Fluid Catalytic Cracking Gasoline Research Articles

Single and combined effects of Bottom Cracking (BCA) and Propylene Booster (PBA) separate particles additives addition to a Fluid Catalytic Cracking (FCC) catalyst on the FCC product distribution and quality

In the present work, we have investigated how the single and combined addition of commercial separate particle additives, such as Bottom Cracking additive (BCA) and Propylene Booster additive (ZSM-5 based-PBA), to a FCC USY catalyst can influence the product distribution and quality during FCC processing. Due to the relatively low catalytic activity of the BCA additive, the increasing single addition of BCA implies a higher ratio of thermal to catalytic cracking, leading in particular to higher dry-gases and coke selectivities and a lower gasoline pool quality. The Bottom Cracking ability of the BCA additive is feed dependent and starts to be representative for high addition levels of about 50–60wt%, allowing the increase of the LCO pool selectivity and quality. The single and low addition level (i.e. 10wt%) of ZSM-5 based additive allows to drastically improve the light alkenes selectivity at the expense of the gasoline selectivity, improving, due to concentration effects, the quality of the FCC gasoline pool, but generally limiting the LCO selectivity and quality while the coke selectivity is little increased. The combined use of both additives looks like an interesting upgrading strategy considering that it is possible to keep a high catalytic activity, to fully take advantage of the beneficial effects of the ZSM-5 and BCA additives, and to mitigate at the same time the increase of the coke and dry gases selectivities.

A process for producing ultraclean gasoline by coupling efficient hydrodesulfurization and directional olefin conversion

To solve the contradiction between ultradeep hydrodesulfurization (HDS) and octane recovery in clean gasoline production, this article proposes a novel two‐stage fluid catalytic cracking (FCC) gasoline hydro‐upgrading process with the selective HDS catalyst in the first reactor and the complemental HDS and octane recovery catalyst in the second reactor. The process achieved the relayed removal of sulfur‐containing compounds with different natures, providing itself with excellent HDS performance, and the hydroisomerization and aromatization of olefins in the second stage endowed the process with superior octane recovery ability and high product yield while remarkably reducing the olefin content of FCC gasoline. The process was also featured by low hydrogen consumption due to the low first‐stage olefin saturation and the balanced second‐stage hydrogenation and dehydrogenation. The two‐stage process developed here sheds a light for efficiently producing ultralow sulfur gasoline from the poor‐quality FCC gasoline of high olefin and sulfur contents. © 2012 American Institute of Chemical Engineers AIChE J, 59: 571–581, 2013

Study on Olefin Decrement Reformulation and Increasing Light Olefins of FCC Gasoline by Catalytic Cracking

Catalytic upgrading of fluid catalytic cracked (FCC) gasoline obtained from Huabei Petrochemical Company, PetroChina (Renqiu, Hebei, China), was investigated using a microreactor and gas chromatograph integrated unit in order to decrease the content of olefins in gasoline and increase the light olefins (ethylene, propylene, and butylene) content. The experimental results showed that the olefin content in upgraded gasoline can be decreased from 42.6% in raw material to nearly 10%, meeting the requirements of the new gasoline standard, whereas iso-alkane and aromatics contents were markedly increased, from 28.4 and 18.2% to 47 and 36.1%, respectively, so the octane number of gasoline should not be reduced. In addition, higher yields of light olefins were obtained after FCC gasoline was reformulated under laboratory conditions. Higher reaction temperature, longer reaction time, higher weight ratio of catalyst to oil, and higher catalyst activity were beneficial to decrease the olefin content of FCC gasoline and increase the yields of light olefins.

Computational investigation of hydrodynamics and cracking reaction in a heavy oil riser reactor

This paper presents a computational investigation of hydrodynamics, heat transfer and cracking reaction in a heavy oil riser operated in a novel operating mode of low temperature contact and high catalyst-to-oil ratio. Through incorporating feedstock vaporization and a 12-lump cracking kinetics model, a validated gas–solid flow model has been extended to the analysis of the hydrodynamic and reaction behavior in an industrial riser. The results indicate that the hydrodynamics, temperature and species concentration exhibit significantly nonuniform behavior inside the riser, especially in the atomization nozzle region. The lump concentration profiles along the riser height provide useful information for riser optimization. Compared to conventional fluid catalytic cracking (FCC) process, feedstock conversion and gasoline yield are respectively increased by 1.9units and 1.0unit in the new FCC process, the yield of liquefied petroleum gas is increased by about 1.0unit while dry gas yield is reduced by about 0.3unit.

