To address the critical challenge where the excessively high Minimum Miscibility Pressure (MMP) restricts the effectiveness of CO2 flooding, this study proposes a novel strategy utilizing SiO2-ethanol nanofluids (SiO2-C2H6O NFs) as additives to reduce the MMP. By systematically optimizing particle size, concentration, and dispersant types, a 5 nm/5 wt% SiO2 nanofluid with polyvinylpyrrolidone (PVP) as the dispersant was successfully prepared, demonstrating excellent long-term dispersion stability. Phase equilibrium experiments indicate that after adding 20 vol% of the optimized nanofluid into crude oil model components (n-alkanes and cycloalkanes), the solubility of CO2 in the oil phase is significantly enhanced. The maximum average equilibrium pressure reduction (P-AVG) reached 2.24 MPa, effectively lowering the MMP of the system. Furthermore, a modified PR-vdW1 equation of state considering nano-confinement effects was developed and validated to systematically reveal the phase equilibrium behavior of CO2-alkane systems within nanopores. This research not only enriches the fundamental thermodynamic data for CO2-hydrocarbon systems but also provides a novel and efficient technical pathway for improving CO2 flooding efficiency and achieving synergistic carbon emission reduction.

There are bottleneck problems in the binary replacement process of flue gas (CO2+N2), such as the decreased stability of the sediment layer of hydrates after replacement and the decline in replacement efficiency. This paper innovatively proposes a pathway for the replacement of natural gas hydrates by flue gas with the synergistic effect of C3H8. The study reveals that doping a trace amount of C3H8 (approximately 2% (mol)) can increase the dissociation enthalpy value of flue gas hydrates by nearly 20 kJ & centerdot;mol- 1. The crystal structure of the hydrates significantly transforms from the sI type to the sII type, which promotes the occupation of N2 molecules in the small cages (with an increase of about 5%). This leads to a reduction of the phase equilibrium conditions by 15% to 25% through molecular scale pressure sharing. C3H8 and N2 have a synergistic effect on the recovery of CH4 hydrates. Compared with the flue gas without C3H8 doping, the flue gas doped with 3.5% C3H8 can increase the CH4 recovery rate by approximately 4.5% and the N2 sequestration rate by about 5%, while maintaining a high CO2 sequestration rate. Since it is a surface reaction, doping an excessive amount of C3H8 (more than 5%) does not significantly improve the CH4 recovery rate. This study provides a new option for the design of engineering schemes and processes for the replacement-based exploitation of natural gas hydrates. (c) 2025 The Chemical Industry and Engineering Society of China, and Chemical Industry Press Co., Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

A novel process was developed by integrating supercritical CO2 (ScCO2) with precise thermal control to enhance the separation efficiency of azeotropic mixtures. By adjusting temperature and pressure, key ScCO2 properties such as density, solvent power, and viscosity were tuned to regulate the distribution of components between the solvent and ScCO2 phases. Vapor-liquid equilibrium data for six ternary systems were obtained using a constant-volume method (313.15-343.15 K). Based on phase equilibrium and component distribution analysis, four systems were identified as suitable: CO2-dimethyl carbonate-methanol, CO2-dimethyl carbonate-ethanol, CO2-toluene-methanol, and CO2-toluene-ethanol. An orthogonal experimental design was used to determine optimal conditions, yielding separation efficiencies of 97.88%, 98.05%, 98.06%, and 98.69%, respectively. These results offer theoretical support for improving ScCO2 separation technologies.

