Desulfurization Of Gasoline Research Articles

Selection and crosslinking modification of membrane material for FCC gasoline desulfurization

Selection and modification of membrane material is important fundamental research for fluid catalytic cracking (FCC) gasoline desulfurization by membrane process. Solubility parameters of FCC gasoline components and typical polymeric membrane materials were calculated and given out. For thiophene species, which are the primary ones in FCC gasoline, solubility parameters were about 19–21 (J/cm 3) 1/2, while about 14–15 (J/cm 3) 1/2 for most hydrocarbon species in FCC gasoline. The distinct difference in solubility parameter between the two typical species was just the key to fulfill the separation. By the study and analysis of solubility parameter theory, pervaporation (PV) performance and membrane preparation, polyethylene glycol (PEG) was determined as the promising membrane material for gasoline desulfurization. In spite of its desulfurization capacity, PEG needs modification for its easier swelling and unstable PV performance. According to the comparison on PV performance of PEG before and after modification as well as the swelling experiments, crosslinking was an effective modification way for PEG membrane applied in gasoline desulfurization. After crosslinking, not only the sulfur enrichment factor increased distinctly, but also the membrane performance was stable which was the most important point for practical application. Sulfur enrichment factor increased with the increase of amount of crosslinking agent and crosslinking time, while total permeation flux decreased. Unfavorable results occurred with exorbitant crosslinking resulted form excessive crosslinking agent and overlong crosslinking time. Since sulfur enrichment factor was for key consideration, 16% of crosslinking agent amount and 60 min of crosslinking time were more practical.

Extractive Desulfurization of Gasoline Using Imidazolium-Based Phosphoric Ionic Liquids

Sulfur partition coefficients for sulfur compounds 3-methylthiophene (3-MT), benzothiophene (BT), and dibenzothiophene (DBT) between phosphoric ionic liquids (ILs), namely, N-methyl-N-methylimidazolium dimethyl phosphate ([MMIM][DMP]), N-ethyl-N-methylimidazolium diethyl phosphate ([EMIM][DEP]), and N-butyl-N-methylimidazolium dibutyl phosphate (BMIM][DBP]), and gasoline were determined experimentally at 298.15 K over a wide range of sulfur content and compared with other IL extractants. The solubility of sulfur (as DBT, BT) in ILs aqueous solution at 298.15 K and varying water content was also measured. It was shown that the desulfurization ability of the ILs for each sulfur component (DBT, BT, 3-MT) followed the order of [BMIM][DBP] > [EMIM][DEP] ≫ [MMIM][DMP], and the sulfur removal selectivity for a specified IL followed the order of DBT > BT > 3-MT. The phosphoric ILs are insoluble in gasoline while the fuel solubility in ILs is noticeable and follows the order of [BMIM][DBP] ≫ [EMIM][DEP] > [MMIM][DMP]. Considering the relatively high sulfur removal ability, low fuel dissolvability, and small influence on the gasoline treated, [EMIM][DEP] might be used as a promising solvent for the desulfurization of gasoline via an extractive desulfurization (EDS) process. The sulfur components in the spent ILs could be conveniently separated via a water dilution process.

Montmorillonite Assembled with Nano-SiO2-particles for Gasoline Desulfurization

Montmorillonite Assembled with Nano-SiO2-particles for Gasoline Desulfurization

Pervaporation performance of crosslinked polyethylene glycol membranes for deep desulfurization of FCC gasoline

An crosslinked polyethylene glycol (PEG) membrane was prepared for fluid catalytic cracking (FCC) gasoline desulfurization. Sulfur enrichment factor come to 4.75 and 3.51 for typical FCC gasoline feed with sulfur content of 238.28 and 1227.24 μg/g, respectively. Pervaporation performance of membranes kept stable within the long time run of 500 h, which indicated that crosslinked PEG membranes had the property of resisting pollution. Judging from chromatographic analysis, the membranes were more efficient for thiophene species. Effects of operation conditions including permeate pressure, feed temperature, feed flow rate and feed sulfur content level on the pervaporation performance were investigated. Permeation flux decreased with increasing permeate pressure while increased with the operating temperature increase. Sulfur enrichment factor increased firstly and decreased then when permeate pressure and temperature rose. The peak value occurred at 10.5 mm Hg and 358 K for model compounds feed (378 K for FCC gasoline feed). Arrhenius relationship existed between flux and operating temperature. Both sulfur enrichment factor and flux were shown to increase with increasing feed flow rate. Permeation flux increased while sulfur enrichment factor decreased as the feed sulfur content increased, but the influence of increasing sulfur content on pervaporation performance weakened when sulfur content come to 600 μg/g.

