Diesel Ultradeep Hydrodesulfurization over Trimetallic WMoNi

Subscriber access provided by Binghamton University | Libraries

Article

Diesel ultra-deep hydrodesulfurization over trimetallic WMoNi catalysts by liquid-phase preparation method in slurry bed reactor Yongjun Liu, Shuzheng Song, Xuan Deng, and Wei Huang Energy Fuels, Just Accepted Manuscript • Publication Date (Web): 05 Jun 2017 Downloaded from http://pubs.acs.org on June 7, 2017

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Energy & Fuels is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 35

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

Diesel ultra-deep hydrodesulfurization over trimetallic WMoNi catalysts by liquid-phase preparation method in slurry bed reactor Yong-Jun Liu, Shu-Zheng Song, Xuan Deng, Wei Huang*, Key Laboratory of Coal Science and Technology of Ministry of Education and Shanxi Province, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China ABSTRACT A series of Ni-Mo-W slurry catalysts were prepared by a novel complete liquid-phase method and tested for diesel ultra-deep hydrodesulfurization (HDS) in a slurry bed reactor. Results showed that Ni-Mo-W catalysts prepared by this novel method exhibited a relatively high HDS efficiency, reaching approximately 96 %. Characterization results showed that a suitable amount of W was beneficial for the dispersion of MoS2 species and the production of small particles. Meanwhile, the catalysts incorporate a suitable amount of W had shorter slab length and more stacking number of MS2, which would enhance the HDS activity. It was also found that HDS efficiency was closely related to (Ni+Mo+W)/(Ti+Al) atomic ratios on the catalysts surface. The incorporation of a suitable amount of W was beneficial for the HDS reproduction and the best catalytic performance was obtained when the Ni:W atomic ratio was 1:0.5. Keywords: Diesel; Hydrodesulfurization; Ni-Mo-W catalysts; Complete liquid-phase method; Slurry bed 1. Introduction

*

Corresponding author. Tel. /fax: +86 351 6018073. E-mail address: [email protected] (W. Huang)

ACS Paragon Plus Environment

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

Nowadays, the quantity of pollutants emitting into the atmosphere has increased drastically as the use of diesel fuels increased, thus the production of clean fuels to meet the strict environmental regulations has become one of the main challenges in catalysis [1]. It is reported that the sulfur content of diesel needs to be lower than 10 ppm according to the Euro V standard since 2009 [2,3]. Therefore, the ultradeep hydrodesulfurization (HDS) must be proceeded in order to produce such fuel. And the design and preparation of novel and more efficient catalysts is urgently required to realize the production of clean fuels with ultra-low sulfur contents. Currently, based on the industrial (commercial) operating conditions, most researches of diesel HDS were carried out on the fix bed reactor which can meet the requirement of low-sulfur content of diesel [4-6]. However, it has shortcomings of high equipment capital and poor heat transfer efficiency for a large-scale, which easily cause local temperature too high and thus lead to the deactivation of catalysts [7]. On the contrary, a slurry bed reactor has the advantages of simple construction and lower capital requirement for a large-scale, excellent heat transfer performance, good temperature control, online catalyst replacement and withdrawal [8]. A slurry bed reactor has been successfully used in Fischer-Tropsch synthesis, methanol synthesis and dimethyl ether synthesis. Nevertheless, there was not yet an industrial HDS technology using slurry reactors. Díaz de León et al. [9,10] investigated the hydrodesulfurization (HDS) of 4,6-dimethyl- dibenzothiophene (4,6-DMDBT) over NiW/-Al2O3 catalyst in slurry reactor, results showed that the catalysts with the highest HDS activity (90 %) exhibited better hydrogenolysis, which probably


Page 2 of 35

Page 3 of 35

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

enhanced the dispersion of W and Ni entities. Liu et al.[11] found that the catalyst was composed of stacked MoS2 particles with high layers and much smaller nickel containing compounds, exhibiting high HDS catalytic activity of 4,6-DMDBT and FCC diesel in slurry reactor. Several reports involved in HDS reaction were summarized and compared in Table 1. It could be seen from Table 1 that the HDS performance was significantly different in various catalysts, reactors and feedstocks. Till now, few reports simultaneously focused on diesel HDS reaction over trimetallic Ni-Mo-W catalysts in slurry bed reactor. In addition, our group proposed a novel catalyst preparation method-complete liquid-phase method, its main innovation lies in the catalysts prepared directly from solution to the slurry [12]. This method was first used in dimethyl ether (DME) synthesis from syngas by one step in the slurry bed reactor, which exhibited relatively high CO conversion and DME selectivity [13]. In addition, we found that the catalyst showed high activity of desulfuration when it was used in the pilot-scale experiment. Thus, this method was then used to prepare the Ni-Mo catalysts for the HDS of sulfide diesel by 4, 6-DMDBT in a slurry reactor, and the sulfur content of diesel could be reduced from 374 to 12 ppm [14]. Unfortunately, this result was difficult to reproduce because Ni (NO3)2·6H2O was easily deliquesced in the air. Recently, trimetallic WMoNi sulfide catalysts were reported more active than bimetallic W(Mo)Ni sulfide ones for the HDS of sulfur-containing model molecules and diesel fuels [15,16]. It was concluded that the NiWMoS phase was more active than NiMoS and NiWS ones since the synergetic effects between Ni sulfide species


