Sodium-ion capacitors represent a novel class of energy storage device that integrates the respective advantages of sodium-ion batteries and electric double-layer capacitors. Nevertheless, the mismatch between the positive and negative electrode kinetics of sodium ion capacitors can lead to their low power density and poor cycling stability. Since the advent of single-atom catalysis, single-atom metals have garnered substantial attention in energy storage research due to their high atomic efficiency, exceptional catalytic activity, superior selectivity, and remarkable stability.Firstly, the challenges faced by electrode materials for sodium ion capacitors were elaborated, and the energy storage mechanism of sodium ion capacitors was analyzed. Secondly, the characteristics of single atom catalysts and the preparation methods of carbon supported metal single atom materials were introduced. Then, the application progress of metal monatomic materials in sodium ion capacitors was summarized. Finally, the application prospects of metal single atoms in sodium ion capacitors were discussed.
Betaine surfactants have been widely used as oil displacement agents for tertiary oil recovery due to their unique amphiphilic structure,high surface activity,low critical micelle concentration and good emulsification performance.To investigate the effect of alkyl carbon chain number on the chemical flooding performance of betaine surfactants,5 kinds of betaine solutions with alkyl carbon chain number (n) of 12,14,16,18 and 20 were selected,and their interfacial tension and emulsification properties were tested.The parameters of radial distribution,density distribution,mean azimuth shift,rotation radius and binding energy were analyzed by using MS software，and conducted indoor simulated oil displacement experiments.The results show that with the increase of the number of carbon atoms of long alkyl chain,the oil displacement performance of surfactants was first enhanced and then weakened,and the chemical displacement performance of C16HBC surfactants in betaine was the best.The effects of betaine solution with different alkyl carbon chain number on its energy,radial distribution,density distribution, mean orientation shift, binding energy and other parameters were determined by molecular simulation studies.Simulation oil displacement experiments verified that C16HBC surfactant could significantly improve oil recovery by 20.7%.
The study of the environmental hazards of chemical gas pipeline rupture is of great significance to the design of explosion prevention measures and the development of emergency response programs. Taking a typical overhead gas pipeline as the research object, the environmental hazards of the whole process of natural gas leakage diffusion, jet fire, vapor cloud flash fire and explosion accident development were analyzed. The results show that when designing explosion-proof measures and formulating emergency plans, the explosion risk area should be calculated according to the low wind speed. Natural gas leakage mainly affects the chemical park B area, office buildings A， B， C, street stores A. The downwind direction of the occurrence of jet fire accident 8.7~76.1 m is a high-risk area, affecting the area of the chemical park B area, office buildings B and the street stores A. The area affected by the vapor cloud flash fire is Chemical Park B, Chemical Park A, Office Buildings A, B, C, D, Street Shops A, Residential Area A, the main road and the edge of the Science and Technology Park, so the area should be evacuated in advance of the fire. Natural gas explosion damage area is downwind -47.1~67.2 m, mainly affecting the chemical park B, chemical park A, office buildings B, street stores A, residential neighborhoods A.
The carboxyl nitrile hard glue wastewater contains raw materials, by-products and some auxiliary materials that are not fully involved in the reaction, and has the characteristics of high chemical oxygen demand (COD), high mass concentration of Pull apart powder（BX）, high viscosity and toxicity, resulting in the poor operation of the water treatment process. The pretreatment process with "air flotation, membrane separation and ozone oxidation" as the core was adopted to remove COD and decoking powder from carboxyl nitrile hard adhesive wastewater, so as to improve the biodegradability of wastewater. This pretreatment process had problems such as rubber caking and blocking, filter device blocking and so on, and the overall operation effect was poor. The pretreatment process was improved by increasing the influent flow rate to 105 m3/h, increasing the chemical backwash time and backwash frequency, adjusting the ozone quality concentration to 35 mg/L, and decreasing the height of the packing layer of the ozone catalyst layer to 650 mm. The results show that when the effluent COD is stable at about 1 100 mg/L, the mass concentration of BX is maintained at about 40 mg/L, and BOD/COD (BOD is the ratio of biological oxygen demand) is about 0.30, the influent conditions of the subsequent process can be met, and the stable operation of the system can be ensured.
CO2 geological storage is one of the most important means to mitigate the greenhouse effect.The safety of CO2 securely stored in underground reservoirs largely depends on the mechanical integrity of the caprock.This paper establishes a coupled fluid-solid model for CO2 geological storage to study the changes in pore pressure,vertical displacement,and effective stress in the caprock during the CO2 injection process.It analyzes the effects of CO2 injection rate,caprock elastic parameters,and geostress factors on the occurrence of tensile and shear failures in the caprock.The results indicate that,at the initial stage of CO2 injection, changes in pore pressure,vertical displacement,and effective stress at the bottom of the cap near the injection well are significant but gradually stabilize thereafter.The area near the injection well is considered the most critical part of the caprock,where the risk of mechanical failure is greatest.During the CO2 injection process,the injection rate and geostress factors have the most significant impact on the occurrence of mechanical failures in the caprock.The findings of this study provide a theoretical basis for assessing the long-term stability and safety of CO2 geological storage systems.