The Desulfurization of Fluid Catalytic Cracking Gasoline by Extractive Distillation

Desulfurization of fluid catalytic cracking gasoline was investigated in a lab scale extractive distillation column. Before the extractive distillation, fluid catalytic cracking gasoline was distillated into light and heavy fractions. Then, the light fraction was desulfurized by extractive distillation using dimethylformamide as the solvent. Factors impacting the desulfurization efficiency of the extractive distillation were studied. Under optimal desulfurization conditions, distillate yield reaches 60.8 vol%, and sulfur content of the product was 48.0 ppmw. The desulfurization efficiency could reach up to 89%. Paraffins, olefins, napthenes, and aromatics group analysis results showed that the process could transfer the majority of olefins in fluid catalytic cracking gasoline into the distillate. These high octane number olefins are good blends for producing high quality Europe IV gasoline.

Reactive Characteristics and Adsorption Heat of Ni/ZnO–SiO2–Al2O3 Adsorbent by Reactive Adsorption Desulfurization

Reactive adsorption desulfurization (RADS) experiments of fluid catalytic cracking (FCC) gasoline and a model gasoline over an Ni/ZnO–SiO2–Al2O3 adsorbent were carried out in a fixed-fluidized bed reactor at low pressures in an H2 atmosphere. The results show that hydrogenation, hydrogen transfer, and polymerization reactions accompany RADS. Sulfidation and carbon deposits, which can lead to decreases in the regeneration rate and amount of activated Ni, are crucial to the decay of desulfurization and the olefin-hydrogenation capability of the adsorbents. The obvious reduction of C5 and C6 olefins in FCC gasoline mainly contribute to the drop in octane number of the desulfurization product. The desulfurization experiment on model gasoline and the adsorption heats of model compounds show that RADS removes sulfur from sulfur-containing compound through S–M interactions rather than by π-complexation over the Ni/ZnO–SiO2–Al2O3 adsorbent. The adsorption heat of sulfur-containing compound is proportional to the ...

Catalytic Mechanism of MCM-41 Supported Phosphoric Acid Catalyst for FCC Gasoline Desulfurization by Alkylation: Experimental and Theoretical Investigation

The desulfurization of fluid catalytic cracking (FCC) gasoline by alkylation over solid acid catalysts is considered to be a viable and less costly path to meet environmental regulations of sulfur emissions. However, side reactions in the process lead to significant levels of coke, which will greatly reduce the lifetime of the catalyst. In this paper, the catalytic mechanism of MCM-41 supported phosphoric acid catalyst for gasoline desulfurization by alkylation has been investigated by using experimental methods and quantum chemical calculations to study the catalytic behavior for the adsorption and reaction of different reactants, which can help optimize the reaction conditions and preparation methods of the catalyst for a more efficient alkylation process. The results showed that both the typical main and side reactions in the alkylation process started from a stable alkoxide intermediate that was formed by protonation of olefin adsorbed on the catalyst. Thiophenic compounds were more inclined to be adsorbed on the alkoxide intermediate than olefins for further reaction, and the activation energy for the alkylation of thiophenic sulfurs with alkenes was obviously lower than that for alkene oligomerization. Moreover, the thiophene alkylation was exothermic while the olefin oligomerization was endothermic. On the basis of these findings obtained by experimental and theoretical investigation, two methods that might be useful to further inhibit the occurrence of side reactions and improve the catalyst performance in the alkylation process were proposed.

Gasoline upgrading by self-etherification with ethanol on modified beta-zeolite

This research studied the modification of beta-zeolite for self-etherification process of fluidized catalytic cracking (FCC) gasoline and ethanol. The catalytic activity of reducing olefins in FCC gasoline accompanied with higher ethanol substitution was evaluated; moreover, the influences of Si/Al ratio in beta zeolite and the addition of copper (Cu) or magnesium (Mg) in the beta zeolite on the reaction performance were also investigated. It was found that the beta zeolite with Si/Al ratio of 27 (beta 27) can enhance higher ethanol conversion than those of 42 and 77. In addition, the modification of beta 27 by Cu (Cu-beta 27) can further improve the ethanol conversion from 38.2% (beta 27) to 55.1%, and the olefin content reduction from 46.2% (beta 27) to 62.4%. The improvement of the catalytic activity also enhances the obtained gasoline properties i.e. lower blending Reid vapor pressure (bRvp) and higher research octane number (RON).

