Catalytic Cracking Of Naphtha Research Articles

Preparation of spinnable mesophase pitch from pyrolyzed fuel oil by pressurized heat treatment and its application of carbon fiber

Petroleum residues are produced as by-products of petroleum refining. Recently, various effective non-fuel uses of petroleum residues have been considered toward a carbon-neutral society. Pyrolysis fuel oil (PFO) is one of the petroleum residues. Advanced utilization of PFO for future non-combustion applications is required. In this study, Mesophase pitch-based carbon fibers (MPCF) were successfully produced from PFO. Spinnable mesophase pitch (SMP), a precursor of MPCF, was prepared using PFO as a raw material through the pressurized heat treatment at 420°C-430 °C. PFO is from the naphtha catalytic cracking process for ethylene production and is mainly composed of 2–4 condensed polycyclic aromatic hydrocarbons (PAHs). The high temperature pressurized heat treatment could result in the PFO-derived SMPs with yield of 23.0 wt% and excellent spinnability. On the other hand, without pressurized heat treatment, the yield was 8.5 wt%. This indicates that pressurized heat treatment significantly contributed to the yield improvement. In addition, the preference for the conversion of PFO molecules into highly condensed PAHs via cata-condensation during pressurized heat treatment at 420°C-430 °C was observed, which may be the main reason for the high yield and excellent spinnability of the resulting SMPs. As a result, the obtained PFO-derived SMPs though the such high-temperature pressurized heat treatment provided the typical radial-random transversal textures and general mechanical performances of MPCF: The tensile strength and Young's modulus of the PFO-derived MPCF graphitized at 2400 °C showed high values of 1.9–2.7 GPa and 554–635 GPa, respectively.

Transition metal modified hierarchical ZSM-5 nanosheet for catalytic cracking of n-pentane to light olefins

Catalytic cracking of naphtha is an effective way to produce light olefins, in which zeolite catalyst plays an important role. In this work, hierarchical ZSM-5 self-pillared nanosheet (NS) supporting Ca, Fe and Zr is prepared for catalytic cracking of n-pentane to produce ethylene and propylene. Hierarchical pores by self-pillared nanosheet zeolite aggregates delivers enhanced exposed surface, thus giving improved conversion of n-pentane and yield of olefins, in comparison with conventional microporous ones. Moreover, different metal sites intrigue various reaction pathways in cracking. The dehydrogenation-cracking of n-pentane is demonstrated by Ca/NS catalyst with enhanced conversion of reactant and selectivity of olefins. The introduction of Fe on NS (Fe/NS) sacrifices part of acidities and inhibits the hydrogen transfer reaction by monomolecular cracking pathway, leading to enhanced olefin selectivity and catalytic stability, but decreased conversion of n-pentane. Zr incorporation promotes utilization of Brønsted acid sites through bimolecular cracking routes. The interaction between reactants and Brønsted acid sites or olefins carbenium ions could be promoted by the introduced framework Zr, which improves the conversion of n-pentane, but leading to reduced olefin selectivity with relative low stability.

Reaction mechanism study of catalytic conversion of light straight-run naphtha to light olefins over micro-spherical HZSM-5 zeolite catalyst

Catalytic conversion of naphtha has attracted attention as an alternative method to the conventional thermal cracking to produce light olefins in an environment-friendly and energy-efficient way. In this work, a reaction mechanism study of light straight run naphtha cracking over micro-spherical catalyst containing HZSM-5 was systematically investigated using single hydrocarbon feeds, and the straight run naphtha itself. The identified reaction pathways from the single feeds along with the naphtha experimental data have been utilized to investigate reaction pathways of the naphtha conversion reactions. The experimental tests were carried out in the temperature ranges of 450–650 ℃ and space-times of 0.3–1.5 min using a fixed bed micro-reactor in isothermal and isobaric conditions. The product distribution for the naphtha feed shows that light paraffins and light olefins are the primary products, which are products of monomolecular protolytic cracking of the paraffin components of the naphtha feed. The olefin interconversion reactions illustrated that oligomerization and cracking by β-scission dominate the secondary reactions of naphtha catalytic cracking conversions. The experiments conducted on cyclohexane, cyclohexene and n-hexane single feeds revealed that BTX formation proceeds through the formation of C6-C8 naphthenes, and C6-C8 cyclo-olefinic intermediates. Low temperatures and space times promote the selectivity to propylene while the selectivity of ethylene increases with temperature. The degree of thermal cracking (DTC) illustrated that thermal cracking is considerable only for temperatures of higher than 550 ℃.

