EDTA对NiW／Al2O3催化剂表面金属分散性、形貌及HDN性能的影响

为提高负载催化剂中金属的分散性,以含EDTA螫合剂的浸渍液浸渍制备了NiW／Al2O3加氢处理脱氮催化剂,其中络合剂与Ni的摩尔比为1：1,考察了EDTA对活性金属分散性及加氢脱氮性能的影响。通过BET、XRD、XPS和HRTEM表征发现,EDTA的引人,可以提高M和W在氧化铝载体表面的分散性,W／A1原子比从0．096提高到0．127。EDTA的引入,同时减弱了活性金属与氧化铝载体间的相互作用,有利于形成堆积程度较高的WS：相。EDTA的引入,可以大幅提高催化剂对喹啉的加氢脱氮活性,相对于传统方法制备的催化剂,其加氢脱氮活性可提高27％。     

Study on the hydrodesulfurization and the hydrodenitrogenation over Al2Oa-ZrO2 supported Ni2P catalysts

采用浸渍-沉淀法制备Al2O3-ZrO2复合氧化物,通过程序升温还原法制备Ni2P/Al2O3-ZrO2催化剂。运用X射线衍射、N2吸附-脱附、X射线光电子能谱技术对载体和催化剂进行表征,并以噻吩加氢脱硫、吡啶加氢脱氮反应为探针考察复合氧化物对Ni2P催化剂加氢活性的影响。结果表明,在Al2O3表面引入少量ZrO2,既保持了γ-Al2O3大比表面积的结构优势,又减少了P或Ni与Al2O3表面的接触,促进Ni2P的形成。载体中ZrO2质量分数20%的Ni2P/Al2O3-ZrO2催化剂活性最高,载体焙烧温度过高会导致催化剂活性下降。     

Al2O3-ZrO2负载Ni2P催化剂加氢脱硫脱氮活性

采用浸渍-沉淀法制备Al2O3-ZrO2复合氧化物,通过程序升温还原法制备Ni2P/Al2O3-ZrO2催化剂。运用X射线衍射、N2吸附-脱附、X射线光电子能谱技术对载体和催化剂进行表征,并以噻吩加氢脱硫、吡啶加氢脱氮反应为探针考察复合氧化物对Ni2P催化剂加氢活性的影响。结果表明,在Al2O3表面引入少量ZrO2,既保持了γ-Al2O3大比表面积的结构优势,又减少了P或Ni与Al2O3表面的接触,促进Ni2P的形成。载体中ZrO2质量分数20%的Ni2P/Al2O3-ZrO2催化剂活性最高,载体焙烧温度过高会导致催化剂活性下降。     

乙二胺四乙酸对NiMo/Al_2O_3催化剂加氢脱氮性能的影响

以氧化铝为载体,Ni和Mo为金属活性组分,添加不同含量乙二胺四乙酸,采用等体积浸渍法制备系列Ni Mo(x)/Al_2O_3(x为乙二胺四乙酸与Ni物质的量比)重质油加氢处理催化剂,考察乙二胺四乙酸加入量对催化剂加氢脱氮性能的影响,并采用N_2物理吸附-脱附、XRD和HRTEM等对催化剂进行表征。结果表明,乙二胺四乙酸的加入增强了金属组分与氧化铝载体间的相互作用,降低了MoS_2活性相的堆垛层数和片层长度,促进了活性相的分散。乙二胺四乙酸与Ni物质的量比为0.5时,MoS_2活性相堆垛层数和片层长度达到良好的结合,对应的催化剂Ni Mo(0.5)/Al_2O_3具有最优的加氢脱氮性能。     

氧化铝对煤焦油加氢催化剂活性影响的研究

选用不同规格的氧化铝粉体,通过挤条、浸渍的方式,制备了一系列的Ni-Mo/Al2O3煤焦油加氢精制催化剂。通过氮气物理吸附、XRD等表征方式考察了催化剂的孔结构性质、活性金属在氧化铝表面的分布情况,同时考察了不同催化剂在煤焦油加氢过程中的加氢能力。研究发现,氧化铝载体的性质对活性金属在其表面的分散性能有一定的影响,进一步对其在煤焦油加氢过程中的精制活性有显著的影响。     

