Method for desulfurization of a hydrocarbon composition
11559794 · 2023-01-24
Assignee
Inventors
- Khalid R. ALHOOSHANI (Dhahran, SA)
- Saheed Adewale GANIYU (Dhahran, SA)
- Abdulkadir Tanimu (Dhahran, SA)
Cpc classification
C10G45/08
CHEMISTRY; METALLURGY
B01J29/0341
PERFORMING OPERATIONS; TRANSPORTING
C10G49/002
CHEMISTRY; METALLURGY
C10L2290/544
CHEMISTRY; METALLURGY
B01J37/0018
PERFORMING OPERATIONS; TRANSPORTING
C10L2270/026
CHEMISTRY; METALLURGY
International classification
C10G45/08
CHEMISTRY; METALLURGY
B01J37/10
PERFORMING OPERATIONS; TRANSPORTING
B01J35/00
PERFORMING OPERATIONS; TRANSPORTING
Abstract
A robust catalyst useful for hydrodesulfurization (HDS) of sulfur-containing hydrocarbons such as sulfur-containing diesel fuel. The catalyst contains a modified mesoporous silica, such as SBA-15, Zr atoms, Ni, Mo, Ce atoms. A method for removing sulfur from a hydrocarbon, such as diesel fuel or a refinery feedstock using the catalyst. A one-pot method for making the catalyst.
Claims
1. A method for desulfurizing a hydrocarbon containing sulfur, comprising: contacting the hydrocarbon with a catalyst in the presence of hydrogen at a pressure in the range of 1-10 MPa at a temperature ranging from 100−600° C., wherein the catalyst comprises mesoporous silica doped with Ce, Zr, Mo, and Ni, and the catalyst further comprises Zr and Ce atoms; wherein the mesoporous silica comprises Santa Barbara Amorphous-15 (“SBA-15”); and wherein the catalyst comprises Zr in an amount of 1.0 wt. % to 6 wt. % and Ce in an amount of 0.5 wt. % to 2.5 wt. %, each relative to the weight of the catalyst.
2. The method of claim 1, wherein the catalyst has not been calcined.
3. The method of claim 1, wherein the catalyst has been presulfided.
4. The method of claim 1, wherein the catalyst has a molar ratio of Zr to Ce ranges of 2:1 to 40:1.
5. The method of claim 1, wherein the catalyst comprises Zr in an amount of 2.0 wt. % to 4 wt. % and Ce in an amount of 1 wt. % to 2.0 wt. % each relative to the weight of the catalyst.
6. The method of claim 1, wherein the catalyst comprises 10 to 16 wt % Mo and 1 to 6 wt % Ni based on the weight of the catalyst.
7. The method of claim 1, wherein the catalyst has a BET surface area ranging from 300.9 to 332.6 m.sup.2/g, a microporous surface area ranging from 32.1 to 35.5 m.sup.2/g, and/or an external surface area ranging from 269 to 297 m.sup.2/g.
8. The method of claim 1, wherein the catalyst has a microporous pore volume ranging from 0.016 to 0.018 cm.sup.3/g; a total pore volume ranging from 0.49 to 0.54 cm.sup.3/g; and/or an average pore size ranging from 5.56 to 6.14 nm.
9. A method for desulfurizing a hydrocarbon containing sulfur, comprising: contacting the hydrocarbon with a catalyst in the presence of hydrogen at a pressure in the range of 1-10 MPa at a temperature ranging from 100-600° C.; wherein the catalyst comprises mesoporous silica doped with Ce, Zr, Mo, and Ni, and further comprises Zr and Ce atoms; wherein the mesoporous silica comprises Santa Barbara Amorphous-15 (“SBA-15”); and wherein the catalyst has a BET surface area ranging from 300.9 to 332.6 m.sup.2/g; a microporous surface area ranging from 32.1 to 35.5 m.sup.2/g; an external surface area ranging from 269 to 297 m.sup.2/g; a microporous pore volume ranging from 0.016 to 0.018 cm.sup.3/g; a total pore volume ranging from 0.49 to 0.54 cm.sup.3/g; and an average pore size ranging from 5.56 to 6.14 nm.
10. The method of claim 1, wherein the catalyst has been presulfided.
11. The method of claim 1, wherein distribution of Lewis acid sites in the catalyst ranges from about 457 to about 505 and/or the distribution of Bronsted acid sites ranges from 800 to 870, as determined by pyridine FTIR analysis.
12. The method of claim 1, wherein Ni and Mo are homogeneously dispersed on the mesoporous silica of the catalyst and their individual metal crystallite peaks are not detectable by X-ray diffraction.
13. The method of claim 1, further comprising sulfiding the catalyst prior to the contacting and/or wherein said contacting takes place in a stirred batch reactor or in a fixed bed reactor at a hydrogen pressure of 3 to 6 MPa and at a temperature ranging from 300 to 400° C.
