Real Gas Oil Research Articles

Deep oxidative desulfurization of gas oil by iron(III)-substituted polyoxometalate immobilized on nickel(II) oxide, ((n-C4H9)4N)4H[PW11FeO39]@NiO, as an efficient nanocatalyst

Sulfur compounds are among the most unfavorable constituents of petroleum derivatives, so stringent regulations have been established to curb their atmospheric emissions. In this regard, a new nanocomposite ((n-C4H9)4N)4H[PW11FeO39]@NiO) was synthesized composed of quaternary ammonium bromide salt of ironIII-substituted Keggin-type polyoxometalate immobilized on nickel(II) oxide nanoceramics via sol–gel method. The assembled (n-C4H9)4N)4H[PW11FeO39]@NiO nanocomposite was identified by FT-IR, UV–Vis, XRD, SEM, EDX, and TGA-DTG methods. The characterization results exhibited that ((n-C4H9)4N)4H[PW11FeO39] dispersed uniformly over the surface of the NiO nanoceramics. The ((n-C4H9)4N)4H[PW11FeO39]@NiO nanocomposite was employed as a heterogeneous nanocatalyst in the extractive coupled oxidation desulfurization (ECOD) of real gas oil and dibenzothiophene (DBT) as a model compound. Under relatively moderate conditions, the catalytic performance of the ((n-C4H9)4N)4H[PW11FeO39]@NiO in the ECOD procedure was studied by incorporating acetic acid/hydrogen peroxide as an oxidant system at a volume ratio of 1:2. According to the ECOD results, the ((n-C4H9)4N)4H[PW11FeO39]@NiO demonstrated the effectiveness of up to 95% with 0.1 g at 60 °C under optimal operating conditions. Moreover, the ((n-C4H9)4N)4H[PW11FeO39]@NiO nanocatalyst could be separated and reused for five runs without a noticeable decrease in the ECOD process. This study provides a promising way to meet the target of ultra-low sulfur as an essential process in oil refineries.

Keggin- and Dawson-type polyoxotungstates immobilized on poly(3,4-ethylenedioxythiophene)-coated zerovalent iron nanoparticles: Synthesis, characterization and their catalytic oxidative desulfurization activity

This work reports synthesis of new and hybrid nanocomposites composed of Keggin- and Dawson-type polyoxotungstates (POTs), namely Na3[PW12O40] (PW12) and K6[P2W18O62] (P2W18), immobilized on poly(3,4-ethylenedioxythiophene) (PEDOT) coated zerovalent iron (Fe0). The synthesized catalyst samples were analyzed by different characterization techniques including powder XRD, VSM, FESEM, EDX and DRS. The Fe0@PEDOT\\POTs magnetic nanocomposites have been investigated as efficient heterogeneous nanocatalysts for catalytic oxidative desulfurization (ODS) of model and real gasoil fuels. The catalytic ODS was carried out at various experimental conditions to assess the influences of individual reaction variables, such as nanocatalyst dosage, sulfur content (in model fuel), reaction time and reaction temperature. At the same experimental conditions, Keggin POTs-based catalyst (Fe0@PEDOT\\PW12) exhibited higher desulfurization activities (98.6% and 93.2% for model fuel and real gasoil, respectively) than Dawson- POTs-based (Fe0@PEDOT\\P2W18) catalyst (93.1% and 84% for model fuel and real gasoil, respectively). According to the results, the Fe0@PEDOT\\PW12 reusable nanocatalyst can retain high desulfurization efficiency after six reaction cycles.

Synthesis and characterization of new nano organic-inorganic hybrid (TBA)4PW11Fe@TiO2@PVA as a promising phase-transfer catalyst for oxidative desulfurization of real fuel

In this work, an efficient oxidative desulfurization (ODS) process of real gas oil and model oils was introduced using (TBA)4PW11Fe@TiO2@PVA phase-transfer catalyst. The catalyst was successfully prepared by the composition of the quaternary ammonium salt of mono iron-substituted phosphotungstate (abbreviated as (TBA)4PW11Fe), titanium dioxide (TiO2), and polyvinyl alcohol (PVA). The nanocomposite obtained was characterized through FT-IR, UV–vis, XRD, and SEM techniques. The spectroscopic characterization revealed that the (TBA)4PW11Fe was immobilized on the surface of TiO2@PVA. The results of catalytic tests showed the outstanding ODS performance of (TBA)4PW11Fe@TiO2@PVA in the removal of thiophenic compounds. Under optimized reaction conditions, the ODS efficiencies of benzothiophene (BT), dibenzothiophene (DBT), 4-methyldibenzothiophene (4-MDBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) reach 96, 99, 97, and 98%, respectively. The desulfurization system can be recycled five times with merely a slight decrease in activity.

