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1.
以脱硫选择性不同的2组催化裂化汽油加氢脱硫催化剂为研究对象,采用CO吸附原位红外光谱表征了2组催化剂的活性相特征,并通过分子模拟计算方法比较了助剂Co加入前后噻吩和1-己烯在催化剂表面的电荷分布、吸附能及其加氢反应的活化能等,探讨了助剂Co的加入对选择性加氢脱硫催化剂脱硫选择性的作用机理.结果表明,加氢脱硫催化剂CoMoS活性相的增加有利于提高催化剂的加氢脱硫/加氢降烯烃(HDS/HYD)选择性.与1-己烯加氢位相比,Co的加入显著提高了噻吩分子加氢位的缺电子性,噻吩在催化剂表面的吸附度增强,显著降低噻吩加氢反应的能垒,从而使噻吩加氢反应更易进行.这也表明CoMoS为高HDS活性、高HDS/HYD选择性的活性相.  相似文献   

2.
采用固相合成法制备了ZnO—ZrO2载体,并采用浸渍法制备了镍基催化剂,以噻吩加氢脱硫反应为探针考察了Co、Mo的掺杂对Ni/ZnO—ZrO2催化性能的影响.采用NH,吸附红外光谱(IR)、程序升温脱附(TPD)、程序升温还原(TPR)、X射线衍射(XRD)等技术对催化剂进行了表征.研究结果表明,ZnO-ZrO2复合载体对噻吩加氢脱硫反应有一定的活性,反应温度为400℃时噻吩转化率为6.4%;Co的加入提高了Ni/ZnO-ZrO2的催化活性,噻吩转化率可达97.3%;相反,Mo的掺杂则降低了Ni/ZnO—ZrO2的催化活性,噻吩转化率为65.0%.这是由于Co的掺杂使活性组分Ni分散度提高,氧化态的Ni变得容易还原,在同样的还原条件下催化剂表面有更多的活性中心;而Mo掺杂则使Ni/ZnO—ZrO2催化剂中氧化态的Ni变得难以还原,部分以NiO形式存在,活性中心数量减少.三种催化剂表面均存在L酸中心,Co掺杂使Ni/ZnO-ZrO2催化剂表面弱酸中心和中等强度酸中心的强度及数量均增大.No掺杂则减弱了催化剂表面弱酸中心和中强酸中心的强度.对其酸量则影响不大.  相似文献   

3.
 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.  相似文献   

4.
采用连续流动微反装置考察了活性组分Ni/((Ni+W)原子比及预硫化条件对NiW/γ-Al2O3催化剂噻吩加脱硫(HDS)反应活性的影响,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都影响NiW/γ-Al2O3催化剂的HDS反应活性,对于在较低温度(300℃)下硫化的催化剂,当反应温度较低(260-290℃)时,最佳Ni(Ni+W)原子比为0.50,而当反应温度较高(330-360℃),最佳Ni(Ni+W)原子比为0.23,当催化剂在300-500℃下硫化时,其噻吩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较高的HDS反应活性。  相似文献   

5.
石油馏份油加氢精制的核心是馏份油的加氢脱硫(HDS)和加氢脱氮(HDN)。目前用于基础研究与工业过程的加氢精制催化剂主要是负载型过渡金属硫化物[Co(Ni)Mo(W)/γ-AI2O3]^[1,2]。近年来的研究结果表明,在活性相中引入其它适宜种类的助剂组元有助于催化剂活性及产物选择性的改善^[3,4]。本文以Keggin型钼磷酸为硫化物前体活性相钼磷源、硝酸镍为镍源制成不同钼含量的负载型硫化态三组元催化剂(NiMoP/γ-AI2O3),并在TPR及连续流动固定床反应装置上考察了催化剂的氢还原性能及模型底物噻吩HDS反应活性。  相似文献   

6.
Mo、W对Ni/γ-Al2O3催化剂烯烃加氢性能的影响   总被引:1,自引:0,他引:1  
采用浸渍法制备了一系列NiM/γ-Al2O3(M=Mo、W)催化剂。通过馏分油(沸点70℃~350℃)烯烃的加氢饱和,考察了Mo、W对Ni基催化剂加氢性能的影响,并采用TPR、XRD、XPS对催化剂进行表征。TPR结果表明,添加助剂Mo(W)降低了低温还原峰温度,但还原度有所降低,而且NiMo催化剂还原度的降低幅度比NiW催化剂更大;XRD结果表明,Mo(W)的添加提高了活性组分Ni的分散度,并且Mo的助分散作用优于W;XPS结果表明,Mo(W)的引入提高了催化剂体系“表面NiAl2O4”的比例,Ni2p3/2谱峰的化学位移说明助剂的添加增强了Ni与载体γ-Al2O3之间的相互作用。  相似文献   