14. The method of claim 1, wherein the hydrocarbon is fuel for an automotive vehicle, aircraft, railroad locomotives, ships, gas or oil burning power plants, or residential or industrial furnace or wherein the hydrocarbon is a refinery feedstock.
15. The method of claim 1, wherein the hydrocarbon is diesel fuel which contains dibenzothiophene.
16. A method for desulfurizing a hydrocarbon containing sulfur, comprising: contacting the hydrocarbon with a catalyst in the presence of hydrogen at a pressure in the range of 1-10 MPa at a temperature ranging from 100-600° C., wherein the catalyst comprises: mesoporous silica doped with Ce, Zr, Mo, and Ni, and further comprising Zr and Ce atoms, wherein the mesoporous silica comprises Santa Barbara Amorphous-15 (“SBA-15”), wherein Zr is present in an amount of 1.0 wt. % to 6 wt. %, Ce is present in an amount of 0.5 wt. % to 2.5 wt. %, Mo is present in an amount of 12 to 14 wt %, and Ni is present in an amount of 4 to 5 wt %, based on the weight of the catalyst.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
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DETAILED DESCRIPTION OF THE INVENTION
(10) Various embodiments of the invention include, but are not limited to those described below.
(11) One embodiment of the invention is directed to a catalyst comprising mesoporous silica doped with Ce, Zr, Mo and Ni. Among its other uses, the catalyst may be used to desulfurize hydrocarbons, such as diesel and other kinds of hydrocarbon feedstocks or fuels containing sulfur. Preferably, this catalyst is produced by a one-pot method that does not require or include calcining. In preferred embodiments, the doped catalyst comprises a mesoporous silica that is Santa Barbara Amorphous-15 (“SBA-15”) or a functional equivalent thereof. The amounts of Ce-, Zr-, Mo- and Ni-containing oxides or other compounds in the doped catalyst, exclusive of the weight of the SBA-15, or other mesoporous silica support, may range from <0.5, 0.5, 1, 1, 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, or >50 wt % of the total weight of the catalyst.
(12) Advantageously, each of the ZrO.sub.x and CeO.sub.y materials constitute about 1-10 wt. % of the catalyst, preferably about 4, 5, or 6 wt % of the catalyst; Mo-containing precursors constitute a about 8 to 18 wt. %, preferably about 12, 13 or 14 wt. % of the catalyst; Ni-containing precursors constitute about 1-6 wt. %, preferably about 2, 3 or 4 wt. % of the catalyst. Altogether, these dopants constitute about 20 to 32 wt. %, preferably about 25, 26 or 27 wt. % of catalyst, preferably with the balance comprising SBA-15 or other mesoporous silica support. Typically, Zr and Ce are derived from oxide precursors such as ZrO.sub.2 and CeO.sub.2 and the weight percent or wt. %/wt. % ratios are based on the weights of these oxide precursors. For example, in one embodiment a ratio of 1:20 was used to relate these oxide dopants with the silica support. Thus, for 1.2 g of support, 0.06 g each of the dopants was used, and since these were derived from their precursors, it amounted to 0.234 g and 0.191 g for the zirconium (iv) butoxide (80%) and ammonium cerium (iv) nitrate precursors respectively.
(13) The weight ratio of the ZrO.sub.x or CeO.sub.y, such as ZrO.sub.2 or CeO.sub.2, in the catalyst to the weight of the silica support may range from 1:5 to 1:50, preferably about 1:10 to 1:30, more preferably about 1:20.
(14) The weight ratio of the ZrO.sub.x to CeO.sub.y, such as ZrO.sub.2 to CeO.sub.2, in the catalyst may range from 1:5 to 5:1, 1:4 to 4:1, 1:3 to 3:1, 1:2 to 2:1, 1:1.5 to 1.5:1, 1:1.25 to 1.25:1, and preferably about 1:1.
(15) In one embodiment, the catalyst has a BET surface area ranging from 250, 275, 300, 305, 310, 315, 320, 325, 330, 335, 340, to 350 m.sup.2/g and/or a microporous surface area ranging from 30, 31, 32, 32.1, 32.5, 33.0, 33.5, 34.0, 34.5, 35.0 35.5, 35, 36, 37, 38, 39, to 40 m.sup.2/g; and/or an external surface area ranging from 250, 255, 260, 265, 266, 267, 268, 269, 297, 298, 299, or 300 m.sup.2/g or any intermediate value within these ranges.
(16) In another embodiment, the catalyst has a microporous pore volume ranging from 0.016, 0.017 to 0.018 cm.sup.3/g; and/or a total pore volume ranging from 0.49, 0.50, 0.51, 0.52, 0.53 to 0.54 cm.sup.3/g; and/or an average pore size ranging from 5.50, 5.75, 6.00, 6.25 to 6.50 or any intermediate value within these ranges.
