Fluid Catalytic Cracking Gasoline Research Articles

Desulfurization reactions of thiophene and cyclohexane over Zn and Nb modified zeolites in FCC process

In refineries, one of the most important production units is Fluid Catalytic Cracking (FCC). In them, the incorporation of additives to the catalyst is a very interesting option to reduce the sulfur content of gasoline, and thus obtain commercial fuel specifications. In this study, the transformation of thiophene into a cyclohexane (HC) stream for its in-situ desulfurization has been investigated, using catalysts based on niobium or zinc (6 wt%) incorporated into three types of zeolites: HUSY, HBeta and HZSM-5. Catalytic tests were carried out at 773 K in an automatically controlled fixed-bed tubular reactor. The reaction products were analyzed online by gas chromatography, with FID detector for hydrocarbons and SCD for sulfur compounds, and the catalysts were characterized by XRD, FTIR, N2 adsorption isotherms, HRTEM, XRF, 29Si and 27Al solid state NMR, NH3-TPD and FTIR-pyridine techniques. The results indicate that the addition of metals did not significantly alter the textural and structural properties of the zeolites, and that the Nb/HB and Nb/HY catalysts were the most effective in the conversion of thiophene, and selective toward paraffins and H2S mainly. The performance of these materials was attributed to the existence of an optimal balance between the Brønsted and Lewis acid sites, which increased the hydrogen transfer coefficient (HTC) during the cyclohexane transformation, resulting in higher desulfurization activity. The addition of zinc drastically increased the density of the Lewis acid sites and decreased the HTC, favoring the production of aromatics and thiophene condensation reactions, thus transferring sulfur to the gasoline streams. In general, the catalysts investigated are of significant interest as additives for sulfur reduction in FCC gasoline streams, either by producing easily removable H2S or by transferring sulfur to heavier fractions.

Design and control of fluid catalytic cracking gasoline fractionator

The gasoline fractionation scheme used in catalytic cracking has a significant impact on the blended gasoline's octane number. This study proposes an improved three-cut fractionation scheme for the fluid catalytic cracking gasoline fractionator and optimizes the process with respect to evaluation metrics such as total annual cost (TAC), light gasoline recovery, and CO2 emissions (ECO2). To achieve energy efficiency and reduce emissions in the process, the dividing wall column is employed for process intensification. In comparison to the cascaded binary columns process, the middle cracked naphtha recovery of the FCC-DWC-M has increased by 1.96%, the TAC has decreased by 22.15%, and the ECO2 has decreased by 26.18%. Finally, the study investigates the dynamic characteristics of the FCC-DWC-M process, establishes a control scheme, and examines its performance while experiencing disturbances in feed flow rates of ±10% and ±20%. The findings indicate exceptional control performance of the FCC-DWC-M process.

A multiscale adaptive framework based on convolutional neural network: Application to fluid catalytic cracking product yield prediction

Since chemical processes are highly non-linear and multiscale, it is vital to deeply mine the multiscale coupling relationships embedded in the massive process data for the prediction and anomaly tracing of crucial process parameters and production indicators. While the integrated method of adaptive signal decomposition combined with time series models could effectively predict process variables, it does have limitations in capturing the high-frequency detail of the operation state when applied to complex chemical processes. In light of this, a novel Multiscale Multi-radius Multi-step Convolutional Neural Network (MsrtNet) is proposed for mining spatiotemporal multiscale information. First, the industrial data from the Fluid Catalytic Cracking (FCC) process decomposition using Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN) extract the multi-energy scale information of the feature subset. Then, convolution kernels with varying stride and padding structures are established to decouple the long-period operation process information encapsulated within the multi-energy scale data. Finally, a reconciliation network is trained to reconstruct the multiscale prediction results and obtain the final output. MsrtNet is initially assessed for its capability to untangle the spatiotemporal multiscale relationships among variables in the Tennessee Eastman Process (TEP). Subsequently, the performance of MsrtNet is evaluated in predicting product yield for a 2.80 × 106 t/a FCC unit, taking diesel and gasoline yield as examples. In conclusion, MsrtNet can decouple and effectively extract spatiotemporal multiscale information from chemical process data and achieve a approximately reduction of 30% in prediction error compared to other time-series models. Furthermore, its robustness and transferability underscore its promising potential for broader applications.