La、EDTA改性对Ni-W/TiO_2-Al_2O_3催化剂结构及加氢脱硫性能的影响

采用等体积浸渍法制备了以TiO_2-Al_2O_3为载体,Ni、W为活性金属组分的加氢脱硫催化剂,考察了稀土金属镧(La)、乙二胺四乙酸(EDTA)改性以及La-EDTA组合改性对催化剂结构和加氢脱硫性能的影响。通过X射线衍射、N2吸附-脱附、H2-程序升温还原和扫描电子显微镜对催化剂进行表征分析。结果表明,La和EDTA均可改善活性组分与载体间的相互作用,增加了Ni-W-S活性相的数量,有利于金属组分的还原;同时能够丰富催化剂孔道,抑制催化剂表面金属离子聚集,得到更好的孔结构、更高的活性相分散度。La或EDTA以及两者同时改性后的催化剂噻吩硫脱除率均明显高于未改性催化剂,其中Ni-W-La-E催化剂上噻吩转化率为99.7%。     

制备条件对Ni_2P/TiO_2-Al_2O_3催化剂的HDN性能影响

采用原位还原技术制备出Ni2P/TiO2-Al2O3催化剂,以喹啉为模型化合物对催化剂的加氢脱氮性能进行评价。主要考察复合载体中不同钛铝配比、不同Ni/P摩尔比对催化剂活性的影响及确定活性组分Ni2P负载量,确定该加氢脱氮催化剂最佳制备方法为:当n(Ti)/n(Al)=1/4,Ni2P负载量25%(wt)。在压力为3 MPa,体积空速为3 h-1,氢油体积比为500,反应温度为360℃的条件下,催化剂的加氢脱氮活性最高,可达98%。     

磷、柠檬酸改性对MoW/Ni/Al2O3催化剂性质及加氢脱氮性能的影响

采用等体积浸渍法制备了以γ-Al₂O₃为载体,Ni、Mo、W为活性金属组分的三金属催化剂,考察了磷改性、柠檬酸改性以及磷-柠檬酸组合改性对催化剂性质、加氢脱氮性能和脱氮选择性的影响。通过NH₃-TPD、Py-IR、H₂-TPR、XPS和HRTEM对催化剂进行表征,结果表明：磷改性不但提高了催化剂的表面弱酸量,而且提高了金属的硫化性能,促进碱性氮和非碱性氮的脱除,但磷改性导致金属活性相的堆垛层数偏高、分散度下降;柠檬酸改性降低了催化剂活性金属氧化物的硫化温度,提高了催化剂的加氢活性,但对氢解性能基本没有影响,表现为非碱性氮脱除性能的提高;而磷-柠檬酸组合改性,不但提高了催化剂的氢解性能,而且改善了其加氢活性,使催化剂对焦化蜡油中碱性氮和非碱性氮的脱除率均得到大幅提升,分别达到80.1%、54.9%。     

载体对镍系催化剂催化对硝基苯酚加氢制对氨基苯酚的影响

采用浸渍法制备了Ni/Al2O3、Ni/TiO2、Ni/活性炭和Ni/硅藻土等一系列镍系催化剂,研究了其催化对硝基苯酚加氢制备对氨基苯酚的活性.负载型镍系催化剂具有单一的对氨基苯酚选择性.不同载体负载的催化剂上对硝基苯酚的转化率顺序为:Ni/活性炭>Ni/硅藻土>Ni/TiO2Ni/Al2O3.高比表面积以及金属镍在活性炭上的良好分散性使得Ni/活性炭催化活性最高;NiO与硅藻土间弱相互作用,有助于提高活性;而NiO与Al2O3之间存在相互作用抑制了还原后金属镍的催化加氧活性.     