Pervaporation separation of alkane/thiophene mixtures with PDMS membrane

Worldwide concerns over environment have stimulated increasing interest both in academic and industry for deep desulfurization of gasoline. Polydimethylsiloxane (PDMS) composite membrane was used to separate the binary and multicomponent alkane/thiophene mixtures by pervaporation. Effect of carbon number and concentration of alkane, and of feed temperature, on the separation efficiency of alkane/thiophene mixtures was investigated experimentally. Experimental results of binary mixtures indicated that the total fluxes for different alkane/thiophene mixtures decrease with increase of carbon number in the alkanes. Corresponding activation energies of permeation for alkanes in PDMS membrane increase with increase of carbon number in the alkanes. Differences of molecular size and structure of the alkanes lead to various selectivities thereof within PDMS membrane. In addition, the permeability and activation energy of thiophene in various systems differ from each other due to coupling effect which should be taken into consideration when dealing with multicomponent systems. Pervaporation results of ternary systems indicated that, the increase of content of lighter alkane in feed would result in a larger total flux, but a smaller selectivity to thiophene simultaneously. A quaternary system, the mixture of n-heptane, n-octane, n-nonane and thiophene, was employed to simulate the desulfurization process of gasoline. With the membrane having a PDMS layer of 11 μm, the total flux was measured to be about 1.65 kg/m 2 h, with the corresponding enrichment factor of thiophene 3.9 at 30 °C.

Oxidative Desulfurization of Organic Sulfur in Gasoline over Ag/TS-1

An effective Ag/TS-1 (0.06 wt %) catalyst for oxidative desulfurization of organic sulfur in gasoline was prepared by equal-volume impregnation. The Ag species is highly dispersed, and obvious particles of the Ag species cannot be observed directly in the TEM image. The EDX mapping of a chosen line 1 in the STEM image of the catalyst by line scanning confirmed the existence of the Ag species. It was not homogeneously or randomly dispersed in any part of the titanium silicalite. In fact, they prefer to deposit around Ti species of TS-1 catalyst. A large amount of Ag loading will adversely influence the performance of TS-1 because it will sterically hinder the oxidation of organic sulfur. The oxidative desulfurization of FCC gasoline was carried out over the Ag/TS-1 catalyst with H2O2 as the oxidant and water as the solvent. The results showed that the sulfur content in FCC gasoline was lowered from 136.5 to 18.8 μg/g after 4 h.

Catalytic Desulfurization of Gasoline via Dehydrosulfidation

This study presents a potentially attractive route for the desulfurization of gasoline via catalytic dehydrosulfidation, removal of hydrogen sulfide from sulfur-containing molecules. The proposed s...

Deep Desulfurization of Gasoline by Selective Adsorption over Nickel-Based Adsorbent for Fuel Cell Applications

Adsorptive desulfurization of model gasoline fuels and a real gasoline over a nickel-based adsorbent Ni−Al was conducted in a flowing adsorption system at a temperature range of 25−200 °C under ambient pressure without using H2 gas in order to evaluate the desulfurization performance of the adsorbent for producing ultra-low-sulfur gasoline for fuel cell applications. Adsorptive capacity and selectivity of the Ni−Al adsorbent for various sulfur compounds and the effects of coexisting olefin in gasoline as well as adsorptive conditions on the adsorptive performance were examined. It was found that the nickel-based adsorbent shows high capacity and selectivity for the adsorptive desulfurization of gasoline. Olefins in gasoline have a strong inhibiting effect on the desulfurization performance of the nickel-based adsorbent at room temperature. Increasing the temperature to 200 °C can significantly improve the desulfurization performance of the nickel-based adsorbent for real gasoline. The adsorption mechanism and selectivity are discussed on the basis of the experimental results and computational analysis. The adsorption of sulfur compounds on the nickel surface involves C−S bond cleavage, as evidenced by the formation of ethylbenzene from benzothiophene in the absence of H2 gas in the flow adsorption system.

Hydrodesulfurization and hydroconversion of heavy FCC gasoline on PtPd/H-USY zeolite

In the search for catalysts suitable for upgrading fractions of FCC gasoline, PtPd/USY zeolite was investigated. The objectives of the work were to reduce simultaneously the sulfur, nitrogen and aromatic contents of heavy FCC gasoline having various sulfur (30–203 ppmw) and 28 ppmw nitrogen contents. The process conditions were the following: temperature: 200–300 °C; pressure: 30 bar; liquid hourly space velocity: 1.0–3.0 h −1; H 2/hydrocarbon ratio: 500 m 3/m 3. The results indicated that PtPd/H-USY zeolite catalyst can be applied for the desulfurization of heavy FCC gasoline up to 203 ppm sulfur content. When a base heavy FCC gasoline fraction of 30 ppmw sulfur content was used the catalyst was able to reduce the aromatic content by 14 abs.% as well as sulfur and nitrogen contents to <1 ppmw in one step. Blending calculations were made to evaluate the quality of a full range FCC gasoline obtained by mixing the desulfurized heavy FCC gasoline and the untreated light cut.