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

and the W0.5Mo0.5S2 solid solution existed. In order to achieve this kind of synergetic effects, W and Mo species must closely contact and highly disperse on the support. Also, the highly reducible W and Mo species favored to generate more NiWMoS phases were required [17,18]. Wang et al. [19] found that the addition of W component could enhance the hydrogenation function and improve the HDS activity. Shan et al. [20] reported that highly dispersed W and Mo species and high sulfidability promoted the formation of a large number of metal sulfide slabs, which provided abundant edge sites for dispersing Ni species, and facilitated both textural and chemical synergisms. Thus, more synergetic NiWMoS active phases were obtained. To improve the repeatability of catalyst, Ni content was reduced to below 4wt. %, and W was correspondingly added to the catalysts as a secondary active phase. Therefore, in the present work, a series of trimetallic Ni-Mo-W catalysts were prepared by the complete liquid-phase method and tested for the diesel ultra-deep hydrodesulfurization (HDS) in a slurry bed reactor. And the relationship between the physicochemical properties and the catalytic performance was also clarified. 2. Experimental 2.1 Catalyst preparation The Ni-Mo-W catalysts were prepared by a complete liquid-phase method and more details were as follows: a certain amount of (C3H7O)3Al was added in 90 mL i-C3H7OH and the temperature maintained at 323 K for 3 h as pre-alcoholysis. The resulting solution was kept at room temperature for 12 h. Next, Ti(C3H7O)4 dissolved in i-C3H7OH was added to the above resulting solution. Then, 330 mL deionized


Page 4 of 35

Page 5 of 35

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

water, a certain amount of Ni(NO3)2｀6H2O solution, (NH4)6Mo7O24｀4H2O solution and H40N10O41W12｀xH2O solution were added to the above solution every an hour, respectively. After that, the bath temperature was then raised to 368 K and kept for 6 h until a homogeneous sol was obtained. The sol was aged at room temperature for 9 days, dispersed in paraffin with 0.5 mL sorbitan monooleate (span80) and heated under N2 atmosphere from room temperature to 553 K and kept for 8 h. As a result, a slurry catalyst was subsequently obtained. For each catalyst, the atomic ratio of Ni: W was kept at 1:3.3, 1:1.4, 1:0.5, and 1:0.7, and the corresponding catalysts were denoted as CAT1*, CAT2*, CAT3*, CAT4*, respectively. 2.2 Catalyst characterization The slurry catalysts were centrifuged, extracted with petroleum ether and dried at room temperature before characterization. Powder X-ray diffraction (XRD) patterns (2θ=5~85°) were recorded on a Rigaku D/max-2500 powder diffractometer using Cu Kα radiation with a tube voltage of 40 kV and operated at a scanning rate of 4◦/min. The N2 physisorption was performed at 77 K with a Micromeritics Quanta chrome instrument. Specific surface areas were obtained using Brunauer-Emmett-Teller (BET) method, pore volumes were calculated from N2 adsorption-desorption isotherms and mesopore diameters and size distributions were determined by the Barret -Joyner-Halenda (BJH) method. The NH3 temperature-programmed desorption (NH3-TPD) experiments were carried out in a tubular reactor. The samples were first reduced at 553 K in a flow of 5


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

Page 6 of 35

vol.% H2 + N2 (30 mL/min) for half an hour, After take 20 minutes, the temperature decreased to 323 K and the samples were saturated with NH3 for 30 min and then flushed with He flow to remove all physically adsorbed molecules. After that, the TPD data was collected under He flow (30mL/min) from 323 to 873 K with a heating rate of 10 K/min by an AMETEK mass spectrometer. The acidity properties of different catalysts were characterized by Fourier transform infrared spectroscopy of pyridine adsorption on a PE FTIR Frontier instrument. The system was degassed and evacuated at different temperatures and the IR spectra were recorded in the range of 1425-1550 cm-1. The

structure

morphology

of

the

samples

was

investigated

using

a

JSM-6010PLUS/LV scanning electron microscope (SEM) with an acceleration voltage of 15.0 kV. H2-TPR was carried out in a quartz reactor at atmospheric pressure. 50 mg of sample was pre-treated under He at 423 K for 30 min to remove physically adsorbed water, then a reductive gas (5 % H2/Ar) was introduced at a flow rate of 30 mL·min-1. The reactor temperature was augmented linearly from 323 to 773 K with a heating rate of 10 K·min-1 using a temperature-programmed controller. A thermal conductivity detector (TCD) was used to monitor the consumption of H2. TEM photographs were taken with a JEOL JEM-2999FMII apparatus. Samples dispersed in ethanol and sonicated for 20 min and then deposited over a Formvar copper grid to be observed in the microscope. X-ray photoelectron spectroscopy (XPS) experiments were carried out on an


Page 7 of 35

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

ESCALAB 250 spectrometer (VG Scientific Ltd, UK) equipped with monochromated Al Kα (hυ= 1486.6eV, 150 W) under ultrahigh vacuum (10-7 Pa). The binding energy was calibrated internally by an adventitious carbon deposit C (1 s) and the pass energy was 30 eV. 2.3 Catalytic activity test The ultra-deep HDS performance of diesel was carried out in a slurry bed reactor under continuous mechanical magnetic agitator. Before reaction, about 13 g Ni-Mo-W/AlOOH-TiO2 slurry catalysts were introduced to the reactor and pre-sulfided with H2 and 1 mL CS2 which was dissolved in 50 mL diesel and 70 mL liquid paraffin under 1 MPa, 593 K for 3 h, then the temperature was cooled down to room temperature. Next, the slurry catalyst was flushed with N2 flow to remove all sulfidation mixture. After that, the reactor temperature was raised to 633 K with a heating rate of 2 K/min under H2 flow at 2.5 MPa for 6 h. The HDS products were analyzed using a LC-4 general microcomputer coulomb meter. The catalytic performance (% HDS activity) of the catalysts was calculated by the following formula: HDS activity= (1- Sb/Sa) *100 where Sa was the sulfur content of feed before reaction, Sb was the sulfur content of product after reaction. 3. Results and discussion 3.1 X-ray diffraction The XRD patterns of different Ni-Mo-W catalysts before and after HDS reaction


