Synthesis of Zirconium Modified Spherical Mesostructured Cellular

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Synthesis of Zr Modified Spherical Mesostructured Cellular Foams Silica and Its Hydrodesulfurization Performance for FCC Diesel Bo Wang, Shaotong Song, Longnian Han, Aijun Duan, Chunming Xu, Zhentao Chen, Qian Meng, Xinguo Chen, Jianmei Li, and Dong Wang Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.7b00376 • Publication Date (Web): 23 Mar 2017 Downloaded from http://pubs.acs.org on March 28, 2017

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Synthesis of Zr Modified Spherical Mesostructured Cellular Foams Silica and Its Hydrodesulfurization Performance for FCC Diesel Bo Wang‡1, 3, Shaotong Song‡2, Longnian Han3, *, Aijun Duan1, *, Chunming Xu1, Zhentao Chen1, Qian Meng1, Xinguo Chen3, Jianmei Li1, Dong Wang3 1

State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing, 102249, P. R. China 2

Petrochemical Research Institute, PetroChina Company Limited, Beijing 100195, P. R. China. 3

CNOOC Rersearch Institute of Oil and Petrochemicals, Beijing 102209, China

* corresponding authors, E-mail: [email protected]; [email protected] Abstract: Zr modified spherical mesostructured cellular silica foams (MCFs) with different Zr contents were successfully synthesized via incipient wetness impregnation method. The characterization results of FTIR, SEM and SAXS indicated that zirconium was fabricated into the silicon framework, meanwhile the parent sphere-like morphology and topological structure were retained. Additionally, BET results showed that the as-synthesized materials possessed ultra-large pore volume (1.56 cm3/g), large pore size (15.9 nm) and high surface area (467 m2/g) as the weight percentage of Zr in the support was 12.6 %, demonstrating that MCFs would be an alternative support for hydrotreating catalyst. Furthermore, the corresponding supported NiMo/Zr-MCFs catalysts were well-characterized. It was found that zirconium as an electronic promoter not only facilitated the formation of NiMoO4 precursor but also enhanced the redox

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ability of the catalysts as well as brought Brønsted and Lewis acid sites into MCFs, which were conductive to the HDS performance. Then the catalyst activities were evaluated by using FCC diesel as feedstock, in which NiMo/Zr-MCFs-6.9 catalyst (Si/Zr = 20) had the highest hydrodesulfurization (97.3 %) and hydrodenitrogenation efficiencies (98.1 %), correspondingly, the main reasons could be ascribed to its desirable textural property, suitable redox ability, appropriate dispersion degree of active metals and moderate acid property. Keywords: Mesoporous material, MCFs, Zirconium, Hydrodesulfurization, FCC diesel 1. Introduction The sulfur content of transportation fuels is expected to be severely depleted due to the urgency of solving environmental problems caused by the exhaust emissions, especially SO2 pollutants are easy to result in acid rain and particulate matter (PM) formation. Catalytic hydrotreating is the most efficient sulfur removal technology in the industrial production compared with adsorption, oxidative desulfurization and other technologies [1]. Catering to the increasingly stringent specification of transportation fuels, hydrotreating catalysts with high activity are needed to realize the ultra-deep HDS. Recently, some attempts have been made to achieve higher catalytic activity, such as active metals compatibility [2, 3], metal dispersion [4], supports characteristics [5, 6] and so on. Since the HDS performance has intimate dependence in the properties of supports, the design and application of novel materials to be the catalyst supports have aroused interest of many researchers [7, 8].


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Compared with the traditional γ-Al2O3 supported catalysts, ZrO2 supported catalysts have attracted considerable attention due to their excellent intrinsic HDS activities [9-11]. However, the disadvantages of pure ZrO2 supports such as their low specific surface areas and small pore sizes resulted from the agglomeration of ZrO2 particles are unfavorable to the HDS reaction, which usually result in a lower normalized activity (over per gram of catalyst) than the commercial γ-Al2O3 supported catalysts, therefore, inhibiting their extensive applications in industry [12, 13]. In order to solve this problem, some researchers incorporated ZrO2 into the mesoporous silica materials, which have the outstanding textural characteristics of large surface area, tunable and uniform pore size distribution. Therefore, a series of zirconium-containing materials were prepared involving Zr-MCM-41 [14], Zr-SBA-15 [15-18], Zr-HMS [19], ZrTUD-1 [20, 21] et al. Generally, two typical methods can be used to introduce zirconium into mesoporous materials: direct mixed-gel incorporation [22, 23] and post-synthetic modification [17, 20]. Direct mixedgel synthesis method can incorporate more Zr species into the framework of supports, meanwhile maintain the characteristic textural properties of the parent materials. However, it may cause the collapse of pore structure when adding excessive zirconium. For HDS catalysts, the postsynthetic method, which contains incipient wetness impregnation method and chemical grafting method, is widely used, since (1) the integrity of the structure and texture of the parent materials can be retained when introducing significant amounts of Zr species, (2) Zr species are mostly


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located on the surface of materials, which are conducive to interact with the active metals [24, 25]. However, the post-synthetic method may cause slightly blockage of pore structure. In our previous research, Zr modified mesoporous molecular sieves TUD-1 and the corresponding NiMo supported catalyst were successfully prepared and evaluated by FCC diesel, the catalytic performance exhibited a better HDS efficiency than the pure Si-TDU-1 supported catalysts. It was found that Zr incorporation adjusted the active metals distribution and facilitated to the formation of MoS2 phases with short slab length and appropriate stacking layer [20]. Moreover, Castellon and co-workers [26] compared the activity of Zr-MCM-41 catalysts with the alumina supported catalyst as a reference in dibenzothiophenes (DBT) HDS reaction. The result showed that Zr-containing catalysts exhibited better HDS performances, because Zr modification decreased the stacking layer number of active phases and led to more homogeneous active metal distribution. Besides [27], Zr-SBA-15 catalysts possessed higher activities in 4,6demethyldibenzothiophene (4,6-DMDBT) HDS than the pure SBA-15 catalyst, because the incorporation of Zr acting as electronic promoter could affect the redox ability of catalysts, which made active metals easier to be reduced. Moreover, the introduction of Zr species could overcome the defect of weak acidity caused by their electrically neutral Si framework, and the improvement of surface acidity facilitated to HDS performance [20]. Compared with the above mesoporous materials, mesostructured cellular silica foams (MCFs) exhibits more outstanding textural properties, such as larger pore size (20-50 nm), pore volume


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(2.6 cm3/g) and three-dimensional pore structure, which benefit the diffusion of large molecule reactants and the increase of the accessibility between active sites and reactant molecules. Besides, its large BET surface area (around 1000 m2/g) supplies enough space for better dispersion of active metals [28-30]. Thus, MCFs is thought to be a potential support for hydrodesulfurization catalyst [28]. Based on the excellent catalytic performance brought by the Zr incorporation and the prominent structure properties of MCFs, a series of Zr-MCFs supports with different zirconium contents were synthesized through incipient wetness impregnation method. The BET surface area was still retained as 467 m2/g and pore size was up to 15.9 nm when the wt. % of Zr was as high as 12.6 %. Then, the corresponding NiMo supported catalysts were evaluated by using FCC diesel as feedstock. The relationship between the dispersion degree of Mo species and Zr loading contents were discussed in detail, which will be indicative to the design of HDS catalysts with high efficiency. 2. Experimental Section 2.1 Material synthesis According to our previous research [28], P123 (EO20PO70EO20, Aldrich), 1,3,5trimethylbenzene (TMB) and tetraethyl orthosilicate (TEOS) were respectively used as the template agent, swelling agent and silica source. Typically, 2 g P123 was well-dissolved into 60 g of 2.0 M HCl aqueous solution with stirring at 35 ℃. Then, adding an amount of TMB into the


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mixture and maintaining agitation for a certain time, after that, 6.4 g TEOS was dribbled in the above solution. The obtained mixture was stirred for 10 min and then placed statistic for 24 h under the water-bath of 35 ℃. Finally, the mixture was poured into Teflon bottle and crystallized at 120 ℃ until 24 h later. The final materials were obtained through filtering, washing, drying at 80 ℃ for 12 h and then calcined at 550 ℃ for 6 h under the air environment. Zr-modified MCFs supports were prepared using ZrOCl2·8H2O as zirconium source through incipient wetness impregnation method. Firstly, aqueous solution containing a certain amount of ZrOCl2·8H2O was dropped into the calcined MCFs materials. In order to improve the dispersion of Zr species on the MCFs surface, ultrasonic vibration was used to assist the impregnation. After dispersed in ultrasonic bath for 20 min, the materials were then dryed at 110 ℃ for 4 h and calcined at 550 ℃ for 6 h. In this case, no additional filtering and washing operations were carried out after Zr modification. Zr-containing MCFs materials were named as ZrM-x, where x meant the weight percentage of Zr in the support. The loading content of Zr varied from 2.9 % to 12.6 %, corresponding to the Si/Zr mole ratio from 50 to 10. The corresponding NiMo/ZrM-x catalysts were synthesized successfully via a two-step incipient

wetness

impregnation

method

with

firstly

impregnating

Mo

precursor

((NH4)6Mo7O24·4H2O) and secondly impregnating Ni precursor (Ni(NO3)2·6H2O). After each impregnation step, the as-prepared samples were treated under ultrasonic vibration for 20 min