With the rapid growth of natural gas demand, there is an urgent need to consider the production, supply, storage and marketing structure of natural gas pipeline network, optimize the natural gas sub-customer sales scheme based on system analysis and decision-making theory, and maximize the profitability and economic benefits. With the objective of maximizing the annual total benefit of the natural gas sales pipeline network of the provincial company, taking the gas supply volume from the gas source, the pipeline transmission volume, and the sales volume of the customers as the decision-making variables, and taking into account the node flow balance constraints, the upper and lower limits of the gas volume of the production, supply, storage, and marketing links, the total sales volume of the sub-province constraints, etc., we optimize the gas procurement costs, pipeline costs, storage and transfer costs of storage reservoirs and LNG receiving stations and the customer sales revenues of the gas supply network of the industry chain in the upstream, midstream, and downstream segments. The customer sales revenue adopts the step pricing method, establishes the mathematical model of natural gas customer sales volume optimization, and selects GUROBI solver as the optimization calculation tool to solve the model. The model is tested on the basis of basic data of natural gas pipeline network of a province in the next 10 years to maximize the benefits while meeting the customers' natural gas demand, which verifies the reasonableness and accuracy of the model, and provides advanced analytical tools and technical methods for improving the quality and increasing the efficiency of the natural gas sales business.
In the process of crude oil gathering and transportation,the use of gas or electric energy at the wellhead for its heating and viscosity reduction is prone to cause a large amount of energy consumption and environmental pollution.Solar photovoltaic technology is an efficient and clean new energy technology coupling this technology with thermal storage technology can circumvent the shortcomings of solar energy instability,meet the needs of crude oil viscosity reduction and fixed heating,reduce the consumption of electric energy,and contribute to the carbon peak and carbon neutrality goal.A wellhead crude oil heating system based on thermal energy storage device (TES) and flat-plate solar collector (FPC) is studied,and FPC and crude oil heater in the system are designed and selected.Taking Shengli oilfield as the application scenario of the system,we analyzed and calculated the solar irradiation resources and the heating demand of crude oil at the wellheads in the winter half year (October to March),and reasonably configured the FPC with a heat collection area of 152 m2 and the 17~20 m3 hot and cold water tanks,and gave the operation scheme of the system under different irradiation amounts.The results show that the system can warm up the oilfield wellhead extractive fluid by 25 ℃,work continuously for 24 h per day,reduce carbon dioxide emission by 54.25 t in winter and half a year,and save operation cost by 53 000 yuan,which has good energy-saving and emission reduction benefits and economic benefits.
The authors used a bifunctional reducing agent containing degradable groups and oxidized metal ions as a redox agent to initiate free radical polymerization and synthesize a polymer damper to build degradable groups on the vinyl polymer backbone. The results showed that the azo groups were degradable under high temperature and also had high hydrolytic stability. The degradation behavior of polymeric drag reducers containing temperature-sensitive azo groups was characterized by gel permeation chromatography (GPC), which demonstrated that the polymer backbone contained multiple unstable bonds. It was also found that the drag reducers with azo bonds on the polymer main chain had as good drag reducer properties as the pure drag reducers. However, those with azo bonds in the main chain will lose their damping performance once subjected to high temperatures. This study provides a reference for the selection of low-injury multifunctional slickwater fracturing fluid systems suitable for shale gas reservoirs.
Based on density-functional theory (DFT) and wave function analysis procedures, the optical and molecular absorption properties of two structurally different pentacyclooxonium salt molecules have been investigated, and the physical mechanism of the formation of a built-in electric field due to orbital polarization caused by structural distortions, which induces charge transfer and leads to a nonlinear optical spectrum, has been explored.The properties result from the orbital polarization-induced built-in electric field driving charge transfer due to structural distortion. Theoretical analysis of ultraviolet-visible absorption spectroscopy (UV-vis) spectra is first performed to investigate the optical properties. The electronic excitation characteristics of the built-in electric field-driven charge transfer in molecules are analyzed in detail by transition density matrix (TDM) and charge differential density (CDD). Combining transition electric dipole moment density (TEDM) and transition magnetic dipole moment density (TMDM) analysis, the physical mechanism of the structure-induced chirality in their electronic circular dichroism (ECD) spectra is revealed. The results can provide theoretical references for the preparation of novel chiral materials as well as the research and development of optoelectronic materials and their practical applications.
In the face of the increasingly serious energy crisis and environmental pollution,it is important to develop durable and efficient photocatalytic materials for hydrogen production from water splitting.The MXene@TiO2 of high-performance MXene-based photocatalytic materials (M@T) is synthesized by a one-step hydrothermal method at 160 ℃ using Ti3C2 as the titanium source and TiO2@Ti3C2 derivatives synthesized by a one-step hydrothermal method.Co-MoS2-x O y (C-M) is prepared by sodium molybdate dihydrate (Na2MoO4·2H2O) as molybdenum source,CH3CSNH2 as sulfur source,and cobalt nitrate hexahydrate (Co(NO3)2?6H2O) as cobalt source.M@T/C-M composites are prepared at the ratios of m(M@T)/m(C-M) of 1∶1,1∶2,1∶3 and 1∶4.The structure and surface morphology of different composite systems are characterized by XRD,SEM,XPS,UV-vis,etc.At the same time,the photocatalytic degradation of methylene blue (MB),an organic pollutant in water,is tested by using xenon lamp as the light source.The results show that the M@T/C-M composites are successfully synthesized,and the light absorption range is increased to the visible region.The degradation rate of M@T/C-M(1∶3) in 20 mg/L MB solution is as high as 92.6%.The photodegradation of MB by M@T/C-M photocatalyst is mainly driven by ?OH and ?O