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

were presented in Fig. 1. As seen in Fig.1, the characteristic peak position and intensity of AlOOH (2θ=14°, 28.2°, 38.4°, 49.3°, 64.5°, 72.2°) and weak peak of TiO2 (2θ=25.3°, 48°, 55°) were well conformed to the JCPDF files before and after HDS reaction. In addition, the diffraction peaks for Ni-Mo composite could be detected only for the CAT1*, which indicated that Ni, Mo species were existed in an amorphous state. After HDS reaction, the diffraction peaks of MoS2 were observed. However, it could be obviously found that the intensity of diffraction peaks of MoS2 of CAT1* and CAT2* were much stronger than that of CAT3* and CAT4*. Kim et al. [21] reported that an increase in the dispersion of MoS2 species facilitated the sulfidation, thus it would enhance the HDS activity, which was in agreement with our experimental result. In addition, no characteristic peaks of W phase were detected before and after HDS, this might probably due to the low quantity of W which was below the detection limit of XRD. 3.2 Textural properties The textural properties (BET surface area, pore volume, and pore size) of the Ni-Mo-W catalysts were listed in Table 2. It could be seen that all fresh catalysts had a relatively larger BET surface area. In addition, it was obviously found that the BET surface area increased with the increase of W proportion. After HDS, the BET surface area of all the catalysts decreased, whereas the average pore diameters significantly increased. In addition, it could be found that the variation of textural properties slightly decreased before and after reaction, which illustrated that a small number of W favored the stability of pore structure of catalysts.


Page 8 of 35

Page 9 of 35

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

The N2 adsorption-desorption isotherms and pore size distributions of the four catalysts were depicted in Fig. 2. According to the International Union of Pure and Applied Chemistry (IUPAC) classification, all the catalysts displayed the classical type-IV isotherms, suggesting that they had a mesoporous structure [22,23]. The hysteresis loop of the isotherm for the catalysts was of H1 type, which confirmed cylindrical pores and a uniform particle size [24]. The distribution of pore sizes in Fig. 2(c, d) showed two peaks around 4 nm and 5~10 nm in the four catalysts before reaction. However, after HDS, the previous peak disappeared, because this narrow peak might caused by an artifact resulting from spontaneous evaporation of capillary condensed liquid N2 due to the tensile strength effect, this phenomenon had also been observed and reported by other researcher [25]. 3.3 NH3 Temperature programmed-desorption The surface acidity characteristics of fresh Ni-Mo-W catalysts were determined by NH3-TPD-MS. As shown in Fig. 3, the nature of the acidity observed in all prepared catalysts was mostly weak and/or moderate, characterized by Lewis acid sites in the temperature range between 100 and 300 °C [9]. It was noticed that the intensity of the peak slightly increased with the increasing of W content, illustrating that the amount of weak acid sites of Ni-Mo-W catalysts increased with the increasing of W content. It was reported that both Lewis and Brønsted acid sites as well the total acidity of the oxide catalysts could be correlated with the final catalytic behavior in hydrodesulfurization reaction [9]. However, in this work, the Brønsted acid sites could not be observed, thus, combined with the catalytic performance, it seemed that


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

Lewis acid sites might be the main contribution to the desulfurization reaction. 3.4. Py-IR results Py-IR characterization was studied and shown in Fig. 4. As demonstrated in Figs. 4, it could be seen that spectra contained two main characteristic bands at 1450 cm-1 and 1490 cm-1, respectively. The band located at 1450 cm-1 could be assigned to Lewis (L) acid sites, and the band at 1490 cm-1 could be ascribed to pyridine co-adsorbed on both Lewis and Brønsted acid sites [26]. No characteristic peak appeared at 1540 cm-1, indicating that all catalysts showed no Brønsted acidity, which was in agreement with NH3-TPD result. In addition, it could be seen that the peak of CAT1* catalyst was the biggest, indicating that the total amounts of acidity sites over the CAT1* catalyst was greater than that of others. However, CAT1* showed the poorest catalytic activity toward HDS activity. The result indicated that the acid strength of the catalysts was not directly related to their catalytic performance. 3.5 Scanning electron microscope (SEM) measurements SEM was a useful technique to observe the morphology and the particle size of the catalysts. The representative SEM images of the fresh catalysts were shown in Fig. 5. It could be seen from the SEM images that the four fresh catalysts showed disordered morphologies and different particle sizes. The CAT1* and CAT2* contained irregular stacked particles with size ranging from 0.2 to 2 µm, whereas the CAT3* and CAT4* catalysts formed relatively uniform smaller particles, with particle size around 0.2 to 0.5 µm. This result illustrated that decreasing W content had an obvious effect in decreasing the sizes of the Ni-Mo-W nanoparticles.


