Excessive CO2 emission caused by a large number of human activities is the main cause of global warming,so a method to effectively control the increase in CO2 concentration is urgently needed.Currently,direct air capture is the only technology capable of achieving negative growth of carbon emissions on a large scale.Solid amine adsorbents,especially silicon?based ones, have been widely studied and used to capture CO2 from ambient air due to their advantages of high adsorption capacity,corrosion resistance,and low energy consumption.In this paper,silicon?based solid amine adsorbents were classified according to the mode of loading,and the influence of different silicon?based supports on the adsorbent performance was summarized.At the same time,the problems encountered in the industrial application of powdered solid amine adsorbents were put forward,and the current forming methods of solid amine adsorbents were sorted out.Finally,it is pointed out that the development of formed solid amine adsorbents with high adsorption capacity and high stability is the future trend of CO2 adsorbent industrialization.
The adsorption data of hydrogen in graphene,single?walled carbon nanotubes,and multi?walled carbon nanotubes at 293.15 K and 101.30 kPa were measured experimentally.Through the comparison of the data calculated by different force fields under the same conditions, the optimal force fields of the three carbon materials for calculation were selected.On this basis,the hydrogen adsorption data of the three carbon materials at 0~1 000.00 kPa and 77.00~573.15 K were calculated.The results show that the Dreiding force field is the optimal force field to calculate the hydrogen adsorption and storage in graphene,and the Universal force field is the best force field to calculate that in carbon nanotubes.Under given conditions,the hydrogen adsorption and storage capacity of the three materials is ranked as follows:graphene single?walled carbon nanotubes multi?walled carbon nanotubes.The hydrogen storage capacity is closely related to the specific surface area of the material and its weak binding force with hydrogen.The results can provide data and theoretical support for the molecular simulation of hydrogen adsorption and storage in carbon materials as well as hydrogen storage material design.
Under the national strategy of carbon peak and carbon neutrality in China,utilizing CO2 for enhanced oil recovery becomes an important means of CO2 storage in oilfields. However, there are still challenges in the safe storage and transportation of liquid CO2,in which gas impurities have a great influence on the thermodynamic properties of liquid CO2.Seven common gas impurities were determined by the analysis of CO2 samples obtained in the field,and the changes in physical properties of the CO2 samples containing impurities were simulated by HYSYS and the molecular dynamics simulation method.The physical property diagrams were plotted and compared with those of pure CO2.The results reveal that all seven impurities can enlarge the gas?liquid coexisting region in CO2 phase diagrams,but the enlargement extent differs. The impurities mainly expand the gas?liquid coexisting region by changing the bubble point line,while the dew point line has little change.It is found by molecular dynamics simulation that the electrostatic potential energy plays a dominant role in the CO2 mixture containing C2H6,C3H8,and C2H4.Therefore,compared with the results of the mixture containing H2,CO,CH4,and carbonyl sulfur (OCS),its macroscopic physical properties are less affected by temperature and pressure fluctuations.
In order to study the influences of swing, H2O and N2 on the removal of CO2 from offshore natural gas by adsorption and purification, dynamic penetration experiments of mixed multi?component gas in the dry and aqueous 13X zeolites under static and swing conditions were carried out. Mixtures of CH4/ CO2 and CH4/ CO2/ N2 were obtained by matching CH4, CO2, and N2 in proportion through a mass spectrometer. In addition, under static and swing conditions, the partial pressure of each gas in the mixtures at the exit of the dry and aqueous 13X zeolites at different time was measured during dynamic penetration experiments, and the penetration curve and penetration time were obtained. The adsorption and purification effect of CO2 in the two mixtures in the dry and aqueous 13X zeolites under the two conditions was analyzed according to the penetration time, and then the influences of swing, H2O and N2 on the removal of CO2 from offshore natural gas by adsorption and purification were clarified. The experimental results show that 13X zeolites have the strongest capacity in absorbing CO2 and the weakest capacity in absorbing N2 under static or swing conditions. N2 is conducive to the removal of CO2 from offshore natural gas by adsorption and purification, while the swing and H2O fail to do so.