Alternative Options for Ebullated Bed Vacuum Residue Hydrocracker Naphtha Utilization

The vacuum residue hydrocracker naphtha (VRHN) is a chemically unstable product that during storage changes its colour and forms sediments after two weeks. It cannot be directly exported from the refinery without improving its chemical stability. In this research, the hydrotreatment of H-Oil naphtha with straight run naphtha in a commercial hydrotreater, its co-processing with fluid catalytic cracking (FCC) gasoline in a commercial Prime-G+ post-treater, and its co-processing with vacuum gas oil (VGO) in a commercial FCC unit were discussed. The hydrotreatment improves the chemical stability of H-Oil naphtha and reduces its sulphur content to 3 ppm. The Prime-G+ co-hydrotreating increases the H-Oil naphtha blending research octane number (RON) by 6 points and motor octane number (MON) by 9 points. The FCC co-cracking with VGO enhances the blending RON by 11.5 points and blending MON by 17.6 points. H-Oil naphtha conversion to gaseous products (C1–C4 hydrocarbons) in the commercial FCC unit was found to be 50%. The use of ZSM 5 containing catalyst additive during processing H-Oil naphtha showed to lead to FCC gasoline blending octane enhancement by 2 points. This enabled an increment of low octane number naphtha in the commodity premium near zero sulphur automotive gasoline by 2.4 vol.% and substantial improvement of refinery margin. The processing of H-Oil naphtha in the FCC unit leads also to energy saving as a result of an equivalent lift steam substitution in the FCC riser.

Etherification of olefins from catalytic cracking gasoline to increase its octane number

This study explores the etherification of the olefins in the Fluid Catalytic Cracking (FCC) gasoline, without previous separation of isoamylenes fraction. The bench- scale experiment demonstrated that etherification performed with Purolite CT-275, a macroporous polymeric ion-exchange resin, and different alcohols (methanol, bioethanol, isopropanol and 1-butanol) produces significant conversion of olefins, even for the heavier C6-C9, so that overall conversion of olefins reaches 70% in reaction with ethanol and 83% with isopropanol. As a result, the Motor Octane Number of the gasoline increases by up to two valuable units. The optimization of the reactive distillation parameters was performed by simulation in CHEMCAD 8 and a process flow was suggested for the etherification sequence, in the FCC unit.

Reactive Adsorption Desulfurization Coupling Olefin Conversion in Fluid Catalytic Cracking Gasoline Upgrading Process.

Reactive adsorption desulfurization experiments were carried out on fluid catalytic cracking gasoline over a Ni/ZnO adsorbent in a fixed bed reactor. Results demonstrated that desulfurization is accompanied by hydrogen transfer, while isomerization and aromatization reactions are rare. Reactive adsorption desulfurization coupling olefin conversion was attempted by mixing a catalyst consisting Zn-ZSM-5 with an adsorbent at a certain proportion. The process reduced the loss of octane number and sustained ultradeep desulfurization ability simultaneously. An Fe-modified Ni/ZnO adsorbent was developed, which possessed better olefin retention ability than the Ni/ZnO adsorbent. The Ni-Fe/ZnO adsorbent mixed catalyst exhibited better olefin conversion performance and lower octane number loss than that of the Ni/ZnO adsorbent mixed catalyst because more olefins were retained for isomerization and aromatization reaction on the catalyst. The proportion of the catalyst added and the operating conditions of the process were optimized, ultralow sulfur gasoline was produced, and loss of octane number was low under optimal operating conditions. The amount of octane number lost was reduced by 85% compared with conventional reactive adsorption desulfurization. In addition, the process exhibited excellent desulfurization and olefin conversion performance in multiple regeneration cycles, demonstrating the feasibility of continuous processing.

Reactive Adsorption Desulfurization of Fluid Catalytic Cracking Gasoline: The Effect of Promoters (Fe, Mo, and W) on the Structural and Catalytic Properties of Ni/ZnO Adsorbents

A series of Ni/ZnO adsorbents containing promoters (Fe, Mo, and W) were prepared for reducing the loss of the octane number because of olefin saturation during the reactive adsorption desulfurization (RADS) process. The bimetallic adsorbents synthesized by a two-step impregnation method were analyzed by a series of characterization methods to evaluate the effect of additional metal on the structural and catalytic properties of the traditional Ni/ZnO adsorbent. Hydrogen temperature-programmed reduction (H2-TPR) results showed that the addition of promoter Fe enhanced the reduction performance of NiO, while W hindered the reduction of NiO. The electron density of Ni was modified following the introduction of Fe and W, as analyzed by X-ray photoelectron spectroscopy (XPS), which weakened the adsorption of π complexation between olefins and Ni. Experimental results showed that the desulfurization performance of Ni–Mo was improved but aggravated the loss of the octane number. Ni–W effectively attenuated the olefin saturation reaction but seriously shortened the breakthrough time. The adsorbent modified by Fe can reduce the saturation reaction of olefins and improve the desulfurization performance. In addition, multicycle regeneration experiments proved the excellent regeneration performance of the adsorbent modified by an appropriate amount of Fe. Therefore, the Ni–Fe bimetallic adsorbent may become a novel adsorbent for reactive adsorption desulfurization, which achieves high desulfurization activity and olefin retention ability to satisfy the requirements of fluid catalytic cracking (FCC) gasoline refining.