Page 10 of 35

Page 11 of 35

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

Combined with the following catalyst activity results, the CAT1* and CAT2* catalysts exhibited relatively poor dispersity and larger size of nanoparticles, which might partly be responsible for the lower HDS efficiency of the catalysts. 3.6 The reducibility of catalysts To investigate the reduction behavior of the Ni-Mo-W catalysts, TPR measurements were carried out. It could be seen from Fig. 6 that there were three peaks (α, β and γ) of H2 consumption on all samples. The first peak was ascribed to the reduction of NiO [11]. The peak β might be assigned to the reduction of Mo species [11, 21] and the peak γ was attributed to the reduction of monotungstate (WOx) species [9,27]. It could be found that both peak α and β shifted to lower temperatures with the decrease of W content, suggesting that decreasing W content promoted the reduction of Ni and Mo. Also, the catalysts had relatively larger H2 consumption in the high-temperature region, simultaneously shifting to a lowering in its reductiontemperature with the decrease of W content, which indicated that it had larger amount of reducible WOx as well as lower reducibility. TPR results indicated Ni, Mo and W species had strong interaction with each other and the incorporation of W significantly influenced the reducibility of Ni-Mo-W catalysts. 3.7. HRTEM analysis TEM analysis was also conducted with an aim of confirming the metal dispersion and the particle size in Ni-Mo-W catalysts. As seen in Fig.7, The typical stacked MS2 (M=Mo/W) slabs characterized by black thread-like fringes were observed in the sulfided Ni-Mo-W catalysts. The interplanar distance was calculated about 0.61 nm,


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

which confirmed the (002) basal planes of the crystalline MoS2. In addition, it could be found that the slab lengths and the number of stacked layers of MS2 were different for all catalysts. The stacking number of MS2 increased with the decrease of W content and the slab length of CAT3* catalyst was less than that of others. It was reported that the lengths and the stacking number of MS2 slabs were two key factors in determining HDS performance [28,29]. In this study, the CAT3* exhibited relatively higher HDS efficiency, illustrating that relatively higher staking number and shorter MS2 crystallite length favored to the HDS process, which was consistent with other researchers’ results [30]. 3.8 X-ray photoelectron spectroscopy (XPS) XPS experiment was used to analyze the sulfidation degree of Mo based catalysts, which have great influence on the catalytic HDS activity. Fig. 8-10 showed the Mo3d， W4f and Ni2p XPS spectra of sulfided Ni-Mo-W catalysts. Meanwhile, the results were analyzed with XPS peak software and the binding energy of different levels M4+, M5+,and M6+ (M= Mo/W) and each peak area had been listed in Table 3. As seen in Table 3, the main valence states of Mo were +4, +5, +6, and the valence states of W were +4 and +6. The fitting standards were as follows: the binding energies of Mo3d5/2 and Mo3d3/2 for Mo species were 228.6±0.2 and 231.8±0.2 eV, corresponding to Mo4+(MoS2); Mo species were considered at 230.2 and 233.4 eV for Mo5+(MoSxOy); at 232.6 and 235.8 eV for Mo6+(MoO3) [31]. Similarly, the binding energies of W4f7/2 and W4f5/2 at about 32.1±0.2 and 34.3±0.1 eV, were ascribed to W4+ (WS2), at 36.0 and 38.2 eV were considered as W6+(WO3) [10]. The Ni species


Page 12 of 35

Page 13 of 35

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

existed as NiOx, NiSx and NiMoWS according to the literature [32]. The metal sulfidation degrees of Msulfidation (M = Mo/W) were the ratios of M4+ to the sum of M4+, M5+ and M6+, i.e., Msulfidation = M4+/(M4+ + M5+ + M6+) [33]. The value of Nisulfidation, Wsulfidation, Mosulfidation and the surface (Ni+Mo+W)/(Ti+Al) atomic ratios of spent catalysts was displayed in Table 4. The Mosulfidation value showed that the sulfidation degree of Mo species was in order of CAT1*>CAT3*>CAT4*>CAT2*, as for W and Ni species, the order was CAT1*>CAT2*>CAT3*>CAT4* and CAT4*>CAT2*> CAT1*>CAT3*, respectively. Shan et al. [20] found that higher degree of sulfidation would benefit the HDS reaction. Zhang et al. [7] studied the catalytic performance of NiMo catalysts supported on different crystal alumina materials in the hydrodesulfurization of diesel, XPS data showed that the Mosulfidation were 40.6 % and 39.2 % for NiMo/θ1-Al2O3 and NiMo/θ2-Al2O3 catalysts, respectively. However, the HDS activities were 96.7 % and 98.2 %. Rashidi et al. [23] investigated that impact of support, phosphorus, and/or boron on the structure and catalytic activity, the CoMoPB/NA catalyst with Mosulfidation about 51.7 % less than that of CoMoP/NA (62.8%) and CoMoB/NA (64.6%) catalysts, but it showed the best HDS efficiency. Moreover, Liu et al. [30] found the catalysts with bimodal mesoporous structure exhibited higher HDS activity than that of catalyst with mono-modal structure. The results indicated that the reaction of HDS was not controlled by a single parameter, but the concurrence of many factors. Meanwhile, it could be found that the surface Ni/(Al+Ti), Mo/(Al+Ti) and (Ni+Mo+W)/(Al+Ti) ratios of CAT3* were greater than that of others despite they having the same W/Mo/Ni content. This demonstrated that


