H₂S and CO.     

煤基合成气甲烷化用镍基催化剂失活热力学和抗失活预测

利用热力学数据对煤基合成气甲烷化用镍基催化剂硫中毒以及积炭热力学进行了详细的计算。计算发现,活性金属Ni、Mo在甲烷化反应条件下与H₂S、COS发生反应是自发进行的过程。10^-10数量级分压的H₂S含量、10^-14数量级分压的COS含量即可使镍金属活性组分生成硫化镍而使催化剂失活;当Mo作为助剂添加到Ni基催化剂时,硫含量不能超过10^-6数量级。不同温度区间发生的积炭反应类型不同,当温度为633.15～898.15K时,积炭反应主要以CO歧化反应、CO还原反应为主;898.15～983.15K时以CH₄裂解反应为主。另外,在0.1MPa下,添加摩尔分数为11.11%及以上含量水蒸气可以避免积炭。     

Ruthenium molybdenum sulphide catalysts : physicochemical characterization and catalytic properties in HDS, hydrogenation and HDN reactions.

Alumina supported RuMo sulphide catalysts having different weights of metal content and atomic composition ratios R=Ru/(Ru+Mo) were prepared by using ammonium heptamolybdate dissolved in water or a 10% (NH₄)₂S-H₂O solution and RuCl₃.3H₂O as precursor compounds. Their activities were studied in the hydrodesulphurization (HDS) of thiophene and in the hydrogenation (HYD) of biphenyl, and optimized in terms of the preparation method and the sulphidation process. Some hydrodenitrogenation (HDN) tests were also performed on these catalysts. Electron microscopy and XPS measurements were performed, and the nature of the active phase was discussed.     

锆基双金属氧化物催化剂硫中毒的研究

在工业二氧化碳加氢制甲醇过程中,硫化氢气体的引入将对该过程中使用的催化剂活性及稳定性带来负面的影响。基于此,采用微反应合成法成功制备了InZrO_x和ZnZrO_x锆基催化剂,并研究了在二氧化碳加氢反应中,硫化氢气体对锆基催化剂的结构性质及其催化性能的影响规律。结果表明,在T=573 K、p=3.0 MPa和GHSV=18 000 mL/(g_cat·h)条件下,仅通入二氧化碳/氢气反应气时,InZrO_x和ZnZrO_x催化剂的二氧化碳转化率和甲醇选择性分别为7.2%、9.3%和93%、92%。在二氧化碳/氢气原料气中通入体积分数为5×10^-3硫化氢气体时,InZrO_x和ZnZrO_x催化剂的二氧化碳转化率和甲醇选择性都降为0,这主要是因为硫化氢气体占据了氧空位,导致锆基双金属氧化物催化剂硫中毒失活。当停止通硫化氢气体时,InZrO_x和ZnZrO_x催化剂的二氧化碳转化率和甲醇选择...     

Effect of palladium on sulfur resistance in Pt–Pd bimetallic catalysts

The interactions of H₂ and H₂S molecules with Pt–Pd bimetallic catalysts were investigated at the molecular level using a DFT (density functional theory) approach to better understand the structures and properties of active sites, and the relations between structural changes and sulfur resistance. It was found that when alloying the Pt catalyst with a small amount of Pd at a particular surface atomic ratio range, both H₂ and H₂S showed different adsorption properties compared to those on monometallic Pt or Pd catalyst. The adsorptions of both H₂ and H₂S were enhanced, but the adsorption energy of H₂ increased more than that of H₂S, indicating that the adsorption of H₂S became less favorable compared with H₂ on the bimetallic Pt–Pd catalyst surface. The desorption energy of hydrogen from monometallic Pt or Pd, as well as bimetallic Pt–Pd supported on zeolite, were calculated by temperature-programmed desorption (TPD), the values were compared against the DFT results to explain experimentally and theoretically why the bimetallic Pt–Pd catalyst has better sulfur resistance than monometallic Pt catalyst.     

MoO_3-CeO-Co_3O_4催化剂CO催化氧化及耐硫性能

采用共沉淀法和浸渍法联用制备不同Mo质量分数的x MoO_3-6CeO-Co_3O_4催化剂,测试催化剂催化氧化CO效率及其耐硫性能,并对催化剂进行BET、SEM、FT-IR和H2-TPR等表征。结果表明,MoO_3的添加可以提高催化剂低温活性,5.61MoO_3-6CeO-Co_3O_4催化剂低温活性最佳,40℃时CO去除率达98%,耐硫性能达90 min。     