Brønsted acid properties of hydrodesulfuriaztion catalysts for minimizing the loss of octane number: A DFT and microkinetic study

In order to reduce the loss of octane number during HDS process by enhancing the isomerization ability of HDS catalysts, the catalysis performance of 1-hexene isomerization on different introduced Brønsted acid are studied based on density functional theory (DFT) and microkinetic method. The influence of acid strength and acid density on the adsorption and reaction of 1-hexene are investigated. There is obviously weaker adsorption strength of thiophene (the representation of sulfide in fluid catalytic cracking gasoline) than 1-hexene on Brønsted acid, which indicates thiophene hardly affect the 1-hexene isomerization process. The reaction rate of 1-hexene isomerization on strong Brønsted acid (HZSM-5/Al zeolite) is about 10 4 times higher than that on weak Brønsted acid (HZSM-5/B zeolite). The increasing of Brønsted acid density would bring the slight reduction of acid strength, which makes the 1-hexene isomerization reaction rate is slightly decreased, and the reaction rate on HZSM-5/2Al drops to about 76% of that on HZSM-5/Al. Through comparison, it is found that the reaction rate of 1-hexene isomerization at the strong Brønsted acid reaction center is about 10 5 times that of 1-hexene hydrogenation saturation reaction rate at previous reported sulfur vacancy. Thus, it could be theoretically clarified that the introduction of strong Brønsted acid active centers in the support of HDS catalysts is beneficial to the isomerization of n-olefins, which providing the theoretical guidance to design the catalysts with minimizing octane number loss during the HDS process of FCC gasoline. • Increasing B acid density leads to the reduction of B acid strength. • The rate of isomerization on HZSM-5/Al zeolite is about 10 4 times higher than that on HZSM-5/B zeolite. • Increasing B acid density slightly reduces the 1-hexene isomerization rate. • Introduction of strong B acid site in the HDS catalysts is beneficial to maintain octane number.

Reducing the Olefin Content in Light Fluid Catalytic Cracking Gasoline by Treatment with Nitrous Oxide

Reducing the Olefin Content in Light Fluid Catalytic Cracking Gasoline by Treatment with Nitrous Oxide

Multi-Objective Nonlinear Programming Model for Reducing Octane Number Loss in Gasoline Refining Process Based on Data Mining Technology

To simultaneously reduce automobile exhaust pollution to the environment and satisfy the demand for high-quality gasoline, the treatment of fluid catalytic cracking (FCC) gasoline is urgently needed to minimize octane number (RON) loss. We presented a new systematic method for determining an optimal operation scheme for minimising RON loss and operational risks. Firstly, many data were collected and preprocessed. Then, grey correlative degree analysis and Pearson correlation analysis were used to reduce the dimensionality, and the major variables with representativeness and independence were selected from the 367 variables. Then, the RON and sulfur (S) content were predicted by multiple nonlinear regression. A multi-objective nonlinear optimization model was established with the maximum reduction in RON loss and minimum operational risk as the objective function. Finally, the optimal operation scheme of the operating variable corresponding to the sample with a RON loss reduction greater than 30% in 325 samples was solved in Python.

Applicability of CNT as support candidate for thiophene hydrodesulfurization and 1-octene hydrogenation catalyst

The application of carbon nanotubes (CNT) as a support candidate for hydrotreating catalysts for FCC (fluid catalytic cracking) gasoline was researched in the microreactor with a fixed bed at experimental conditions. The CNT synthesized using the AC arc discharge method was functionalized by chemical treatment with nitric acid. Scanning electron spectroscopy (SEM), X-ray diffraction (XRD) and X-photoelectron spectroscopy (XPS) of the functionalized CNT show that during the functionalization of it, HNO3 impurities unwanted for further application were removed and carbon nanostructures haveoxidized, and therefore they have oxide functional groups attached to those walls. At all the conditions observed, the Ni-Mo/CNT catalysts and Co-Mo-0.25 catalyst showed better hydrodesulfurization activities in comparison with the conventional Ni-Mo/γ-Al2O3. As shown in the XRD analysis, the Ni–W/CNT catalysts showed lowest thiophene hydrodesulfurization activity in the temperature range observed, but they showed very good hydrogenation activity on model compounds used.Catalytic performance tests of different catalysts showed that good applicability of the CNT as support candidate for the hydrotreating catalysts. It also was experimentally demonstrated that the Ni-Mo/CNT and Co-Mo/CNT can be the best hydrotreating catalysts.