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

the textural synergism might exist in the metal sulfide phase [18], which might be one reason for relatively high HDS efficiency. 3.9 Catalytic activity The catalytic performance was evaluated for all catalysts and the results were given in Table 5. As seen in Table 5, the catalysts prepared by complete liquid-phase method exhibited a relatively higher activity, and almost all the desulfurization rate of diesel reached 92 %. It was found that the HDS efficiency decreased with the increasing of W content, which illustrated that a small amount of W not only benefitted to reproduce the results but also favored improve the HDS efficiency. And the best catalytic performance was obtained when the Ni: W atomic ratio was 1:0.5. 4. Conclusion Ni-Mo-W catalysts prepared by complete liquid-phase method exhibited high diesel HDS efficiency (reaching approximately 96 %) in a slurry bed reactor. A small amount of W was beneficial to the dispersion of MoS2 species and the production of small particles. In addition, it was concluded that HDS efficiency was closely related to the (Ni+Mo+W)/(Ti+Al) atomic ratios on the catalysts surface. Meanwhile, the catalysts incorporation of a suitable amount of W had shorter slab length and more stacking number of MS2, which was beneficial for the high HDS efficiency reproduction and the best catalytic performance was obtained when the Ni:W atomic ratio was 1:0.5. This work provided us a new potential method for preparing highly commercial catalysts with higher HDS active. Acknowledgments


Page 14 of 35

Page 15 of 35

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

The work was supported by the Key Program of National Natural Science Foundation of China (No.21336006), the National Natural Science Foundation of China (21176167), and the National Key Technology R&D Program (Grant No.2013BAC14B04).

References [1] EU Fuel Regulations. http://www.dieselnet.com/standards/eu/fuel.php. [2] Fabián, S. M.; Jorge, A.; Ignacio, E. Dynamic modeling and simulation of hydrotreating of gas oil obtained from heavy crude oil. Appl. Catal. A: Gen. 2012, 425-426, 13-27. [3] Stanislaus, A.; Marafi, A.; Rana, M. S. Recent advances in the science and technology of ultra low sulfur diesel (ULSD) production. Catal. Today 2010, 153, 1-68. [4] Sun, F. X; Wu, W. C.; Wu, Z. L.; Guo, J.; Wei, Z. B.; Yang, Y. X.; Jiang, Z. X.; Tian, F. P.; Li, C. Dibenzothiophene hydrodesulfurization activity and surface sites of silica-supported MoP, Ni2P, and N-Mo-W catalysts. J. Catal. 2004, 228(2), 298-310. [5] Song, C. S. An overview of new approaches to deep desulfurization for ultra-clean gasoline, diesel fuel and jet fuel. Catal. Today 2003, 86(1), 211-263. [6] Xu, K.; Li, Y. F.; Xu, X. W.; Zhou, C.; Liu, Z. C.; Yang, F.; Zhang, L. Q.; Wang, G.; Gao, J. S.; Xu, C. M. Single-walled carbon nanotubes supported Ni-Y as catalyst for ultra-deep hydrodesulfurization of gasoline and diesel. Fuel 2015, 160, 291-296. [7] Zhang, M. H.; Fan, J. Y.; Chi, K. B.; Duan, A. J.; Zhao, Z.; Meng, X. L.; Zhang, H. L. Synthesis, characterization, and catalytic performance of NiMo catalysts supported on different crystal alumina materials in the hydrodesulfurization of diesel. Fuel Process. Technol. 2017, 156, 446-453.


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

[8] Wang, T. F.; Wang, J. F.; Jin Y. Slurry reactors for gas-to-liquid processes: A review. Ind. Eng. Chem. Res. 2007, 46, 5824-5847. [9] Díaz de León, J. N.; Zepeda, T. A.; Alonso-Nuñez, G.; Galván, D. H.; Pawelec, B.; Fuentes, S. Insight of 1D γ-Al2O3 nanorods decoration by NiWS nanoslabs in ultra-deep hydrodesulfurization catalyst. J. Catal. 2015, 321, 51-61. [10] Díaz de León, J. N.; Picquart, M.; Massin, L.; Vrinat, M.; de los Reyes, J. A. Hydrodesulfurization of sulfur refractory compounds: Effect of gallium as an additive in NiWS/Al2O3 catalysts. J. Mol. Catal. 2012, 363-364, 311-321. [11] Liu, H.; Yin, C. L.; Li, H.; Liu, B.; Li, X. H.; Chai, Y. M.; Li, Y. P.; Liu, C. G. Synthesis, characterization and hydrodesulfurization properties of nickel-copper-molybdenum catalysts for the production of ultra-low sulfur diesel. Fuel 2014, 129, 138-146. [12] Gao, Z. H.; Hao, L. F.; Huang, W.; Xie, K. C. A novel liquid-phase technology for the preparation of slurry catalysts. Catal. Lett. 2005, 102(3-4), 139-141. [13] Wang, P.; Huang, W.; Zhang, G. Z.; Gao, Z. H.; Tang, Y.; Sun, K.; Zhang, X. Y. The facile preparation of Cu-Zn-Al oxide composite catalysts with high stability and performance for the production of dimethyl ether using modified aluminum alkoxide, J. Ind. Eng. Chem. 2015, 26, 243-250. [14] Shi, L.; Huang, W.; Song, S. Z.; Li, Z. B. Effect of the fluorine addition method on the hydrodesuIfurization performance of NiMo catalysts overslurry bed. Acta Phys. -Chim. Sin. 2015, 31(8), 1559-1566. [15] Mendoza-Nieto, J. A.; Vera-Vallejo, O.; Escobar-Alarcón, L.; Solís-Casados, D.; Klimova, T. Development of new trimetallic NiMoW catalysts supported on SBA-15 for deep hydrodesulf-


