Alkylation Desulfurization Research Articles

Imidazole-methane sulfonic ionic liquids used for catalytic alkylation desulfurization and enhancement of microchannel technology

Imidazole-methane sulfonic ionic liquids (C4(MIM)-MSA) were synthesized and used for catalytic alkylation of thiophene. The determination of sulfur content in alkylated desulfurized oil shows that the ionic liquid has excellent alkylation desulfurization effect. Compared with pure acid catalyst, ILs catalytic reaction has higher selectivity. The alkylation desulfurization mechanism of ionic liquid was proved by the determination of oil component changes before and after desulfurization and the characterization of ionic liquid structure. Microchannel technology is used to enhance alkylation reaction, and the optimum reaction conditions are experimentally selected. The microchannel reactor can shorten the alkylation desulfurization reaction time significantly and only need 2 min to complete the reaction, which is much lower than the conventional stirring reaction time of 30 min. The desulfurization rate of model oil is 93.8% and FCC desulfurization rate is 96.3% (final distillation point is 160 °C).

Hierarchical ZSM-5 zeolite obtained by designed organosiloxane: synthesis, characterization, and catalytic applications

A new strategy was implemented to synthesize hierarchical ZSM-5 zeolite, which uses self-made organosilanized double-terminal amino polyetheramine (ODAP) as a soft template to generate mesopores. The influence of the additional amount of ODAP on the textural properties and morphologies of the hierarchical ZSM-5 zeolite was investigated. The obtained hierarchical ZSM-5 zeolite was characterized by X-ray diffraction, N2 physical adsorption, SEM, temperature-programmed desorption of NH3, and other methods. The analysis of the experimental results shows that the maximum total BET specific surface area and mesoporous specific surface area of the optimized hierarchical ZSM-5 zeolite reached 609 and 278 m2/g, respectively. Because the synthesized hierarchical ZSM-5 zeolite has a large mesoporous specific surface area and abundant surface acidity, in terms of reactant conversion and product selectivity, compared with microporous zeolite, it exhibits excellent catalytic performance in the thiophene alkylation desulfurization reaction. This synthesis strategy can be extended to the preparation of zeolites with different framework structures, which is of great significance.

Graphene modified porous organic polymer supported phosphotungstic acid catalyst for alkylation desulfurization

A new strategy of using graphene to modify porous organic solid acid catalyst for alkylation desulfurization is proposed by taking advantage of the π-π interaction between graphene and thiophenic sulfur. A graphene-modified sulfonated porous organic polymer (POP) supported phosphotungstic acid (HPW) catalyst (HPW/POP-G-SO3H) is successfully prepared by the solution polymerization-sulfonation-impregnation method. Steam adsorption experiment results show that graphene modification could increase the adsorption capacity of 3- methylthiophene (3-MT), but has little effect on the adsorption of isopentane; therefore, the selective adsorption of 3-MT could be enhanced. DFT calculations plus dispersion corrections also show that the adsorption energy of 3-MT on graphene is higher than that of isopentene on graphene and higher than those of 3-MT and isopentene on sulfonated POP. Subsequently, the catalytic activity test of alkylation desulfurization confirms that graphene-modified supported HPW catalyst shows higher alkylation desulfurization activity. This could support our assumptions. After recycles of 6 times, the 3-MT conversion on HPW/POP-G-SO3H catalyst decreases slightly, which possesses good recycling performance. Therefore, HPW/POP-G-SO3H catalyst will have broad application prospects in the field of alkylation desulfurization.

Mesoporous Silica Encapsulated Phosphotungstic Acid Catalysts for Alkylation Desulfurization of Gasoline

An effective, green method was proposed to prepare mesoporous SiO2 encapsulated phosphotungstic acid (HPW) catalysts for alkylation desulfurization of 3-methylthiophene (3-MT). 3-aminopropyl triethoxysilane (APTES) was added to promote the formation of SiO2 gel and immobilize HPW during preparation. Then, SiO2 encapsulated HPW catalysts were characterized by XRD, N2 physical adsorption, SEM, TEM, EDS, Ultraviolet–Visible spectrum, FTIR, NH3-TPD to study the physical and chemical properties. Characterization results show that the initial Keggin structure of HPW was remained during the preparation and there exist strong interaction between HPW and SiO2. Activity of catalysts is superior to that of reported SBA-15 encapsulated HPW catalysts, due to more effective encapsulation of HPW. The conversion of 3-MT could reach 99% with HPW content of 30.8% under reaction conditions (reaction temperature of 363 K, reaction time of 60 min and 1% catalyst dosage). Reducing the olefin content will not reduce the conversion of 3-MT but could effectively reduce the self-polymerization of olefin, which is also beneficial to reusability of catalysts.