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and dried at 110 ℃ for 4 h, and then calcined at 550 ℃ for 6 h. All the obtained catalysts had the same active metal loadings (15.5 wt% MoO3 and 3.5 wt% NiO). The reference conventional NiMo/γ-Al2O3 catalysts were prepared using the same impregnation method as NiMo/ZrM-x catalysts, of which the γ-Al2O3 supports were obtained from the calcination of pseudoboehmite (bought from Zhengzhou Aluminum Industry Research Institute). 2.2 Characterization Small angle X-ray scattering (SAXS) patterns were measured on a NanoSTAR small-angle Xray scattering system (Bruker, Germany) using Cu kα radiation (40 KV, 35 mA) resource. N2 physisorption were characterized in a Micromeritics Tristar 3020 instruments. The pore sizes and the specific surface areas were obtained using the Barrett–Joyner–Halenda (BJH) method and the Brunauer-Emmett-Teller (BET) method respectively. And the total volumes of micro and mesopores were calculated from the adsorbed amounts of nitrogen at the relative pressure of P/P0=0.99. The normalized BET surface areas (NSBET) were calculated as the following equation: NSBET = SBET of catalyst/[(1-y) × SBET of support]

(1)

Where y represents the weight fraction of zirconium incorporated in the supports. The scanning electron microscopy (SEM) images were observed on a Cambridge S-360 instrument, and the transmission elecrtron microscopy (TEM) images were obtained through a


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JEOL JEM 2100 electron microscope. The EDS elemental mapping analyses were characterized on a Tecnai F20 electron microscopy. H2-TPR analysis was recorded using a Quantachrome apparatus (Autosorb-iQ USA). First, 0.1 g sample was loaded into the reaction tube and treated at 400 ℃ for 2 h in the atmosphere of Ar gas and then cooled to 50 ℃. After that, the Ar stream was changed to 10% H2/Ar and the temperature was ramped from 50 ℃ to 1000 ℃ with the rate of 10 ℃·min-1 and kept for 30 min. The TCD signal reflected the H2 adsorption amount. UV-vis diffuse reflectance spectroscopy was measured on a Hitachi U-4100 spectrophotomer in the wavenumbers ranging from 200 to 800 nm with the integration sphere diffusion reflectance attachment. Fourier transform infrared (FTIR) spectra were recorded on a DIGILAB FTS-3000 apparatus using KBr as diluent with the wavenumber range of 400 to 4000 cm-1. PyFTIR analyzed the acidity of NiMo/ZrM-x catalysts on a MAGNAIR 560 FTIR spectrophotometer with a resolution of 1 cm-1. The Raman spectra of the prepared catalysts were recorded on a Renishaw Invia Raman spectrometer with the He/Cd laser wavelength of 532 nm. XPS tests of the sulfided catalysts was measured in a Thermo Fisher K-Alpha spectrometer using Alkα (hν = 1484.6 ev). All the obtained data need to be calibrated by taking C 1s spectrum (Binding energy = 284.6 ev) as a standard. 2.3 Catalytic activity


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The catalytic activities were evaluated in a fixed bed reactor by using FCC diesel as feedstock, the sulfur and nitrogen content are 1013.8 mg·L-1 and 640.3 mg·L-1. Before the HDS test, 2 g fresh catalysts with the sizes of 40-60 mesh were loaded in the reaction tube, followed by in situ presulfidation using the mixture of 2.5 wt% CS2-cyclohexane under the conditions of 340 ℃ and 4 MPa. After presulfurization, the temperature and pressure were increased to 350 ℃ and 5 MPa, the H2/Oil and WHSV were maintained to 600 ml·ml-1 and 1.0 h-1 respectively, until the reaction finished. HDS and HDN efficiencies were calculated as follow: HDS efficiency (%) = (Sf - Sp)/Sf × 100%

(2)

HDN efficiency (%) = (Nf - Np)/Nf × 100%

(3)

Where Sf and Sp represents the sulfur content of feedstock and products, Nf and Np refers to the nitrogen content in feedstock and products. All the sulfur and nitrogen contents were obtained by using RPP-2000 SN sulfur and nitrogen analyzer, and the deviation of which is within 2 µg·ml-1. 3. Results 3.1 Characterization of the Zr-MCFs-x supports 3.1.1 SAXS Figure 1 shows the SAXS results of pure MCFs and the ZrM-x materials with different Zr contents. The scatting pattern of the pure MCFs material has three well-resolved peaks; one of which is the principal peak with high intensity at 0.256 nm-1 and two higher q value peaks are in relatively weaker intensity at 0.426 nm-1 and 0.626 nm-1 respectively, corresponding to the (100),


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(110) and (210) reflections associated with mesocellular foam structures [31]. The existence of higher q value peaks indicates that the materials are well-crystallized and also have narrow pore size distributions [29]. From Figure 1, with the addition of Zr, the scattering peaks are kept and the peak positions shift to larger q value, demonstrating that the original topological structures of the parent MCFs material are retained but the pore sizes become smaller. Besides, the weakened peak intensities confirm that the Zr species are primarily located on the surface of MCFs materials, in accordance with the published results in the previous researches [28, 29]. 3.1.2 X-ray diffraction To confirm the existing form of ZrO2 on the surface of MCFs, the wide angle XRD analysis is performed and the results are shown in Figure 2. All the materials exhibit broad diffraction peaks at about 22 º, denoting the presence of amorphous silica [24]. Additionally, no diffraction peaks of ZrO2 are observed when wt. % of Zr varies from 2.9 % to 6.9 %, suggesting that zirconium species are completely incorporated into the skeleton of MCFs or the dimensions of ZrO2 nanoparticles on the surface of MCFs are too small (less than 4 nm) to be detected by XRD analysis. However, with the excessive loading of Zr species (wt. % of Zr is 12.6 %), the characteristic peaks belonging to tetragonal ZrO2 at 30.17 º, 50.07 ºand 60.15 ºas well as monoclinic ZrO2 at 34.19 º appear [20], demonstrating the existence of large ZrO2 clusters. The similar phenomenon was reported by Amezcua et al [25]. They synthesized titania-modified


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SBA-16 through the incipient wetness impregnation method, when the wt. % of TiO2 was higher than 10 %, the TiO2-anatase phase appeared, and more Ti loadings, the size of the TiO2 crystallites increased. 3.1.3 BET The nitrogen absorption-desorption isotherms and the pore size distributions (PSDs) of ZrM-x supports are shown in Figure 3(a&b). From Figure 3a, all materials exhibit typical type IV adsorption isotherms with H1 hysteresis loops and sharp capillary condensation steps at high P/P0 values (about 0.85), demonstrating that the as-synthesized materials in this research possess ultra-large pore sizes and narrow pore size distributions, which is consistent with the results in Figure 2b. The textural and structural properties are summarized in Table 1. Compared with the pure silica MCFs, the specific surface areas, pore volumes and pore sizes of ZrM-x supports prepared by the incipient wetness impregnation method reduce apparently, which can be attributed to the coverage of the surface and possible blockage of the pore structure. To confirm the location of Zr species, the normalized BET surface areas which are correlated to the wt. % of ZrO2 are calculated in Eq.(1) [32], and slightly pore-plugging phenomena are found. From Table 1, the BET surface areas decrease with the increasing contents of Zr addition, indicating that parts of Zr species cannot be incorporated into the framework of MCFs while they exist as single phases and


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are loaded on the surface of supports. These phenomena are consistent with the SAXS and XRD characterization results. 3.1.3 FTIR FTIR spectra of pure MCFs and ZrM-4.7 (Si/Zr = 30) support are shown in Figure 4. The peaks centered at 460 and 808 cm-1 are due to the symmetric stretching vibration of Si-O-Si bridges [20], while the peaks at 1084 cm-1 and the broad peaks at 1231 cm-1 are assigned to the asymmetric stretching vibrations of Si-O-Si [33]. The band at 1640 cm-1 is the characteristic peak of the surface silanol group [34]. For the ZrM-4.7 material (Si/Zr = 30), the peak at 950 cm-1 attributing to the stretching of Si-O- species in Si-O-H shifts to 960 cm-1. It should be noted that the peak at around 960 cm-1 is correspond to the synergistic effect of the Si-O-H and Si-O-Zr groups [12, 20, 35], indicating that zirconium atoms are incorporated into the silicon framework successfully. 3.1.4 UV-vis DRS spectroscopy UV-vis spectroscopy can characterize the coordination state of zirconium ions in mesoporous materials [18]. Figure 5 shows the UV-vis spectra of ZrO2, ZrOCl2·8H2O (the Zr source) and ZrM-x series materials. According to the previous research [36], the peaks at 200-220 nm are assigned to the characteristic of Zr atoms in tetrahedral coordination, of which Zr atoms exist in the form of Zr(OSi)4 in the framework of silica-based materials [37, 38]. The adsorption at 230 nm is ascribed to the characteristic peak of O2-→Zr4+ bands involving Zr-O-Zr bond, which