(17) In one embodiment, the BET surface area of the catalyst ranges from 300.9, 305, 310, 315, 320, 325, 330 to 332.6 m.sup.2/g; a microporous surface area ranging from 32.1, 33, 34, 35 to 35.5 m.sup.2/g; an external surface area ranging from 269, 270, 275, 280, 285, 290, 295 to 297 m.sup.2/g; a microporous pore volume ranging from 0.016, 0.017 to 0.018 cm.sup.3/g; a total pore volume ranging from 0.49, 0.50, 0.51, 0.52, 0.53 to 0.54 cm.sup.3/g; and an average pore size ranging from 5.56, 5.60, 5.65, 5.70, 5.75, 5.80, 5.85, 5.90, 5.95, 6.00 to 6.14.
(18) In one embodiment, the mesoporous silica is SBA-15 and the catalyst has not been calcined. As shown by Table 5 and
(19) In another embodiment, the distribution of Lewis acid sites ranges from about 457, 460, 470, 480, 490, 500 to about 505 and/or the distribution of Bronsted acid sites ranges from 193, 195, 200, 205, 210 to 215.
(20) In another embodiment, the catalyst has a percentage of Mo.sup.4+ (3d.sub.5/2) ranging from 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, to 34, a percentage of Mo.sup.6+ (3d.sub.5/2) ranging from 43, 44, 45, 50, 55, 60, to 65, a percentage of Mo.sup.6+ (3d.sub.312) ranging from 23, 24, 25, 26, 27 to 28, respectively as measured by XPS spectra at 229.5, 231.8 and 235.6 eV.
(21) In one embodiment the catalyst has an active phase dispersion of NiMo which is characterized by the absence of their individual metal crystallite peaks.
(22) Another aspect of the invention is directed to a method for desulfurizing a hydrocarbon containing sulfur comprising, consisting essentially of, or consisting of contacting the catalyst as disclosed herein with the hydrocarbon in the presence of hydrogen at a pressure in the range of <1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or >10 MPa at a temperature ranging from <100, 100, 200, 300, 400, 500, 600 or >600° C. Advantageously, during desulfurization pressure may range from 4-6 MPa or 40, 50 to 60 bar, the temperature range from 250, 350 to 450° C., and a stirring rate range from about 100, 200, 300, 400 or 500 rpm.
(23) In other embodiments, the contacting takes place in a stirred batch reactor or in a fixed bed reactor at a hydrogen pressure of 3, 4, 5, to 6 MPa and at a temperature ranging from 300, 350 to 400° C.
(24) In some preferred embodiments, this method comprises sulfiding the catalyst or modified SBA-15 or other mesoporous silica prior to using it to desulfurize a hydrocarbon. Metals are often deposited on the alumina substrate in their benign oxide forms and must be converted to the corresponding sulfide before they will catalyze hydrodesulfurization (HDS) and hydrodenitrification (HDN) reactions. Advantageously, sulfiding may comprise simultaneous calcination and reduction of the Mo and NiMo metal oxides in the catalysts under the flow of 5 to 20% m preferably about 10% H.sub.2/He at about 300-500° C., preferably at about 400° C. After reduction, the furnace temperature may be brought down to about 300 to 400° C., preferably to about 350° C. and a 1-5 wt. %, preferably about a 2 wt. % CS.sub.2 solution in cyclohexane can be flowed through the furnace at 0.1 to 2.0 mL/min for 1-10 h, preferably at about 0.5 mL/min for 5 h.
(25) In this method the hydrocarbon containing sulfur may be a feedstock undergoing refining, or a fuel for an automotive vehicle, aircraft, railroad locomotives, ships, gas or oil burning power plants, or residential or industrial furnace.
(26) Another aspect of the invention is directed to a one-pot synthesis method for making the catalyst of embodiment 1, comprising, consisting essentially of, or consisting of admixing zirconium (IV) butoxide, tetraethyl ortho silicate (TEOS), poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol)(pluronic P123), hydrochloric acid, and deionized water to form a mixture; adding an aqueous solution containing Mo, Ni and Ce to the mixture; hydrothermally treating the resulting mixture at a temperature of at least 90° C.; and separating and drying solid material from the mixture. In some embodiments, nickel precursors such as nickel acetate and nickel carbonate, molybdenum precursors such as molybdenum acetate and molybdenum nitrate, and cerium precursors cerium isopropoxide and cerium nitrate hexahydrate may be used to produce a catalyst as disclosed herein.
(27) In some embodiments the aqueous solution contains nickel (II) carbonate, ammonium molybdate (VI) tetrahydrate, and ammonium cerium nitrate and the admixing further comprises stirring the mixture at a temperature ranging from <20, 20, 30, 40, 50, 60 or >60° C. for an hour or more; and wherein the hydrothermally treating comprises autoclaving the mixture at a temperature of about 250, 300, 325, 350, 375 or 400° C. at a pressure ranging from 20 to 80 bar, centrifuging the autoclaved mixture to recover solid components, and drying the solid components.