Catalytic conversion of n-Dodecane to lower olefins hydrogen carriers over bran-shaped modified MCM-22 zeolite catalyst: SiO2/Al2O3 ratio effects

The demand-supply gap for light olefins and aromatics has been enormous in recent years. This imbalance is anticipated to grow exponentially due to their extensive use in manufacturing plastics, textiles, pharmacological intermediates, climate-neutral synthetic fuels, and hydrogen carriers. Production of light olefins through the catalytic cracking of naphtha is widely regarded as one of the most prestigious methods. Despite this, selecting an effective and efficient catalyst is one of the most challenging aspects of the scaling-up process. In this study, a highly active, modified MCM-22 catalyst has been synthesized by a hydrothermal method. Various techniques are used for the characterization of catalysts, including scanning electron microscopy (SEM), X-ray diffraction (XRD), N2 adsorption-desorption, temperature-programmed desorption of ammonia (NH3-TPD), and solid-state nuclear magnetic resonance experiments (NMR) with Al and Si. The cracking of n-dodecane to lower olefins was performed, and it was found that the conversion rates were highly correlated with the SiO2/Al2O3 ratio of the MCM-22 samples. Sample Si0.5 (SiO2/Al2O3 ∼ 28.9) showed a typical photograph of the MWW phase with a bran or flake shape in a stacking mode. The Si0.5 sample has a superior external surface area than other samples (up to ca. 130 m2/g) caused by a smaller particle with an average crystal size of around 15 nm, resulting in maximum catalytic performance towards light olefins. It was discovered that Si0.5 had a diminishing tendency in the paraffinic selectivity but had a robust selectivity for olefins (propylene and butylene in particular). This research may provide academics and the industry with new prospects for improving the catalytic cracking of n-dodecane into light olefins.

Selective production of light olefins over zeolite catalysts: Impacts of topology, acidity, and particle size

Compared to conventional steam cracking, catalytic cracking of naphtha and methanol-to-olefins (MTO) over zeolite catalysts have been proved as the most successful processes for producing light olefins. To achieve the maximum light olefins yield and the longest lifetime, zeolite catalysts with excellent catalytic performance should be designed, by choosing suitable structure and regulating their physicochemical properties. In this review, the impacts of topology, acidity, and particle size of zeolites on the catalytic performance of naphtha cracking and MTO reactions, especially the light olefins selectivity and lifetime are systematically discussed. We hope that this review can be helpful not only to deeply understand the structure–property-performance relationship of various zeolite catalysts, but also to design more excellent zeolite catalysts for these two processes.

Increased Light Olefin Production by Sequential Dehydrogenation and Cracking Reactions

In this study, a sequential reaction using selected metal oxides, followed by ZSM-5-based catalysts, was employed to demonstrate a promising route for enhancing light olefin production in the catalytic cracking of naphtha. The rationale for the reaction is based on the induction of alkenes into hydrocarbon feeds prior to cracking. The optimum olefin induction was achieved by carefully optimizing the dehydrogenation active sites Mo/Al2O3 catalyst. The formed alkenes have a lower activation energy for C-H/C-C bond breaking compared to alkanes. This could accelerate the formation of carbenium ions, thus promoting the conversion of n-octane to produce light olefins. Detailed product distribution and DFT calculation indicated a remarkable increase in ethylene and propylene production in the final product through a modified reaction pathway. Compared with the common metal-promoted zeolite catalysts, the new route could avoid the block of zeolite channels and corresponding decreased catalytic cracking activity. The feasibility of the proposed route was confirmed with different ratios of dehydrogenation catalyst to the reactant. The highest yields of ethylene and propylene reached 13.22% and 33.12% with ratios of Mo/Al2O3 and ZSM-5-based catalyst to n-octane both 10:1 at 600 °C. Stability tests showed that the catalytic activity of the double-bed system was stable over 10 cycles.