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reflects the existence of nano-sized ZrO2 on the surface of MCFs [38]. It is obvious that the bands which are attributed to nano-sized ZrO2 blue shift, indicating that Zr species were successfully incorporated into the silicon skeleton. Moreover, except for the pure ZrO2 and ZrOCl2·8H2O, all modified materials exhibit broad peaks at about 317 nm with relatively weak intensities, which are assigned to the multi-coordinated Zr species or ZrO2 oligomers [37]. It should be noted that the peaks become intensified when increasing the Zr contents, denoting that suitable amounts of Zr can be fabricated into the framework of MCFs rather than present as the isolated phases. 3.1.5 SEM & TEM characterizations The field emission scanning electron microscope (SEM) can be performed to investigate the effect of Zr modification on the morphology of MCFs, and the images are displayed in Figure 5. All samples exhibit highly mono-dispersed particles with respect to their original sphere-like morphologies, representing that the incorporation of Zr species do not lead to the significant change of morphology. However, as Figure 6(a) shows, when incorporating excessive zirconium (wt. % of Zr is 12.6 %), small amount of ZrO2 particles are formed on the surface of spherical Zr-MCFs, which is in accordance with the XRD and UV-vis DRS characterizations. The TEM images of the representative sample ZrM-4.7 (Si/Zr = 30) are shown in Figure 7(a). Compared with the pure MCFs, the typical mesostructured cellular foam structure was retained, indicating that the Zr incorporation did not cause the damage of pore structure. Additionally,


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ZrO2 crystallization phases are hardly observed, denoting that the Zr species achieve a highly dispersion on the surface of MCFs. From TEM image in Figure 7(a), the supports possess ultralarge pore sizes, corresponding well with the BET results. 3.2. Characterization of the NiMo/Zr-MCFs-x catalysts 3.2.1 SAXS The SAXS profiles of the prepared NiMo/ZrM-x catalysts are shown in Figure S1. It should be noticed that the catalysts still exhibited the same characteristic peaks of mesocellular foam structure with their corresponding supports at low q value, indicating that the topological structure are well-retained after loading Ni and Mo active metals. However, the peaks are relatively weaker than the corresponding supports since parts of the material surfaces and pore channels are covered or blocked by the active components after impregnation. 3.2.2 BET N2 physisorption isotherms and the detailed textural properties of the corresponding supported NiMo/ZrM-x and the reference NiMo/γ-Al2O3 catalysts are shown in Figure 8 and Table 2 respectively. From Figure 8, NiMo/γ-Al2O3 catalyst exhibits a typical H4 hysteresis loop, indicating the presence of inter-particle space. Although the pore size is slightly smaller than the MCFs supported catalysts, its surface area and pore volume are significantly lower. For the NiMo/ZrM-x series catalysts, the hysteresis loops retain their original shape characteristics of MCFs materials. In comparison with the pure supports (Table 1), all the catalysts exhibit sharp


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decreases in pore volumes and specific surface areas resulted from the metal coverage and pore blockage. However, NiMo/ZrM-6.9 (Si/Zr = 20) catalyst possesses the greatest pore structure with BET surface area of 347 m2/g and BJH pore diameter of 12.5 nm. 3.2.2 Raman spectroscopy Raman spectra are sensitive to the crystalline symmetry and can identify the conditions of the active metal oxides presented on the catalysts [17, 39]. For all NiMo/ZrM-x catalysts, four bands at 361, 818, 900 and 955 cm-1 respectively are observed. The band centered at 361 cm-1 is attributed to the vibration of terminal Mo=O band in form of MoO42- (tetrahedral coordination). The weak intensity peak at about 818 cm-1 is ascribed to the characteristic feature of the Mo=O stretching vibrations presented in orthorhombic MoO3, indicating the existence of highly dispersed orthorhombic MoO3 on the catalyst surfaces [28]. Moreover, the sharp bands at 955 cm-1 confirm the presence of β-NiMoO4 crystalline phases [40]. These species are the precursors of type II NiMoS phases in the sulfided catalysts, which have a good linear relationship with HDS efficiency [41, 42]. However, the peak at 948 cm-1, which is assigned to the Mo7O246species, are not found clearly because the amount of NiMoO4 precursor phases are distinguishably higher than Mo7O246- [43]. With the increase of zirconium contents, the peak intensities at 955 cm-1 increase until the wt. % of Zr reaches 6.9 % (Si/Zr = 20), and then become less intensified with further increase of zirconium in the supports, meaning that only suitable amount of Zr species should be beneficial to the formation of NiMoO4 precursor phases.


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As for NiMo/γ-Al2O3 catalyst, only three peaks are observed. The intensive peaks at 361 and 838 cm-1 are the characteristic of MoO42- [2]. The broad peak at about 955 cm-1 represents the formation of Mo8O264-, which is unfavorable to HDS reaction [18]. 3.2.4 H2-TPR H2-TPR analysis of NiMo/ZrM-x can be used to further investigate the effect of zirconium on the interaction between active metals and supports (MSI) as well as the reducibility of active metal oxides. As shown in Figure 10, all the TCD signals of catalysts display two reduction peaks at the region of 400-560 ℃ and 700-850 ℃ respectively. The reduction peak at lower temperature region is attributed to the reduction of amorphous multilayered octahedral Mo species (Mo6++ 2e-→Mo4+), of which the Mo4+ species are weakly bonded to the supports and are believed to be the precursors of the type-II NiMoS active phases with short slab lengths and suitable layers of active phases [42]. For NiMo/ZrM-x series catalysts, NiMo/ZrM-6.9 catalyst (Si/Zr = 20) exhibits a maximal peak area of low temperature peak, reflecting that it has the highest amounts of NiMoO4 precursor phases [28]. Furthermore, it also confirms that appropriate contents of Zr species are conductive to the formation of NiMoO4 phases, which is consistent with the Raman results. Besides, the high temperature reduction peaks are assigned to the second reduction step of polymolybdate in octahedral coordination or deep reduction of tetrahedral coordinated monomeric Mo species (Mo4++ 4e- → Mo) [44, 45]. As shown in Figure 10, for all catalysts, no bulk MoO3 peaks appears at 600–630 °C, demonstrating that Mo species are highly


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dispersed on the support, which is in accordance with the UV-vis spectra characterization (Fig S2) [46]. It should be noted that the TPR peaks shift to lower temperatures with the addition of Zr contents, meaning that the incorporation of zirconium can adjust the MSI. However, compared with the modified Si-based catalysts, NiMo/γ-Al2O3 catalyst has the highest reduction temperature, meaning the strongest MSI in γ-Al2O3 supported catalyst. It is well-known that the strong MSI may impel the formation of type I NiMoS active phases, which are unfacilitate to the hydrogenation performance [45]. Among all the catalysts, NiMo/ZrM-6.9 catalyst (Si/Zr = 20) has the lowest reduction temperature, indicating the weakest MSI and the highest reducibility. Therefore, it may have the best catalytic performance, which should be confirmed by the evaluation results. 3.2.5 EDS elemental mapping Zr, Ni and Mo elements distributions are observed through EDS elemental mapping technology, and the images are shown in Figure 11(a-c). It is obvious that all catalysts exhibit typical mesoporous foam topological structures, corresponding well with the SAXS results (Fig S1). However, the metal elements cannot be observed due to high distributions, furthermore, with the help of element mapping analysis, the distributions of active metals are revealed intuitively as shown in Fig 11. Generally, Zr signals detected on these three catalysts exhibit slight aggregations with the increase of Zr loading. It is obvious that the active metals display relatively large aggregations when incorporating small amount of Zr species (wt. % of Zr is


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2.9 %) based on the Mo and Ni mapping results in the right figures of Fig 11(c), which can be attributed to the weak metal support interaction. However, with the further addition of Zr (wt. % of Zr varies from 2.9 % to 6.9 %), the Ni and Mo phases exhibit better dispersion, indicating that Zr modification can adjust MSI and therefore enhance the dispersity of active metals. It is wellknown that suitable distributions of active metals are favorable to HDS reactions. 3.2.6 XPS analysis XPS analysis can be used to obtain the information about valance change and surface contents of various compounds (Zr, Mo and Ni) as well as the sulfidation degree of Mo and Ni species. As shown in Figure 12(a), the wide-scan XPS spectrum shows that the sample mainly contains O, Si, Zr, Mo, Ni and C elements. The O1s spectrum of O element in NiMo/ZrM-12.6 catalyst (Si/Zr = 10) is presented in Figure 12(b). Among which, the peak centered at 532.9 and 532 ev are respectively assigned to the Si-O-Si bridge and the Si-OH bridge on the surface of samples [47]. Additionally, the less intensified peak appearing at 530.9 ev demonstrates the existence of Si-O-Zr, indicating the presence of Zr atoms in the framework of MCFs [48]. Zirconium species incorporated into the framework of MCFs usually act as electronic promoters, which could modulate the reducibility of catalysts [20]. Figure 13 exhibits a series of Zr 3d XPS scans of NiMo/ZrM-x catalysts. According to the literatures [49], the Zr 3d XPS spectrum of pure ZrO2 powder (Fig S3) exhibits two peaks at 182.2 ev and 184.6 ev respectively, corresponding to the Zr 3d5/2 and Zr 3d3/2 in the Zr4+ state. However, all the positions of the Zr 3d