Kinetic Model Considering Reactant Oriented Selective Deactivation for Secondary Reactions of Fluid Catalytic Cracking Gasoline

The lumped scheme with consideration of catalyst deactivation was adopted to simulate catalytic cracking of gasoline for predicting the product distribution of secondary reactions. A reactant oriented selective deactivation model was developed using a new strategy of selective deactivation coupled with nonselective independence deactivation. Catalyst deactivation was correlated with the time on stream rather than coke content. Furthermore, a hybrid self-adaptive genetic algorithm (termed AGA/SA), which incorporated evolution strategies and simulated annealing into a genetic algorithm, was developed and applied in parameter estimation of the proposed model. Results suggest that the lumped kinetic scheme incorporating a deactivation function could enhance its fundamentality and the predication accuracy. AGA/SA exhibits the desired improvements such as rapid convergence, high efficiency, strong in hill-climbing, and effective in escaping the local optimum. Good agreement between the predicted results and exp...

The Aromatization of Different FCC Naphtha Fractions over a P-Zn/HZSM-5 Catalyst

The aromatization reaction performance of P-Zn/HZSM-5 catalyst was investigated on a fixed bed reactor using five fluid catalytic cracked (FCC) gasoline fractions (<100°C, 50°C–100°C, <120°C, 75°C–120°C, and full fraction) as feedstock, and the effect of feedstock on aromatization is discussed. The results showed that the activity and stability of P-Zn/HZSM-5 catalyst for the aromatization of the 50°C–100°C fraction were high in definite reaction conditions. After 16 hr, the content of olefin and aromatics in liquid product were 5.23 and 79.9%, respectively. The liquid product of low olefin and high aromatics was obtained. The distribution of benzene, toluene, and xylene in liquid product of 50°C–100°C fraction was investigated during aromatization, and the result showed that the toluene content was maximum among the three aromatics contents, the benzene content was minimum at the beginning of the reaction, xylene content became maximum, and benzene was still minimum after reacting for 20 hr. The content of C9 + aromatics increased at the first stage of the reaction and then decreased with the increasing reaction time.

Preparation of the Modified Y Zeolite for Removal of Organic Sulfur Compounds from FCC Gasoline

Ce(IV)-loaded modified NaY (NH4Y) zeolite was prepared for selective adsorptive desulfurization from fluid catalytic cracked (FCC) gasoline. Ce(β)Y was obtained from NH4Y using a liquid-phase ion-exchange method. Ce(IV)Y was obtained from calcining Ce(β)Y at 550°C. The structures of the Ce(IV)Y and NaY samples, selective adsorption of organic sulfur compounds on Ce(IV)Y and NaY zeolite, sulfur content of FCC gasoline, and mechanism for adsorption of thiophene on Ce(IV)Y and NaY zeolite were investigated using X-ray diffraction (XRD), gas chromatography–sulfur chemiluminescence detection (GC-SCD), sulfur analysis, Fourier transform infrared (FTIR), frequency response (FR), and intelligent gravimetric analysis (IGA). The selective adsorption desulfurization from FCC gasoline containing organic sulfur compounds (S = 135 μg/g) was investigated with Ce(IV)Y adsorbent for removal. The sulfur content was reduced to 20.14 μg/g. The thiophene adsorption mechanism showed that Ce(IV)Y can adsorb thiophene via π electronic interaction directly, and thiophene and Ce(IV) can form a stable sulfur–metal bond (S-M bond) that enhances the adsorption capacity of Ce(IV)Y for thiophene. This method for the modification of NaY zeolite provides a promising selective desulfurization process to prepare clean fuels.

Enhanced pervaporative desulfurization by polydimethylsiloxane membranes embedded with silver/silica core–shell microspheres