CoMoS/modified-kaolin bi-functional hydrodesulfurization-olefin skeletal isomerization catalyst for FCC naphtha hydro-upgrading

Aiming at developing a bifunctional selective hydrodesulfurization (HDS) - olefin skeletal isomerization catalyst for fluid catalytic cracking (FCC) naphtha hydro-upgrading, in this article we present an acid-assisted dealumination method, the acid-modified kaolin (AMK-850-27) with tailored porosity and acidity and CoMoS bi-functional catalysts CoMo/AMK-850-27 was obtained. The catalytic performance was assessed with model FCC naphtha that is composed of thiophene (300 mg/kg) and 1-hexene (20%) in heptane. Compared with two catalysts used γ-Al2O3 and HZSM-5 as supports, CoMoS catalyst prepared with AMK-850-27 displayed compromise catalytic performance: balanced HDS activity and selectivity, high skeletal isomerization activity and low cracking activity, and excellent octane number preservation performance. This can be attributed to the following reasons: (i) AMK-850-27 possesses micro-meso-macro porosities and appropriate Brönsted acidity that can benefit skeletal isomerization activity but depress cracking activity; and (ii) The olefin isomers are more difficult to be hydrogenated than the corresponding linear terminal ones due to the steric effect of the branched olefins. This investigation providesa novel route to achieving deep desulfurization, appropriate olefin reduction and octane number preservation for FCC naphtha upgrading, acidic support with meso-macro-porosity can benefit olefin skeletal isomerization and the HDS selectivity but lower hydrocarbon cracking activity.

Seeds induced Beta zeolite synthesis with low SDA for n-heptane catalytic cracking reaction

Due to higher thermal and hydrothermal stability, suitable acidity properties, Beta zeolite is considered as promising catalyst for naphtha catalytic cracking process. However, high cost and environmental pollution issue limit its industrial application by using high content of N-containing organic structural directing agent (SDA). In this paper, different SiO2/Al2O3 ratios of Beta zeolites were prepared assisting by seeds induced method with low SDA and cheap industrial silica sol as the silicon source. Physical and chemical properties of as-prepared Beta zeolites were characterized by XRD, N2 adsorption-desorption, NH3-TPD, Py-FTIR and SEM. N-Heptane was used as model compound for catalytic cracking performance evaluation. The results showed that Beta zeolite with high SAR was successfully synthesized, which had well defined crystallinity, proper specific surface area and pore structure, high B/L ratio and strong acid site. n-Heptane catalytic cracking performance showed high yield of low-carbon olefins with relative low activity on hydrogen transfer reaction and coke formation.

Research on thermodynamic and simulation method of extractive distillation for desulfurization of FCC naphtha

Simulations can effectively and accurately determine optimal process conditions without extensive experiments in the desulfurization of fluid catalytic cracking (FCC) naphtha by extractive distillation. The UNIFAC-original model in Aspen Plus v8.8 is suitable for simulating the process with several components. However, the lack of group binary interaction parameters between the solvent and sulfides in FCC naphtha reduced the accuracy of the UNIFAC-original model in Aspen Plus v8.8. Consequently, the required group binary interaction parameters were calculated using binary vapor–liquid equilibrium (VLE) for improved accuracy. The obtained VLE data were thermodynamically consistent. The empty group binary interaction parameters were calculated using the VLE data. An accurate simulation method was obtained for the desulfurization of FCC naphtha using these parameters, and the absolute deviation between the simulated and experimental results was 0.4 wt%. Subsequently, sensitivity analysis was performed to obtain the optimal process conditions. The experimental results correlated well with the simulation results, thereby proving that the parameters were regulated and that the simulation demonstrated high accuracy. Moreover, the sulfur content in the raffinate could be decreased to 4.37 mg/kg. Thus, refineries can rapidly establish their optimal process conditions through simulation.

Rational screening of transition metal single-atom-doped ZSM-5 zeolite catalyst for naphtha cracking from microkinetic analysis

Metal doped ZSM-5 catalyst has attracted much attention due to its unique catalytic activity for C–H bond activation. In this work, based on density functional theory (DFT) calculations and microkinetic analysis, we prospectively explored the catalytic activity of 12 kinds of transition metals (M = Fe, Co, Ni, Cu, Mo, Ru, Rh, Pd, Ag, W, Pt, Au) single-atom-doped ZSM-5 zeolite catalysts in the catalytic cracking of naphtha. The results show that there is a strong electronic interaction between metal atom and ZSM-5 skeleton. This induced stable structure could improve the adsorption ability of hydrocarbon, thus promoting the activation of C–H bond and the cracking of carbenium ion. Moreover, C and H binding energy were identified as descriptors in describing catalytic activity via good scaling relations. The turnover frequency volcano diagram shows that the Ag and Cu doped ZSM-5 zeolite catalyst is close to the best choice. In addition, Pd and Mo are potential metal choices with good selectivity through selectivity analysis. This work has important guiding significance for understanding the fluid catalytic cracking (FCC) mechanism and designing high-efficiency cracking catalysts.