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peaks shift to lower binding energy, denoting that the valence of Zr cations in NiMo/ZrM-x is less than 4. Moreover, with the incorporated content of Zr species increasing, the peaks shift to lower binding energy range, demonstrating that more tetravalent Zr cations are reduced to trivalent. It further confirms the electronic promoter effect of Zr. Then, curve fitting has been done according to the peak shape to investigate the reduction states of zirconia in NiMo/ZrM-x catalysts. As shown in Fig S3, the peaks at 182.2 ev and 184.6 ev (intensity ratio = 3:2) indicate the existence of Zr4+, while the peaks at 181 ev and 182.4 ev (intensity ratio = 3:2) are assigned to Zr 3d5/2 and Zr 3d3/2 in Zr3+ states respectively [48, 50], suggesting the reduction of Zr4+→Zr3+. Since the peaks of Zr3+ are in weak intensities and the decreases in binding energy of Zr 3d spectra are less than 1 ev, it is thought that the majority of zirconium ions are still in Zr4+ species [51]. However, XPS characterization can only provide the information about the object surface, it can be implied that ZrO2 on the surface or Zr(OSi)4 near the surface are partially reduced to Zr3+ phases. The fitting results are listed in Table 3, in which the reduction degree of Zr species acting as electronic promoter can be reflected by the atomic ratio of Zr3+ to the total of Zr4+ and Zr3+. It can be seen that the percentages of Zr3+/Zrtotal follow the order of NiMo/ZrM-6.9 > NiMo/ZrM-12.6 > NiMo/ZrM-4.7 > NiMo/ZrM-3.6 > NiMo/ZrM-2.9. Figure 14 shows the Mo 3d XPS spectra of various sulfided catalysts, which are decomposed into three well-resolved contributions. According to the previous researches [28, 52, 53], the bimodal peaks at around 228.7 ± 0.1 ev and 231.8 ± 0.1 ev, which have a fixed intensity ratio of


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3:2, are assigned to the 3d5/2 and 3d3/2 spectra of Mo4+ (corresponding to MoS2) respectively. The relatively less intensified peak at 232.3 ± 0.1 ev is attributed to the Mo6+ 3d5/2 for the MoO3 species, indicating that partial Mo species are in oxidation state rather than in completely sulfurized states. And the characteristic binding energy of Mo5+ species (MoOxSy) can also be observed at 228.8 ± 0.1 ev despite of their relatively weak intensity, while the bands centered at about 226.0 ev are assigned to the S 2s curves [54]. The fitting results obtained through the deconvolution method [52] are summarized in Table 4, in which the sulfidation degree of Mo species can be expressed by using the proportion of Mo4+ phases in the total Mo species. It is worthy to note that the loading of Zr species impacts the sulfidity of Mo species, although the influence is not linear. From Table 4, as loading small amount of Zr species (wt. % of Zr varies from 2.9 % to 6.9 %), the sulfidation degrees increase gradually, which correspond well with the Zr3+/Zrtotal results. However, the fractions of Mo4+ decrease when the wt. % of Zr is 12.6 %. From the wide-angle XRD patterns (Fig 2) and Zr 3d fitting results of NiMo/ZrM-12.6 catalysts (Si/Zr = 10) (Table 3), the tetragonal and monoclinic ZrO2 appear and the fractions of Zr3+/Zrtotal decrease in comparison to NiMo/ZrM-6.9 catalysts (Si/Zr = 20). As a result, the decrease of sulfidation degree is caused by the aggregation of ZrO2, indicating that only introducing suitable zirconium can facilitate to the HDS performance. The Ni 2p XPS spectra are decomposed into three peaks at 855.3 ± 0.2 ev, 861.2 ± 0.1 ev and 852.2 ± 0.1 ev, corresponding to NiMoS, NiO and NiSx (Ni9S8, Ni3S2 and NiS) respectively [55].


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The detailed fitting results are displayed in Table 5. Among which, the sulfidation degree of Ni species can be calculated by using the total amount of Ni species divided by the sulfided Ni (NiMoS and NiSx). It is obvious that the fractions of NiMoS and Ni sulfidity increase with the addition of Zr, demonstrating that the incorporation of Zr species facilitates the formation of NiMoS phases. This is consistent with the Raman result. The amounts of NiMoS phases follow the order of NiMo/ZrM-6.9 > NiMo/ZrM-12.6 > NiMo/ZrM-4.7 > NiMo/ZrM-3.6 > NiMo/ZrM2.9 > NiMo/γ-Al2O3, in accordance with Mo 3d fitting results. It indicates that the moderate amounts of Zr modification facilitate to the formation of active sites, therein improve the HDS efficiency. 3.2.7 Pyridine-FTIR spectroscopy Pyridine-FTIR analysis can characterize the acid type and acid distribution of catalysts, which are vital important to the HDS and HDN reaction. The obtained signals in the region of 14001700 cm-1 are shown in Figure 16. Generally, the adsorption peaks at about 1540 and 1640 cm-1 indicate the existence of Brønsted acid sites, while the bands at 1450 and 1610 cm-1 reflect the presence of Lewis acid sites. Moreover, the band at 1492 cm-1 is corresponding to the pyridine molecules bound to both of Brønsted and Lewis acid sites [56, 57]. The acid distributions and specific acid amounts are listed in Table 6, in which the total amounts of acid sites are quantitatively obtained from the pyridine adsorption IR spectra after degassing at 200 ℃, and the amounts of medium and strong acid sites depend on the IR pyridine


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adsorption spectra after degassing at 350℃. It should be noted that as the wt. % of Zr varies from 2.9 % to 6.9 %, the acidities of catalysts exhibit an upward trend, it is since the atomic radius of Zr4+ (r=0.084 nm) is much larger than that of Si4+ (r=0.026 nm) [47], therefore, when Si4+ is insitu substituted with Zr4+, the bond length of Zr-O-Si is distinguishably different from that of SiO-Si, and may cause the structural distortion. The existence of Zr atoms changes the electronic density around Si, resulting in the strength weakness of SiO-H bond on the surface of the catalysts, which facilitate to the formation of Brønsted acid sites [58]. Additionally, zirconia species are usually in a coordination number of 7 or 8 [59], when the octahedral coordinated zirconium atoms are fabricated into the silicon skeleton, the coordination unsaturated positions can produce more vacancies in the d orbital of Zr atoms, which result in the formation of Lewis acid sites [59]. From Table 6, the amounts of total acid sites follow the order: NiMo/γ-Al2O3 > NiMo/ZrM-6.9 ≈ NiMo/ZrM-12.6 > NiMo/ZrM-4.7 > NiMo/ZrM-3.6 > NiMo/ZrM-2.9. Moreover, the medium and strong acidities follow the order of NiMo/γ-Al2O3 > NiMo/ZrM-6.9 > NiMo/ZrM-12.6 > NiMo/ZrM-4.7 > NiMo/ZrM-3.6 > NiMo/ZrM-2.9. NiMo/ZrM-6.9 catalyst (Si/Zr = 20) should be more suitable for HDS reaction due to its moderate acidity and the synergistic effect of B and L acid sites [60], which can be confirmed by the evaluation results. 3.3 Catalytic activity evaluation In the present research, all the catalysts with different Zr contents and the reference NiMo/γAl2O3 were evaluated in a fixed bed micro-reactor using FCC diesel as feedstock. As the results


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shown in Figure 17, the catalytic activities of NiMo/ZrM-x catalysts are all higher than the traditional NiMo/γ-Al2O3 catalyst. And the HDS efficiencies increase at first and obtain the maximum value of 97.3% when the wt. % of Zr is 6.9 % (Si/Zr = 20), then decrease to 96.5% when the wt. % of Zr is as high as 12.6 % (Si/Zr = 10). Furthermore, all catalysts exhibit excellent HDN activities (higher than 94%), of which the best performance occurred when the wt. % of Zr is 6.9 %. In summary, NiMo/ZrM-6.9 (Si/Zr = 20) has the optimal catalytic activities in both HDS and HDN reactions, corresponding well to the results of H2-TPR, Raman, XPS and Pyridine FTIR characterizations. 4. Discussion HDS efficiencies are intimately correlated with the textural properties, acidity, reducibility of catalysts and the sulfidation degree of the sulfided active phases. The textural properties affect the diffusion of diesel molecules into the internal pore structures. NiMo/ZrM-6.9 catalyst (Si/Zr = 20) possessed the largest pore size (12.5 nm), specific surface area (347 m2/g) and relatively larger pore volume (1.16 cm3/g) in comparison with those of NiMo/ZrM-2.9 (Si/Zr = 50) (12.2 nm, 332 m2/g, 1.18 cm3g), NiMo/ZrM-12.6 (Si/Zr = 10) (12 nm, 292 m2/g, 0.98 cm3g) and the reference traditional NiMo/γ-Al2O3 (11.7 nm, 147 m2/g, 0.45 cm3/g) catalysts. Since the large specific surface areas can supply enough space to achieve a suitable dispersion of active metals and a high sulfidation degree of catalysts, large pore size and pore volume can efficiently reduce the diffusion resistance, which will be beneficial to enhance


