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Table of Content

    30 December 2022, Volume 24 Issue 4
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    2022, 24(4):  0. 
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    Content of this issue.
    Scientific Research
    A chemical kinetic perspective on the high-temperature oxidation of methane/propane through experiments and kinetic analysis
    Ma Shoutao, Yang Zhe, Zhu Yunfeng, Sun Bing, Jiang Jie, Xu Wei, Meng Ruiji
    2022, 24(4):  1-11. 
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    In the conversion of methane and propane under high temperature and pressure, the ignition delay time is a key parameter to consider for the inherent safer design of process. In this manuscript, the ignition delay time characteristics of methane and propane (700k~1000K, 10 and 20bar) were studied by means of experiments and kinetic modeling tools in the stoichiometric ratio of fuel to oxygen. All the experimental data are designed by isentropic compression and adiabatic core to meet the reliable experimental data which can be used to generate and verify the detailed chemical kinetic model. The ignition delay time of methane and propane was recorded by rapid compression machine (RCM) and compared to the predicted data obtained by NUIGMech 3.0 mechanism. To test the applicability of NUIGMech 3.0 mechanism under different reaction conditions, the influence of temperature over the range of 700K to 1000K (and the influence of pressure over the range of 10bar to 20bar) on ignition delay time was studied. The results show that NUIGMech 3.0 mechanism can reasonably reproduce the ignition delay time of the experiment under a wide range of conditions studied. The constant volume model of chemical kinetic mechanism was used to reveal the effect of temperature on the elementary reaction, and the negative temperature coefficient (NTC) behavior of propane was also found at the pressure of 20 bar. The experimental data can provide a reference for the correction and application of kinetic data, and also provide a theoretical basis for the safe conversion of low-carbon hydrocarbon chemicals.
    Mechanistic Insights into the Catalytic Cracking of Cyclohexane
    Chen Hui, Yan Jiasong, Su Youyou, Wei Xueer, Li Rui, Wang Peng, Yu Shanqing, Dai Zhenyu
    2022, 24(4):  12-20. 
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    Although naphthenes have long been identified as important feedstock components for the production of light olefins and aromatics in fluid catalytic cracking units, their cacking mechanism and microscopic reaction networks, such as activation modes, ring-opening paths, and aromatization production, remain debated. In this context, we reported experimental and computational work aimed at elucidating the reaction network of naphthenes in fluid catalytic cracking using cyclohexane as the model naphthene. First, the main reactions for the formation of highly selective and value-added products such as light olefins and aromatics were discussed. Then, the proportions of cyclohexane activation via (i) the non-classical carbonium mechanism and (ii) the classical carbenium mechanism were analyzed by data fitting methods, which revealed that around 32.6% of cyclohexane was initiated by path (i), and the remaining naphthene was activated by path (ii). Moreover, our DFT results showed that the ring opening of cyclohexane through pathway (i) was more difficult than that through path (ii), and ring opening followed by the ring contraction of cyclohexane carbenium ions was the most energetically favorable route among the different ring-opening ways.
    Effect of Intermolecular Interaction on Stability of Asphaltene–Hydrogen Donor System
    Sun Yudong, Li Maolin, Liu Ziyuan, Xiao Shengyu
    2022, 24(4):  21-28. 
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    The stability of three ASP-HD system including Asphaltene-1-methylnaphthalene, Asphaltene-tetralin and Asphaltene-decalin with the mass ratio of 1:10 was investigated by Turbiscan stability analyzer. The interaction between hydrogen donor molecules and asphaltene unit was simulated and calculated by Gaussian and Multiwfn, and then NCI analysis was performed. The result shows that the stability sequence of the three ASP-HD system was as follows: asphaltene-(1-methylnaphthalene) system, asphaltene-tetralin system and asphaltene-decalin system. The main reason for the stability difference of the three systems is that the interaction between hydrogen donor molecules and asphaltene unit is different. T-stacking interaction strength between the hydrogen donor molecules and the asphaltene unit is decreased in the following sequences: (1-methylnaphthalene)-asphaltene unit, tetralin-asphaltene unit, decalin-asphaltene unit. Qualitative analysis showes that the T-stacking interaction between hydrogen donor molecules and asphaltene unit is mainly van der Waals force, but the proportion of hydrogen bonds in the weak interaction is different.
