Octane Loss Research Articles

Optimization Modeling and Empirical Research on Gasoline Octane Loss Based on Data Analysis

Gasoline is one of the most consumed light petroleum products in transportation and other industries. This paper proposes a method for optimizing gasoline octane loss using data analysis technology aimed at optimizing the production process and minimizing the loss of gasoline octane. Firstly, the data are screened and the high-dimensional data are reduced to construct the neural network prediction model optimized by genetic algorithm. After utilizing the model for prediction, the optimal operating condition is achieved. Secondly, ensuring that the gasoline emission meets the standard, the octane loss is reduced by adjusting the operating variables. Thirdly, actual data are collected and calculated to obtain the main operating variables and their optimal operating conditions of a petrochemical company affecting the catalytic cracking gasoline S-Zorb unit, thus providing companies using S-Zorb units with reference data for optimizing gasoline catalytic cracking processes. Fourthly, the superiority of the proposed method was verified by comparing it with the other methods. This paper intends to contribute to better modeling the progress of gasoline catalytic cracking by adequately considering the impact of multiple factors, improving the quality of refined oil products of chemical enterprises, saving the economic cost of chemical enterprises, and protecting the atmospheric environment.

Research on Forecast of Gasoline Octane Loss Based on Neural Network

Low-sulfur gasoline has become the world’s fuel development trend. However, the existing technology generally reduces the gasoline octane number in the process of desulfurization and olefin reduction of FCC gasoline. How to predict the octane loss of gasoline is very important for subsequent related research. This paper analyzes and screens the refinery data of chemical plants, builds a neural network-based gasoline octane loss prediction model, inputs 12 main operating variables to predict the octane loss, and verifies it with real data. The results show that the training effect of the model is good, and the training error is within 1%, which provides a reference for the research on predicting the loss of gasoline octane number.

Production of a gasoline blending component with high-octane and low sulfur from coal tar light oil over sulfided CoMoP/η-Al2O3

Coal tar light oil (CTLO), an unclean byproduct of coal chemical industry, is a potential material for the manufacture of high-octane gasoline blending component. CoMo/η-Al2O3, a catalyst with lower desulfurization performance but less octane loss, is selected from four catalysts to further reduce sulfur content of CTLO by phosphorus modification. Catalysts modified by various content of phosphorus are characterized by a series of methods. The results show that addition of appropriate amount of phosphorus can improve the structure and acidity of catalysts, and weaken the interaction between active component and carrier. Furthermore, most of naphthalene in CTLO is converted into tetralin with 1.5 wt% phosphorus loading, and tetralin can play an important role of hydrogen transfer during catalytic hydrogenation process, which promotes the removal of heteroatom compounds. When the loading of phosphorus is 1.5 wt%, the content of S, N heteroatom compounds is only 7.2 mg/kg, 0.021% in product oil respectively, which is beneficial to reduce automobile emissions. Meanwhile, the RON reaches 105.3, and only decreases by 2.2 units compared to the original CTLO. Product oil catalyzed by CoMoP1.5/η-Al2O3 can be used as excellent high-octane gasoline blending component with low sulfur.

Quantitative relationship between olefin saturation and octane loss during HDS process: An insight from molecular structure to experimental activity

Given the demand for clean gasoline with ultralow sulfur and olefin contents, reduced olefin content, which inevitably results in a large octane number loss, is urgently needed. The key to finding a solution for octane number loss is to identify the relationship between olefin hydrogenation and the loss of octane number of gasoline. The negative effect of certain olefins on octane number was first investigated by setting different olefins saturated in the same amount. C5–C7 olefins exhibit the most adverse effect on octane number than others. In addition, the saturation amounts of various olefins were also studied by fluid catalytic cracking (FCC) gasoline hydrogenation experiment. Given the negative effect and saturation amount, the sequence of octane number loss based on olefin hydrogenation is C5 ≈ C6 > C7 > C8 > C9 > C10, wherein C5–C7 olefins, which present high saturation amounts in the hydrogenation experiment, are the main contributing factors of octane number loss in gasoline hydrogenation. Based on the above studies, the formula of the loss of octane number was developed, which can estimate the loss of octane number of gasoline with the error range of less than 0.5 units Research Octane Number.