(28) Santa Barbara Amorphous-15 (SBA-15) is a highly stable mesoporous silica sieve. It has a high hydrothermal and mechanical stability characterized by a framework of uniform hexagonal pores that feature a narrow pore-size distribution and a tunable pore diameter of 5 nm to 15 nm and walls which range between 3.1 nm and 6.4 nm. SBA mesoporous silica 15 has a high internal surface area. Characteristics of and methods for producing SBA-15 are incorporated by reference to hypertext transfer protocol secure://www.acsmaterial.com/sba-15-20g.html (last accessed Nov. 22, 2019). Other types of mesoporous silica that may be used instead of SBA-15 include MCM-41 (Mobil Composition of Matter No. 41) or dendritic mesoporous silica. In some embodiments, SBA-16, KIT-16, or other nanosized silicas may be used.
(29) The term “biheteroatom” as used herein refers to the incorporation of both Zr and Ce atoms into SBA-15 or into another mesoporous silica. As shown by the inventors catalytic parameters such as surface acidity and active phase dispersion are influenced by incorporation of ZrCe biheteroatoms in a SBA-15 support.
(30) In some embodiments, the catalyst may further contain Co, Fe, Pd, Pt, W, and/or Zn or other metals. In other embodiments, these elements will be absent or substantially absent, for example, their presence will not modify the hydrodesulfurization activity of a catalyst containing them by more than 0.5, 1 or 2%.
(31) As disclosed herein, the developed catalysts were tested for HDS activity of dibenzothiophene (DBT) in a batch reactor. Catalytic parameters such as surface acidity and active phase dispersion were noticed to be influenced by the ZrCe biheteroatoms incorporated in the SBA-15 support. Thorough characterization of the catalysts was performed to understand their physico-chemical properties and how their structure relates to their HDS activity. The BET surface area result showed that ZrCe incorporation to form ZrCeSMN-S catalyst enhanced the surface area of the catalyst, although on calcination the surface area decreased significantly. The py-FTIR and NH.sub.3-TPD showed that the surface acidity strength of the catalysts increased when ZrCe were incorporated to the SBA-15 support, and the XPS analysis proved the presence of MoS.sub.2 in large amount in ZrCeSMN-S catalyst than in the other supported catalysts. The catalytic performance test of the catalysts showed that ZrCeSMN-S had the highest HDS activity and this was correlated to its structural properties such as large surface, better acidic strength and active phase dispersion.
Example
(32) Materials. Tetraethoxysilane (TEOS), zirconium (iv) butoxide (80%), pluronic P123, nickel (ii) carbonate, DBT (98%) and dodecane were purchased from Sigma-Aldrich. Ammonium molybdate (vi) tetrahydrate (99%) was bought from ACROS organics, USA. Ammonium cerium (iv) nitrate, was ordered from Riedel-de Haen AG, USA. Deionized water was generated in-house using Thermo Scientific Barnstead NANOPURE after distillation with a Labstrong FiSTREEM™ II Glass Still distillater.
(33) Single pot synthesis of ZrCe-SBA-15 NiMo catalysts. A SBA-15 step-by-step preparation method has previously been reported and details of this method are incorporate by reference to S. A. Ganiyu, et al., Ind. Eng. Chem. Res. 56(18) (2017) 5201-9. 10.1021/acs.iecr.7b00719.
(34) Modification of SBA-15 with Zr and Ce heteroatoms (20:1 ratio), and the incorporation of active Ni (and/or) Mo metal species were carried out following our previously reported single pot synthesis approach which is incorporated by reference to Saniyu et al., Appl. Catal. B Environ 203 (2017).
(35) Zr-modified SBA-15 was prepared by dropwise addition of 0.234 g of Zirconium (iv) butoxide to a mixture of 4.16 g TEOS, 2 g pluronic P123, 10.3 mL hydrochloric acid and 65 mL deionized water after stirring for 2 h. The mixture, which was kept at 40° C., was stirred continuously for 24 h before addition of an aqueous solution of 13 wt. % Mo and 3 wt. % Ni. After stirring for 30 min, the mixture was transferred to a Teflon autoclave for hydrothermal synthesis in an oven preconditioned at 90° C. The autoclave was kept in the oven for additional 24 h before centrifuging and drying at 100° C. for 10 h. Bi-heteroatom modification with both Zr and Ce was carried out following the same procedure as above, except that 0.191 g of ammonium cerium nitrate was further added to the mixture before stirring for 24 h.
(36) Detailed description of the prepared catalysts is provided in Table 1.