Page 16 of 35

Page 17 of 35

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

urization. Fuel 2013, 110, 268-277. [16] Cervantes-Gaxiola, M. E.; Arroyo-Albiter, M.; Pérez-Larios, A.; Balbuena, P. B.; EspinoValencia, J. Experimental and theoretical study of NiMoW, NiMo, and NiW sulfide catalysts supported on an Al-Ti-Mg mixed oxide during the hydrodesulfurization of dibenzothiophene. Fuel 2013, 113, 733-743. [17] Byskov, L. S.; Nørskov, J. K.; Clausen, B. S.; Topsøe, H. DFT calculations of unpromoted and promoted MoS 2-based hydrodesulfurization catalysts. J. Catal. 1999, 187, 109-122. [18] Zdraz il, M. Recent advances in catalysis over sulphides. Catal. Today 1988, 3, 269-365. [19] Wang, H. Y.; Dai, F.; Li, Z. X.; Li, C. S. Upgrading shale oil distillation to clean fuel by coupled hydrogenation and ring opening reaction of aromatics on W-Ni/γ-Al2O3 catalysts. Energy Fuels. 2015, 29(8), 4902-4910. [20] Shan, S. F.; Liu, H. Y.; Yue,Y. Y.; Shi, G.; Bao, X. J. Trimetallic WMoNi diesel ultra-deep hydrodesulfurization catalysts with enhanced synergism prepared from inorganic-organic hybrid nanocrystals. J. Catal. 2016, 344, 325-333. [21] Kim, H.; Lee, J. J.; Moon, S. H. Hydrodesulfurization of dibenzothiophene compounds using fluorinated NiMo/Al2O3 catalysts. Appl. Catal. B: Environ. 2003, 44(4), 287-299. [22] Lai, W. K.; Pang, L. Q.; Zheng, J. B.; Li, J. J.; Wu, Z. F.; Yi, X. D. Efficient one pot synthesis of mesoporous NiMo-Al2O3 catalysts for dibenzothiophene hydrodesulfurization. Fuel Process. Technol. 2013, 110. 8-16. [23] Rashidi, F.; Sasaki, T.; Rashidi, A. M.; Kharat, A. N.; Jozani, K. J.; Ultra deep hydrodesulfurization of diesel fuels using highly efficient nanoaluminasupported catalysts: impact of support, phosphorus, and/or boron on the structure and catalytic activity. J. Catal. 2013, 299,


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

321-335. [24] Sanchez-Valente, J.; Bokhimi, X.; Hernandez, F. Physicochemical and catalytic properties of Sol-Gel aluminas aged under hydrothermal conditions. Langmuir 2003, 19, 3583-3588. [25] Mishra, H. K.; Stanciulesu, M.; CHarland, J. P.; Kelly, J. F. Mesoporous titania-alumina mixed oxide: a preliminary study on synthesis and application in selective catalytic reduction of NOx. Appl. Surf. Sci. 2008, 254, 7098-7103. [26] Pieterse, J. A.; Veefkind-Reyes, S.; Seshan, K.; Domokos, L.; Lercher, J. A. On the accessibility of acid sites in ferrierite for pyridine. J. Catal. 1999, 187, 518-520. [27] Fan, Yu.; Xiao, Han.; Shi, Gang.; Liu, H. Y.; Qian, Y.; Wang, T. H.; Gong, G. B.; Bao X. J. Citric acid-assisted hydrothermal method for preparing NiW/USY-Al2O3 ultradeep hydrodesulfurization catalysts. J. Catal. 2011, 279, 27-35. [28] Guzmán M.; Huirache-Acuña R.; Loricera C.; Hernández J. R.; Díaz de León, J. N.; de los Reyes, J. A.; Pawelec, B. Removal of refractory S-containing compounds from liquid fuels over P-loaded NiMoW/SBA-16 sulfide catalysts. Fuel, 2013, 103, 321-333. [29] Li, H. F.; Li, M. F.; Chu, Y.; Liu, F.; Nie, H. Essential role of citric acid in preparation of efficient NiW/Al2O3 HDS catalysts. Appl. Catal. A: Gen. 201l, 403, 75-82. [30] 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: Environ. 2012, 121-122, 5056. [31] Xu, J. D.; Huang, T. T.; Fan, Y. Highly efficient NiMo/SiO2-Al2O3 hydrodesulfurization catalyst prepared from gemini surfactant-dispersed Mo precursor. Appl. Catal. B: Environ. 2017, 203, 839-850. [32] Ninh, T. K.T.; Massin, L.; Laurenti, D.; Vrinat, M.; A new approach in the evaluation of the


Page 18 of 35

Page 19 of 35

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

support effect for NiMo hydrodesulfurization catalysts. Appl. Catal. A: Gen. 2011, 407, 29-39. [33] Duan, A. J.; Li, T. S.; Zhao, Z.; Liu, B. J.; Zhou, X. F.; Jiang, G. Y.; Liu, J.; Wei, Y. C.; Pan, H. F. Appl. Catal. B: Environ. Synthesis of hierarchically porous L-KIT-6 silica-alumina material and the super catalytic performances for hydrodesulfurization of benzothiophene. 2015, 165, 763-773. [34] Zhang, L.; Long, X. Y.; Li D. D.; Gao, X. D. Study on high-performance unsupported Ni-Mo-W hydrotreating catalyst. Catal. Commun. 2011, 12, 927-931. [35] Wang, W. Y.; Zhang, K.; Qiao, Z. Q.; Li, L.; Liu, P. L.; Yang, Y. Q. Hydrodeoxygenation of p-cresol on unsupported Ni-W-Mo-S catalysts prepared by one step hydrothermal method. Catal. Commun. 2014, 56, 17-22.