Deep desulfurization of gasoline by selective adsorption over solid adsorbents and impact of analytical methods on ppm-level sulfur quantification for fuel cell applications

The objectives of this work were to comparatively study the performance of a Ni-based adsorbent and a Cu(I)Y-zeolite for the desulfurization of a commercial gasoline by fixed-bed adsorption experiments at room temperature and 200°C, and to clarify the impacts of analytical methods on the ppm-level sulfur quantification in desulfurized liquid fuels for fuel cell applications. A series of standard fuel samples containing known amounts of sulfur compounds in n-decane was prepared and was analyzed by using gas chromatograph coupled with a flame photometric detector (GC-FPD), pulsed flame photometric detector (GC-PFPD) and a total sulfur analyzer. The results show that the GC-FPD and GC-PFPD are not suitable for quantitative estimation of total sulfur concentration in complex hydrocarbon fuels at low ppm-level without considering both the nonlinear response and the quenching effect. The adsorptive desulfurization of a commercial gasoline over the Cu(I)Y-zeolite and a Ni-based adsorbent was conducted and compared using a fixed-bed adsorption system. The Cu(I)Y-zeolite prepared in the present study showed a breakthrough capacity of 0.22mgS/g of adsorbent (mg/g) at room temperature for removing sulfur in a commercial gasoline to less than 1ppmw. Under the same experimental conditions, the Ni-based adsorbent exhibited a breakthrough capacity of 0.37mg/g. The breakthrough capacity of the Ni-based adsorbent was increased by 38% at 200°C. Moreover, the breakthrough capacity of the Ni-based adsorbent corresponding to the outlet sulfur level of 10ppmw was 7.3mg/g, which was over an order of magnitude higher than that of Cu(I)Y-zeolite.

Desulfurization of transportation fuels by π-complexation sorbents: Cu(I)-, Ni(II)-, and Zn(II)-zeolites

New π-complexation-based sorbents were studied for desulfurization of diesel, gasoline, and jet fuels. The sorbents were obtained by ion exchanging faujasite type zeolites with Cu+, Ni2+ or Zn2+ cations using different techniques, including liquid phase ion exchange (LPIE). Hydrolysis of the cations in aqueous solutions should be avoided in order to increase the ion exchange level when aqueous solutions are used. Cation hydrolysis limitation could be avoided when vapor phase (VPIE) and solid-state (SSIE) ion exchange techniques are used instead. The deep-desulfurization (sulfur levels of <1ppmw) tests were performed using fixed-bed adsorption techniques. The treated and untreated fuels were fully characterized using the latest generation of FPD detectors in our laboratory, which are capable of eliminating quenching effects. After proper optimization and calibration of the detector non-linear response, as done in all our previous work, it was possible to detect sulfur concentration as low as 20ppbwS. The data was verified using total sulfur analyzers. The π-complexation sorbents desulfurization performance decreases as follows: Cu(I)-Y(VPIE) > Ni(II)-Y(SSIE) > Ni(II)-X(LPIE) > Zn(II)-X(LPIE) > Zn(II)-Y(LPIE). Molecular orbital calculations indicate the sorbents performance decreases as follows: Cu+ > Ni2+ > Zn2+. This agrees well with the experimental results. The best sorbent, Cu(I)-Y(VPIE), has breakthrough adsorption capacities of 0.395 and 0.278mmolS/g of sorbent for commercial jet fuel (364.1ppmwS) and diesel (297.2ppmwS), respectively.

Desulfurization of Gasoline by Extraction with New Ionic Liquids

CuCl-based ionic liquid was synthesized by mixing 1-butyl-3-methylimidazolium chloride with purified anhydrous CuCl, and its structures were studied using fast atom bombardment mass spectrometry (FAB-MS). It was determined that Cu(I) anionic species such as CuCl2-, Cu2Cl3-, and Cu3Cl4- existed in the ionic liquid, and these anions were moisture-insensitive and stable in air. CuCl-based ionic liquid exhibited remarkable desulfurization ability in the desulfurization of gasoline when used as an extraction absorbent. The effectiveness of sulfur removal may be attributed to the π-complexation of Cu(I) with thiophene, which shows promise as an approach for the deep desulfurization of motor fuel.