    Hydrogenation Behavior of Hydrogen Peroxide in a Microreactor
    Zhu Hongwei, Sun Bing, Jin Yan, Feng Junjie, Zhao Chenyang, Yan Junjie, Jiang Jie, Xu Wei
    2022, 24(4):  29-35. 
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    The hydrogenation of hydrogen peroxide is an unwanted side reaction in the direct synthesis of hydrogen peroxide and remains a problem to solve. The mechanism of this reaction has been studied with batch reactors but the slow heat and mass transfer in batch reactors hindered the understanding of its intrinsic kinetics. In this study, a microreactor is employed to investigate the parameters that influence the hydrogenation reaction, including flow rate, channel length, hydrogen pressure, solvent composition, and initial hydrogen peroxide concentration. The activity of different catalysts was compared and the hydrogenation law was confirmed, providing guiding information to better control the hydrogenation process.
    Preparation of a TiO2@o-Vanillin@TEOS-APTES Nanocontainer and Its Anti-Corrosion Performance on Steel
    Wu Yaqi, Xing Jinjuan, Qian Jianhua, Liu Lin
    2022, 24(4):  36-50. 
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    A TiO2@o-vanillin@TEOS-APTES nanocontainer was prepared by an experimental process in which, first, 2-hydroxy-3-methoxybenzaldehyde (o-vanillin) was loaded in a TiO2 container to obtain TiO2@o-vanillin. Then, TiO2@o-vanillin was encapsulated by tetraethyl orthosilicate (TEOS). Finally, 3-aminopropyl triethoxysilane (APTES) was used to modify the obtained sample. The morphology, structural phase and thermal stability of the TiO2@o-vanillin@TEOS-APTES nanocontainer were analyzed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD) and thermal gravimetric analysis (TG). The release rate of o-vanillin was investigated using an ultraviolet-visible (UV-vis) spectrometer. The anti-corrosion performances of the epoxy, epoxy@o-vanillin and epoxy@TiO2@o-vanillin@TEOS-APTES coatings on steel sheets were evaluated using an electrochemical method and scarification experiments. The results showed that the impedance value of the epoxy@TiO2@o-vanillin@TEOS-APTES coating was two orders of magnitude higher than that of the blank epoxy coating, and one order of magnitude higher than that of the epoxy@o-vanillin coating. The maximum inhibition rate of the epoxy@TiO2@o-vanillin@TEOS-APTES coating on the steel can reach 97.3%. The scarification experiments confirmed that the epoxy@TiO2@o-vanillin@TEOS-APTES coating had the best anti-corrosion performance.
    Influence of Oil and Water Components on Wall-sticking Occurrence Temperature in High Water-cut Crude Oil Pipeline
    Cheng Xianwen, Huang Qiyu, Wang Kun, Cui Yue, Hei Shunan, Yu Le
    2022, 24(4):  51-63. 
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    To study the wall-sticking phenomenon and prevent pipeline blockage accidents, two analytical methods are used to evaluate the influence of different crude oil components on the wall-sticking occurrence temperature (WSOT). The WSOT and the interactions among oil, water, and surface solids are measured and calculated by various devices under different values of the wax content, water pH, and salinity. The results show that there is greater correlation between the wax content and WSOT than between resins/asphaltenes and WSOT. Furthermore, the wax content, water pH, and salinity have different effects on WSOT. There is generally a positive correlation between wax content and WSOT, whereas the maximum WSOT occurs when the water pH is in the range 5.7 – 6.5, and decreases under more acidic or alkaline conditions. As the salinity increases, WSOT decreases slightly, but quickly becomes saturated. In terms of interactions, variations in the interfacial tension and adhesion work with pH and salinity are consistent with that of WSOT, while the contact angle exhibits the opposite relation.