(37) TABLE-US-00001 TABLE 1 Catalyst description Code Description SM-S Mo doped SBA-15 ZrSM-S Zr and Mo doped SBA-15 ZrSMN-S Zr, Ni and Mo doped SBA-15 ZrCeSM-S Zr, Ce and Mo doped SBA-15 ZrCeSMN-S Zr, Ce, Ni, and Mo doped SBA-15 ZrCeSMN-C-S Zr, Ce, Ni and Mo doped SBA-15 with calcination
(38) Textural properties of catalysis. The catalysts surface areas, pore sizes and pore volumes were measured on a Micromeritics ASAP 2020 using N.sub.2 adsorption-desorption isotherms at 77k. Before the measurement, the catalysts were first degassed with a vacuum at 250° C. for 3 h to remove impurities. The Brunauer, Emmett, and Teller (BET) method was used to calculate the surface area and an absorption branch of the Barrett, Joyner, and Halenda (BJH) method was applied to calculate the pore size and pore volume of the catalysts.
(39) X-ray diffraction. The catalysts' crystallinity and the nature of their active metal phases on the supports were determined by recording their X-ray diffraction pattern between 20° to 80° 2θ using Rigaku Ultima IV X-ray diffractometer. The operation was performed at 40 kv and 40 mA with a scanning speed of 10°/min.
(40) Fourier transformation infrared (FTIR) spectroscopy. The catalysts FTIR spectra were recorded on a Nicolet 6700 FTIR spectrometer within a wavelength range of 400-4000 cm.sup.−1. Prior to the FTIR analysis, the catalysts were mixed in 1:100 ratio with KBr and pelletized using the hydraulic press pelletizer. The formed tiny pellets were inserted into the FTIR cell for analysis.
(41) Pyridine FTIR. The nature and amount of catalysts surface acidity were determined using an in-situ pyridine FTIR (with self-supported wafer). The samples, placed in a Specac cell, were pretreated under vacuum of 1.33×10.sup.−3 Pa at 300 C for 1 h, and pyridine vapor adsorption at 150° C. for 30 min. Excess pyridine vapor was expelled from the treated samples by degassing at 200° C., and the total acidity due to Lewis and Bronsted acid sites were recorded.
(42) Temperature programmed desorption of ammonia (NH.sub.3-TPD). Ammonia TPD (NH.sub.3-TPD) was utilized to measure the acidic property of the catalysts. The measurements were conducted on a micromeritics Chemisorp 2750 using 10 wt. % NH.sub.3. Roughly 100 mg of the catalysts in their oxide form was loaded into a quartz tube, which was later covered. High purity helium was purged through the tube at 600° C. for 30 min, then cooled to 100° C. Thereafter, NH.sub.3 was passed through the samples for 30 min at 100° C., followed by helium for 60 min to remove excess NH.sub.3. The temperature was raised to 900° C. at 10° C./min in order to desorb the ammonia, and the thermal conductivity detector (TCD) signal was recorded against the desorption temperature
(43) Temperature programmed reduction by hydrogen (TPR-H.sub.2). The reducibility of the metal oxides in the catalysts by H.sub.2 were determined by temperature-programmed reduction with hydrogen as a probe molecule. The analysis was carried out using an AutoChem II-2920 Micromeritics Chemisorption analyzer. Before the analysis, about 50 mg of the catalysts were heated to 500° C. for one hour under a steady flow of high purity helium to remove impurities, and later cooled to room temperature under the same condition of helium flow. Then the system gas flow was switched to 10% H.sub.2 in helium and the temperature was raised to 1000° C. at 10° C./min ramping. Under these conditions, the amount of H.sub.2 consumed at the reducible temperatures was recorded.
(44) Field emission scanning electron microscopy (FESEM). The catalysts surface morphologies were recorded on a Field Emission Scanning Electron Microscope FESEM (TESCAN, LYRA 3) using a secondary electron (SE) and the back scattered electron (BSE) mode at an accelerating voltage of 20 kV.
(45) X-ray photoelectron spectroscopy (XPS). The different Mo bonding states and their binding energies in the sulfided catalysts were determined by X-ray photoelectron spectroscopy (XPS) using PHI 5000 Versa Probe II, ULVAC-PHI Inc. spectroscope. Disc pelletized catalysts samples prepared using hydraulic press pelletizer were first subjected to high vacuum before the XPS analysis.
(46) Catalysts presulfidation and performance evaluation. All the prepared catalysts were presulfided without calcining except for ZrCeSMN, which a half of its portion was calcined to study the effect of calcination on the catalysts performance. The presulfidation was carried out in quartz tubular furnace after the reduction of the NiMo metal oxides in the catalysts under the flow of 5% H.sub.2 in helium at 400° C. to their respective metals. After reduction, the furnace temperature was brought down to 350° C. and the 5% H.sub.2 flow was substituted with a 2 wt. % CS.sub.2 solution in cyclohexane. The solution was flowed through the furnace at 0.5 mL/min for 5 h. Presulfided catalysts were pelletized, crushed and sieved within 300-500 microns.