Melting-type acidic quaternary ammonium ionic liquids as catalysts for alkylation desulfurization of FCC gasoline

The melting-type of caprolactam-tetrabutylammonium bromide acidic quaternary ammonium ionic liquids (ILs) were synthesized as catalysts for the olefin alkylation thiophenic sulfur (OATS) in FCC gasoline. [CPL-TBAB]2HSO4 with high acid strength showed the best desulfurization performance. GC–MS analysis suggested that the alkylation products of model oil were mainly mono-alkyl or di-alkyl thiophenic sulfides. The decrease of acid strength made the activity of IL degraded. Re-cation regeneration of cationic ligands with higher price recovered from the used IL was proposed to restore the acid strength by adding new anionic groups, and it showed a similar desulfurization activity as the fresh IL.

Alkylation desulfurization of FCC gasoline catalyzed by glycerol-based solid acid catalyst

ABSTRACTA novel high acid site density carbon-based solid acid catalyst was prepared and first applied in the FCC gasoline alkylation desulfurization. The catalyst was synthesized by a facile approach and characterized by X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR), Brunauer–Emmett–Teller analysis (BET) and Gas Chromatography-Mass Spectrometer (GC-MS). The desulfurization performance of this solid acid catalyst was investigated and optimized.

Alkylation desulfurization of FCC gasoline over organic-inorganic heteropoly acid catalyst

The alkylation reaction of thiophenic sulfides with olefin in model fluid catalytic cracking (FCC) gasoline has been carried out over many kinds of organic-inorganic heteropoly acids, H3PW12O40, and AlPW12O40. The results have showed that organic-inorganic heteropoly acid [Bmim]H2PW12O40 exhibits the best catalytic activity for the alkylation of thiophene (T), 2-methyl thiophene (2-MT) and 3-methyl thiophene (3-MT). Many effect factors for the alkylation of thiophenic sulfides catalyzed by [Bmim]H2PW12O40 have been fully investigated. Under the optimal reaction conditions (the catalyst dosage 1wt%, reaction temperature 120°C, reaction time 40min and the stirring rate 500rpm), the conversions of T, 2-MT and 3-MT all can nearly reach up to 100%. [Bmim]H2PW12O40 has also exhibited good stability and recyclability. The conversions of thiophenic sulfides nearly remain unchanged during 11 recycles of [Bmim]H2PW12O40. Apparent reaction kinetics for the alkylation of thiophenic sulfides is studied. The alkylations of T, 2-MT and 3-MT all show the pseudo-first-order kinetic characteristics. The order of the reaction rate constants of three thiophenic sulfides is 2-MT>3-MT>T. However, the calculated apparent activation energies of T, 2-MT and 3-MT are 62, 45.54 and 71.33kJ/mol, respectively. So, the order of apparent activation energies is 3-MT>T>2-MT.

A further catalysis mechanism study on Amberlyst 35 resins application in alkylation desulfurization of gasoline

Olefinic alkylation of thiophenic sulfurs (OATS) technology can be handled under mild conditions without any hydrogen consumption, which is a promising way to produce clean gasoline. However, the side reaction in this desulfurization process would lead to significant levels of coke. To maintain the high activity for alkylation of sulfurs, the selectivity of OATS catalyst must be improved by reducing side reactions. In this paper, the catalytic mechanism of macroporous sulfonic resins Amberlyst 35 (A35) in the OATS process was further investigated by the calculation of density functional theory (DFT), to understand the reaction path of different reactant at molecular level. The calculated results indicated that the beginning of main and side reactions were both from a stable alkoxide intermediate, which was the protonation product of adsorbed olefin on the catalyst. Compared with alkenes, thiophenic compounds were more inclined to be coadsorbed on the alkoxide intermediate for further reaction, and the alkylation rate of sulfurs with alkenes was faster than the self-dimerization of alkenes. Moreover, the calculated results also indicated that the alkylation of thiophenic sulfurs as main reaction was exothermic while the dimerization of alkenes as side reaction was endothermic over A35. Additionally, the conversion curves of different reactants over A35 and the related kinetics at different temperature were also studied by experimental methods. The obtained experimental results could be used to verify the reliability of relevant theoretical calculations. Based on the differences in the reaction mechanisms obtained by the theoretical and experimental studies, two measures were proposed, which would be useful to reduce side reactions to a lower extent. The study would be beneficial to the further industrial application of A35 in the alkylation desulfurization of gasoline.