Kinetics and Mechanism of Liquid-Phase Oxidation of Thiophene over TS-1 Using H2O2Under Mild Conditions

Thiophene is a typical thiophenic sulfur compound in gasoline. Using n-octane containing thiophene as the model compound, the oxidation of thiophene, which is a key step for the oxidative deep desulfurization of gasoline, was carried out to study the reactivity of thiophene in oxidation reactions. It has been observed that thiophene oxidation can occur using water or t-butanol as solvent. Kinetics of the reaction shows a pseudo-first-order toward thiophene or catalyst and a zero order toward hydrogen peroxide. The mechanism for this unique reaction was proposed as the activation of conjugated electron in thiophene ring.

An overview of new approaches to deep desulfurization for ultra-clean gasoline, diesel fuel and jet fuel

This review discusses the problems of sulfur reduction in highway and non-road fuels and presents an overview of new approaches and emerging technologies for ultra-deep desulfurization of refinery streams for ultra-clean (ultra-low-sulfur) gasoline, diesel fuels and jet fuels. The issues of gasoline and diesel deep desulfurization are becoming more serious because the crude oils refined in the US are getting higher in sulfur contents and heavier in density, while the regulated sulfur limits are becoming lower and lower. Current gasoline desulfurization problem is dominated by the issues of sulfur removal from FCC naphtha, which contributes about 35% of gasoline pool but over 90% of sulfur in gasoline. Deep reduction of gasoline sulfur (from 330 to 30 ppm) must be made without decreasing octane number or losing gasoline yield. The problem is complicated by the high olefins contents of FCC naphtha which contributes to octane number enhancement but can be saturated under HDS conditions. Deep reduction of diesel sulfur (from 500 to <15 ppm sulfur) is dictated largely by 4,6-dimethyldibenzothiophene, which represents the least reactive sulfur compounds that have substitutions on both 4- and 6-positions. The deep HDS problem of diesel streams is exacerbated by the inhibiting effects of co-existing polyaromatics and nitrogen compounds in the feed as well as H 2S in the product. The approaches to deep desulfurization include catalysts and process developments for hydrodesulfurization (HDS), and adsorbents or reagents and methods for non-HDS-type processing schemes. The needs for dearomatization of diesel and jet fuels are also discussed along with some approaches. Overall, new and more effective approaches and continuing catalysis and processing research are needed for producing affordable ultra-clean (ultra-low-sulfur and low-aromatics) transportation fuels and non-road fuels, because meeting the new government sulfur regulations in 2006–2010 (15 ppm sulfur in highway diesel fuels by 2006 and non-road diesel fuels by 2010; 30 ppm sulfur in gasoline by 2006) is only a milestone. Desulfurization research should also take into consideration of the fuel-cell fuel processing needs, which will have a more stringent requirement on desulfurization (e.g., <1 ppm sulfur) than IC engines. The society at large is stepping on the road to zero sulfur fuel, so researchers should begin with the end in mind and try to develop long-term solutions.

A new approach to deep desulfurization of gasoline, diesel fuel and jet fuel by selective adsorption for ultra-clean fuels and for fuel cell applications : Ma, X. et al. Catalysis Today, 2002, 77, (1–2), 107–116

A new approach to deep desulfurization of gasoline, diesel fuel and jet fuel by selective adsorption for ultra-clean fuels and for fuel cell applications : Ma, X. et al. Catalysis Today, 2002, 77, (1–2), 107–116

Desulfurization of Commercial Liquid Fuels by Selective Adsorption via π-Complexation with Cu(I)−Y Zeolite

Desulfurization of commercial gasoline and diesel by a π-complexation adsorbent, Cu(I)−Y zeolite, was studied in a fixed-bed adsorber operated at ambient temperature and pressure. The sulfur contents in the effluents were below (or well below) the detection limit using flame photometric detection (FPD), i.e., below 0.28 ppmw sulfur. Thus, these “sulfur-free” fuels are well suited for fuel cell applications. Furthermore, it is demonstrated that using a thin layer of a guard bed (e.g., activated carbon, AC) could significantly increase the sulfur capacities of the π-complexation sorbent. For a feed gasoline containing 335 ppmw sulfur, Cu(I)−Y produced 14.7 cm3 of sulfur-free gasoline/g of sorbent. When using AC as a guard bed, 19.6 cm3 of sulfur-free gasoline/g of combined sorbent was produced. For the case of diesel fuel, 34.3 cm3 of “sulfur-free” diesel was produced per 1 g of combined sorbent. The π-complexation sorbents have proven to be by far the most sulfur-selective as well as having the highest sulfur capacities. Gas chromatography−FPD results showed that the π-complexation sorbents selectively adsorbed highly substituted thiophenes, benzothiophenes, and dibenzothiophenes from gasoline and diesel, which is not possible by using conventional hydrodesulfurization reactors.