超顺磁负载型催化剂 H3PW12O40/γ-Fe2O3催化噻吩和烯烃的烷基化反应简

The alkylation of sulfur compounds with olefine is considered to be an attractive way to attain high level of sulfur removal by raising the boiling point of sulfur-containing compounds to ease their separation from lighl fractions by distillation. A series of superparamagnetic supported catalysts, used for alkylation of thiophene with 1-octene, were prepared by loading H3PW12040 （HPW） onto commercially available nanoparticles γ-Fe2O3 through incipient wet impregnation method. The catalysts were characterized by X-ray diffraction （XRD）, Fourier transform infra-red （FT-IR）, thermo gravimetric analysis （TG）, N2-adsorption and vibrating sample magnetometer （VSM）. The physicochemical characterization reveals that 7-Fe203 could be accommodated to immobilize and disperse HPW. Moreover, possessing high magnetization of 26.1 A.mZ.kg-1 and with mesoporous structure with specific surface area of 35.9 m2·g^-1, the 40% （by mass） HPW loading catalyst is considered the proper catalyst for olefinic alkylation of thiophenic sulfur （OATS） and can be separated in an external magnetic field. The catalytic activity was investigated in the alkylation reaction of thiophene with 1-octene, and the conversion of thiophene is up to 46% at 160 ℃ in 3 h. The 40% （by mass） H3PW12O40/γ-Fe2O3 catalyst can be reused 6 times without too much loss of activit and keeps its property of superparamagnetism.     

油页岩微波热解气态产物析出特性

利用微波化学试验装置研究了油页岩微波热解过程中挥发分析出特性, 考察了微波功率、热解温度、不同热解温度阶段和催化剂对气体组成的影响。结果表明:微波加热能够提高油页岩热解气中H₂、CO和C₂H₄的析出, 降低CO₂的析出;50%(1600W)微波功率时烃类的析出量最大;在150~350℃的低温阶段热解气的析出量大, 主要由吸附气体的释放, 不稳定支链和基团的分解产生;温度升高, 气态产物的析出主要由脱氢、芳构化、缩聚和自由基反应产生。催化剂促进了气体的析出, 但不同类型催化剂对油页岩热解气组成的影响不同, 分子筛的吸附作用促进二次分解和缩聚反应;黏土类催化剂在质子酸作用下促进有机质催化裂解加氢反应, 加快断链和基团的稳定;金属类催化剂是强吸波性介质, 能够提高升温速率, 促进热解反应, 其次促进氢自由基的产生和转移。     

Effect of Zr-SBA-15 support on catalytic functionalities of Mo, CoMo, NiMo hydrotreating catalysts

SBA-15 and ZrO₂ (10–50 wt.%) containing SBA-15 mesoporous materials were prepared by direct and post-synthesis methods. Characterization using low angle XRD, pore size distribution, CO₂ chemisorption indicate that hexagonal mesoporous structure is retained even after ZrO₂ addition (25 wt.%). Mo, CoMo and NiMo catalysts prepared using these supports were examined by XRD, oxygen chemisorption, temperature programmed reduction (TPR). The catalysts were tested for hydrodesulfurization (HDS) of thiophene and hydrogenation (HYD) of cyclohexene. HDS of thiophene for 8%Mo, 3%Co8%Mo, and 3%Ni8%Mo increases with increasing ZrO₂ loading in SBA-15 up to 25 wt.%. Oxygen chemisorption and TPR hydrogen consumption indicated that the molybdenum dispersion and anion vacancies, and catalytic activities are significantly influenced by ZrO₂ content in Zr-SBA-15. A comparison indicated that TiO₂-SBA-15, ZrO₂-SBA-15 supported CoMo catalysts show higher activities for hydrodesulfurization.     

还原温度对Mo基催化剂物相及其加氢脱氧性能的影响

以碳纳米管(CNTs)为载体,通过控制催化剂合成的还原温度制备了一系列负载型Mo基催化剂。采用XRD、TEM、N₂物理吸附、XPS以及NH₃/H₂-TPD等技术对催化剂进行了表征,并研究了Mo基催化剂对硬脂酸催化加氢脱氧性能的影响。结果表明:随着还原温度的升高,催化剂表面的Mo物种逐渐被还原,还原过程为:MoO₃→MoO₂→Mo→Mo₂C。还原温度为450℃和550℃时,催化剂的活性相为MoO₂;还原温度为600℃时,催化剂的活性相为MoO₂/Mo/β-Mo₂C的混合相;还原温度为650℃和700℃时,催化剂的活性相全部转化为β-Mo₂C。与活性相MoO₂催化剂相比,β-Mo₂C催化剂具有更高的加氢脱氧活性。此外,还原温度为600℃的MoO₂/Mo/β-Mo₂C混合相催化剂因具有较大的比表面积、较多的酸中心数量和较强的H₂吸附能力,使得该催化剂在硬脂酸加氢脱氧反应中表现出最优越的催化活性。