柠檬酸对Ni-W焦化蜡油加氢处理催化剂性能的影响

以含改性HY分子筛的TiO₂-SiO₂复合氧化物为载体,以Ni、W为活性金属组分,采用等体积溶液浸渍法制得了焦化蜡油加氢处理催化剂,考察了浸渍液中加入柠檬酸对催化剂性质及加氢精制性能的影响。BET、FT-IR、XRD、UV-Vis DRS和TG-DSC等表征结果表明,柠檬酸与金属组分间的络合作用提高了金属活性组分的分散度,改变了金属组分的存在状态,促进了单一形式的聚钨酸盐和高活性的六配位八面体Ni物种的形成。柠檬酸改性的Ni-W系催化剂对焦化蜡油的加氢精制性能明显改善,尤其是加氢脱氮性能得以大幅度提高。     

Ni/W比对NiWCx催化剂加氢性能的影响

过渡金属碳化物具有类似贵金属的电子结构和加氢性能。采用等体积浸渍法制备了不同Ni/W比的NiW/γ-Al₂O₃催化剂,以程序升温碳化法转化为NiW碳化物后对芳烃模型化合物和低温煤焦油中分离所得芳烃组分进行加氢处理。催化剂的N₂吸附、XRD、H₂-TPR和SEM表征表明,Ni的添加促进了载体表面WO₃物种的分散和还原,抑制了WO₃晶体的团聚和大晶粒的生成。萘的加氢实验表明,Ni/W原子比为0.6时催化剂的活性最佳,而添加苯酚和吡啶后的模型油加氢过程中萘的转化率和十氢萘的产率均明显下降,Ni/W原子比为0.47和0.6的催化剂性能相近,煤焦油中芳烃组分加氢后Ni/W原子比为0.47的催化剂性能更优。结果表明,Ni和W均具有良好的加氢活性,但Ni耐杂原子性能较差,二者存在一个最佳的配比以使加氢性能更优。有杂原子化合物存在时,如煤基芳烃组分的加氢,Ni/W原子比为0.47的NiW碳化物催化剂具有更好的加氢性能。     

Highly dispersed NiW/γ-Al2O3 catalyst prepared by hydrothermal deposition method

This article describes a novel hydrothermal deposition method for preparing highly dispersed NiW/γ-Al₂O₃ catalysts and demonstrates its advantages over the conventional impregnation method. Via the hydrothermal precipitation reactions between sodium tungstate and hydrochloric acid and between nickel nitrate and urea, respectively, the active species W and Ni were deposited on γ-Al₂O₃. In the hydrothermal deposition of WO₃, a surfactant hexadecyltrimethyl ammonium bromide (CTAB) was used to prevent the aggregation of WO₃. The characterization results obtained by means of X-ray photoelectron spectroscopy (XPS), N₂ adsorption and high-resolution transmission electron microscopy (HRTEM) measurements showed that compared with the catalyst prepared by the conventional impregnation method, the catalyst with the same metal contents prepared by the hydrothermal deposition had much higher W and Ni dispersion, higher specific surface area, larger pore volume, the significantly decreased slab length and slightly increased stacking degree of sulfided W species, leading to the significantly enhanced dibenzothiophene (DBT) hydrodesulfurization (HDS) activity. The DBT HDS assessment results also revealed that the catalyst containing 17.7 wt% WO₃ and 2.4 wt% NiO prepared by the hydrothermal deposition method had the similar DBT HDS activity as a commercial NiW/γ-Al₂O₃ catalyst containing 23 wt% WO₃ and 2.6 wt% NiO, resulting in the greatly decreased amount of active metals for achieving the same HDS activity.     

费托合成蜡USY分子筛基加氢裂化催化剂的制备及其性能

以Ni/W为加氢活性组分,USY/SiO2-Al2O3为载体,采用浸渍法制备了费托合成蜡加氢裂化催化剂,对其进行了表征、活性相研究及活性评价. 结果表明,Ni/W以高分散度形式分散在催化剂载体上,催化剂具有比表面积较大、吸附能力强的中孔结构,在340, 548和870℃上有3个还原峰,分别对应NiO?Ni, W6+?W4+及W4+?W2+或W. 硫化态催化剂表面同时含NiWS, WS2和NiSx等活性相,WS2相片晶堆垛层数决定催化剂的活性. 烯烃具有较高的加氢反应活性,烷烃会裂化异构成小分子的烯烃,其中有的吸附态可能是进一步形成小分子烷烃过程中产生的中间过渡态. 在温度370℃、压力6.4 MPa、氢油体积流量比800、空速2.5 h-1的条件下,石蜡转化率约为50%,柴油的选择性约为90%. Ni/W均匀浸渍在USY/SiO2-Al2O3载体上,可获得相对均衡的加氢-裂解性能匹配,在不降低蜡转化率的同时保证了柴油的高选择性.     