(47) HDS performance study of the presulfided catalysts was carried out in a Parr 4576B batch reactor operated at 350° C., 5 MPa H.sub.2 pressure and 300 rpm stirring rate. Roughly 100 mg of the presulfided catalyst was added to 100 mL of model fuel containing 1000 ppm DBT in diesel. The reaction was performed for 5 h after the reaction conditions have been stabilized, and product sampling were done at an hour interval.
(48) Surface area and porosity. The BET surface area, pore size and pore volume of catalysts are parameters employed to help understand the catalytic performance behavior demonstrated by the catalysts and are incorporated by reference to R. M. Rioux, et al., J. Phys. Chem. B 109(6) (2005) 2192-202. 10.1021/jp048867x.
(49) Six catalysts' textural properties were measured and are summarized in Table 2. The BET surface area of SM was 245.9 m.sup.2/g and it was further observed that by incorporation of Zr the surface area increased to 260.64 m.sup.2/g. The observed trend shows that incorporation of Zr led to the increased surface area perhaps due to its large atomic size as compared to Si. However, subsequent addition of Ni to form ZrSMN-S catalysts resulted in slight decrease in the surface area and this can be attributed to the blockage of the void spaces within the support framework.
(50) TABLE-US-00002 TABLE 2 Textural properties of catalysts. BET Microporous External Microporous Total Average Surface Surface Surface Pore Pore Pore Area Area Area Volume Volume Size (m.sup.2/g) (m.sup.2/g) (m.sup.2/g) (cm.sup.3/g) (cm.sup.3/g) (nm) SM-S 245.9 31.9 214 0.0158 0.408 6.11 ZrSM-S 287.63 33.1 254.4 0.0165 0.499 6.05 ZrSMN-S 260.64 26.6 244.08 0.0131 0.451 5.54 ZrCeSM-S 327.57 33.2 287.56 0.0167 0.489 5.63 ZrCeSMN-S 316.76 33.8 282.97 0.0169 0.511 5.85 ZrCeSMN-C-S 226.86 27.5 199.38 0.0136 0.436 6.66
(51) The effect of biheteroatoms on the surface area was investigated by addition of Ce to the ZrSM-S to form ZrCeSM-S. It was observed that ceria incorporation lowered the surface area of ZrSM-S, which is probably because Ce is incorporated in the extra framework of the SBA-15.
(52) Surprisingly, however, introduction of Ni to the ZrCeSM-S resulted in the formation of large surface area ZrCeSMN-S (316.76 m.sup.2/g) even larger than ZrSM-S. It was also surprising that incorporation of Zr and Ce biheteroatoms to the SBA-15 support and the active NiMo species did not disrupt the mesoporosity nature of the support significantly as all catalysts' isotherms follow the H1 hysteresis loop (
(53) Subsequent calcination of the ZrCeSMN-S for 5 h to form ZrCeSMN-C-S significantly decreased the surface area to 226.86 m.sup.2/g, even though it resulted to an increase in average pore size as shown in
(54) X-Ray diffraction (XRD). The XRD pattern of the sulfided catalysts is presented in
(55) Fourier transformation infrared (FTIR) spectroscopy. FTIR spectroscopy was performed to have some idea about the functional groups present in the sulfided catalysts. The FTIR spectra of the catalysts (in their sulfided form) is shown in
(56) The ZrCeSMN-C-S catalyst, however, showed a significant decrease in the water molecule adsorption bands which was due to the catalyst calcination.
(57) The Si—O—Si stretching vibration band was observed within the range of 1150-1250 cm.sup.−1 in all the catalysts though at different intensities. The slight difference in Si—O—Si band wavelength and intensity in the catalysts was probably due to the incorporation of the Zr and Ce heteroatoms which substituted the silicon in Si—O—Si to form Si—O—Zr and Si—O—Ce respectively.
(58) Py-FTIR. The type, strength and amount of acidity in the sulfided catalysts was measured using the Py-FTIR. Typically, the free pyridine v8a mode adsorption band is observed at frequency of 1582 cm.sup.−1, and a shift to a range of 1590-1630 cm.sup.−1 indicates a Lewis acid sites.
(59) The further away the shift is from the pyridine peak the more is the strength of the Lewis acidity. Bronsted acidity due to the v19b mode of pyridine adsorption is observed at a frequency of 1540 cm.sup.−1. The py-FTIR results presented in
(60) As shown by Table 3, the intensity of the acid sites (both Lewis and Bronsted) as well as the acid strength increased with the incorporation of the Zr and Ce heteroatoms to the supports, except in ZrCeSMN-C-S where the high temperature calcination resulted in metals agglomeration. Thus, incorporation of biheteroatoms increased the acidity of the catalysts that had not been subjected to high temperature calcination.