A deep eutectic solvent was synthesized by the stirring method with Br?nsted acid (carboxylic acid) and Lews acid (ferric chloride) as raw materials. It was then analyzed with a Fourier transform infrared (FTIR) spectrometer. The results showed that the deep eutectic solvent was formed by hydrogen bonding between Br?nsted acid and Lews acid. Extraction desulfurization with this deep eutectic solvent as the extractant was investigated, and the optimum desulfurization conditions were obtained as follows. When the molar ratio of Br?nsted acid to Lews acid is 1
Titanium dioxide (TiO2) is a traditional photocatalyst material.However, due to its wide band gap (3.2 eV) and the easy recombination of photogenerated carriers,it is necessary to enhance the effective absorption of sunlight,promote the separation of photogenerated carriers,and inhibit their recombination by doping noble metals,transition metals,anions and constructing heterojunctions.TiO2/CdS heterojunctions were prepared in two steps.Firstly,TiO2 nanotube arrays were prepared by multiple voltage anodization.Then,with TiO2 nanotubes as the base,CdS quantum dots were uniformly deposited inside and outside the nanotubes through chemical bath deposition.The composition,morphology,and optical properties of TiO2/CdS heterojunctions were characterized by X?ray diffraction,scanning electron microscopy (SEM),transmission electron microscopy (TEM),X?ray photoelectron spectroscopy (XPS),and UV?visible spectroscopy (UV?VIS).The prepared TiO2/CdS heterojunctions effectively inhibited the recombination of photogenerated carriers,promoted the transfer of excited electrons,and improved the hydrogen production efficiency by photocatalysis.The hydrogen production efficiency of sample TiO2(1.0)?CdS(1.0) reached 1.30 mmol/（g
The BaTiO3?TiO2 composites were prepared by using hydrate barium hydroxide (Ba(OH)2·8H2O) and titanium dioxide (TiO2) as raw materials with soft chemical hydrothermal method at 120 ℃ and different Ba/Ti molar ratios.The structure of the prepared composites with different Ba/Ti molar ratios was analyzed by X?ray diffraction (XRD),scanning electron microscopy (SEM),and UV?visible absorption spectroscopy (UV?Vis),the degradation effect of the complex on the simulated degradation pollutant,rhodamine B (RhB) was investigated.The results indicate that the BaTiO3?TiO2 composites obtained at a Ba/Ti molar ratio of 0.50 have an excellent catalytic effect for the degradation of rhodamine B (RhB) during the simulation of dye wastewater degradation.Meanwhile,more active sites formed at the Ba/Ti molar ratio of 0.50, which facilitated the photocatalytic reaction.
Electrochemical treatment technologies have been widely used to remove heavy metals in water.Specifically,carbon?based electrodes show positive application prospects in electrochemical treatment and recovery of heavy metals due to their strong electrical conductivity,large specific surface area,and controllable structure.This paper reviewed the research progress in the removal and recovery of heavy metals in electrochemical fields,such as electro?adsorption,electro?reduction,electro?oxidation,and electro?deposition by carbon?based electrodes including carbon nanotubes,graphene,and activated carbon.In addition,the development trends of removing heavy metals by electrochemical treatment technologies based on carbon materials were predicted.
A block in Changqing oilfield has high heterogeneity,and there are high?capacity channels, microfractures and high?permeability zones in its formations. During the implementation of natural gas flooding, the high risk of gas channeling must be considered. The traditional polymer microspheres are characterized by fast water absorption and expansion rate.It is easy to shear and crush its plugging strength is low. In view of these shortages,a polymer microsphere featuring delayed swelling was thus synthesized by introducing and activating a crosslinker and adopting inverse emulsion polymerization to address those defects. Its structure was characterized by a laser particle size analyzer and a polarizing microscope. Laboratory experiments were conducted to systematically evaluate the performance of the polymer microsphere featuring delayed swelling in temperature resistance,salt resistance,swelling,stability,and plugging during natural gas flooding.The results show that with a temperature resistance of 85 ℃, a salt resistance of 100 000 mg/L, a swelling time delay of 7 days, a particle size enlargement factor of 5.5, long?term stability (more than 6 months), and a plugging rate of more than 92.0%, the proposed polymer microsphere featuring delayed swelling can be used for plugging deep microfractures and high?permeability zones in the formations.
The expansion of the swept volume of injected water by polymers in the porous medium is the main mechanism for polymer flooding to increase oil recovery.The transport of polymer and the oil displacement effect were investigated.Experiments have shown that there is no positive correlation between the viscosity of the polymer flooding agent and the oil displacement effect.The viscosity of the salt?resistant polymer (52.4 mPa?s) is higher than that of the "high?resolution" polymer (35.6 mPa?s ),but it has poor compatibility with the pore?throat structure of the reservoir and poor injection and shear resistance.The oil displacement experiments demonstrate that the overall recovery increase by salt?resistant polymer flooding (6.94%) is lower than that of "high score" polymer flooding (18.94%). Therefore, compared with the "high?score" polymer of "equal viscosity" or "equal concentration", the salt?resistant polymer has a worse ability to expand the swept volume.
Laboratory research on protective agents for reservoirs was carried out to solve the problem of reservoir damage during drilling in Biyang Sag of Henan Oilfield.Under alkaline conditions,starch microspheres were prepared with corn starch, epichlorohydrin, and polyethylene glycol 20000 as the main raw materials, and then the starch?based protective agent DYB for reservoirs was prepared by the compound of the starch microspheres, regenerated fiber, calcium carbonate (QS?2), and emulsified asphalt (SFT). Scanning electron microscope and thermogravimetric analyzer were used to study the micromorphology and thermal stability of the synthesized product and evaluate the performance of DYB, such as shale rolling recovery and plugging. The results indicate that the particle size of starch microspheres is in the range of 3~5 μm, and the shale recovery rate of DYB in the base slurry is over 85.0%, the API filtration loss of the base slurry after aging at 120~180 ℃ is controlled within 12 mL. After 3.0% DYB is added to the simulated field drilling fluid, its pressure?bearing capacity in the sand bed can reach 4.00 MPa, while the membrane pressure?bearing capacity in the artificial core is over 10.00 MPa, and the recovery value of core permeability is over 82.0%.