Synthesis and characterization of new organic–inorganic nanohybrid film (TBA)PWFe/PVA/CTS as an efficient and reusable amphiphilic catalyst for ODS of real fuel

In this work, we report a new catalytic oxidative desulfurization (CODS) system based on (TBA)PWFe/PVA/CTS nanohybrid film as a highly active catalyst. The nanohybrid material was successfully fabricated by the composition of tetra (n‐butyl) ammonium salt of Fe‐substituted phosphotungstate, ((n‐C4H9)4N)4[PW11Fe(H2O)O39] abbreviated as (TBA)PWFe, polyvinyl alcohol (PVA), and chitosan (CTS). The composite was characterized using various analytical techniques including FT‐IR, UV–vis, XRD, and SEM. The results revealed the hydrogen‐bonding interaction between inorganic (TBA)PWFe clusters and organic polymers. The catalytic activity of (TBA)PWFe/PVA/CTS was evaluated in the CODS of real gas oil. Also, the solutions of heterocyclic thiophenic compounds (HTCs) in n‐heptane were tasted as simulated fuels. It was found that the removal efficiency of HTCs in the presence of (TBA)PWFe/PVA/CTS catalyst reached as high as 95% at 60 °C after 2 h. The significant catalytic performance of the nanohybrid film might be attributed to its amphiphilicity and multifunctional active sites, which enhances adsorption and oxidation of sulfur compounds. Moreover, the (TBA)PWFe/PVA/CTS composite can be easily recovered and reused by simple filtration, making it a suitable catalyst for cleaner processing.

Oxidative Desulfurization of Gas Oil Catalyzed by (TBA)4PW11Fe@PbO as an Efficient and Recoverable Heterogeneous Phase-Transfer Nanocatalyst

In this paper, a tetra(n-butyl)ammonium salt of ironIII-substituted phosphotungstate@lead oxide composite, (TBA)4PW11Fe@PbO, was successfully synthesized by the thermal decomposition method as a nanocatalyst for oxidative desulfurization (ODS) of gas oil. The incorporation of the materials was confirmed by Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible (UV–vis), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and 31P nuclear magnetic resonance (NMR) characterization methods. To evaluate the catalytic activity of (TBA)4PW11Fe@PbO, the ODS process was carried out using a CH3COOH/H2O2 oxidizing agent at 60 °C. From the attained results, the total sulfur and mercaptan content of real gas oil were reduced with 97% efficiency after 2 h. Furthermore, the various comparative experiments were performed to investigate the capability of (TBA)4PW11Fe@PbO in ODS of prepared model fuel. Results were indicated that the kinetics of sulfur oxida...

On the Preferred Active Sites of Promoted MoS2 for Hydrodesulfurization with Minimal Organonitrogen Inhibition

Hydrodesulfurization is a process to produce ultralow-sulfur diesel fuel. Although promoted molybdenum sulfide (MoS2) catalysts have been used industrially for several decades, the active site requirements for selective hydrodesulfurization of organosulfur compounds with minimal inhibition by organonitrogen constituents of a real gasoil feed has not been resolved. Using molecular binding energy descriptors derived from plane wave density functional theory calculations for comparative adsorption of organosulfur and organonitrogen compounds, we analyzed more than 20 potential sites on unpromoted and Ni- and Co-promoted MoS2. We find that hydrogen sulfide and ammonia are simple descriptors of adsorption of sterically unhindered organosulfur and organonitrogen compounds such as dibenzothiophene and acridine, respectively. Further, organonitrogen compounds in gasoil bind more strongly than organosulfur compounds on all sites except on sites with exposed metal atoms on the corner and sulfur edges of promoted Mo...