Effect of zeolite structure and addition of steam on naphtha catalytic cracking to improve olefin production

In this study, steam catalytic cracking of dodecane (a model representative of naphtha) was investigated both with and without steam. The reaction utilized the different 3D sinusoidal microporous channels in submicron ZSM-5 and BEA zeolite crystals to convert dodecane to light olefins. Although both synthesized submicron catalysts (400–500 nm) have similar Brønsted/Lewis acid ratios, the BEA zeolite exhibited higher surface acidity than ZSM-5 zeolite. In addition, the steam addition has significantly affected the zeolites structure, even though their cracking activity was not affected. However, the zeolites structural modification has shown significant effect on the pore shape selectivity which result in different light olefins yields. During catalytic cracking in the absence of steam, hydrogen transfer reaction was less favored over BEA zeolite, which result in higher light olefins selectivity and dry gas formation than with ZSM-5 zeolite. In the presence of steam, ZSM-5 pore-shape modification favored the monomolecular cracking pathway leading to achieving higher light olefin yield than that observed over BEA zeolite. The study demonstrated that ethylene/propylene ratio (E/P) is impacted by zeolite structure which is affected by the steam addition during the reaction.

Improving Both the Activity and Selectivity of CoMo/δ-Al2O3 by Phosphorous Modification for the Hydrodesulfurization of Fluid Catalytic Cracking Naphtha

Improving Both the Activity and Selectivity of CoMo/δ-Al₂O₃ by Phosphorous Modification for the Hydrodesulfurization of Fluid Catalytic Cracking Naphtha

Molecular-Level modeling for naphtha olefin reduction in FCC subsidiary Riser: From laboratory reactor to pilot plant

In this work, molecular-level kinetic modeling was developed for the fluid catalytic cracking (FCC) naphtha olefin reduction process in a subsidiary riser. A transfer strategy for model parameters between different scale reactors was proposed. A molecular-level kinetic model was developed for a laboratory-scale fixed fluidized bed (FFB). The kinetic parameters were tuned using systematic experimental data of FFB under different conditions. Then, a molecular-level process model was built for a pilot riser. The kinetic parameter of the pilot riser model was transferred from the FFB model using only one scale-up experimental data to tune the transferring factors. The obtained riser model can accurately predict the fraction yield, naphtha composition, and temperature profile while the feedstock and operating conditions were changed.

Insight into reaction path and mechanism of catalytic cracking of n-hexane in HZSM-5 zeolites

The n-hexane was used as a model compound to study the catalytic cracking behavior of light hydrocarbon in HZSM-5 zeolites, and the law of product selectivity of real acid-catalyzed reaction was investigated by analyzing the product distributions. The results showed that no pyrolysis reaction was found at 300°C. Only the acid catalytic reaction took place by the mechanism of carbocation, whose activity was positively correlated to the amount of Brønsted (B) acid sites. The selectivity of ethane, ethylene and propane was negatively correlated, while that of propylene was positively correlated with the Si/Al ratios and catalyst to oil ratios, suggesting that low acid density might be more favorable for monomolecular cracking reactions. It was worth nothing that the total selectivity of C4 products was much higher than that of C2 products. Combined with the quantum chemistry calculation results, it could be confirmed that the super-stability of C2H+ 5 carbenium ion from the monomolecular cracking of n-hexane made it difficult to produce ethylene and ethane through hydrogen transfer reaction. It’s easier to form a C8 carbenium ion (C8H+ 19) with another n-hexane molecule, and then to generate more C4 products. These results revealed the nature of the low selectivity of ethylene in light hydrocarbon catalytic cracking products. It could be concluded that the product selectivity of catalytic cracking of light hydrocarbons could be modulated by controlling reaction paths depending on the catalyst acid properties and the catalyst to oil ratios. This work will provide important theoretical support for the catalyst design and process development of naphtha catalytic cracking.