    Process Research
    Optimized Process and Design: Incomplete Combustion in FCC Regenerators to Produce CO
    Yi Cai, Li Shiyu, Liu Zhiqiang
    2022, 24(4):  64-75. 
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    The catalyst regeneration process running under the partial oxidation mode in traditional fluid catalytic cracking (FCC) units needs a carbon monoxide (CO) boiler to burn the flue gas, resulting in a large volume of CO2 emissions. In this study, the performance of a set of industrial serial-type FCC regenerators and the changes in flue gas composition were analyzed by establishing a model of the regenerators and the flue gas energy recovery section. Considering the value of utilizing CO, based on the simulation, this paper proposes two schemes for maximizing CO content in the flue gas of regenerators. The two sets of optimal process operating parameters were obtained using a genetic algorithm. Compared with the original process, the CO contents of flue gas in the two optimized processes increased to 6.6% and 12.5%, CO2 emissions were reduced by 48.4% and 96.7%, and the costs of CO production were 0.57 $/Nm3 and 0.84 $/Nm3, respectively.
    Diffusion Characteristics and Removal of Cyclohexane in Polyolefin Elastomer Melt
    Qi Jibing, Yang Tong, Liu Yandong, Yuan Zhiguo, Zhang Qiaoling, Liu Youzhi, Yi Jianjun
    2022, 24(4):  76-85. 
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    Diffusion coefficient of volatiles in polymer solutions is a crucial parameter to describe the mass transfer efficiency and ability of volatiles. In this research, polyolefin elastomer (POE) was used as polymer, and cyclohexane was used as volatiles, the gravimetric analysis was applied to measure the diffusion coefficient of cyclohexane in POE. The devolatilization rate of POE-cyclohexane system under different conditions was measured. The effects of temperature, film sample thickness and initial concentration of volatiles on the devolatilization rate were discussed. Based on the devolatilization rate data, the average diffusion coefficient of cyclohexane in POE was obtained by fitting with the mathematical model. Experimental results indicate that the devolatilization rate increased with increasing temperature and initial concentration of volatiles, but decreased with increasing thickness of sample. With the thickness increases, the overall diffusion resistance increases. With the temperature increases, the molecular movement increases, resulting in the increase of average diffusion coefficient. The diffusion coefficient of POE-cyclohexane system with temperature follows the Arrhenius law. The diffusion activation energy E=6201.73 J·mol-1, and the pre-exponential factor of the diffusion coefficient D0=2.64×10-10 m2/s. This work can provide basic data for exploring the devolatilization of POE polymer, and provide a useful reference for enhancing the effect of devolatilization.
    Removal of Basic and Non-Basic Nitrogen Compounds from Model Oil by FeCl3-Based Ionic Liquids
    Li Wenshen, Liu Jie
    2022, 24(4):  86-92. 
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    FeCl3-based ionic liquids (ILs) with lower viscosity, prepared from the interaction of anhydrous FeCl3 and alkyl imidazolium bromide ([1-alkyl-3-methyl-imidazolium]Br, alkyl=ethyl, butyl, hexyl, octyl), were highly effective for denitrogenation of model oil containing quinoline or indole. The results showed that the chain length of the alkyl group on the imidazolium cation had no noticeable influence on the N-extraction efficiency. With the selected IL [Bmim]Br/FeCl3, up to 99.1% N-extraction efficiency of quinoline can be attained at extraction temperature of 30 ℃, IL/oil mass ratio of 1/7 and extraction time of 30 min, and indole extraction efficiency can also reach 98.9% by increasing the mass ratio of IL/oil to 1:1. Moreover, the extraction efficiency of quinoline can still reach 92.3% after four recycles of the IL.
    Selection of Extraction Solvents for Bitumen from Indonesian Oil Sands through Solubility Parameters
    Cui Wenlong, Zhu Qingqing, Zhao Chenze, Wang Cheli
    2022, 24(4):  93-97. 