(61) TABLE-US-00003 TABLE 3 The distribution of the acidic sites in the catalysts obtained from py-FTIR Catalysts L L + B B B/L SM 105.8 150.9 256.8 1.43 ZrSM 197.0 176.5 373.5 0.89 ZrSMN 207.5 185.9 393.4 0.89 ZrCeSM 394.4 152.2 546.6 0.39 ZrCeSMN 480.6 355.1 835.7 0.74 ZrCeSMN-C 156.5 47.14 203.6 0.30
(62) In Table 3, the descriptions: “L”, “B”, “L+B” and “B/L” are Lewis acid sites, Bronsted acid sites, sum of Lewis and Bronsted acid sites and the ratio of Bronsted sites to Lewis sites respectively.
(63) Temperature programmed desorption of ammonia (NH.sub.3-TPD). The NH.sub.3-TPD is a complimentary technique to the pyr-FTIR and is often utilized to characterize the strength and available acid sites in catalysts as described by M. Tamura, et al., Appl. Catal. A Gen. 433-434 (2012) 135-45. 10.1016/j.apcata.2012.05.008, incorporated herein by reference in its entirety.
(64) The NH.sub.3-TPD experiments were carried out to determine the acidic strength of the NiMo ZrCe-modified SBA-15 supported catalysts, and the obtained TPD profiles are shown in
(65) TABLE-US-00004 TABLE 4 NH.sub.3-TPD and H.sub.2-TPR of the catalysts NH.sub.3-TPD H.sub.2-TPR Quantity Quantity Peak (cm.sup.3/g (cm.sup.3/g Catalysts Temp.(s) STP) Peak Temp.(s) STP) SM 153, 688 42.2, 53.4 370 204.4 ZrSM 176, 688 18.2, 56.7 222, 391 27.8, 83 ZrSMN 185, 602 17.8, 56.9 384 179 ZrCeSM 188, 696 9.3, 63.6 208, 393 18.8, 90.9 ZrCeSMN 186, 691 16.7, 82.8 227, 311, 337 30.1, 48.4, 103.5 ZrCeSMN-C 190, 688 9.1, 60.2 377, 639 149.3, 4.4
(66) Temperature-programmed reduction (H.sub.2-TPR). TPR is a power tool used to check the reduction pattern of metal oxide catalysts. Here, the TPR was performed to understand the role of ZrCe heteroatoms on the reducing behavior of the SBA-1S supported NiMo catalysts. As shown in
(67) After incorporation of Zr and ZrCe to the support, this reduction peak shifted to 391° C. and 393° C. respectively confirming an increase in the strength of the metal-support interaction. However, the addition of Ni promoter to the ZrSM and ZrCeSM lowers the reduction temperature of the Mo.sup.6+ species. The high temperature reduction peak characteristic of Mo.sup.4+ to Mo.sup.6+ reduction gave an inconclusive pattern in all the catalysts as was similarly observed by Tatiana et al. See Klimova et al., id. (2009).
(68) Field emission scanning electron microscopy (FESEM). The FESEM images of the catalysts are displayed in
(69) Careful observation of the images showed that the size of the micro-sized rod decreased when Zr and Ce were incorporated to the SBA-15 framework. It was further observed that the micro-sized cylindrical rods in ZrCeSMN-C are stacked in multi-layers and this somewhat affect the dispersion of the active species on the modified support as is observed in the particle density due to NiMo loading on the catalyst.
(70) X-ray photoelectron spectroscopy (XPS). The binding states and binding energy of Mo phases in the sulfided catalysts was determined using XPS. The information was utilized to have a fair understanding of the degree of sulfidation of the Mo in the catalysts. See H. Liu, et al., Appl. Catal. B Environ. 174-175 (2015) 264-76. 10.1016/j.apcatb 2015.02.009, incorporated herein by reference in its entirety.
(71) The results of the Mo XPS analysis obtained after peaks deconvolution is shown in
(72) TABLE-US-00005 TABLE 5 Different Mo phases obtained from the XPS spectra Percent molybdenum in various oxidation states Mo.sup.4+ (3d.sub.5/2) Mo.sup.6+ (3d.sub.5/2) Mo.sup.6+ (3d.sub.3/2) Binding Energy Catalysts 229.5 eV 231.8 eV 235.6 eV SM 0.03 64.07 35.92 ZrSM 19.33 56.95 23.72 ZrSMN 23.96 51.97 24.07 ZrCeSM 21.94 54.83 23.23 ZrCeSMN 28.04 53.81 18.14 ZrCeSMN-C — 61.25 38.75
(73) From the
(74) Catalysts presulfidation and performance evaluation. The developed catalysts were evaluated for HDS using diesel fuel spiked with 1000 ppm DBT and the performance result is presented in Table 6. After 1 h of reaction, it was estimated that 30.26% of DBT has been removed from the diesel using the SM-S catalyst, and this percent got increased by approximately 15% and 29% when ZrCeSM-S and ZrCeSMN-S were used for the HDS reaction respectively. The percent sulfur removal after the 2.sup.nd, 3.sup.rd, 4.sup.th, and 5.sup.th hour follows the same trend, and by the 5.sup.th hour, almost 96% of sulfur had been removed by ZrCeSMN-S. However, when the ZrCeSMN-C-S was used for the HDS, a significant drop in conversion was noted, see
(75) The observed trend in HDS performance was correlated to the physicochemical properties of the catalysts such as surface acidity, metal support interaction and active phase dispersion. The ZrCeSMN-S catalyst that showed the highest HDS performance happens to have the largest surface area and this textural property may result in more active phase loading and dispersion which are likely to result in better EMS experience.