Modeling, simulation, and optimization for producing ultra-low sulfur and high-octane number gasoline by separation and conversion of fluid catalytic cracking naphtha

Contradiction between the desulfurization and loss of octane number (ON) for fluid catalytic cracking (FCC) naphtha is the long-term problem of clean gasoline production. Moreover, ON loss is substantially aggravated during deep hydrodesulfurization because of the global limited supply of sulfur for gasoline. This paper introduced a novel process for ultra-clean gasoline production that solves the above problem by using a unique separation approach. The components were separated by the coupling of distillation and solvent extraction, which the separation efficiency depends on the relationship between solvent and feedstock components. However, the compositions of FCC naphtha are complicated and always changing due to different processing technologies. Therefore, changes in the material composition must be considered during production. In this study, ternary liquid–liquid equilibrium (LLE) was explored to investigate the interaction of olefin, sulfide, and sulfolane solvent. A universal quasi-chemical functional group activity coefficient (UNIFAC) group contribution model was selected to predict the product composition when the FCC naphtha was treated by this process. The lack and necessity of group interaction parameters for the prediction were obtained through the regressive calculation of LLE results. A simulation method was established by Aspen Plus, and the reliability was well illustrated. Finally, the high olefin content of FCC naphtha critical components was analyzed by this simulation method. The sulfur and olefin levels of the product were 9.0 mg/kg and 18.6 wt%, respectively. The operation conditions simulated using the proposed technique met the requirements for the latest commercial gasoline worldwide.

Fundamental research on the influence of mercaptan and thioether structure on the solvent extraction of fluid catalytic cracking naphtha

The thioether and mercaptan components (over 50–100 mg/kg) of fluid catalytic cracking (FCC) naphtha must be removed to satisfy the rigorous sulfur content standard of the vehicle gasoline. Owing to the difference between the structures of thioether and mercaptan and that of thiophenic sulfur, the desulfurization process is usually divided. A serious loss of octane number (ON) occurs during typical desulfurization when the sulfur content is reduced to 10 mg/kg. With the oriented separation of FCC naphtha critical components process, the standard of sulfur content with losing 1 unit of ON can be satisfied. However, thioether and mercaptan require individual technologies for removal. Thioether, mercaptan, and thiophenic sulfur must be synchronously removed to improve the efficiency, simplify the technology, and reduce the energy consumption. In this study, quantum chemical calculation and ternary liquid–liquid equilibrium experiment were combined to investigate the effect of thioether and mercaptan structures on the sulfoxide solvent extraction performance. The results showed that the Van der Waals’ force was the main interaction between the thioether/mercaptan and the solvent because the peaks of solvent and sulfide by RDG analysis were located at −0.01 to 0.01 a.u. In addition, the dipole moment, steric hindrance, and displacement affected the solvent extraction performance. The selectivity coefficient θ¯ of C3 thioether and mercaptan was 5.80 and 6.48 by DMSO solvent, respectively, which were greater than those of C4 sulfides (4.48 and 5.56). The interaction energy Eint of DMSO-ethyl methyl sulfide and DMSO- propanethiol were −32.75 and −33.68 kJ/mol while DMSO-diethyl sulfide and DMSO- butanethiol were −24.72 and −29.20 kJ/mol. It also proves that the C3 thioether and mercaptan could better extract into the solvent. In this way, the extractive desulfurization rate of the real FCC naphtha by DMSO was 80%. Therefore, the use of sulfoxide composite solvent can simultaneously extract the thioether, mercaptan, and thiophenic sulfur. This analytical method could be used to predict the synchronous extraction performance for FCC naphtha sulfides by other typical solvents.

Desulfurization of Fluid Catalytic Cracking Naphtha by Extractive Distillation: A Universal Simulation Method Established Using the Universal Quasi-Chemical Functional Group Activity Coefficient Model