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the accessibility of the active sites located inside the pore channels to the large molecule reactants. The reducibility and sulfidity of catalysts are prominently related to the MSI. And the incorporation of Zr species can modify the dispersion of active metals and redox ability of catalysts, which can be confirmed by EDS element mapping and H2-TPR characterizations. From the EDS elemental mapping images in Figure 11, it was shown that NiMo/ZrM-6.9 catalyst (Si/Zr = 20) had a better active metal distribution than NiMo/ZrM-2.9 (Si/Zr = 50), furthermore, the H2-TPR analysis results in Figure 10 also revealed that NiMo/ZrM-6.9 catalyst had the lowest reduction temperature (495 ℃) compared with those of NiMo/ZrM-2.9 (539 ℃) and NiMo/γ-Al2O3 (542 ℃), indicating that NiMo/ZrM-6.9 had the best redox ability. The moderate MSI and high reducibility make active phases easier to be sulfided and lead to the formation of type II NiMoS phases which expose more brim and edge sites for promoting the HDS reaction. From XPS analysis results, the strong MSI in NiMo/γ-Al2O3 catalyst resulted in the lowest sulfidity of Mo species (44.2%). However, NiMo/ZrM-6.9 catalyst, which had the highest Zr3+/Zrtotal (7.6%) value, possessed the greatest Mosulfidity (67.3%) and Nisulfidity (72.2%) levels, meaning that Zr species acting as electronic promoter facilitated to the formation of β-NiMoO4 precursor phases. This result was in consistency with the Raman characterization. Besides, appropriate acidity is also a crucial factor in HDS reaction. From the pyridine FTIR results in Table 6, although NiMo/γ-Al2O3 catalyst had the highest amount of Lewis acid sites


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(79.6 µmol·g-1) which facilitated hydrogenation reaction, the absence of Brønsted acid sites was still inferior to HDS reactions since the existence of them was advantageous to the bond fissions of C-S and alkyl isomerization in HDS reaction [26]. However, for the SiO2-based catalysts, the addition of Zr species introduced both two types of acid sites and modulated the acid property of silica. Among all the catalysts, NiMo/ZrM-6.9 catalyst not only had the highest total acidities (57 µmol·g-1), but also possessed the greatest medium and strong acidities (22 µmol·g-1) than the other modified catalysts, so exhibited the best catalytic performance. Above all, the synergistic effects of the appropriate textural property, moderate acidity, suitable active metal dispersion, desireable reducibility and sulfidity made the NiMo/ZrM-6.9 catalyst possessed the best HDS performance, furthermore, the HDS activities followed the order of NiMo/ZrM-6.9 > NiMo/ZrM-12.6 > NiMo/ZrM-2.9 > NiMo/γ-Al2O3. The systematic study of the electronic promoter effect of Zr in this research will be valuable for the application of additive promoter in the design and development of novel HDS catalysts. 5. Conclusion In this research, a novel kind of Zr modified materials, Zr-MCFs, were successfully synthesized by incipient wetness impregnation method. The SAXS and FTIR characterization results indicated that Zr species were successfully fabricated into the pure MCFs framework through post-synthetic method, while there was no significant effect on the parent topological structure. The corresponding NiMo/ZrM-x catalysts and the traditional NiMo/γ-Al2O3 catalyst


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were prepared and characterized by SAXS, N2 physisorption, UV-vis DRS, Raman, H2-TPR, HAADF STEM, EDS elemental mapping, Pyridine FTIR and XPS technologies. The EDS mapping and H2-TPR results demonstrated that Zr species adjusted the active metal dispersions and resulted in the better redox ability due to the multivalent characteristics of zirconium. The Raman results showed that the addition of Zr facilitated the formation of NiMoO4 precursor phases, the pyridine FTIR results identified that the modification of Zr brought both Lewis and Brønsted acid sites into the catalyst surfaces. XPS technique confirmed that Zr species acting as electronic promoter could improve the sulfidation of active phases. Furthermore, NiMo/ZrM-6.9 catalyst (Si/Zr = 20) had the highest Zr3+/Zrtotal (7.6%) and exhibited the largest Mosulfidity (67.3%) and Nisulfidity (72.2%). The HDS efficiencies of FCC diesel showed that NiMo/ZrM-6.9 catalyst displayed the highest HDS (97.3%) and HDN efficiencies (98.7%) due to the synergistic effects of its appropriate textural property, moderate acidity, suitable active metal dispersion, highest reducibility and sulfidity. Acknowledgement This work was financially supported by CNOOC project (CNOOC-KJ 135 FZDXM 00 LH 003 LH-2016); the National Science Foundation of China (No.21676298, U1463207 and 21503152); Opening Project of Guangxi Key Laboratory of Petrochemical Resource Processing


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and Process Intensification Technology (2015K003); CNPC Key Research Project and KLGCP (GCP 201401). Reference (1) Trejo, F.; Rana, M. S.; Ancheyta, J. CoMo/MgO-Al2O3, supported catalysts: An alternative approach to prepare HDS catalysts. Catal. Today 2008, 130 (2), 327-336. (2) Marina, E.; Roel, P. Hydrodesulfurization of dibenzothiophene and 4,6-dimethyldibenzo thiophene over sulfide NiMo/γ-Al2O3, CoMo/γ-Al2O3, and Mo/γ-Al2O3 catalysts. J. Catal. 2004, 225 (2), 417-427. (3) Kim, J. H.; Ma, X. L. A.; Song, C.; Lee, Y. K.; Oyama, S. T. Kinetics of two pathways for 4,6-dimethyldibenzothiophene hydrodesulfurization over NiMo, CoMo Sulfide, and Nickel Phosphide catalysts. Energy Fuels 2005, 19 (2), 353-364. (4) Olivas, A.; Zepeda, T. A.; Impact of Al and Ti ions on the dispersion and performance of supported NiMo(W)/SBA-15 catalysts in the HDS and HYD reactions. Catal. Today 2009, 143 (1-2), 120-125. (5) Luo, Y.; Guda, V. K.; Hassan, E. B.; Steele, P. H.; Mitchell, B.; Yu, F. Hydrodeoxygenation of oxidized distilled bio-oil for the production of gasoline fuel type. Energ. Convers. Manage. 2016, 112, 319-327.


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(6) Purón, H.; Pinilla, J. L.; Berrueco, C.; Millian, M. Hydrocracking of Maya Vacuum Residue with NiMo Catalysts Supported on Mesoporous Alumina and Silica-Alumina. Energy Fuels 2013, 27 (7), 3952-3960. (7) Karakhanov, E.; Kardasheva, Y.; Kulikov, L.; Maximov, A.; Zolotukhina, A.; Vinnikova, M.; Ivanov, A. Sulfide Catalysts Supported on Porous Aromatic Frameworks for Naphthalene Hydroprocessing. Catalysts 2016, 6 (8), 122. (8) Duan, A. J.; Li, T. S.; Zhen, Z.; Liu, B. J.; Zhou, X. F.; Jiang, G. Y.; Liu, J.; Wei, Y. C.; Pan, H. F. Synthesis of hierarchically porous L-KIT-6 silica-alumina material and the super catalytic performances for hydrodesulfurization of benzothiophene. Appl. Catal., B 2015, 165, 763-773. (9) Jia, M.; Afanasiev, P.; Vrinat, M. The influence of preparation method on the properties of NiMo sulfide catalysts supported on ZrO2. Appl. Catal., A 2005, 278 (2), 213-221. (10) Afanasiev, P.; Cattenot, M.; Geantet, C.; Matsubayashi, N.; Sato, K.; Shimada, S. (Ni)W/ZrO2, Hydrotreating catalysts prepared in molten salts. Appl. Catal., A 2002, 237 (1-2), 227-237. (11) Shimada, H. Morphology and orientation of MoS2, clusters on Al2O3 and TiO2 supports and their effect on catalytic performance. Catal. Today 2003, 86 (1-4), 17-29. (12) Jia, M.; Afanasiev, P.; Vrinat, M.; Li, W. Z.; Xu, H. Y.; Ge, Q. J. Study of NiMo/ZrO2 catalysts for hydrodesulfurization. Petrochem. Technol. 2005, 34 (3), 218-221.