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

Table and Figure captions Table 1 The HDS activity in different literatures. Table 2 Textural properties of different catalysts Table 3 XPS parameters derived from curve fitting of Mo3d and W4f Table 4 The sulfidation degree of metal and the surface atomic ratios of all sulfided catalysts. Table 5 HDS activity of the sulfided catalysts. Fig. 1. X-ray diffraction patterns of fresh and spent catalysts. Fig. 2. N2 adsorption-desorption isotherms (a, b) and BJH pore size distributions (c, d) of fresh catalysts (a, c) and spent catalysts (b, d). Fig. 3. NH3-TPD profiles of the fresh catalysts. Fig. 4. Py-FTIR spectra of the fresh catalysts. Fig. 5. SEM images of the fresh catalysts:(A):CAT1* (B)CAT2* (C)CAT3* (D)CAT4*. Fig. 6. TPR profiles of the fresh catalysts Fig. 7. TEM images of the four catalysts. (A) CAT1* (B) CAT2* (C) CAT3* (D) CAT4*. Fig. 8. Mo3d XPS spectra of the spent catalysts Fig. 9. W4f XPS spectra of the spent catalysts Fig. 10. Ni2p XPS pattern of spent catalysts


Page 20 of 35

Page 21 of 35

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 1 The HDS activity in different literatures. Catalysts

reactors

feedstocks

HDS activity/ %

NiMo [6]

fixed bed

4,6-DMDBT

93.9

NiWS [7]

slurry bed

4,6-DMDBT

90

NiMo [8]

slurry bed

4,6-DMDBT

85.3

WMoNi [9]

fixed bed

diesel

97.5


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

Page 22 of 35

Table 2 Textural properties of different catalysts Before reaction

After reaction

Catalysts A (m2/g)

Vp (cm3/g)

Dp(nm)

A (m2/g)

Vp (cm3/g)

Dp(nm)

CAT1*

446.2

0.608

5.5

264.2

0.640

9.7

CAT2*

422.4

0.661

6.3

288.8

0.647

9.0

CAT3*

385.0

0.540

5.6

293.4

0.546

7.4

CAT4*

407.0

0.596

5.9

295.5

0.600

8.1


Page 23 of 35

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 3 XPS parameters derived from curve fitting of Mo3d and W4f Catalyst

CAT1*

CAT2*

CAT3*

CAT4*

Energy level

BE(eV)

Area

Energy level

BE

Area

Mo4+3d5/2

228.6

206.0

Mo3d3/2

231.8

137.4

Mo5+3d5/2

230.2

100.8

Mo3d3/2

233.4

67.2

Mo6+3d5/2

232.6

189.6

Mo3d3/2

235.8

126.4

W4+4f7/2

32.0

377.4

W4f5/2

34.2

283.0

W6+4f7/2

35.6

774.0

W4f5/2

37.8

580.5

Mo4+3d5/2

228.5

218.3

Mo3d3/2

231.7

145.5

Mo5+3d5/2

230.2

213.0

Mo3d3/2

233.4

142.0

Mo6+3d5/2

232.3

278.5

Mo3d3/2

235.5

185.7

W4+4f7/2

32.3

156.7

W4f5/2

34.4

117.6

W6+4f7/2

36.0

498.0

W4f5/2

38.1

373.4

Mo4+3d5/2

228.8

667.1

Mo3d3/2

232.0

444.7

Mo5+3d5/2

230.2

507.0

Mo3d3/2

233.4

338.0

Mo6+3d5/2

232.6

687.6

Mo3d3/2

235.8

458.4

W4+4f7/2

32.0

66.6

W4f5/2

34.2

49.9

W6+4f7/2

36.5

698.0

W4f5/2

38.7

523.5

Mo4+3d5/2

228.7

1354.9

Mo3d3/2

231.9

903.3

Mo5+3d5/2

230.2

1529.8

Mo3d3/2

233.4

1019.9

Mo6+3d5/2

232.6

1355.8

Mo3d3/2

235.8

903.9

W4+4f7/2

32.3

247.6

W4f5/2

34.4

185.7

W6+4f7/2

36.0

2888.1

W4f5/2

38.1

2166.1


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

Page 24 of 35

Table 4 The sulfidation degree of metal and the surface atomic ratios of all sulfided catalysts. Surface atomic ratio

Sulfidation (%) Catalyst Ni

Mo

W

Ni/(Al+Ti)

Mo/(Al+Ti)

W/(Al+Ti)

(Ni+Mo+W)/(Al+Ti)

CAT1*

27.9

43.9

33.4

0.040

0.029

0.048

0.117

CAT2*

37.0

30.8

23.9

0.039

0.054

0.038

0.132

CAT3*

27.7

32.2

8.7

0.041

0.093

0.027

0.161

CAT4*

41.1

32.0

7.9

0.034

0.054

0.035

0.124


Page 25 of 35

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 5 HDS activity of the sulfided catalysts. Catalyst

Sa/(µg.g-1)

Sb/(µg.g-1)