The extractive distillation process is gradually being used for the desulfurization of fluid catalytic cracking (FCC) naphtha because of its excellent octane number protection performance during desulfurization. The key to this process is the separation of sulfides. However, the composition of FCC naphtha is complicated and easily changes, which seriously affect the separation performance. The operating conditions need to be adjusted frequently with the change in the different properties of feedstocks, which cost time, manpower, and investment. In this study, we introduce a simulation method using the universal quasi-chemical functional group activity coefficient (UNIFAC) model to predict the process of desulfurization. In the simulation, the group binary parameters for the UNIFAC model seriously affect the reliability of the method. Therefore, the lacking parameters of the solvent and sulfides were first regressively calculated by the experimental results of the binary vapor–liquid equilibrium (VLE). All the values of (D–J) by the Herington integral method were under 10, which means that the parameters obtained in this work were well correlated to those of the VLE experiments. Based on this, the prediction simulation method was established and the maximum error of the compositions of the products between simulation and real-oil experiment was only 0.5 wt %. According to the simulation, 98% of sulfides could be extracted under the optimal conditions (113 °C at the extraction column, 178 °C at the solvent recycle column, etc.). The rule of the extraction of sulfides was thiophene sulfur > mercaptan sulfur > thioether sulfur, which is consistent with the VLE study results. The sulfur content of the raffinate oil was decreased to 9.3 mg/kg. It well met the latest gasoline standard and is appropriate for the prediction of the desulfurization of FCC naphtha by the extractive distillation process.

High efficient separation of olefin from fluid catalytic cracking naphtha: Separation mechanism and universal simulation method

AbstractThe fluid catalytic cracking (FCC) naphtha critical component‐oriented separation process is an efficient method to produce ultra‐low‐sulfur (<10 μg/g) gasoline with minimal loss of octane number (<1 RON). However, the product quality is highly dependent on the structure of the components of FCC naphtha. Aromatics and thiophene sulfides without a methyl side chain favor the separation of olefin. The major impulse of olefin separation is the solvent‐induced dipole of aromatics or thiophene sulfides, leading to a “Plane‐to‐Plane” combination between the solvent and aromatics or thiophene sulfides, accompanied by a steric hindrance due to their side chains. This condition resulted in 2–3 times greater θ of benzene and thiophene compared with that of toluene and 3‐methylthiophene. In addition, an improved non‐random two‐liquid model was proposed based on the above results, and a simulation method for FCC naphtha solvent extraction process was established. The calculation results accorded well with industry data.

Synergism of Titanium in MFI Zeolite to Acidity with Its Appliance to N-Hexane Catalytic Cracking Reaction

Catalytic cracking of naphtha is now a process of huge development potential to produce light olefins, which are important basic raw materials used in various industries, but current industrial catalysts like ZSM-5 zeolites suffer from low selectivity and high energy consumption. Here, Ti/Al-containing nanosize MFI-structure zeolites in-situly synthesized through one-pot method were applied to the catalytic cracking using n-hexane as the model reactant. The maximum mass yield of combined light olefins reaches 49.2% with 99% conversion at 600°C and 1 atm. Multiple characterizations are used to identify the Ti-related active species and their effect on the performance. It was found that a higher proportion of LAS caused by Ti was beneficial to the activation of reactant, and the slightly increased amount of BAS leaded to more alkanes converting into light olefins. This understanding may open new opportunities for design and modification of catalytic cracking catalysts.

Influence of the alumina crystal phase on the performance of CoMo/Al2O3 catalysts for the selective hydrodesulfurization of fluid catalytic cracking naphtha

To achieve a high desulfurization degree while minimizing the olefin hydrogenation (HYD) is the biggest challenge in the selective hydrodesulfurization (HDS) of fluid catalytic cracking (FCC) naphtha. In this work, alumina with different crystal phases (γ-Al2O3, δ-Al2O3 and θ-Al2O3) were utilized as carriers to prepare CoMo/Al2O3 selective HDS catalysts. The influence of alumina crystal phase on the morphology of active phase and catalytic performance of their corresponding CoMo/Al2O3 catalysts has been studied in detail. It was found that CoMo/δ-Al2O3 showed the highest HDS activity due to an appropriate weakened metal-support interaction and the modest Mo dispersion. However, CoMo/θ-Al2O3 showed a much higher HDS selectivity than that of CoMo/γ-Al2O3 and CoMo/δ-Al2O3. The significantly enhanced HDS selectivity was attributed to a notably larger edge-to-corner ratio of CoMoS slabs (fe/fc)CoMo, thus resulting in a slightly reduction of HDS activity while a significantly decreased olefin HYD activity. Besides, the large pores of θ-Al2O3 are beneficial for weakening the internal diffusion resistance when utilizing full-size catalysts. Therefore, θ-Al2O3 is an ideal carrier to prepare the industrial CoMo/Al2O3 catalysts for the HDS of FCC naphtha.