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(19) Kostova, N.; Spojakina, A. A.; Jiratova, K.; Solcova, O.; Dimitrov, L. D.; Petrov, L. A. Hexagonal mesoporous silicas with and without Zr as supports for HDS catalysts. Catal. Today 2001, 65 (65), 217-223. (20) Fu, J. Y.; Zheng, P.; Du, P.; Duan, A. J.; Zhao, Z.; Jiang, G. Y.; Liu, J.; Wei, Y. C.; Xu, C. M.; Chi, K. B. Zirconium modified TUD-1 mesoporous catalysts for the hydrodesulfurization of FCC diesel. Appl. Catal., A 2015, 502, 320-328. (21) Pachamuthu, M. P.; Srinivasan, V. V.; Maheswari, R.; Shanthi, K.; Ramanathan, A. Lewis Acidic Zr-TUD-1 as Catalyst for tert-Butylation of Phenol. Appl. Catal., A 2013, 462-463 (27), 143-149. (22) Yang, X. M.; Zhou, L. P.; Chen, C.; Li, X. Q.; Xu, J. Direct synthesis and characterization of bifunctional Me-Zr-MCM-41. Mater. Lett. 2009, 63 (20), 1754-1756. (23) Li, F. X.; Feng, Y.; Li, Y. L.; Xie, K. C. Direct synthesis of Zr-SBA-15 mesoporous molecular sieves with high zirconium loading: Characterization and catalytic performance after sulfated. Microporous Mesoporous Mater. 2007, 101 (1-2), 250-255. (24) Gao, D.; Duan, A.; Zhang, X.; Zhao, Z.; Hong, E.; Li, J.; Wang, H. Synthesis of NiMo catalysts supported on mesoporous Al-SBA-15 with different morphologies and their catalytic performance of DBT HDS. Appl. Catal., B 2015, 165, 269-284.


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(25) Amezcua, J. C.; Lizama, L.; Salcedo, C.; Puente, I.; Dominguez, J. M.; Klimova, T. NiMo catalysts

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(31) On, D. T.; Kaliaguine, S. Zeolite-Coated mesostructured cellular silica foams. J. Am. Chem. Soc. 2003, 125(3): 618-619. (32) Vradman, L.; Landau, M. V.; Herskowitz, M.; Ezersky, V.; Talianker, M.; Nikitenko, S.; Koltypin, Y.; Gedanken, A. High loading of short WS2 slabs inside SBA-15: promotion with nickel and performance in hydrodesulfurization and hydrogenation. J. Catal. 2003, 213 (2), 163175. (33) Jiang, T. S.; Wu, D. L.; Song, J. M.; Zhou, X. P.; Zhao, Q.; Ji, M.; Yin, H. B. Synthesis and characterization of mesoporous ZrMCM-48 molecular sieves with good thermal and hydrothermal stability. Powder Technol. 2011, 207 (1), 422-427. (34) Yu, J. G.; Yu, J. C.; Bei, C.; Zhao, X. J.; Zheng, Z.; Li, A. S. K. Atomic force microscopic studies of porous TiO2 thin films prepared by the sol-gel method. J. Sol-Gel Sci. Technol. 2002, 24 (3), 229-240. (35) Pan, Q.; Ramanathan, A.; Snavely, W. K.; Chaudhari, R. V.; Subramaniam, B. Synthesis and Dehydration Activity of Novel Lewis Acidic Ordered Mesoporous Silicate: Zr-KIT-6. Ind. Eng. Chem. Res. 2013, 52 (44), 15481-15487. (36) Rakshe, B.; Ramaswamy, V.; Ramaswamy, A. V. Crystalline, microporous zirconium silicates with MFI structure. J. Catal. 1996, 163 (2), 501-505.


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(37) Du, Y. C.; Liu, S.; Zhang, Y. L; Nawaz, F.; Ji, Y. Y.; Xiao, F. S. Urea-assisted synthesis of hydrothermally stable Zr-SBA-15 and catalytic properties over their sulfated samples. Microporous Mesoporous Mater. 2009, 121 (1-3), 185-193. (38) Chaudhari, K.; Bal, R.; Das, T. K.; Chandwadkar, A.; Srinivas, D.; Sivasanker, S. Electron spin resonance investigations on the location and reducibility of zirconium in mesoporous Zr−MCM-41 molecular sieves. J. Phy. Chem. B 2000, 104 (47), 11066-11074. (39) Parola, V. L.; Deganello, G.; Venezia, A. M. CoMo catalysts supported on aluminosilicates: synergy between support and sodium effects. Appl. Catal., A 2004, 260 (2), 237-247. (40) Badoga, S.; Mouli, K. C.; Soni, K. K.; Dalai, A. K.; Adjaye, J. Beneficial influence of EDTA on the structure and catalytic properties of sulfide NiMo/SBA-15 catalysts for hydrotreating of light gas oil. Appl. Catal., B 2012, 125, 67-84. (41) Zhou, X. F.; Duan, A. J.; Zhao, Z.; Gong, Y. J.; Wu, H. D.; Li, J. M.; Wei, Y. C.; Jiang, G. Y.; Liu, J.; Zhang, Y. Synthesis of hierarchically porous silicas with mesophase transformations in a four-component microemulsion-type system and the catalytic performance for dibenzothiophene hydrodesulfurization. J. Mater. Chem. 2014, 2 (19), 6823-6833. (42) Topsøe, H.; Clausen, B. S.; Candia, R.; Wivel, C.; Morup, S. In situ Mössbauer emission spectroscopy studies of unsupported and supported sulfide CoMo hydrodesulfurization catalysts: Evidence for and nature of a CoMoS phase. J. Catal. 1981, 68 (2), 433-452.


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(43) Otto, K.; Hubbard, C. P.; Weber, W. H.; Graham, G. W. Raman spectroscopy of palladium oxide on γ-alumina applicable to automotive catalysts: Nondestructive, quantitative analysis; oxidation kinetics; fluorescence quenching. Appl. Catal., B 1992, 1 (4), 317-327. (44) Calderón-Magdaleno, M. Á.; Mendoza-Nieto, J. A.; Klimova, T. E. Effect of the amount of citric acid used in the preparation of NiMo/SBA-15 catalysts on their performance in HDS of dibenzothiophene-type compounds. Catal. Today 2014, s 220–222 (3), 78-88. (45) Liu, X. M.; Li, X.; Yan, Z. F. Facile route to prepare bimodal mesoporous γ-Al2O3 as support for highly active CoMo-based hydrodesulfurization catalyst. Appl. Catal., B 2012, s 121122, 50–56. (46) Wang, Z. G.; Fu, J. Y.; Deng, Y. C.; Duan, A. J.; Zhao, Z.; Jiang, G. Y.; Liu, J.; Wei, Y. C.; Zhao, S. Q. Synthesis of aluminum-modified 3D mesoporous TUD-1 materials and their hydrotreating performance of FCC diesel. Rsc Adv. 2014, 5 (7), 5221-5230. (47) Jiang, T. S.; Li, Y. H.; Zhou, X. P.; Zhao, Q.; Yin, H. B. Thermal and hydrothermal stability of Zr-MCM-41 mesoporous molecular sieves obtained by microwave irradiation. J. Chem. Sci. 2010, 122 (3), 371-379. (48) Zhang, H. L.; Wang, D. Z.; Yang, B.; Huang, N. K. XPS Measurement for the Elements in the Interface between Oxygen Ion Irradiated ZrO2-Y2O3 Films and Iron Substrate. Physica Status Solidi 1997, 160 (160), 145-150.


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(49) Miteva, V. A.; Stanchev, A.; Marashev, Y.; Kelly, R.; Licciardello, A. On the mechanism of bombardment-induced oxygen redistribution at ZrO2 surfaces. Vacuum 1996, 47 (10), 12351238. (50) Huang, N. K.; Kheyrish, H.; Colligon, J. S. Microstructure of Zirconia Films Prepared by Argon Ion Beam Enhanced Deposition. Physica Status Solidi 1992, 132 (2), 405-411. (51) Wang, W.; Guo, H. T.; Gao, J. P.; Dong, X. H.; Qin, Q. X. XPS, UPS and ESR studies on the interfacial interaction in Ni-ZrO2 composite plating. J. Mater. Sci. 2000, 35 (6), 1495-1499. (52) Du, P.; Zheng, P.; Song, S. T.; Wang, X. L.; Zhang, M. H.; Chi, K. B.; Xu, C. M.; Duan, A. J.; Zhao, Z. Synthesis of a novel micro/mesoporous composite material Beta-FDU-12 and its hydro-upgrading performance for FCC gasoline. Rsc Adv. 2015, 6 (2), 1018-1026. (53) Cao, Z. K.; Duan, A. J.; Zhao, Z.; Li, J. M.; Wei, Y. C.; Jiang, G. Y.; Liu, J. A simple twostep method to synthesize the well-ordered mesoporous composite Ti-FDU-12 and its application in the hydrodesulfurization of DBT and 4,6-DMDBT. J. Mater. Chem. 2014, 2 (46), 1973819749. (54) Han, W.; Yuan, P.; Fan, Y.; Shi, G.; Liu, H. Y.; Bai, D. J.; Bao, X. J. Preparation of supported hydrodesulfurization catalysts with enhanced performance using Mo-based inorganic– organic hybrid nanocrystals as a superior precursor. J. Mater. Chem. 2012, 22 (22), 2534025353.