Pervaporative desulfurization based on membrane technology provides a promising alternative for removal of sulfur substances (as represented by thiophene) in fluid catalytic cracking (FCC) gasoline. The present study focused on the performance enhancement of polydimethylsiloxane (PDMS) membrane by incorporation of core–shell structured silver/silica microspheres. A silane coupling agent, N-[3-(trimethoxysily)propyl]-ethylenediamine (TSD), was used to chelate the Ag+ via its amino groups and attach the silver seeds onto the silica surface via condensation of its methoxyl groups. The resultant microspheres were characterized by Zeta-positron annihilation lifetime spectroscopy (ZetaPALS), inductively coupled plasmaoptical emission spectrophotometer (ICP), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The Ag+/SiO2–PDMS composite membranes were prepared by blending PDMS with the as-synthesized silver/silica microspheres. PALS analysis was used to correlate the apparent fractional free volume with permeation flux. The sorption selectivity towards thiophene was enhanced after incorporation of silver/silica microspheres due to the π-complexation between the silver on the microsphere surface and the thiophene molecules. The pervaporative desulfurization performance of the composite membrane was investigated using thiophene/n-octane mixture as a model gasoline. The composite membrane exhibited an optimum desulfurization performance with a permeation flux of 7.76kg/(m2h) and an enrichment factor of 4.3 at the doping content of 5%.

One-Step Oxidation–Desulfurization of FCC Gasoline Catalyzed by Tungstophosphoric Acid

The sulfur compounds in fluid catalytic cracked (FCC) gasoline were removed with a one-step oxidation–extraction method. Tungstophosphoric acid (HPWA), tert-butyl hydroperoxide (TBHP), and ethanol were used as catalyst, oxidant, and solvent, respectively. TBHP has a higher desulfurization degree and oil yield than hydrogen peroxide, and HPWA exhibited higher desulfurization degree and oil yield than the other kinds of acids. The one-step process has a higher desulfurization degree than the two-step process. The optimal operating parameters were obtained as follows: the catalyst amount was 5 wt%, the mole ratio of oxygen in the oxidant to the sulfur in the gasoline (O/S) was 10, the reaction temperature was 60°C, and the reaction time was 2 hr. Under these conditions, the desulfurization degree and yield of oil were both in the range of 85–90%.

Modeling of the FCC Gasoline Desulfurization Process by Liquid Extraction with Sulfolane

Extractive desulfurization of fluid catalytic cracking (FCC) gasoline with sulfolane was studied in a batch apparatus. The influence of three inlet parameters (temperature, inlet sulfur content, and solvent ratio) on the process response, that is, desulfurization efficiency, was investigated with the use of a Box-Behnken experimental design by response surface methodology. A mathematical model that can be used for predicting sulfur content in raffinate after extractive batch processing with sulfolane was statistically developed and proven with analysis of variance. Statistical analysis showed that the largest influence on desulfurization efficiency was solvent ratio, the second most significant influence was inlet sulfur content, followed by temperature, and last the interaction between solvent ratio and inlet sulfur content. The obtained second-order polynomial model shows that maximum desulfurization efficiency of 65.34% can be achieved at temperature of 50°C and higher values of inlet sulfur content and solver ratio in the researched range of inlet parameter values.

The performance of solid phosphoric acid catalysts and macroporous sulfonic resins on gasoline alkylation desulfurization

Sulfur removal has received increasing attention in recent years primarily for environmental protection purpose. As an attractive technology in the case of gasoline, OATS (olefinic alkylation of thiophenic sulfur) proposed to separate sulfur compounds by distillation after being weighed down by alkylation with olefins in the feed. In this paper, alkylation reactions of thiophenic compounds were studied over solid phosphoric acid catalysts (SPAM and SPAS using MCM-41 and Silicalite-1 zeolite as supporters respectively) and macroporous sulfonic resins (including NKC-9, D005-2 and Amberlyst 35) with model gasoline and FCC (fluid catalytic cracking) gasoline. Results showed that macroporous sulfonic resins showed better performance than solid phosphoric acid catalysts under milder conditions in both feeds. Among the resins, Amberlyst 35 was the most suitable catalyst for the application of catalytic distillation for its good performance at the temperature range of 353–413 K in FCC gasoline. However, the selectivity of isoamylene dimerization over Amberlyst 35 decreased with the temperature, which was harmful to the product yield and catalyst stability. Besides, different activity orders of solid phosphoric acid catalysts in model gasoline and FCC gasoline were explained by combining the acidic properties of the catalysts with the species of olefins in two feeds.