HDS activity/%

CAT1*

462.0

48.7

89.5

CAT2*

462.0

35.6

92.3

CAT3*

462.0

16.1

96.5

CAT4*

462.0

20.8

95.5


Energy & Fuels

■ AlOOH ★ TiO2

■ AlOOH ● TiO2

● NiMoO4.xH2O ■ ■ ●

■ ▼ ■

■ ★

■ ★

■

■

●

I n te n sity

■

▼ MoS2

■

● In te n sity

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 26 of 35

■ ●

▼ ■

Cat1*

Cat1*

Cat2*

Cat2*

Cat3*

Cat3*

Cat4* 10

20

30

40

50

60

70

80

Cat4* 10

20

30

2θ/degree（ fresh）

40

50

2θ/degree（ spent）

Fig. 1. X-ray diffraction patterns of fresh and spent catalysts


60

70

80

Page 27 of 35

450

450

Cat1* Cat2* Cat3* Cat4*

350 300

Cat1*

400

Cat2* Q u a n tity A d so r b e d (c m 3 /g )

Q u a n tity A d so r b e d (cm 3 /g )

400

250 200 150 100

350

Cat3*

300

Cat4*

250 200 150 100

50

50

0.0

0.2

0.4

0.6

0.8

1.0

0.0

0.2

0.4

0.6

0.8

Relative Pressure(P/P0）

Relative Pressure(P/P0)

(a) fresh

(b) spent

1.6

1.0

1.6

Cat1*

Cat1* Cat2*

1.4

d v /d lo g (w ) P o r e V o lu m e (c m 3 /g )

d v /d lo g (w ) P o r e V o lu m e (c m 3 /g )

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

Cat3* Cat4*

1.2 1.0 0.8 0.6 0.4 0.2 0.0 0

5

10

15

20

25

30

35

1.4

Cat2* Cat3* Cat4*

1.2 1.0 0.8 0.6 0.4 0.2 0.0 0

5

10

Pore width(nm) (c) fresh

15

20

Pore width(nm) (d) spent

25

30

35

Fig. 2. N2 adsorption-desorption isotherms (a, b) and BJH pore size distributions (c, d) of fresh catalysts (a, c) and spent catalysts (b, d)


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

NH3 desorption

Energy & Fuels

Page 28 of 35

o

120 C

Cat1* Cat2* Cat3* Cat4*

100

200

300

400

500

600

o

Temperature ( C)

Fig. 3. The NH3-TPD profiles of the fresh catalysts


Page 29 of 35

423K

CAT1* CAT2* CAT3* CAT4*

1425

673K

CAT1* CAT2* CAT3* CAT4*

L

Absorbance

Absorbance

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

1450

1475 1500 -1 Wavenumber (cm )

1525

1550

1425

1450

1475 1500 1525 -1 Wavenumber (cm )

Fig. 4. Py-FTIR spectra of the fresh catalysts


1550

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

Fig. 5. The SEM images of the fresh catalysts:(A):CAT1* (B)CAT2* (C)CAT3* (D)CAT4*.


Page 30 of 35

Page 31 of 35

α

β

γ

H2 consumption

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

CAT1* CAT2* CAT3* CAT4* 200

300

400

500 o

Temperature ( C)

Fig. 6. TPR profiles of the fresh catalysts


600

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

Fig. 7. TEM images of the four catalysts. (A) CAT1* (B) CAT2* (C) CAT3* (D) CAT4*


Page 32 of 35

Page 33 of 35

CAT1* Mo3d

Mo4+

CAT2* Mo3d

Mo4+ S2s from sulfide and S22-

Mo5+ I n t e n s ity ( c p s )

I n t e n s ity ( c p s )

Mo5+ Mo6+

238

236

234

232

230

228

226

224

S2s from sulfide and S22-

Mo6+

240

238

236

234

B.E.(eV)

CAT4* Mo3d

232

230

226

224

Mo5+

228

226

224

Mo6+

I n te n s it y (c p s )


234

228

Mo4+

Mo6+

236

230

Mo4+

Mo5+

238

232

B.E.(eV)

CAT3* Mo3d

I n te n s it y (c p s )

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


238

236

234

B.E.(eV)

232

230

B.E.(eV)

Fig. 8. Mo3d XPS spectra of the spent catalysts


228

226

224

Energy & Fuels

W6+ CAT1* W4f

CAT2* W4f W4+ W4+



W6+

40

38

36

34

32

30

42

40

38

B.E.(eV)

36

34

32

30

B.E.(eV)

CAT3* W4f

CAT4* W4f W6+ I n te n s it y (c p s )

W6+ I n te n s it y (c p s )

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 34 of 35

W4+

44

42

40

38

36

34

32

30

W4+

44

42

40

B.E.(eV)

38

36

B.E.(eV)

Fig. 9. W4f XPS spectra of the spent catalysts


34

32

30

Page 35 of 35

CAT1*Ni2p

CAT2*Ni2p NiMoWS

Intensity

NiMoWS NiOx

NiOx

NiSx Intensity

NiSx

848

850

852

854

856

858

860

862

848

864

850

852

854

856

B.E.(eV)

858

860

862

864

B.E.(eV)

CAT4*Ni2p

CAT3*Ni2p

NiMoWS NiMoWS

NiOx

NiOx NiSx

NiSx Intensity

Intensity

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

848

850

852

854

856

B.E.(eV)

858

860

862

864

848

850

852

854

Fig. 10. Ni2p XPS pattern of spent catalysts


856

B.E.(eV)

858

860

862

864

Diesel Ultradeep Hydrodesulfurization over Trimetallic WMoNi

Recommend Documents