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(55) Lai, W. K.; Song, W. J.; Pang, L. Q; Wu, Z. F.; Zheng, N.; Li, J. J.; Zheng, J. B.; Yi, X. D.; Fang, W. P. The effect of starch addition on combustion synthesis of NiMo-Al2O3 catalysts for hydrodesulfurization. J. Catal. 2013, 303 (13), 80-91. (56) Song, S. T.; Zhou, X. F.; Duan, A. J.; Zhao, Z.; Chi, K. B.; Zhang, M. H.; Jiang, G. Y.; Liu, J.; Li, J. M.; Wang, X. L. Synthesis of mesoporous silica material with ultra-large pore sizes and the HDS performance of dibenzothiophene. Microporous Mesoporous Mater. 2016, 226, 510521. (57) Li, T. S.; Duan, A. J.; Zhao, Z.; Liu, B. J. Jiang, G. Y.; Liu, J.; Wei, Y. C.; Pan, H. F. Synthesis of ordered hierarchically porous L-SBA-15 material and its hydro-upgrading performance for FCC gasoline. Fuel 2014, 117 (1), 974-980. (58) Chen, L. F.; Noreña, L. E.; Navarrete, J.; Wang, J. A. Improvement of surface acidity and structural regularity of Zr-modified mesoporous MCM-41. Mater. Chem. Phys. 2006, 97 (97), 236-242. (59) Yang, L. S.; Yang, X. K.; Tian, E.; Vattipalli, V.; Lin, H. F. Mechanistic insights into the production of methyl lactate by catalytic conversion of carbohydrates on mesoporous Zr-SBA15. J. Catal. 2016, 333, 207-216. (60) Wang, X. L.; Fang, H.; Zhao, Z.; Xu, C. M.; Chen, Z. T.; Zhang, M. H.; Du, P.; Song, S. T.; Zheng, P.; Chi, K. B. Effect of promoters on the HDS activity of alumina-supported Co-Mo sulfide catalysts. Rsc Adv. 2015, 5 (121), 99706-99711.


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AUTHOR INFORMATION Corresponding Author * corresponding authors, E-mail: [email protected]; [email protected] Author Contributions The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. ‡These authors contributed equally.


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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

FIGURES Figure 1. SAXS patterns of ZrM-x composites. Figure 2. Wide angle XRD patterns of ZrM-x materials. Figure 3. N2 adsorption-desorption isotherms (a) and pore size distributions (b) of ZrM-x supports. Figure 4. FTIR spectra of (a) pure MCFs, (b) ZrM-4.7. Figure 5. UV-vis DRS spectra of (a) pure ZrO2, (b) ZrOCl2·8H2O, (c) ZrM-12.6, (d) ZrM-6.9, (e) ZrM-2.9, (f) pure MCFs. Figure 6. SEM images of ZrM-x materials. Figure 7. TEM images of (a) ZrM-4.7, (b) pure MCFs. Figure 8. N2 physisorption isotherms (a) and pore size distributions (b) of NiMo/ZrM-x and NiMo/γ-Al2O3 catalysts. Figure 9. Raman spectra of NiMo/ZrM-x catalysts. Figure 10. H2-TPR profiles of NiMo/ZrM-x catalysts. Figure 11. HAADF-STEM image and EDS elemental mapping analysis of NiMo/ZrM-x catalysts. Figure 12. XPS spectra of NiMo/ZrM-12.6 (a), O1s XPS spectra of NiMo/ZrM-12.6 (b). Figure 13. Zr 3d XPS spectra of NiMo/ZrM-x catalysts. Figure 14. Mo 3d XPS spectra of the sulfided NiMo/ZrM-x and NiMo/γ-Al2O3 catalysts. Figure 15. Ni 2p XPS spectra of the sulfided NiMo/ZrM-x catalysts. 38 ACS Paragon Plus Environment

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Figure 16. The pyridine IR spectra of NiMo/ZrM-x and NiMo/γ-Al2O3 catalysts. Figure 17. HDS performance of the sulfided NiMo/ZrM-x and NiMo/γ-Al2O3 catalysts.


Energy & Fuels

(a)

Ln(I)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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(b) (c) (d) (e) (f) 0.00

0.05

0.10

0.15

0.20

q/nm-1

Figure 1. SAXS patterns of ZrM-x composites. (a) ZrM-12.6, (b) ZrM-6.9, (c) ZrM-4.7, (d) ZrM-3.6, (e) ZrM-2.9, (f) Pure MCFs


Page 41 of 64

T: tetragonal ZrO2

T

M: monoclinic ZrO2

M T

Intensity/a.u.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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M (a) (b) (c) (d) (e) (f)

20

40

60

80

2θ/ degree

Figure 2. Wide angle XRD patterns of ZrM-x materials (a) ZrM-12.6, (b) ZrM-6.9, (c) ZrM-4.7, (d) ZrM-3.6, (e) ZrM-2.9, (f) Pure MCFs


Energy & Fuels

(a)

(b)

-1 Volume adsorped/mg L

ZrM-12.6

ZrM-172.6

3 dV/dlog(D)/cm g-1

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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ZrM-6.9 ZrM-4.7 ZrM-3.6 ZrM-2.9

ZrM-6.9 ZrM-4.7 ZrM-3.6 ZrM-2.9

Pure MCFs 0.0

0.2

Pure MCFs

0.4

0.6

0.8

0

1.0

30

Relative Pressure (P/Po)

60

90

120

150

Pore Diameter (nm)

Figure 3. N2 adsorption-desorption isotherms (a) and pore size distributions (b) of ZrM-x supports


Page 43 of 64

-1 460 cm

-1 808 cm -1 950 cm

-1

1640 cm -1 1231 cm

Transmittance/a.u.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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(a)

-1

960 cm

-1

(b)

1084 cm

400

600

800

1000

1200

1400

Wavenumber/cm-1

Figure 4. FTIR spectra of (a) pure MCFs, (b) ZrM-4.7


1600

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210 230 310

Intensity/a.u.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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(a) (b) (c) (d) (e) (f)

200

300

400

500

600

700

800

Wavelength/nm

Figure 5. UV-vis DRS spectra of (a) pure ZrO2, (b) ZrOCl2·8H2O, (c) ZrM-12.6 (d) ZrM-6.9, (e) ZrM-2.9 (f) pure MCFs


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Figure 6. SEM images of ZrM-x materials (a) ZrM-12.6, (b) ZrM-4.7, (c) ZrM-2.9


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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Figure 7. TEM images of (a) ZrM-4.7, (b) pure MCFs


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(b)

dV/dlog(D) /cm3 g-1

(a)

Volume adsorped/mg L-1

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

NiMo/ZrM-12.6 NiMo/ZrM-6.9 NiMo/ZrM-4.7 NiMo/ZrM-3.6 NiMo/ZrM-2.9

NiMo/ZrM-12.6 NiMo/ZrM-6.9 NiMo/ZrM-4.7 NiMo/ZrM-3.6 NiMo/ZrM-2.9

NiMo/γ-Al2O3

0.0

0.2

NiMo/γ-Al2O3

0.4

0.6

0.8

1.0

0

30

Relative pressure (P/P0)

60

90

120

150

Pore diameter (nm)

Figure 8. N2 physisorption isotherms (a) and pore size distributions (b) of NiMo/ZrM-x and NiMo/γ-Al2O3 catalysts


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-1

955 cm

-1

900 cm -1

-1

361 cm

818 cm

(a)

Intensity/a.u.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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(b) (c) (d) -1 838 cm

(e) (f)

200

400

600

800

1000

1200

1400

Wavenumber/cm-1

Figure 9. Raman spectra of NiMo/ZrM-x catalysts (a) NiMo/ZrM-12.6, (b) NiMo/ZrM6.9, (c) NiMo/ZrM-4.7, (d) NiMo/ZrM-3.6, (e) NiMo/ZrM-2.9, (f) NiMo/γ-Al2O3


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505 495

NiMo/ZrM-12.6 524

TCD Signal/a.u.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

NiMo/ZrM-6.9 536 539

NiMo/ZrM-4.7

542

NiMo/ZrM-3.6 NiMo/ZrM-2.9

NiMo/Al2O3

200

300

400

500

600

700

o

Temperature/ C

Figure 10. H2-TPR profiles of NiMo/ZrM-x catalysts.


800

900

Energy & Fuels

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Figure 11. HAADF-STEM image and EDS elemental mapping analysis of

NiMo/ZrM-x catalysts (a) NiMo/ZrM-6.9, (b) NiMo/ZrM-4.7, (c) NiMo/ZrM-2.9


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(b)

C1s Mo3d Zr3d Si2s S2p Si2p

OKLL

1200

1000

800

600

400

200

Si-O-Si

Intensity/a.u.