Conventional amine-based solvent CO 2 absorption faces the problems of high regeneration energy consumption and serious equipment corrosion. In this paper, a composite absorber with liquid-liquid phase change characteristics is innovatively proposed: a ternary system of AEEA/NHD/H 2 O. At the optimal operating temperature (313.15 K), the mass ratio of NHD to H 2 O is 10:10, and the concentration of AEEA is 15 wt.%, the CO 2 absorption capacity reaches 0.98 mol CO 2 /mol amine, and the proportion of rich-phase CO 2 is increased to 97.6%, and the solution viscosity is only 14.29 mPa·s. Compared with the traditional 30 wt.% MEA industrial absorbent, the absorption capacity of this system is increased by 121%, and the CO 2 desorption capacity was 0.79 mol CO 2 ·mol -1 amine by adding 5 mL of lean-phase solution and stirring for 33 min at the desorption temperature of 393.15 K. The regeneration efficiency reaches 60.93%, and the absorption capacity decreases by only 9% after five consecutive absorption-desorption cycles. The energy consumption of the system was stabilized at 2.37 GJ/t CO 2 , which was 38.4% lower than that of the 30 wt.% MEA system. This study provides a novel technical solution for industrial carbon capture with high efficiency and low consumption.

In this study, the crude oil used is sourced from Zhoucheng Joint Station of the Jiangsu Oilfield. To improve its demulsification performance, a polyether demulsifier, developed using tea polyphenol amine resin as the starting material, is designed based on the characteristics of the crude oil. It features a high molecular weight, strong structural stability, and a multi-branched structure, offering excellent demulsification performance. A series of diblock and triblock polyethers were synthesized via polymerization of ethylene oxide (EO) and propylene oxide (PO) using potassium hydroxide as a catalyst. The demulsifier’s performance was evaluated through dehydration tests and infrared spectroscopy to optimize the synthesis process of the triblock polyether demulsifier. The effects of dehydration time, temperature, dosage, pH and HLB on demulsification performance were investigated The optimal demulsification conditions were identified based on the dehydration rate. The results show that the synthesized demulsifier exhibits good performance for the crude oil used in this study, providing a reference for future demulsifiers research.

Hydrate-based CO2 sequestration is an effective method for reducing the greenhouse effect, and the presence of porous media and NaCl can impact the formation characteristics of hydrates. This study uses the constant volume temperature search method to investigate the effects of quartz sand particle size (0.006-0.03 mm), water saturation (30%- 90%), and NaCl concentration (1%-9%) on the phase equilibrium and kinetics of CO2 hydrates within a temperature range of 273-285 K and pressure range of 1.0-3.5 MPa. The results indicate that a decrease in quartz sand particle size or an increase in NaCl concentration shifts the hydrate phase equilibrium curve towards lower temperatures and higher pressures, making hydrate generation conditions more demanding. In different particle size systems, there are no significant changes in the rate of CO2 hydrate formation or conversion rate. The highest hydrate conversion rate of 71.1% is observed in a 0.015 mm particle size system. With increasing water saturation, both the generation rate and conversion rate of CO2 hydrates show a trend of first increasing and then decreasing. Meanwhile, low concentrations of NaCl (1%-3%) are found to enhance the formation and conversion rates of CO2 hydrates. However, as NaCl concentration increases, the rate of CO2 hydrate formation and conversion rate decrease.

Oil and water separation has always been a top priority in the oil industry. In this study, a series of hyperbranched fluorinated polyamine-amine polymers (HFPA1-5) were synthesized directly using an improved "one-pot method." The highly active fluorinated p-trifluoromethylaniline was used as the core raw material, while diethylenetriamine and methylacrylate were used as the chain segment. A hyperbranched fluorine-containing polyamine-amine demulsifier (NHFPA6) was obtained through nano-grafting copolymerization of HFPA5. To enhance the demulsification and dehydration performance, the copolymerized HFPA6 was modified and combined. Then, the effects of the combination ratio, demulsifier concentration,demulsification time, and demulsification temperature on the demulsification effect were investigated. The results revealed that a combination ratio of DE-401:NHFPA6=1:1, a demulsification temperature of 50 degrees C, a demulsification time of 60 min, and a demulsifier concentration of 150 mg/L yielded a dehydration rate as high as 99.80%. A response surface optimization design of demulsification conditions was performed. The model verified that the optimal demulsification conditions were 50 degrees C, 300 mg/L, and 90 min. However, considering the economic benefits of factories, it is more favorable to selectdemulsification conditions with a shorter time and lower concentration when the dehydration standard is met. Therefore,the demulsification conditions were selected as 50 degrees C, 150 mg/L, and 60 min. Compared to existing demulsifiers, the demulsifier developed in this study exhibits a lower demulsification temperature and higher demulsification efficiency. Key words:hyperbranched; fluorinated polyamine-amine; nano-SiO2