Desulfurization of FCC Gasoline by Solvent Extraction and Photooxidation

A deep desulfurization process for FCC light gasoline has been investigated. The process is comprised of liquid-liquid extraction with acetonitrile, and photooxidation with ultraviolet light from a high-pressure mercury lamp. After the extraction the sulfur-containing compounds transfer from the oil to the solvent and then the solvent containing these sulfur compounds was photo-irradiated with ultraviolet light from a high pressure mercury lamp 300 W and with λ 200–300 nm, using strengthen electronic stirrer during the irradiation .The oil from the solvent was recovered with water. An azeotropic mixture (containing 86% acetonitrile and 14% water) was recovered successfully with one distillation column, and can reuse. The total sulfur content in this gasoline decreased from 309 to 68 ppm following 8 h of photo-irradiation .The total yield of the oil vary between 90–96%. The main sulfur compounds of this gasoline are alkyl substituted thiophenes.

S-Methylsulfonium Salts Obtained by Desulfurization of Vacuum Gas Oil and Catalytic-Cracked Gasoline as Thermal Latent Polymerization Initiator.

S-Methylsulfonium salts, obtained by desulfurization of vacuum gas oil (VGO) and catalytic-cracked gasoline (CCG) based on alkylation and a subsequent precipitation process, were used as initiator for polymerization of epoxide (glycidyl phenyl ether: GPE). The initiation behavior and activity for the salts obtained from VGO and CCG were compared with those obtained from light oil. Both the salts from VGO and CCG showed almost no activity at room temperature but become active with an increase of temperature, thus indicating that the salts act as thermal latent initiator. The initiation activity for the salts from VGO was relatively low, but the salts from CCG showed significantly higher activity than the salts from light oil. Most of the salts, obtained from CCG, are derived from less nucleophilic thiophenes, and therefore unstable against thermal stimulation, thus giving the higher initiation activity.

A new approach to deep desulfurization of gasoline, diesel fuel and jet fuel by selective adsorption for ultra-clean fuels and for fuel cell applications

In order to further reduce the sulfur content in liquid hydrocarbon fuels (gasoline, diesel fuel and jet fuel) for producing ultra-clean transportation fuels and for fuel cell applications, we explored a new desulfurization process by selective adsorption for removing sulfur (SARS). An adsorbent was developed and used for adsorption desulfurization of diesel fuel, gasoline and jet fuel at room temperature. The results indicate that the transition metal-based adsorbent developed in this work is effective for selectively adsorbing the sulfur compounds, even the refractory sulfur compounds in diesel fuels. The SARS process can effectively remove sulfur compounds in the liquid hydrocarbon fuels at ambient temperature under atmospheric pressure with low investment and operating cost. On the basis of the present study, a novel integrated process is proposed for deep desulfurization of the liquid hydrocarbon fuels in a future refinery, which combines a selective adsorption (SARS) of the sulfur compounds and a hydrodesulfurization process of the concentrated sulfur fraction (HDSCS). The SARS concept may be used for on-site or on-board removal of sulfur from fuels for fuel cell systems.

A Novel Desulfurization Process for Fuel Oils Based on the Formation and Subsequent Precipitation of S-Alkylsulfonium Salts. 2. Catalytic-Cracked Gasoline

A desulfurization process, based on the formation and subsequent precipitation of S-alkylsulfonium salts using alkylating agents (CH3I and AgBF4), has been applied to the desulfurization of catalytic-cracked gasoline (CCG). The desulfurization reactivity of each sulfur compound (thiol, disulfide, benzothiophene, tetrahydrothiophene, and thiophenes) in n-decane solution, as a model gasoline, was compared with that obtained from actual CCG. The sulfur compounds in CCG are methylated by the addition of the alkylating agents under moderate conditions and are removed as the precipitates of the corresponding S-alkylsulfonium salts. By employing this new process, the sulfur content of the CCG was decreased from 100 ppm to less than 30 ppm. The benzothiophene in CCG was found to be the most difficult compound to desulfurize, whereas the thiophenes were the most difficult compounds for the model gasoline. Although the olefin concentration was decreased significantly following desulfurization, the resulting CCG dem...