Investigation of hydrodearomatization of gas oils on noble metal/support catalysts

Due to the more and stricter requirements of diesel fuels, one of the most important key factors of production of modern diesel fuel blending components is the two-stage deep hydrodesulphurization and hydrodearomatization, where in the second step noble metal catalysts are used for the deep hydrodearomatization of prehydrogenated feeds. In this paper, the results of hydrodearomatization of different sulphur- and nitrogen containing real gas oil fractions on PtPd/USY zeolite, PtPd/amorphous SiO 2–Al 2O 3 and PtPd/γ–Al 2O 3 catalysts are presented. In case of PtPd/USY catalyst, the effect of Pd/Pt atomic ratio on the sulphur tolerance was also investigated, additionally, the effect of sulphur and nitrogen content of the feeds and the process conditions on HDA, HDN and HDS activities were studied. The main goal of our experiments was to find a bimetallic PtPd/USY catalyst possessing Pd/Pt mass ratio of 2:1 (Pd/Pt atomic ratio of 3.7:1), which was suitable for the deep hydrodearomatization of relatively high sulphur (up to 300 mg S/kg) and nitrogen (up to 200 mg N/kg) containing feeds. In case of optimal process parameters ( T = 310 °C, P = 60 bar, LHSV = 1.0–1.5 h −1, H 2/hydrocarbon volume ratio = 600 N m 3/m 3), low total aromatic (<10%), practically sulphur and nitrogen free products (≤10 mg S/kg and ≤1 mg N/kg) having high cetane number (56–58) could be produced, which are less pollutant diesel fuel blending components. The relatively high activity for hydrodesulphurization and hydrodearomatization, and the low hydrocracking activity of this catalyst provides flexibility for the two-step deep hydrodesulphurization and deep hydrodearomatization processes. It means that applying this catalyst, the deep hydrodearomatization and further deep heteroatom removal of different feeds can be performed with high gas oil yield. Therefore, it is not necessary to apply deep hydrodesulphurization to max. 50 or 10 mg S/kg in the first stage on transition metal/support catalysts.

Characterization and Catalytic Activities of ZrO2-TiO2 Supported Hydrodesulfurization Catalysts

Pure ZrO2, TiO2, and ZiO2-TiO2 mixed oxides are prepared by urea hydrolysis. Hydrotreating catalysts containing 8 wt% (MoO3) and 3 wt% (NiO) are prepared using these oxides and characterized by the Brunauer, Emmett, and Teller (BET) surface area, pore volume, X-ray diffraction, Fourier transform infrared, differential thermal analysis, and scanning electron microscopy. Thiophene hydrodesulfurization, cyclohexene hydrogenation, and cumene hydrocracking are taken as model reactions for evaluating catalytic activities in a micro-catalytic reactor at 350°C and atmospheric pressure. Sulfided catalysts showed a wide range of activity variation as a function of support composition, which established that NiMo sulfided active phases strongly depend on the nature and composition of the support. It is found that catalytic activities increase with increasing zirconia content in mixed oxide and reach maximum values for 20% zirconia content. (20%) Zr/Ti mixed oxide supported catalyst was tested at high pressure with real gas oil feedstock. A thorough study of the relationship between operating conditions and product quality would contribute much to the optimization of hydrotreatment processes.

High Quality Diesel by Hydrotreating Gas Oil over Modified Titania-supported NiMo Catalysts

In this work, two methods of preparing alumina-titania and ceria-titania mixed oxide supports were studied: In the first method, alumina or ceria were precipitated on the surface of a commercial titanium oxide. In the second method, alumina or ceria were impregnated on the surface of titania. In all catalysts under study, NiO comprises 3 wt% while MoO3 comprises 8 wt% in addition to 89 wt% of the support material. Surface area and pore volume measurements for the supports and catalysts were obtained from the analysis of nitrogen adsorption-desorption isotherms. Al, Ce, Ni, and Mo contents and coke percent of the spent catalysts were determined by x-ray fluorescence method. Characterization of the samples have been studied by DTA and XRD. The HDS activities have been studied, and two types of catalytic tests were used. One type of measurement was a screening test using the pulse technique. The second type was focused on studying the effect of important process variables as reaction temperature, hydrogen pressure, and LHSV on the extent of HDS of real gas oil (GO) feedstock and simultaneous HDS and HDN on the selected screened catalysts by using the continuous-flow high-pressure fixed-bed cata-test unit. The results revealed that titania containing Al or Ce catalysts are much more active than the conventional NiMo/Al2O3 catalysts on HDS and HDN reactions. They also demonstrate high aromatic saturation capabilities.