The use of hydrates to store CO2 is considered an effective method that can be implemented. However, the problems of interfacial hydrate film formation and low mass transfer efficiency when forming CO2 hydrate under static conditions still need to be solved. This study compared the growth modes of CH4 hydrate and CO2 hydrate under static conditions and believed that the wall-climbing growth mode of CH4 hydrate can be used to generate CO2 hydrate. It is proposed to use the residual shell of CH4 hydrate as a water-absorbing medium to change the mode in which CO2 hydrate is preferentially generated in the main body of the liquid phase. In this method, CO2 hydrate shows a faster formation rate and almost no induction time, which is attributed to the larger gas-liquid contact area provided by the shell, the residual ring in decomposed water on the surface, and the crystal structure inside the shell. When sodium dodecanoate (SD) is used as a promotor for CH4 hydrate to regenerate CO2 hydrate, the observation of the hydrate growth morphology shows that CO2 hydrate can grow on the CH4 hydrate shell. It does not have the wall climbing height of CH4 hydrate but grows toward the center of the reactor. When SDS is combined with SD to regenerate CO2 hydrate as an accelerator in the CH4 hydrate generation process, filamentous growth of CO2 hydrate can be observed.

Based on the MnOx/TiO2 catalyst prepared by the sol–gel method as the substrate, the impregnation method was used to simulate the deactivation process of the alkali metal K of the MnOx/TiO2 catalyst, and the regeneration experiment of the deactivated K–MnOx/TiO2 catalyst was carried out by water washing and acid washing. The effects of methods and process conditions on the regeneration effect of deactivated catalysts were discussed emphatically. The results show that the regeneration effect of acid washing on the deactivated catalyst is obviously better than that of water washing. Under the conditions of ultrasonic frequency of 30 kHz, HNO3 concentration of 0.3 mol l–1, acid washing for 45 min and calcination at 400°C for 4 h, the removal rate of NO by the catalyst can be recovered from 35 to 89

Excessive carbon dioxide (CO2) emissions can lead to environmental problems, and the use of phase change absorbents for CO2 capture has received much attention due to their excellent absorption and desorption properties. Herein, a novel liquid–liquid phase change absorbent consisting of N‐aminoethylpiperazine (AEP), diethylene glycol dimethyl ether (DEGDME), and H2O is utilized. Under the optimal absorption conditions, the absorption capacity is 1.23 mol CO2·mol−1 amine. The rich‐phase viscosity of the AEP/DEGDME/H2O solution is only 6.2 mPa s−1, and the rich phase‐to‐volume ratio is 52.7%, which is suitable for industrial applications. After five cycles of absorption–desorption experiments, the cyclic capacity reaches 0.62 mol CO2·mol−1 amine. However, it should be noted that this leads to an increase in the viscosity of the solution with time. The 13C Nuclear Magnetic Resonance characterization is used to analyze the material distribution and phase separation mechanism, and it is found that during the absorption process, the carbamate and carbonate products generated by the reaction of the amino group in the AEP with CO2 are mainly located in the rich phase, while the DEGDME and H2O mainly remain in the lean phase. In the desorption process, most of the absorbed products are decomposed, and the regeneration efficiency is 66.8%. Through the regeneration energy consumption experiment, when the regeneration efficiency is 56%–67%, the total regeneration energy consumption is 2.71–2.89 GJ t−1 CO2, which is 0.91–1.09 GJ t−1 CO2 lower than that of the regeneration efficiency of 30 wt% MEA solution at 63%, which indicates that this absorbent has certain energy‐saving advantages.