Alkylation desulfurization of FCC gasoline catalyzed by pyridine ionic liquid

Brønsted acidic ionic liquid [BPY]HSO4 was synthesized and characterized by FT-IR and 1H-NMR. [BPY]HSO4 was then used as a catalyst in alkylation desulfurization of FCC gasoline; the effects of the reaction temperature, time and mass ratio of ionic liquid to oil on the desulfurization efficiency and FCC gasoline quality were investigated. The results showed that after reaction for 90 min under 65°C and an ionic liquid to oil mass ratio of 0.09, the sulfur content of FCC gasoline is decreased from 580.0 to 6.4 μg/g, with a desulfurization rate of 98.90%, which can meet the request of Chinese National Standard V for the sulfur content in motor gasoline (< 10 μg/g). A survey on the distribution of sulfur compounds indicated that sulfur compounds are transferred from light fraction (< 170°C) to heavy fraction (> 170°C) with the help of [BPY]HSO4 and the sulfur compounds in heavy fraction can then be removed further by hydrodesulfurization. PONA results indicated that the alkylation desulfurization catalyzed by [BPY]HSO4 has little effect on hydrocarbon composition and octane number of FCC gasoline. Moreover, the [BPY]HSO4 ionic liquid can be recycled through extraction and reused in the alkylation desulfurization.

C9 Fraction Alkylation Desulfurization over Amberlyst 36 Resin:The Kinetics of 2‐Ethylthiophen, 2,5‐Dimethylthiophene, and 2‐n‐Propylthiophene with Isoamylene

ABSTRACTC9 fraction is the by‐products of catalytic reforming and ethylene cracker; it is considered as a kind of petroleum resin raw material. Recently, it was studied for the use as a gasoline additive to enhance the economic benefits. However, C9 fractions are getting higher in sulfur contents. As conventional hydrotreating technology leads to significant octane number loss and processing costs, the alkylation desulfurization process, which could reduce the sulfuric compounds to hydrogen sulfide by catalytic alkylation with olefins and distillation followed by, is a rather attractive way of reducing the sulfur of C9 fraction. In this paper, different kinds of thiophenic compounds, including 2‐ethylthiophen, 2,5‐dimethylthiophene, and 2‐n‐propylthiophene, were selected as the model compounds. Thiophenic compounds were studied first by the alkylation reaction over macroporous sulfonic resin Amberlyst 36, and the octane number of C9 fraction was measured. It was found that isoamylene and Amberlyst 36 resin had a significant effect on the alkylation desulfurization of thiophenic compounds with the conversion, reaching to above 99%. And the octane number of C9 fraction was increased by alkylation desulfurization over Amberlyst 36 resin. Moreover, the alkylation of thiophenic sulfurs could be described as a pseudo–first–order reaction as well as the reaction rate constant, and the activation energy of alkylation reactions was calculated.

Alkylation desulfurization of the C9 fraction over Amberlyst 36 resin

Conversions of thiophenic compounds close to 99% with increased octane number of the C9 fraction were obtained after alkylation desulfurization over Amberlyst 36 resin, suggesting a new way to reduce the sulfur content in the C9 fraction.

Sensitivity and economic analysis of a catalytic distillation process for alkylation desulfurization of fluid catalytic cracking (FCC) gasoline

ABSTRACTBACKGROUNDThe issues of gasoline desulfurization are becoming more important because the regulated sulfur limits are being set lower and lower. Among the new desulfurization technologies, the olefin alkylation of thiophenic sulfur (OATS) process is more attractive than hydrodesulfurization because of its mild operating conditions and low loss of octane number. In this work, a sensitivity analysis and an economic analysis of a catalytic distillation process for alkylation desulfurization of fluid catalytic cracking (FCC) gasoline are presented. The objective is to evaluate the effects of various design and operating parameters on the OATS process by using a realistic FCC gasoline fraction.RESULTSA sensitivity analysis performed for operating pressure, reflux ratio, bottom flow rate, feed conditions, number of separate stages, number of reactive stages, catalyst weight, feed location, reactive zone position, and an economic analysis based on total annual costs (TAC) for these variables were studied.CONCLUSIONThe results show the qualitative environmental and economic effect of several design variables and operating conditions on the OATS process and provide a direction to the further design. In addition, more attention should be paid to feed flow rate control. © 2014 Society of Chemical Industry