Intelligent selection and optimization method of feature variables in fluid catalytic cracking gasoline refining process

To suppress the research octane number (RON) loss in the gasoline refining process, an intelligent selection and optimization method of feature variables is proposed. In the methodology, the random forest-based feature selection algorithm is first used to calculate the importance of each feature variable, so that the main variables are selected for the prediction modeling of the RON loss and sulfur content. Next, the long short-term memory network is introduced to establish the nonlinear mapping relationship between the main feature variables and the product yield. Finally, an objective function for minimizing RON loss under the constraints of RON loss reduction and product sulfur content is constructed, and the optimal values of feature variables are obtained by the continuous iterative solution with a hybrid grey wolf optimizer algorithm. Based on real-world data in industrial processes, experimental results verify the feasibility and effectiveness of the proposed method.

A Lumped Kinetic Model of M-DSO Process for Fluid Catalytic Cracking Gasoline Hydro-Upgrading

Selective hydrogenation of fluid catalytic cracking (FCC) gasoline is an effective method to reduce the sulfur and olefin contents in it for clean gasoline. Based on the characteristics of the DSO-M and M-DSO processes for the hydro-upgrading of heavy fraction of FCC gasoline hydro-upgrading and the contribution of different hydrocarbons to the octane number, two five-lump reaction networks for M upgrading stage and DSO hydro-desulfurization stage respectively were constructed. According to the experimental data from a micro-tubular fixed bed reactor for FCC gasoline hydro-upgrading, the kinetic parameters of the 5-lump models for M and DSO stages were worked out respectively by Runge–Kutta algorithm and genetic algorithm. The kinetic analysis demonstrates that M-DSO process is better than DSO-M process. Moreover, verification indicates that the models established have good reliability and extrapolation.

Synergistic Catalysis of Thermoregulated Ionic Liquid/p-Toluenesulfonic Acid for Alkylation Desulfurization of Fluid Catalytic Cracking Gasoline

The olefin alkylation of thiophenic sulfur (OATS) in model fluid catalytic cracking (FCC) gasoline was carried out using temperature-responsive catalyst which was prepared by mixing the temperature...

Three-Dimensional Graphene Oxide-Supported Zinc Oxide Scaffold as a High-Efficiency Adsorbent for Desulfurization

Sulfur oxides are air pollutants derived mainly from the combustion of gasoline. Reducing the sulfur content of fluid catalytic cracking (FCC) gasoline is of key importance for the prevention and control of atmospheric pollution. We describe herein the fabrication and characterization of a porous, three-dimensional (3D) graphene oxide-supported zinc oxide (GO/ZnO) scaffold as an adsorbent for desulfurization with various model compounds and real FCC gasoline. The uniform and stable dispersion of ZnO nanoparticles on the surface of GO facilitates the specific binding of sulfides. Moreover, GO synergistically adsorbs aryl sulfides via [Formula: see text]–[Formula: see text] stacking interactions. The GO/ZnO nanosheets were further self-assembled into a 3D porous scaffold that effectively trapped sulfides and inhibited desorption. These scaffolds exhibited excellent desulfurization performance with maximum sulfur capacity up to 29.73[Formula: see text]mg S/g. This work provides a novel perspective on the fabrication of high-efficiency adsorbents for gasoline pretreatment.

Conceptual Fluid Catalytic Cracking Process with the Additional Regenerated Catalyst Circulation Path for Gasoline Reprocessing and Upgrading with Minimum Loss

Directly reprocessing fluid catalytic cracking (FCC) gasoline in the FCC unit is a simple method for gasoline upgrading. The gasoline distillate is typically reprocessed in the main riser reactor (...