Mn/TiO2 catalysts exhibited more excellent activity and higher selectivity in low-temperature SCR of NOx with NH3. Alkali metal, particularly potassium presented in the ash, could severely deactivate SCR catalyst and then reduce its lifetime. In this study, sol-gel Mn/TiO2 catalyst was employed to evaluate its SCR activity with and without the presence of KNO3 at 100-300 degrees C. The influence of various parameters such as KNO3 loading amount, calcination time, temperature and catalyst deactivation was investigated. The characterization results indicated that the doping of potassium on Mn/TiO2 surface obviously resulted in a great decrease of reducibility, surface acidity and NH3 adsorption capacity. XPS spectra revealed the decrease of Mn4+ atomic concentration and chemisorbed oxygen species caused by potassium doping. In addition, obvious variation of potassium states (K1.04Ti8O16) was detected for K-Mn/TiO2 catalyst after calcining treatment, which may lead to a poorer performance of SCR catalyst.

Through the improved recycling and sampling mechanism, the new phase equilibrium data of CO2 in ethanol and alkanes were measured at the temperature of 313.15 K to 343.15 K and the pressure of 1.39 MPa to 13.51 MPa. Using modified hetero valence (S-i(r)). A new formula of molecular bond index is obtained, which is combined with the improved solubility semi empirical model to obtain a new solubility calculation model. The phase equilibrium data of CO2 in alcohol / alkane are substituted into the calculation model for primary correlation. The results show that the average relative deviation between the calculated and experimental values of alkanes is 7.23%, which is about 12% higher than the initial improved correlation results; The average relative deviation between the calculated value and the experimental value of alcohol is 6.12%, which is about 23% higher than the initial improvement value.

Supercritical CO2 (ScCO2) is widely used in the extraction of natural organic compounds because of its superior solubility and high selectivity. Thermal diffusion is a method of separating substances based on temperature gradient, which has been applied to the separation of isotopes. A new process for the separation of alcohol hydrocarbon azeotropes by supercritical CO2 and thermal diffusion coupling was proposed in this paper. Taking five binary azeotropic systems of ethanol-n-hexane, ethanol-n-heptane, isopropanol-n-hexane, isopropanol-nheptane and nonanol-n-dodecane as the research objects, the best process for separating alcohol hydrocarbon azeotropes by ScCO2 coupled thermal diffusion was explored. The results showed that the process can effectively separate the above five binary alcohol hydrocarbon mixture systems. The optimum process operating conditions were as follows: the separation time was 180 min, the separation pressure was >= 9 MPa, the temperature difference between the two walls was 70-80 ?, and when the separation effect of each system was greater than 90%, the continuous separation times of the system was ethanol-n-hexane for 3 times; Ethanol-n-heptane, 4 times; Isopropanol-n-hexane, 4 times; Isopropanol-n-heptane, 5 times.

A new green lubricating base oil was synthesized from soybean oil and triethyl silane by a combination of transesterification and hydrosilylation. The factors affecting the process of hydrosilylation were thoroughly investigated. AlCl 3 /C catalyst as catalyst for hydrosilylation showed better catalytic performance, and a higher yield of 36.79% was obtained under optimal condition of molar ratio of transesterified soybean oils/triethyl silane (1:1.1), reaction temperature 120°C, and reaction time 8 h. In addition, the performance of silicon-based soybean base oil was tested according to industry standards. Compared with soybean oil, silicon-based soybean base oil was obtained with high viscosity index, good pour point of −17°C, and excellent wear characteristic.

CO2气体水合物形成热力学性质是实施海水淡化、沼气纯化、碳捕集和封存、能源利用、天然气储存等技术的关键.采用恒容温度搜索法,在温度272.75～294.35 K,压力0.35～4.50 MPa的范围内,探究了四种季铵盐促进剂对CO2气体水合物相平衡的影响.结果表明,相同条件下,季铵盐作用下CO2水合物的相平衡温度由高到低分别为:四丁基氟化铵(TBAF)>四丁基溴化铵(TBAB)>四丁基氯化铵(TBAC)>苄基三乙基氯化铵(TEBAC).基于Clausius-Clapeyron方程,计算了不同体系的相变潜热,探讨了其对水合物稳定性的影响.可以看出,水合物的相平衡压力对数与温度倒数呈线性关系,其中,TBAF、TBAB作用下的CO2水合物相变潜热相接近且明显高于其他季铵盐,说明其促进效果最好,所对应的水合物生成条件也最为温和.利用Chen-Guo模型,结合PR状态方程和改进Joshi经验活度模型,分别计算了TBAF、TBAB、TBAC和TEBAC作用下CO2水合物热力学相平衡数据,计算结果与实验数据吻合良好,最大平均相对误差为7.50％.