Synergism Between Ni and W in the Niw/ γ-Al2O3 Hydrotreating Catalysts

A series of NiW/ γ-Al₂O₃ catalysts (20 and 30 wt% W and 1–5 wt% Ni) have been prepared and studied by TPR and XPS. HDS activity has been tested in the thiophene conversion. The effect of Ni and W loadings on the formation of different structures is presented. In the calcined catalysts several phases coexist, concentrations of which depend on the Ni/(Ni+W) atomic ratio. The Ni synergistic effect in the HDS reaction is confirmed by the increase in the HDS activity (~10–15 times). This effect is ascribed to the formation of an active NiWS phase of high dispersion from the mixed NiW oxide precursors. At higher Ni/Ni+W ratio a redistribution of active components in additional amount ofNiWS phase during sulfidation is suggested.     

以类水滑石为前体的Ni催化剂及其催化甲烷水蒸气重整制氢:催化活性和动力学(英文)

Ni/Mg–Al catalysts derived from hydrotalcite-type precursors were prepared by a co-precipitation technique and applied to steam reforming of methane. By comparison with Ni/γ-Al2O3 and Ni/α-Al2O3 catalysts prepared by in-cipient wetness impregnation, the Ni/Mg–Al catalyst presented much higher activity as a result of higher specific surface area and better Ni dispersion. The Ni/Mg–Al catalyst with a Ni/Mg/Al molar ratio of 0.5:2.5:1 exhibited the highest activity for steam methane reforming and was selected for kinetic investigation. With external and inter-nal diffusion limitations eliminated, kinetic experiments were carried out at atmospheric pressure and over a temperature range of 823–973 K. The results demonstrated that the overal conversion of CH4 and the conversion of CH4 to CO2 were strongly influenced by reaction temperature, residence time of reactants as wel as molar ratio of steam to methane. A classical Langmuir–Hinshelwood kinetic model proposed by Xu and Froment (1989) fitted the experimental data with excellent agreement. The estimated adsorption parameters were consistent thermodynamical y.     

甘油水蒸汽重整制氢Ni、Co、Fe催化剂的研究

采用等体积浸渍法制备了催化剂,研究了Ni/Al2O3,Fe/Al2O3,CoMo/Al2O3和NiCo/Al2O3催化剂对甘油水蒸汽重整制氢反应的催化效果,对催化剂进行BET、TPR、XRD表征,以氢产率为实验指标对催化剂进行了评价。研究结果表明,CoMo/Al2O3催化剂在温度650℃氢产率6.02。NiCo/Al2O3催化剂在温度600℃、水醇比16、液空速0.12 h-1条件下的氢产率为6.08。催化剂活性次序为NiCo/Al2O3Co-Mo/Al2O3Ni/Al2O3Fe/Al2O3。     

Catalytic methanation of syngas over Ni-based catalysts with different supports

Co-precipitation method was selected for the preparation of Ni/Al2O3, Ni/ZrO2 and Ni/CeO2 catalysts, and their performances in methanation were investigated in this study. The structure and surface properties of these catalysts were characterized by BET, XRD, H2-TPD, TEM and H2-TPR. The results showed that the catalytic activity at low temperature followed the order:Ni/Al2O3>Ni/ZrO2>Ni/CeO2. Ni/Al2O3 catalyst presented the best catalytic performance with the highest CH4 selectivity of 94.5%. The characterization results indicated that the dispersion of the active component Ni was the main factor affecting the catalytic activity and the one with higher dispersion gave better performance.