7.
采用孔饱和共浸法制备了一系列具有相同W含量和不同Ni含量的NiW/AI2O3催化剂,并对相应的硫化态催化剂进行了XPS和HREM表征.结果表明,引入的助剂Ni优先修饰WS2晶粒的边角位置,形成高活性的NiWS相.催化剂中助剂Ni在噻吩加氢脱硫反应中的显著促进效应(活性提高了约30倍)与形成的NiWS活性相数量有关.同时,助剂Ni的引入使得催化剂表面WS2晶粒的堆叠程度略有增加,晶片长度略有减小;而且引入助剂后WO,相的硫化度提高了近20%.但相比之下,活性相织构的变化和硫化度的增大对催化脱硫活性的贡献较小,不是Ni产生助剂效应的主要原因.  相似文献   

8.
考察了Ru助剂对Mo和Co-Mo/Al_2O_3催化剂加氢脱硫性能的影响,发现少量Ru(NO_3)_3的引入可显著提高催化剂的HDS(加氢脱硫)和HYD(环己烯加氢)性能。测定了硫化态催化剂的化学吸H_2、O_3和CO量,表明Ru助剂的作用主要是促进催化剂上形成更多的活性中心。  相似文献   

9.
采用等体积浸渍法将硫代硫酸铵(ATS)负载在Mo/AC催化剂上,制备了器外预硫化的Mo/AC-ATS催化剂;以噻吩加氢脱硫(HDS)为探针反应,考察了活化温度和活化时间对预硫化催化剂加氢脱硫活性的影响。研究发现,300 ℃下活化0.5 h所得到的预硫化催化剂具有最好的加氢脱硫活性。与传统硫化剂CS2和DMDS硫化的催化剂相比,采用Mo/AC-ATS催化剂,在最佳活化条件下,噻吩转化率分别提高了34%和42%。XPS、TPR-MS和TEM等表征结果显示,预硫化的Mo/AC-ATS催化剂中Mo4+含量较高,这是其具有较高加氢脱硫活性的主要原因。  相似文献   

10.
 采用孔饱和共浸法制备了一系列具有相同W含量和不同Ni含量的NiW/Al2O3催化剂,并对相应的硫化态催化剂进行了XPS和HREM表征. 结果表明,引入的助剂Ni优先修饰WS2晶粒的边角位置,形成高活性的NiWS相. 催化剂中助剂Ni在噻吩加氢脱硫反应中的显著促进效应(活性提高了约30倍)与形成的NiWS活性相数量有关. 同时,助剂Ni的引入使得催化剂表面WS2晶粒的堆叠程度略有增加,晶片长度略有减小;而且引入助剂后WOx相的硫化度提高了近20%. 但相比之下,活性相织构的变化和硫化度的增大对催化脱硫活性的贡献较小,不是Ni产生助剂效应的主要原因.  相似文献   

11.
Mo(W)-Co(Ni,Fe)簇合物的加氢脱硫催化活性   总被引:1,自引:0,他引:1  
对线型、立方烷型和笼状3种不同构型的Mo(W)-Co(Ni,Fe)-S(O)簇共12种化合物进行了噻吩加氢脱硫和环己烯加氢的催化活性研究.讨论了簇合物的组成,金属原子的配比、价态与催化活性的关系.探讨了不同构型对活性的影响.  相似文献   

12.
用准“原位”XPS技术研究了Mo/Al_2O_3、Mo/TiO_2-Al_2O_3、CO/Al_2O_3、CO/TiO_2-Al_2O_3、Co-Mo-Al_2O_3和Co-Mo/TiO_2-Al_2O_3等催化剂的硫化过程.结果表明:对以Al_2O_3为载体的催化剂,当Mo或Co载量较低(分别低于0.05 gMoO_3/gAl_2O_3或0.03gCoO/gAl_2O_3)时,没有Mo或Co硫化物的生成,而以TiO_2改性的Al_2O_3为载体的催化剂,Mo/TiO_2-Al_2O_3催化剂的硫化较Mo/Al_2O_3容易得多, 表现为在较低温度下,负载在TiO_2改性Al_2O_3载体上的MoO_3,能很快硫化并达到相当大的硫化度, 对Co/Al_2O_3催化剂而言,即使在较高温度400 ℃时,载体上高分散的CoO物种仍难以硫化;而Co_3O_4微晶的硫化却容易得多, 载体用TiO_2改性,并不影响高分散形态的CoO催化剂的硫化,却明显地影响Co_3O_4微晶的硫化.噻吩加氢脱硫(HDS)的活性测量指出,对Co-Mo/Al_2O_3和Co-Mo/TiO_2-Al_2O_3催化剂而言,HDS活性和硫化度之间存在着良好的相关性.并用TiO_2改性载体,可以增加Co-Mo催化剂的HDS活性和硫化度.  相似文献   