An improvement of MCM-41 supported phosphoric acid catalyst for alkylation desulfurization of fluid catalytic cracking gasoline

The theoretical calculation about the catalytic mechanism of MCM-41 supported phosphoric acid (SPAM) in the alkylation desulfurization of fluid catalytic cracking (FCC) gasoline demonstrated that properly reducing the amount of effective acid on the surface was beneficial to further enhancing the catalyst performance. Based on the previously optimized preparation of SPAM (weight ratio of total acid/MCM-41 6:1, calcination temperature 773K and weigh ratio of H3PO4/H4P2O7 1:2.5), an improvement by diluting the concentration of mixed phosphoric acids in the impregnating solution was carried out in this work. The surface structure and catalytic behavior of improved SPAM were investigated by structural characterization and experimental verification, respectively. The results proved that decreasing the concentration of mixed phosphoric acids in the impregnating solution in the preparation of SPAM could effectively reduce the existing acid amount on the catalyst surface by increasing the catalyst crystallinity, and both the surface acid strength and the total acids amount of SPAM were reduced. Moreover, the catalytic activity and selectivity of improved SPAM for thiophenic sulfurs alkylation in the alkylation desulfurization were enhanced and the olefins polymerization reactions were suppressed to a lower extent. Besides, the theoretical calculation was verified by this study, which opened a particularly appealing opportunity for the application of SPAM in the industrial alkylation desulfurization of gasoline.

Removal of Thiophenic Sulfur Compounds from Oil Using Chlorinated Polymers and Lewis Acid Mixture via Adsorption and Friedel-Crafts Alkylation Reaction

For efficient removal of thiophenic sulfur (S-) compounds from oils, a novel method is proposed here, i.e. one-pot alkylation desulfurization (OADS), in which oil insoluble chlorinated polymer such as polyvinyl chloride (PVC) is used as the alkylating regent with Lewis acid as catalyst. The aromatic S-compounds are grafted to the polymer through Friedel-Crafts reaction and removed facilely along with the polymer. The OADS mechanism is identified by scanning electron microscope and analyzer with surface area and pore size of the polymer. The influence of some factors on the OADS is studied, e.g. the type and amount of chlorinated polymers and Lewis acids. It is proved that thiophene and benzothiophene can be removed efficiently from oil by PVC+AlCl3 mixture even in the presence of 25% (by mass) of benzene due to the synergetic effects of the adsorptive desulfurization of AlCl3 and the alkylation desulfurization of PVC.

An insight into effect of methanol on catalytic behavior of Amberlyst 35 resins for alkylation desulfurization of fluid catalytic cracking gasoline

Alkylation desulfurization of fluid catalytic cracking (FCC) gasoline over solid acid catalysts is considered to be a viable path to meet environmental regulations of sulfur emissions. However, side reactions in the process such as alkenes oligomerization and aromatic alkylation lead to the formation of significant amounts of coke, which will greatly reduce the catalyst lifetime and require keeping high catalyst selectivity for thiophenic compounds alkylation. In this paper, both the experimental and theoretical investigations were carried out to further explain the effect of methanol on the catalytic behavior of macroporous sulfonic resins Amberlyst 35 (A35) in the alkylation desulfurization process of FCC gasoline. The results indicated that adding suitable amount of methanol (about 1.0wt% of the feed gasoline) was beneficial to improve the catalytic behavior of A35 in this process. The competition adsorption of suitable amount of methanol and its ether product with isoalkenes could greatly reduce the activated alkenes on the acid sites of A35 and have little impact on the alkylation of thiophenic sulfurs. They could also decrease the alkenes conversion for side reactions of alkenes oligomerization, which was favorable for improving the catalytic selectivity for thiophenic compounds alkylation and prolonging the catalytic lifetime of A35.