Separation of oil and water has always been a top priority in the oil industry. In this study, bisphenol A phenolamine resin (BPA) was synthesized from bisphenol A, diethylenetriamine and formaldehyde. With KOH as a catalyst, the initiator, ethylene oxide (EO) and propylene oxide (PO) were polycondensed into triblock polyethers with different molecular weights, and then crosslinked to increase the molecular weight. The target product was determined by (HNMR)-H-1 and FT-IR, and the synthesis process of triblock polyether demulsifier was optimized by changing the ratio of initiator to head PO, PO to EO and head PO to tail PO. Then, the important influential factors for the demulsification such as the demulsifier concentration, standing time, temperature, pH and Hydrophile-lipophile balance (HLB) values were investigated. The results suggestted that the optimal synthesis ratio of BPA type triblock polyether demulsifier was as follows: initiator/PO = 1: 109, PO/EO = 2: 1, head PO/tail PO = 1: 3. Under demulsification conditions, the dehydration temperature was 50 degrees C, the dosage was 75 mg.L-1, pH was 7.6 and HLB was 9.1, and the dehydration rate reached 92.5% in 90 minutes. Compared with the existing demulsifier, the demulsifier has a lower demulsification temperature and higher demulsification efficiency. Therefore, it can be concluded that the polyether demulsifier has potential application for the crude oil dehydration, and the current work may be helpful to explore the demulsification development.

A new green lubricating base oil was synthesized from soybean oil and triethyl silane by a combination of transesterification and hydrosilylation. The factors affecting the process of hydrosilylation were thoroughly investigated. AlCl3/C catalyst as catalyst for hydrosilylation showed better catalytic performance, and a higher yield of 36.79% was obtained under optimal condition of molar ratio of transesterified soybean oils/triethyl silane (1:1.1), reaction temperature 120 degrees C, and reaction time 8 h. In addition, the performance of silicon-based soybean base oil was tested according to industry standards. Compared with soybean oil, silicon-based soybean base oil was obtained with high viscosity index, good pour point of -17 degrees C, and excellent wear characteristic.

Ethylene oxide (EO), 1,3-propylene oxide (PO), tetrahydrofuran (THF), 1,3-dioxolane (1.3-DX), 1,4-dioxane (1,4-DX) and 1,3,5-trioxane (s-TO) were selected to investigate their thermodynamic promotion effects on CO2 hydrate formation. New hydrate phase equilibrium data of carbon dioxide + epoxy heterocycles + water systems were determined employing an isochoric temperature-search method in the temperature range of (273.15 to 295.35) K and the pressure range of (0.4 to 4.5) MPa. Results showed that the presence of epoxy heterocycles significantly increased the hydrate formation temperature substantially compared with that of pure CO2 hydrate. Under the same conditions, the phase equilibrium temperature of CO2 hydrate under the action of the additive was from low to high: PO < 1,4-DX < 1,3-DX < s-TO < EO < THF. CO2 hydrate dissociation enthalpies with different epoxy heterocycles were also calculated from Clausius-Clapeyron equation to infer their stabilities and the structures formed. It was found that the estimated enthalpy of dissociation was consistent with the superiority sequence obtained from the phase equilibrium data, illustrating that the water-soluble sII clathrate former of THF had the highest hydrate promoting effect. Moreover, Chen-Guo model, associated with a modified Joshi empirical activity model and PR equation of state was proposed further to predict hydrate phase equilibrium. Satisfactory agreement was observed between predictions and experimental data. Analysis of the results confirmed that the proposed thermodynamic model worked well in describing phase behavior of complex hydrates and the maximum relative error of the pressure was less than 8.5%. (C) 2022 Elsevier B.V. All rights reserved.