Upgrading of gas oils: the HDS kinetics of dibenzothiophene and its derivatives in real gas oil

The hydrodesulphurization (HDS) of dibenzothiophene (DBT), 4-methyl dibenzothiophene (4 M-DBT), 4,6-dimethyl dibenzothiophene (4,6 DM-DBT) and 4,6-diethyl dibenzothiophene (4,6 DE-DBT) as real gas oil components on NiMo/Al2O3 catalyst was investigated. On the basis of the first order rate constants of HDS of the individual sulphur compounds reactivities of the investigated compounds decreased in the order DBT ≫ 4 M-DBT > 4,6 DE-DBT ≈ 4,6 DM-DBT. Apparent activation energies of HDS of above sulphur compounds increased from 80.0 to 120.5 kJ/mol.

Selective adsorption of refractory sulfur species on active carbons and carbon based CoMo catalyst

Adsorption technique could be a reliable alternative in removing to a certain remarkable extent the sulfur species from the feedstock of petroleum oil. The performance of various carbons on adsorption of model sulfur compounds in a simulated feed solution and the sulfur containing compounds in the real gas oil was evaluated. The adsorption experiments have been carried out in a batch scale at ambient temperature and under the atmospheric pressure. In general, the most refractory sulfur compounds in the hydrotreatment reactions were selectively removed and adsorbed. It was found that the adsorbents affinities to dibenzothiophene and 4,6-dimethyldibenzothiophene were much more favored and pronounced than the aromatic matrices like fluorene, 1-methylnaphthalene and 9-methylanthracene. Among the sulfur species, 4,6-dimethyldibenzothiophene was the highest to be removed in terms of both selectivity and capacity over all the present adsorbents. The studied adsorbents showed significant capacities for the polyaromatic thiophenes. The electronic characteristics seem to play a certain role in such behavior. Regeneration of the used adsorbent was successfully attained either by washing it with toluene or by the release of the adsorbates through heat treatment. A suggested adsorptive removal process of sulfur compounds from petroleum distillate over carbon supported CoMo catalyst was discussed.

Investigation of the HDS kinetics of dibenzotiophene and its derivatives in real gas oil

The hydrodesulfurization (HDS) of dibenzothiophene (DBT), 4-methyl-dibenzothiophene (4 M-DBT), 4,6-dimethyldibenzothiophene (4,6 DM-DBT) and 4,6-diethyldibenzothiophene (4,6 DE-DBT) as real gas oil components on NiMo/Al2O3 catalyst was investigated. On the basis of the first order rate constants of HDS of the individual sulfur compounds calculated by both integral and differential evaluations the reactivities of the investigated compounds decreased in the order DBT >> 4 M-DBT > 4,6 DE-DBT » 4,6 DM-DBT. Additionally, results showed that product inhibition during HDS does not take place.

Synergism between unsupported Re and Co or Ni sulfide catalysts in the HDS and HDN of gas oil

Two series of unsupported Co–Re and Ni–Re binary sulfide catalysts with variable atomic ratio α = Me/(Me + Re) from 0 to 1 were prepared by the co-maceration method. The catalysts were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), and evaluated in the simultaneous hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) reactions of a real gas oil feed under industrial relevant conditions. The results showed a synergetic effect of the Co or Ni sulfide on the ReS 2 in both HDS and HDN reactions. A maximum in activity at the same atomic ratio α ∼ 0.5 was observed for both reactions and both Co–Re and Ni–Re catalysts. The magnitude of the synergy was generally superior for HDS than for HDN, and at low reaction temperature (598 K) larger for Ni–Re than for Co–Re catalysts, especially in HDS, while at high temperature (648 K) it was reverse. Moreover, the Co–Re catalysts exhibited higher HDN/HDS selectivity than the Ni–Re catalysts. Neither XRD nor XPS results evidenced the presence of a “Co–Re–S” or “Ni–Re–S” like phase. It is suggested that the synergism could be associated to the hydrogen activation and spillover from the Co or Ni sulfide to ReS 2.