(a)

Intensity/a.u.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

O1s

Page 51 of 64

Si-OH Si-O-Zr

0

538

536

Binding energy/ev

534

532

530

528

Binding energy/ev

Figure 12. (a) XPS spectra of NiMo/ZrM-12.6, (b) O1s XPS spectra of NiMo/ZrM-12.6


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(a) NiMo/ZrM-2.9 NiMo/ZrM-3.6

Intensity/a.u.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 52 of 64


NiMo/ZrM-12.6

190

188

186

184

182

180

178

176

174

Binding energy/ev

Figure 13. Zr 3d XPS spectra of NiMo/ZrM-x catalysts


172

170

Page 53 of 64

4+ Mo (5/2),(3/2)

6+ Mo (5/2),(3/2)

5+ Mo (5/2),(3/2)

S2s

240

235

4+ Mo (5/2),(3/2)

(b)

Intensity/a.u.

Intensity/a.u.

(a)

230

225

220

S2s

240

235

4+ Mo (5/2),(3/2)

5+ Mo (5/2),(3/2)

S2s

235

230

225

220

6+ Mo (5/2),(3/2) S2s

240

235

(f)

Intensity/a.u.

5+ Mo (5/2),(3/2)

S2s

240

235

230

230

225

220

Binding energy/ev

4+ Mo (5/2),(3/2)

6+ Mo (5/2),(3/2)

220

5+ Mo (5/2),(3/2)

Binding energy/ev

(e)

225

4+ Mo (5/2),(3/2)

(d)

6+ Mo (5/2),(3/2)

240

230

Binding energy/ev

Intensity/a.u.

Intensity/a.u.

(c)

5+ Mo (5/2),(3/2)

6+ Mo (5/2),(3/2)

Binding energy/ev

Intensity/a.u.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

225

220

4+ Mo (5/2),(3/2)

5+ Mo (5/2),(3/2)

6+ Mo (5/2),(3/2)

S2s

240

Binding energy/ev

235

230

225

220

Binding energy/ev

Figure 14. Mo 3d XPS spectra of the sulfided NiMo/ZrM-x and NiMo/γ-Al2O3 catalysts (a) NiMo/ZrM-12.6, (b) NiMo/ZrM-6.9, (c) NiMo/ZrM-4.7, (d) NiMo/ZrM-3.6, (e) NiMo/ZrM-2.9, (f) NiMo/γ-Al2O3


Energy & Fuels

NiMoS

NiO

NiSx

NiMo/ZrM-12.6

NiMo/ZrM-6.9

Intensity/a.u.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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NiMo/ZrM-4.7 NiMo/ZrM-3.6 NiMo/ZrM-2.9 NiMo/Al2O3 866

864

862

860

858

856

854

852

Binding energy/ev

Figure 15. Ni 2p XPS spectra of the sulfided NiMo/ZrM-x catalysts


850

Page 55 of 64

L

(A)

L

(B)

Absorbance,a.u.

L

Adsorbance, a.u.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

L L+B L

B

(a) (b) (c) (d) (e) (f)

1700

L+B B

B

(a) (b) (c) (d) (e) (f)

1650

1600

1550

1500

1450

1700

1400

1650

Wavenumber/cm-1

1600

1550

1500

1450

1400

Wavenumber/cm-1

Figure 16. The pyridine IR spectra of NiMo/ZrM-x and NiMo/γ-Al2O3 catalysts. (a) NiMo/γ-Al2O3, (b) NiMo/ZrM-12.6, (c) NiMo/ZrM-6.9, (d) NiMo/ZrM-4.7, (e) NiMo/ZrM-3.6 (f) NiMo/ZrM-2.9 after degassing at (A) 200 ℃ and (B) 350 ℃


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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Figure 17. HDS performance of the sulfided NiMo/ZrM-x and NiMo/γ-Al2O3 catalysts


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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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TABLES. Table 1. Textural characteristics of ZrM-x composites. Table 2. Textural characteristics of NiMo/ZrM-x and NiMo/γ-Al2O3 catalysts. Table 3. XPS fitting results of Zr 3d spectra of the sulfided NiMo/ZrM-x catalysts. Table 4. XPS fitting results of Mo 3d spectra of the sulfided NiMo/ZrM-x catalysts. Table 5. XPS fitting results of Ni 2p spectra of the sulfided NiMo/ZrM-x catalysts. Table 6. Amounts of acid sites of NiMo/ZrM-x catalysts determined by pyridine-FTIR


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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 58 of 64

Table 1. Textural characteristics of ZrM-x composites Samples

Si/Zr mole rato

SBET (m2/g)

Vp (cm3/g)

Dpd(nm)[a]

NSBET[b]

ZrM-12.6

10

457

1.56

15.4

0.93

ZrM-6.9

20

497

1.66

15.7

0.96

ZrM-4.7

30

512

1.62

15.6

0.96

ZrM-3.6

40

508

1.67

15.9

0.93

ZrM-2.9

50

531

1.77

15.9

0.97

MCFs

∞

570

2.08

18.8

1

[a]

The pore sizes were calculated from the adsorption branches by BJH method.

[b]

Normalized surface areas were calculated as Eq.1


Page 59 of 64

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Energy & Fuels

Table 2. Textural characteristics of NiMo/ZrM-x and NiMo/γ-Al2O3 catalysts Samples

Si/Zr mole ratio

SBET (m2/g)

Vp (cm3/g)

Dpd(nm)[a]

NiMo/ZrM-12.6

10

292

0.98

12

NiMo/ZrM-6.9

20

347

1.16

12.5

NiMo/ZrM-4.7

30

319

1.15

11.5

NiMo/ZrM-3.6

40

323

1.17

12.4

NiMo/ZrM-2.9

50

332

1.18

12.2

147

0.45

11.7

NiMo/γ-Al2O3 [a]

The pore sizes were calculated from the adsorption branches by BJH method


Energy & Fuels

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Page 60 of 64

Table 3. XPS fitting results of Zr 3d spectra of the sulfided NiMo/ZrM-x catalysts

Zr4+ Catalysts

Si/Zr mole ratio

Zr3+

ar.%

ar.%

ar.%

ar.%

(182.2 ev)

(184.6 ev)

(181.0 ev)

(183.4 ev)

Zr3+/Zrtotal.%

NiMo/ZrM-12.6

10

55.9

37.2

4.1

2.8

6.9

NiMo/ZrM-6.9

20

55.4

37

4.6

3

7.6

NiMo/ZrM-4.7

30

57.2

38.1

2.8

1.9

4.7


40 50

57.7 58

38.5 38.7

2.3 2

1.5 1.3

3.8 3.3


Page 61 of 64

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Table 4. XPS fitting results of Mo 3d spectra of the sulfided catalysts Mo4+ Catalysts

Si/Zr mole ratio

Mo5+

Mo6+

ar.%

ar.%

ar.%

ar.%

ar.%

ar.%

(228.6 ev)

(231.7 ev)

(230.1 ev)

(233.2 ev)

(232.5 ev)

(235.6 ev)

SMo[a]

NiMo/ZrM-12.6

10

38.1

25.4

8.9

5.9

12.9

5.6

63.5

NiMo/ZrM-6.9

20

40.4

26.9

7.8

5.9

11.4

7.5

67.3

NiMo/ZrM-4.7

30

35.3

23.6

9.9

6.6

14.7

9.8

58.9


40 50

34.3 33.9 26.5

22.9 22.6 17.7

8 9.3 2.9

5.3 6.2 1.9

17.7 16.8 30.6

11.8 11.2 20.4

57.2 56.5 44.2

NiMo/γ-Al2O3 [a]

SMo=Mo4+/Mototal


Energy & Fuels

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Page 62 of 64

Table 5. XPS fitting results of Ni 2p spectra of the sulfided catalysts Catalysts

Si/Zr mole ratio

NiMoS ar.%

NiS ar.%

NiO ar.%

Nisulfidity[a]

NiMo/ZrM-12.6

10

63.6

5.7

30.7

69.3

NiMo/ZrM-6.9

20

67.1

5.1

27.8

72.2

NiMo/ZrM-4.7

30

61.5

5.7

32.8

67.2

NiMo/ZrM-3.6

40

59.5

7

33.5

66.5

NiMo/ZrM-2.9

50

58.9

7.2

33.8

66.1

53.1

10.4

36.6

63.5

NiMo/γ-Al2O3 [a]

Nisulfidity = (NiMoS+NiSx)/Nitotal


Page 63 of 64

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Table 6. Amounts of acid sites of NiMo/ZrM-x catalysts determined by pyridineFTIR

Amount of acid sites (µmol g-1) Catalysts

Si/Zr mole ratio

200℃

350℃

L

B

L+B

L

B

L+B

NiMo/ZrM-12.6

10

43

14

57

13

8

21

NiMo/ZrM-6.9

20

39

18

57

12

10

22

NiMo/ZrM-4.7

30

32

13

45

10

7

17


40 50

27 23

15 10

42 33

9 8

5 7

14 15

80

0

80

26

0

26

NiMo/γ-Al2O3


Energy & Fuels

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Page 64 of 64

Synthesis of Zirconium Modified Spherical Mesostructured Cellular

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