Alkylation of Thiophenic Compounds with Olefins and its Kinetics over MCM-41 Supported Phosphoric Acid in FCC Gasoline

The alkylation of thiophenic compounds with olefins in real fluid catalytic cracking (FCC) gasoline was carried out over three kinds of acidic catalysts: HY zeolite, phosphoric acid supported on both kieselguhr and purely siliceous MCM-41 zeolite. The results showed that the MCM-41 supported phosphoric acid catalyst was the most promising to be utilized in the reaction in terms of its activity and stability. Based on its excellent catalytic performance, apparent kinetic models for alkylation of the major thiophenic sulfides were proposed, thus allowing use of the simulation in reaction distillation (RD) technology. Furthermore, numerical regression led to kinetic parameters with narrow spans, suggesting that the proposed models satisfactorily simulate the sulfides removal under the suggested reaction conditions. The MCM-41 supported phosphoric acid catalyst (SPAM) can be efficiently performed during the alkylation of thiophenic sulfides with olefins in gasoline. Based on its excellent catalytic activity and stability, the apparent kinetic models for the alkylation of major sulfides over it were proposed and proved by experimental datum.

Deep Extractive Desulfurization of Gasoline with xEt3NHCl·FeCl3 Ionic Liquids

xEt3NHCl·FeCl3 (x = 1.4−1.8) ionic liquids were synthesized by mixing Et3NHCl and anhydrous FeCl3 at 80 °C. These were liquid at room temperature, with low viscosities, and exhibited remarkable abilities in effective desulfurization of thiophene in n-octane and fluid catalytic cracking (FCC) gasoline. Among them, 1.6Et3NHCl·FeCl3 showed the highest sulfur removal. The anionic species FeCl4− existed in 1.6Et3NHCl·FeCl3 ionic liquid, as detected by electrospray ionization−mass spectrometry (ESI−MS), and the ionic liquid was stable in air and moisture. Sulfur-free (<10 mg/L) gasoline could be obtained after extraction twice using an ionic liquid/oil volume ratio of 1. The ionic liquid could be recycled 10 times by distillation with a slight decrease in activity.

The Effects of Weight Hour Space Velocity on the Products Distribution of Aromatization Reaction of Lanlian FCC Gasoline

By using Lanlian fluid catalytic cracked (FCC) gasoline as a feedstock, the effects of weight hour space velocity (WHSV) on the product distribution, light oil compound, off-gas, and liquefied petroleum gas were researched in a confined fluidized bed reactor. The equation of off-gas yield, liquefied petroleum gas yield, coke yield, and light oil yield with increasing WHSV were established in the experimental data. The experimental result showed that with increasing WHSV, coke, off-gas, and liquefied petroleum gas yield decreased gradually, and light oil yield increased piece by piece; the amount of olefin was enhanced step by step, that of aromatics dropped slowly, and that of saturated hydrocarbon did not change. However, olefin conversion and increasing ratio of aromatics presented a slowly decreasing trend and increasing ratio of saturated hydrocarbon showed no change; hydrogen yield was low and did not change; i-butane and propane decreased, but n-butane increased gradually; C0 3/C= 3 and nC0 4/nC= 4 values did not change, iC0 4/iC= 4 variety had no order; C0 3/C= 3, C0 4/C= 4, and (C0 3 + C0 4)/(C= 3 + C= 4) values showed a decreasing trend.

Experiments of Mercaptans Removal from FCC Gasoline by NaOH Aqueous in Membrane Contactor

The process of mercaptans removal from fluid catalytic cracked (FCC) gasoline by NaOH aqueous in a hollow fiber contactor was studied. The results showed that fractional removal of mercaptans was greater in a hydrophobic membrane than that in a hydrophilic membrane at the same condition. The mass transfer coefficient of mercaptans increased significantly while the gasoline flow rate increased because the predominant resistance lies in the gasoline boundary layer. HA-18 modified the solubility of mercaptans in caustic solution and enhanced mercaptans extraction from gasoline. The membrane module should be cleaned by a prolonged operation to recover the membrane property due to membrane fouling.

Catalytic Coprocessing of Delayed Coker Light Naphtha with Light Straight-run Naphtha/FCC Gasoline

Upgrading of delayed coker light naphtha (DCLN) is difficult due to its high diolefin and silicon content. Mixtures of light straight-run naphtha (LSRN) and DCLN fractions were hydrotreated in two stages over NiMo/Al2O3 and CoMo/Al2O3 catalysts (diolefin saturation followed by hydrodesulphurization (HDS). Naphtha fractions free of diolefins, olefins, sulfur, and silicon were produced, which are excellent feeds for naphtha isomerization. One-stage selective HDS tests were also conducted with blends of DCLN (up to 5 vol%) and fluid catalytic cracked (FCC) gasoline over CoMo/Al2O3. Diolefin-free products of <10 mg/kg sulfur could be produced with a research octene number (RON) loss of max. 3.