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    Indonesian oil sands were separated systematically to investigate the basic composition. Based on this, the extraction effects of solvents with different Hilderbrand solubility parameter (HSP) on bitumen of Indonesian oil sands were compared. Furthermore, the Hansen solubility combination parameter (HSCP) and the Teas triangle were used to explore the rules that could be followed in the separation of oil sands bitumen by solvent extraction. Finally, the SARA fractions of bitumen from Indonesian oil sands were analyzed. The results showed that Indonesian oil sand was oil-wet with bitumen content of 24.93 %. The extraction solvents for bitumen could be selected accurately and conveniently based on the solubility parameter. When the HSPs of the extraction solvent were about 18~19, and the HSCPs were closer to a certain range (=17.5~18.0, =1~3.5, =2~6), the extraction effect of bitumen from Indonesian oil sands was better, and the main component affecting the extraction rate of bitumen were asphaltenes.
    Synthesis of Hierarchical Porous Fe2O3/Al2O3 Materials and Study on Catalytic Viscosity Reduction of Heavy Oil
    Wu Peiyue, Ma Zhaofei, Yang Haiyang, Xiong Pan, Tan Dichen, Yan Xuemin
    2022, 24(4):  98-107. 
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    Fe2O3 nanoparticles were dispersed in the sol solution containing the aluminum component by the prophase doping method, then the composite catalyst hierarchical porous Fe2O3/Al2O3 materials (HPFA) were synthesized through a sol-gel method and phase separation via phase separation method. The performance of HPFA were compared with that of Fe2O3 nanoparticle catalyst. The structure of the composite catalyst was characterized by SEM, XRD and N2 adsorption and desorption. The results show that Fe2O3 nanoparticles could be loaded on porous skeletons to achieve uniform dispersion, avoid agglomeration, and improve the mechanical strength of porous materials significantly. The HPFA were then used as a hydrothermal cracking catalyst in the viscosity reduction process of Tuha thick oil, and the viscosity reduction was investigated. The viscosity reduction rate of HPFA was 81%, which was better than that of Fe2O3 nanoparticles (56%) and hierarchical porous Al2O3 materials (47%).
    Activated Carbon from Rice Husk with One-Step KOH Mechanical Mixing Activation as Adsorbent for Treating Phenolic Wastewater#br#
    Jiang Bolong, Jiang Nan, Shi Shunjie, Cui Yanyan
    2022, 24(4):  108-119. 
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    Phenolic compounds are highly toxic to human beings and harmful to the environment. The aim of this study was to obtain large surface area biocarbons with high phenolic adsorption capacities from cheap and abundant rice husk (RH). For this purpose, the directly mixing of the KOH with RH and activating in flowing N2 atmosphere, namely one-step KOH mechanical mixing activation method was adopted and the effect of the pyrolysis temperature and KOH to RH ratio (x) on the structure of the obtained activated carbon (AC-T-x) adsorbents (T refers the activation temperature of RH in oC) and their adsorptive performances of p-nitrophenol and phenol were studied. The result showed that the optimum pyrolysis temperature of RH was 750 oC. The highest surface area of 2047 m2·g-1 and best adsorption performance were obtained with AC-750-3 prepared with KOH to RH ratio of 3:1. Moreover, it exhibited a maximum adsorption capacity of 175 mg·g-1 for phenol and 430 mg·g-1 for p-nitrophenol, which are higher than most of the reported data. The above results showed that the one-step KOH mechanical mixing activation method is a promising method for RH activation. The adsorption kinetics fitted well with pseudo-second-order model and adsorption isotherms matched the Langmiur model, indicating a monolayer adsorption behavior. The adsorption of phenolic compounds follows mainly the π-π interaction, H-bond mechanisms and hydrophobic interaction.
    Synthesis and Evaluation of Microporous Metal Organic Frameworks for Light Hydrocarbon Adsorption
    Wen Guilin, Li Ying, Li Jianzhe, Li Qingrun, Zhang Hongxing, Xiao Anshan, Tao Bin
    2022, 24(4):  120-128. 