Synthesis and characterization of Beta-FDU-12 and the hydrodesulfurization performance of FCC gasoline and diesel

Micro-mesoporous Beta-FDU-12 (BF) materials were synthesized by a nano-assembling method with different amounts of microporous Beta materials. CoMo catalysts, with Co and Mo active metals supported on BFA composites (a mixture of BF and γ-Al2O3), were prepared by two-step incipient-wetness impregnation procedures. The BF micro/mesoporous materials and their corresponding CoMo/BFA catalysts were characterized by various techniques, including small-angle X-ray scattering (SAXS), X-ray diffraction(XRD), transmission electron microscopy (TEM), Fourier Transform Infrared(FTIR), pyridine-FTIR, nitrogen adsorption-desorption, UV–vis diffuse reflectance spectroscopy (DRS), Raman and X-ray photoelectron spectroscopy(XPS). The characterization results indicated that BF micro/mesoporous materials had the structures with both of the mesoporous FDU-12 materials and microporous Beta materials. Among the catalysts with different mass ratios of Beta/F127, CoMo/BFA2 catalyst showed the best comprehensive hydrofining performance with a hydrodesulfurization (HDS) efficiency of 98.1% and a hydrodenitrogenation (HDN) efficiency of 95.6% for FCC diesel, which was ascribed to the appropriately synergistic effect of pore properties and acid property. Furthermore, after the modification of ethylenediaminetetraacetic acid (EDTA) by the post-treatment method, the dispersibility of Mo species on the catalyst surface was significantly improved, which led to a better hydro-upgrading performance of FCC distillates, whereas gasoline desulfurization efficiency of 94.2% and octane loss of 0.8units, and diesel desulfurization efficiency of 99.0% and denitrification efficiency of 97.3%.

Simple Model for Predicting the Cutting Temperature between Light and Heavy Fractions in Fluid Catalytic Cracking Naphtha Selective Hydrodesulfurization Processes

In selective hydrodesulfurization processes for hydro-upgrading fluid catalytic cracking (FCC) naphtha with high olefin and sulfur contents, it is a common practice to split the feeding full-range FCC naphtha into a light fraction and a heavy fraction. This operation can effectively alleviate olefin saturation and thereby octane loss. Thus, the determination of a suitable cutting temperature plays a vital role in guaranteeing the success of the operation. Starting by fractionating two FCC naphthas into nine narrow cuts, this paper shows that, despite the great differences in the properties of the two FCC naphthas, both hydrocarbons and sulfides have almost the same distributions in the nine cuts. More importantly, it was observed that the distribution of sulfides in the narrow cuts is irrelevant to their true boiling points because of the formation of azeotropes between sulfides and hydrocarbons. On the basis of these findings, a simple model for estimating thiophene content in light FCC naphtha and, ther...

Multidimensional Reaction Control with Beta Type Zeolites in Heavy Oil Catalytic Cracking

Residual feeds to the RFCC process could be well upgraded by catalyst containing FAU (USY) zeolite with higher hydrogen transfer activity, resulting in lower bottom and higher gasoline yields. However, the hydrogen transfer reaction has been shown to have negative aspects among the various reaction elements occurring simultaneously in the catalytic cracking process, because octane loss or coke formation were accelerated in most cases of inappropriate application of catalysts. Multifunctional catalyst was developed by adding beta (*BEA) zeolite to RFCC catalyst, and resulted in improved octane number without sacrificing gasoline yield. Addition of *BEA zeolite to the RFCC catalyst maintained the octane number even in use of catalyst with high hydrogen transferring activity by further isomerizing single branched to multiple branched isoparaffins.

Detailed Kinetic Model for the Hydro-desulfurization of FCC Naphtha

A detailed kinetic model has been developed that describes the selective hydro-desulfurization chemistry of FCC naphtha at minimal olefin saturation. The FCC naphtha is represented by 348 molecular lumps measured by different gas-chromatographic methods. The reaction chemistry is specified in terms of reaction rules using the structure-oriented lumping (SOL) framework. A total of 15 reaction rules, which describe 444 individual reaction steps, have been used to model the governing chemistry. Relative reactivity relationships among different molecular lumps within the same rule have been derived using model feeds or established results from the literature. The kinetic parameters have been estimated from a comprehensive experimental data set comprising of both pilot plant and commercial refinery data spanning a wide range of process conditions and feed compositions. The kinetic model quantitatively predicts the product composition, product properties, extent of hydro-desulfurization, olefin saturation, and the associated octane loss. The modeling framework is generic to naphtha hydroprocessing technologies, and its specific application to the Selective CAtalytic Naphtha hydrofining (SCANfining) process, a proprietary technology of ExxonMobil, is demonstrated.