13.
采用孔饱和浸渍法制备了不同Mo/(Mo+V)原子比的Mo-V/Al2O3催化剂,运用拉曼光谱、H2程序升温还原和高分辨透射电镜对催化剂进行了表征,同时以萘为模型化合物,考察了催化剂的加氢活性;以科威特常渣为原料,考察了其加氢脱金属和脱硫活性.结果表明,在上述反应中,Mo与V具有协同作用.由于渣油中金属和硫的存在形态不同,并且V-Mo-S相和V-S相对于渣油加氢脱金属反应的催化作用要大于渣油加氢脱硫反应,因此与Ni-Mo/Al2O3催化剂相比,Mo-V/Al2O3催化剂的脱金属活性较高,而脱硫活性较低.  相似文献   

14.
A hydrotreating NiMo/γ-Al2O3 catalyst(12 wt% Mo and 1.1 wt% Ni) was prepared by impregnation of the support with the Anderson-type heteropolyoxomolybdate(NH4)4Ni(OH)6Mo6O18.Before impregnation of the support,it was modified with an aqueous solution of H3BO3,Co(NO3)2,or Ni(NO3)2.The catalysts were investigated using N2 adsorption,O2 chemisorption,X-ray diffraction,UV-Vis spectroscopy,Fourier transform infrared spectroscopy,temperature-programmed reduction,temperature-programmed desorption,and X-ray photoelectron spectroscopy.The addition of Co,Ni,or B influenced the Al2O3 phase composition and gave increased catalytic activity for 1-benzothiophene hydrodesulfurization(HDS).X-ray photoelectron spectroscopy confirmed that the prior loading of Ni,Co or B increased the degree of sulfidation of the NiMo/γ-Al2O3 catalysts.The highest HDS activity was observed with the NiMo/γ-Al2O3 catalyst with prior loaded Ni.  相似文献   

15.
Co- or Ni-promoted Mo sulfide catalysts were prepared by combining three methods, sonochemical synthesis of Mo sulfides, promoter addition by chemical vapor deposition (CVD), and fluorination of alumina support, to improve their performance in the hydrodesulfurization (HDS) process. Sonochemically synthesized Mo sulfides exhibited higher HDS activity, particularly for the hydrogenation (HYD) of dibenzothiophene (DBT) compounds, than in the case of the catalysts prepared by impregnation due to the improved dispersion of the Mo species. The addition of Co or Ni to the catalyst by a CVD method allowed the selective decoration of the Mo-sulfide surface with the promoter and accordingly produced greater amounts of the Co–Mo–S and Ni–Mo–S phases, which are known to be active sites for HDS. The performance of catalysts prepared by combining sonochemical and CVD methods was further improved by the addition of fluorine, which generated Brönsted acid sites that were responsible for the HYD route and also for the migration of methyl groups in 4,6-dimethyldibenzothiophene (4,6-DMDBT).  相似文献   

16.
The thiophene hydrodesulfurization (HDS) reaction on γ-Al2O3 supported CoMo, NiMo and NiW sulfide catalysts was compared in order to gain insight into the promoter effect on direct desulfurization (DDS) and hydrogenation (HYD) pathways. Ni-promoted Mo (or W) sulfide catalysts favor the hydrogen transfer reactions relative to CoMo sulfide catalyst, which facilitates the direct route instead. This different performance and also the dependence of the apparent Arrhenius parameters with the catalyst formulation were attributed to the major participation of Mo (or W) edge for the Ni-containing catalysts and S edge for CoMo sulfide catalyst upon the thiophene-HDS reaction.  相似文献   

17.
The Ni2P promoted and γ-Al2O3 supported NiMoW sulfide catalyst consisting of 4 wt% Mo, 22 wt% W, 2 wt% Ni and 2.5 wt% Ni2P was synthesized by a co-impregnation method. The catalysts were characterized by N2 adsorption-desorption, X-ray diffraction (XRD), diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, NH3 temperature-programmed desorption (NH3-TPD) and transmission electron microscopy (TEM). The results showed that Ni2P, Ni, Mo and W species were highly dispersed over γ-Al2O3. The hydrodesulfurization (HDS) of dibenzothiophene (DBT) showed that the presence of Ni2P brought a strong promotional effect on the HDS activity, which was further confirmed by the HDS and hydrodenitrogenation (HDN) of diesel oil under industrial conditions. The enhancement in HDN activity and stability by Ni2P addition could be attributed more to the effect of new active sites of Ni2P than that of acidity modification. The as-prepared Ni2P-NiMoW/γ-Al2O3 catalyst showed better hydrotreating performance than NiMoW/γ-Al2O3 and commercial catalysts.  相似文献   

18.
以大孔Al2O3为基载体,采用沉积-沉淀法和溶胶-沉积法制备了负载型纳米ZrO2/Al2O3复合载体.用XRD、TEM和比表面与孔径测定等手段对载体进行了表征.结果表明,负载型纳米ZrO2/Al2O3复合载体具有较大的比表面积和适宜的孔径分布,纳米ZrO2在载体上呈单层均匀分布.以CH4-CO2重整制合成气为探针反应,考察了Ni/ZrO2/Al2O3催化剂的活性和选择性.  相似文献   

19.
K助化Co—Mo/Al2O3催化剂的表征   总被引:1,自引:0,他引:1  
  相似文献   

20.
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.  相似文献   

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