(76) In addition, the py-FTIR and NH.sub.3-TPD results discussed in section 3.1.4 and 3.1.5 respectively enumerated that the incorporation of Zr and Ce increase the strong acidic sites of the catalyst support and by implication increased the metal-support interaction and active phase dispersion on the SBA-15 support as was further corroborated by the H.sub.2-TPR. On the other hand, the low HDS performance of ZrCeSMN-C-S is related to the relatively low surface area of the catalysts and active phase dispersion.
(77) As shown herein, the modification of SBA-15 by Zr and ZrCe heteroatoms and the loading of the NiMo active species were performed by the single-pot hydrothermal synthesis method. The resultant catalysts: SM-S; ZrSM-S; ZrSMN-S; ZrCeSM-S; ZrCeSMN-S were prepared without calcination of the catalysts oxides and ZrCeSMN-C-S was obtained after calcination of ZrCeSMN oxides. The results demonstrated that ZrCe biheteroatom modification of SBA-15 enhanced its surface area, strength of acidic sites, and active phase dispersion. As a result, the ZrCeSMN-S provided a higher HDS performance than the rest of the catalysts in the series.
(78) Terminology. Terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
(79) As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.
(80) As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items and may be abbreviated as “/”.
(81) As used herein in the specification and claims, including as used in the examples and unless otherwise expressly specified, all numbers may be read as if prefaced by the word “substantially”, “about” or “approximately,” even if the term does not expressly appear. The phrase “about” or “approximately” may be used when describing magnitude and/or position to indicate that the value and/or position described is within a reasonable expected range of values and/or positions. For example, a numeric value may have a value that is +/−0.1% of the stated value (or range of values), +/−1% of the stated value (or range of values), +/−2% of the stated value (or range of values), +/−5% of the stated value (or range of values), +/−10% of the stated value (or range of values), +/−15% of the stated value (or range of values), +/−20% of the stated value (or range of values), etc. Any numerical range recited herein is intended to include all sub-ranges subsumed therein.
(82) Disclosure of values and ranges of values for specific parameters (such as temperatures, molecular weights, weight percentages, etc.) are not exclusive of other values and ranges of values useful herein. It is envisioned that two or more specific exemplified values for a given parameter may define endpoints for a range of values that may be claimed for the parameter. For example, if Parameter X is exemplified herein to have value A and also exemplified to have value Z, it is envisioned that parameter X may have a range of values from about A to about Z. Similarly, it is envisioned that disclosure of two or more ranges of values for a parameter (whether such ranges are nested, overlapping or distinct) subsume all possible combination of ranges for the value that might be claimed using endpoints of the disclosed ranges. For example, if parameter X is exemplified herein to have values in the range of 1-10 it also describes subranges for Parameter X including 1-9, 1-8, 1-7, 2-9, 2-8, 2-7, 3-9, 3-8, 3-7, 2-8, 3-7, 4-6, or 7-10, 8-10 or 9-10 as mere examples. A range encompasses its endpoints as well as values inside of an endpoint, for example, the range 0-5 includes 0, >0, 1, 2, 3, 4, <5 and 5.
(83) As used herein, the words “preferred” and “preferably” refer to embodiments of the technology that afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the technology.
(84) The description and specific examples, while indicating embodiments of the technology, are intended for purposes of illustration only and are not intended to limit the scope of the technology. Moreover, recitation of multiple embodiments having stated features is not intended to exclude other embodiments having additional features, or other embodiments incorporating different combinations of the stated features. Specific examples are provided for illustrative purposes of how to make and use the compositions and methods of this technology and, unless explicitly stated otherwise, are not intended to be a representation that given embodiments of this technology have, or have not, been made or tested.
(85) All publications and patent applications mentioned in this specification are herein incorporated by reference in their entirety to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference, especially referenced is disclosure appearing in the same sentence, paragraph, page or section of the specification in which the incorporation by reference appears.
(86) The citation of references herein does not constitute an admission that those references are prior art or have any relevance to the patentability of the technology disclosed herein. Any discussion of the content of references cited is intended merely to provide a general summary of assertions made by the authors of the references, and does not constitute an admission as to the accuracy of the content of such references.