Catalytic oxidative desulfurization of gasoline using phosphotungstic acid supported on MWW zeolite

Catalysts for the desulfurization of gasoline samples were synthesized via the immobilization of well-dispersed phosphotungstic acid (HPW) on Mobil composition of matter-twenty-two (MWW) zeolite. Characterization results indicated that these catalysts possess a mesoporous structure with the retention of the Keggin structure of immobilized HPW. Relevant reaction parameters influencing sulfur removal were systematically investigated, including HPW loading, catalyst dosage, temperature, initial S-concentration, molar ratio of oxidant to sulfide (O/S), volume ratio of MeCN to model oil (Ext./oil), and sulfide species. The 40 wt-% HPW/MWW catalyst exhibited the highest catalytic activity with 99.6% dibenzothiophene sulfur removal from prepared samples. The 40 wt-% HPW/MWW catalyst was recycled four times and could be easily regenerated. Finally, as an exploratory study, straight-run-gasoline and fluid catalytic cracking gasoline were employed to accurately evaluate the desulfurization performance of 40 wt-% HPW/MWW. Our research provides new insights into the development and application of catalysts for desulfurization of gasoline.

Heat transfer of water-based carbon nanotube nanofluids in the shell and tube cooling heat exchangers of the gasoline product of the residue fluid catalytic cracking unit

In this study, a series of low-concentration carbon nanotubes (CNT) water-based nanofluids (0.0055, 0.055, 0.111 and 0.278 vol%) were used as coolants in a shell and tube cooler of the residue fluid catalytic cracking gasoline product to analyze their effects on heat performance of the heat exchanger. The coolants and gasoline flow in tube side and shell side, respectively. This work was performed through simulating the heat exchanger by ASPEN HTFS+ 7.3 software. The performance of the nanofluids to heat transfer was analyzed in comparison with cooling water. Results illustrated that 0.055% CNT concentration could enhance heat transfer properties of the heat exchanger such as Nusselt number, total heat transfer coefficient and heat transfer rate more than other concentrations. Therefore, the lowest temperature of outlet shell-side fluid was also observed at this concentration. Moreover, increment in mass flow rates of both the tube-side and shell-side fluids caused enhancement of the heat transfer, especially with 0.055 vol% CNT. Although there is an optimum concentration among the studied CNT volume fractions, all nanofluids exhibit better thermal performance of the heat exchanger than cooling water, whereas pressure drop increases with CNT loading.

The effect of carrier in KCoMoS-supported catalysts for hydro-upgrading of model FCC gasoline

K-CoMo/Sup (where Sup = Al2O3, SiO2, TiO2 and ZrO2) catalysts were synthesized using H3PMo12O40, CoCO3, KOH and citric acid. The catalysts were characterized by temperature-programmed reduction (TPR), temperature-programmed desorption of NH3, X-ray photoelectron spectroscopy, transmission electron microscopy. Samples were tested in hydrotreating of model fluid catalytic cracking gasoline and in selective hydrogenation of 1,5-hexadiene and n-heptene-1. The type of used carrier significantly affected the morphology of active phase and catalytic properties. Active sites productivity of K-CoMo/Sup catalysts in hydrodesulfurization (HDS) and olefin hydrogenation (HYDO) reactions as well as HDS/HYDO selectivity correlated with active phase morphology excepting TiO2-supported sample. Productivity of active sites in reactions of selective hydrogenation of diolefin depended on maximum peak reduction obtained from TPR, which in turn was a function of acidity of using supports. The highest HDS/HYDO selectivity was obtained at catalyst which possessed the lowest selectivity towards partial hydrogenation of diolefine compared to complete hydrogenation.

Acid Dicationic Ionic Liquids as Extractants for Extractive Desulfurization

A series of imidazole- and pyridine-based dicationic ionic liquids (DILs) were synthesized and employed in extractive desulfurization (EDS) for the removal of sulfur compounds from commercial fluid catalytic cracking (FCC) gasoline. The influence parameters in the EDS process and regeneration of DILs are discussed. Under optimum operating conditions, the desulfurization efficiency can reach 79.72%. After five cycles, the sulfur content was reduced to less than 10 μg/g, and deep desulfurization was realized. The regeneration of the used DILs was performed by back-extraction, and the Fourier transform infrared and 1H nuclear magnetic resonance (NMR) spectra proved that the structure of DILs did not change. The relationship between acid strength and the desulfurization effect of DILs was studied by UV–vis spectroscopy. According to 1H NMR characterization, the main mechanism of the DILs' EDS process may be the interaction of π–π bonds. It is inferred from the chemical shift that the DILs have larger cation volume, which was conducive to increasing the aromatic π-electron density, producing stronger π–π interaction between the cations and aromatic sulfides, and thus having better EDS effect than ILs with mono-cationic. Finally, the adaptability of DILs was studied, and DILs have excellent desulfurization adaptability for different FCC gasolines.