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    Five microporous MOFs were synthesized and their static adsorption properties for light hydrocarbons were experimentally investigated at 298 K and 150 kPa. Among the five MOFs, HKUST-1 and Ni(bdc)(ted)0.5 exhibited much higher uptakes of ethane and propane than PCN-250, UiO-66, and ZIF-8. Breakthrough experiments were carried out at 298 K and atmospheric pressure on HKUST-1 and two commercially used adsorbents. HKUST-1 exhibited a much lower dynamic than static adsorption capacity. Moreover, HKUST-1 and the two traditional adsorbents could effectively separate binary (ethane/propane) and ternary (ethane/propane/toluene) mixtures.
    Simulation and Optimization
    New Model for Calculating Hydrogen Consumption in Residue Hydrotreating
    Zhang Kui, Nie Hong, Dai Lishun
    2022, 24(4):  129-138. 
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    In the paper, HDCH reaction was employed to simulate the hydrogen consumption during the residue hydrotreating, because the pseudo components- CH and CH2 can be converted with the content of C and H. Through the pilot-scale experiment, the kinetic model of HDCH reaction was constructed and it has high accuracy. By analyzing the running data of industrial residue-hydrotreating unit, the activity change of HDCH reaction was obtained by using the active-region-migration deactivation model. The obtained HDCH activity model has high accuracy that the frequencies of >10% relative errors are less than 1% for CH and H contents. The hydrogen consumption model, the coupling of the HDCH kinetic model and HDCH deactivation model, can be applied to calculate the hydrogen consumption. By adjusting the hydrogen consumption model every 100 days in case 2, the calculated data can match well with the real data when comparing with case 1.
    Effect of Particle Shape on Catalyst Deactivation during 2-Butene and Isobutane Alkylation of Liquid Phase in Fixed-Bed Reactor Using Particle-Resolved CFD Simulation
    Zhang Sizhen, Zhu Zhenxing, Xin Feng, Chu Menghan
    2022, 24(4):  139-150. 
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    How catalyst shape affects its deactivation is a crucial issue for quickly decaying catalysts such as zeolite in 2-butene and isobutane alkylation. In this work, steady simulations are used to determine the temperature and species distribution in fixed beds filled with particles of four shapes. Subsequently, unsteady simulations are used to study the deactivation behavior of the catalysts based on the steady simulation results. We describe the deactivation rate and type of catalyst deactivation by defining a local internal diffusivity, which is affected by catalytic activity. The results reveal that the internal diffusion distance of the catalyst determines the deactivation rate, whereas the local internal diffusivity determines its deactivation type.
    Experimental and Numerical Investigation on Erosion Corrosion of the Air Cooler Tube Bundle in a Residue Hydrotreating Unit
    Jin Haozhe, Yu Chenyang, Gu Youjie, Qian Guangwei, Liu Xiaofei, Ou Guofu, Jia Yongna
    2022, 24(4):  151-162. 
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    Corrosion leakage occurred in the 14th tube bundle of the first row in residual oil hydrotreating air cooler after operating for two years. The failure location was 0.5m away from the outlet header box. In this paper, the erosion-corrosion of the air cooler tube bundle was investigated by experimental and numerical method. Visual inspection, SEM and XRD test were performed, and the failure morphology and material composition proved the damage was caused by erosion-corrosion. SST k-w turbulence model was used to investigate the flow and erosion-corrosion characteristic combined with mass transfer, corrosion rate and ionization equilibrium model. Numerical simulation results show that the increase of water phase volume fraction result in the mass flow rate and concentration of hydrogen sulfide in the process of flow and heat transfer. The mass transfer coefficient and corrosion rate is an important parameter to characterize, and the local concentration of wall shear stress rises the risk of erosion-corrosion. The predicted high-risk area is consistent with the actual failure area, which proved that this failure incident is attributed to the erosion-corrosion in the water phase.