Density Functional Theory Investigation for Catalytic Mechanism of Gasoline Alkylation Desulfurization over NKC-9 Ion-Exchange Resin

The molecular level understanding of the mechanism about the 3-methylthiophene (3MT) alkylation with isobutylene (IB) as well as the side reaction of IB dimerization over NKC-9 cation exchange resi...

Gasoline Desulfurization with Two Catalytic Distillation Columns

A new approach was proposed to remove sulfuric compounds from fluid catalytic cracking (FCC) gasoline by combining an alkylation desulfurization catalytic distillation (ADCD) column with a hydrodesulfurization catalytic distillation (HDS-CD) column. In the ADCD column, isobutylene (IB) and 3-methylthiophene (3MT) were designated as the model compounds for olefin and sulfide, respectively; NKC-9 cation exchange resin was used as the catalyst. In the HDS-CD column, dibenzothiophene (DBT) was chosen as the model sulfides; Nickel phosphide supported on the TiO2-Al2O3 composite oxide prepared by our laboratory were designated as the HDS catalyst. Simulations for these two CD columns were carried out by RADFRAC module of Aspen Plus. The optimization results revealed that the ADCD column had an alkylation selectivity of 96%, and the sulfur content in the overhead stream was less than 8 μg/g. The simulation results of the HDS-CD process showed that the sulfide in the bottom stream of ADCD column can be removed practically by 100% and the clean oil stream from the bottom of HDS-CD column has hardly any sulfur.

Analysis and simulation of reactive distillation for gasoline alkylation desulfurization

The increasingly stringent regulations on sulfur content in fuel require refineries to develop new desulfurization processes. Through the alkylation of thiophene and its derivatives with olefins followed by distillation, alkylation desulfurization is an alternative technology in the case of gasoline for its mild operation conditions and low loss of octane number. In this paper, the application of reactive distillation in gasoline alkylation desulfurization is studied, including a conceptual design and a rigorous steady state simulation. The conceptual design considers three aspects: thermodynamic analysis of the reactive system, benefits and constraints of the reactive distillation, and computation of the reactive residue curve maps. Results show that reactive distillation is feasible for gasoline alkylation desulfurization, and it has no constraints but great potential for its capital savings, improved conversion, reduced by-product formation, improved catalyst stability and avoidance of hot spots. The simulation results show that reactive distillation could obtain product gasoline with sulfur content less than 1ppmw. It is shown that reactive distillation may be considered a viable technological alternative for gasoline alkylation desulfurization.

Deep Desulfurization of Light Oil Using the Imitating Silver Salt ILs Method

Sulfides in oils are harmful in many ways, in particular, deterioration of the environment resulting from sulfur dioxide. A novel desulfurization process for light oil has been investigated. A mixture consisting of benzothiophene (BT), dibenzothiophene (DBT), and oil fractions (235°C–270°C) refined by acid–alkali treatment was employed for alkylation desulfurization tests in a nitrogen atmosphere. The results showed that at a reaction temperature of 30°C, ratio of bromoethane (CH3CH2Br) to sulfur of 30:1 (mol/mol), ratio of silver tetrafluoroborate (AgBF4) to sulfur of 6:1 (mol/mol), and reaction time of 16 hr, the desulfurization yield could reach 76.3%.

Gasoline alkylation desulfurization over Amberlyst 35 resin: Influence of methanol and apparent reaction kinetics

Gasoline desulfurization is receiving attention worldwide due to the increasing stringent regulations on sulfur content for environmental protection purpose. As conventional hydrotreating technology leads to significant octane number loss and processing costs, the gasoline alkylation desulfurization process, which consists of weighing down the sulfuric compounds by catalytic alkylation with olefins present in the feed and distillation followed by, is a rather attractive way. In this paper, firstly alkylation of thiophenic compounds was researched over macroporous sulfonic resin Amberlyst 35 in methanol presence to increase the selectivity of catalyst, then kinetics of thiophenic sulfurs alkylation in FCC gasoline was researched without and with methanol. Results found that appropriate methanol (⩽2 wt.% methanol in model gasoline and ⩽1 wt.% methanol in FCC gasoline) could inhibit olefins oligomerization significantly without influence on the conversions of thiophenic compounds. The alkylation of thiophenic sulfurs could be described as pseudo first order reaction regardless of the existence of methanol. The introduction of methanol decreases the reaction rate constant and increases the activation energy of alkylation reactions.