Effects of Acidic Properties on the Catalytic Performance of CoMo Sulfide Catalysts in Selective Hydrodesulfurization of Gasoline Fractions

Improvement of the selectivity of hydrodesulfurization (HDS) to hydrogenation (HYD) of olefins is crucial to produce sulfur-free gasoline (S < 10 ppm) from fluid catalytic-cracked (FCC) gasoline. CoMo/SiO 2 catalyst, which was less acidic than CoMo/Al 2 O 3 catalyst, showed higher HDS/HYD selectivity than CoMo/Al 2 O 3 catalyst under mild reaction conditions, although both HDS and HYD activities were lower for the former catalyst. However, under more severe reaction conditions, HDS/HYD selectivity over COMO/SiO 2 catalyst decreased to a significantly greater extent than that over CoMo/Al 2 O 3 catalyst. NO adsorption measurements indicated that the formation of coordinatively unsaturated sites (CUS) over CoMo sulfides was more dependent on the reaction severity over the SiO 2 supports. FT-IR data of adsorbed pyridine clearly showed that the strength of Lewis acidity over CUS, in particular, mainly formed under high-temperature conditions, was greater for CoMo/SiO 2 catalyst than for CoMo/Al 2 O 3 catalyst. These results suggest that strong Lewis acid sites over CUS promote a hydrocracking reaction in olefins: however, it is not more disadvantageous than HYD reactions in terms of octane loss. Controlling the Lewis acid properties over CoMo sulfides is effective in selective HDS of FCC gasoline, even when using nonacidic supports.

Study on highly hydrophilic cellulose hollow fiber membrane contactors for thiol sulfur removal

Dispersion-free reactive extraction of thiol compounds from high-sulfur-contained naphtha products into alkali solutions has been studied in a cellulose microporous hollow fiber membrane contactor. A steady extraction was achieved under a long-term operation of 1 month. The constant partition coefficient of thiol in an infinite dilution between the alkali solution and the oil phase was over 940. In addition, the effects of the tube and shell side hydrodynamics on the mass transfer were investigated. The results indicated that the mass transfer resistance in the oil phase boundary layer contributed to more than 95% of the overall mass transfer resistance, while the membrane resistance only accounted for 2% under the operating conditions. The mass transfer flux of thiol extracted from the real naphtha stream containing 883.4 μg g −1 of sulfur came to 2.40 × 10 −5 kg m −2 s −1, and the mass transfer coefficient reached 3.91 × 10 −5 m s −1. The removal efficiency was up to 99% with octane loss less than 3 mg L −1 when the liquid–liquid volume ratio was 1:1. Furthermore, it was also found that the oil phase flowing at the shell was favorable in fast extraction. A diagram predicting the performance of the contactor for the extraction of sulfur from real naphtha streams was established and the prediction showed a good agreement with the experimental data.

Hydrodesulfurization of cracked naphtha over zeolite-supported Ni-Mo-S catalysts

World-wide changes in clean gasoline requirements have recently increased the research work for reducing sulfur in cracked naphtha. In this work, the bifunctional catalyst Ni-Mo/HZSM-5 was prepared and was characterized by temperature-programmed desorption of NH 3 (NH 3-TPD), nitrogen adsorption (BET), FT-IR analysis with adsorbed pyridine as well as by X-ray powder diffraction analysis. NH 3-TPD shows the presence of strong acid sites at about 430 °C in HZSM-5 zeolite and the strong acid is weakened after the Ni-Mo incorporation. FT-IR analysis with adsorbed pyridine reveals that the L acid site in Ni-Mo/HZSM-5 enhances and the L and B acid sites in the inactive catalyst can be recovered by calcination at 500 °C. Hydrodesulfurization of the cracked naphtha was carried out in a 100 mL fixed bed flow reactor and the effects of hydrogen pressure and reaction temperature on the activity of the catalyst were studied. It was revealed that the octane loss with certain HDS% of the hydrotreated naphtha can be reduced greatly in the hydrotreating process over Ni-Mo/HZSM-5 by selecting proper hydrogen pressure, reaction temperature and the content of Ni-Mo in the catalyst.

Skeletal isomerization of light FCC naphtha

The factors affecting the age of olefin skeletal isomerization catalyst are investigated. Molecular sieves with different acid strength and distribution show different activity and stability. Weak and moderate acid centers are responsible for the skeletal isomerization of olefin (SIO) and strong acid sites catalyze dimerization and cracking reaction under the test conditions. The pore structure of molecular sieve influences the products distribution significantly in the skeletal isomerization of 1-hexene. Choosing suitable modification methods to diminish external surface acid center could reduce the influence of external surface coke on molecular sieve activity. Under the same olefin saturation level, the octane loss of light FCC naphtha decreases remarkably by SIO comparing with direct hydrogenation.