Metal?nitrogen doped carbon is an emerging class of non?precious metal electrocatalysts used in carbon dioxide reduction reactions(CO2RR).Metal?nitrogen doped carbon is an emerging class of non?precious metal electrocatalysts in carbon dioxide reduction reactions(CO2RR).Current preparation methods mainly use impregnation?based post?processing,which often involves multiple preparation steps and limited types of metals.In this work,an iron?copper(FeCu) and nitrogen doped carbon catalyst was prepared through a coordination competition strategy.In the preparation,4,4?bipyridine served as ligand and iron nitrate and copper chloride as metal sites to form FeCu coordination polymers,which was directly transformed into FeCu?nitrogen doped porous carbon catalysts.The physicochemical properties such as morphological structure,metal species state and pore structure were characterized by SEM,TEM,XRD and N2 adsorption?desorption,respectively.The performance of different FeCu?nitrogen doped carbon catalysts in electrocatalytic CO2RR to syngas was examined in a three?electrode system.The regulation of n(CO)/n(H2) in syngas was studied by adjusting the metal composition,metal combination and pyrolysis temperature,etc.The n(CO)/n(H2) generated in the wide potential range of -0.7 V to -1.3 V can be regulated in the range of 0.15~3.33,which can meet the supply gas ratios for important reactions such as methanol synthesis,Fischer?Tropsch reaction and syngas fermentation.
In order to investigate the synergistic catalytic aquathermolysis after external catalyst entering the reservoir and complexation with in?situ inorganic minerals,a simulated internal and external synergistic catalyst of montmorillonite?supported zinc citrate complex was prepared,and its catalytic viscosity reduction performance for heavy oil was investigated.The heavy oil before and after the reaction was analyzed by thermogravimetric analysis(TGA),differential scanning calorimetry(DSC),gas chromatography(GC) and elemental analysis(EA).The results showed that the composite catalyst B@Zn(Ⅱ)L increased the viscosity reduction rate of heavy oil from 55.2% to 65.4% at 30 ℃,which confirmed the phenomenon of internal and external source synergistic catalysis in heavy oil thermal recovery.After synergizing the composite catalyst B@Zn(Ⅱ)L with the hydrogen supply agent ethanol,the viscosity reduction rate of heavy oil increased from 65.4% to 80.1%.After the reaction of heavy oil, some of the high hydrocarbon compounds in the heavy oil were cracked into low hydrocarbon compounds after the reaction,and some heavy components were decomposed into light components.Therefore, the wax precipitation point of heavy oil decreased,the mass fraction of N and S decreased,the content of high hydrocarbons decreased,and the content of low carbon hydrocarbons increased.
This paper studies the stability of crude oil emulsion characterized by conductivity difference between upper and lower layers. According to the changes of conductivity in the upper and lower layers of crude oil emulsion system, combined with optical microscope observation, the methods and conditions to characterize the stability of crude oil emulsion can be studied by the difference of conductivity between the upper and lower layers. Research finds that when the crude oil system is demulsified and phase separated, the composition, morphology and conductivity of the upper and lower emulsions will be different.Therefore, the conductivity difference between the upper and lower emulsions can be used as the characterization parameter of emulsion stability. By measuring the conductivity and the difference values of the upper and lower layers of the system at different electrical test signal frequencies (0.1,1.0,10.0,100.0 kHz), it is found that the conductivity values and the difference values at high frequency are greater than those at low frequency, and the sensitivity is higher. In addition,when the conductivity difference is greater than 15%, the system is unstable. The experimental results show that the method is also suitable for emulsion system containing anionic surfactant.
During the injection process, micro?nano bubbles are generated in the oil?displacing agent polyacrylamide (HPAM) system. This will lead to the oxidative degradation of HPAM and the loss of viscosity. In order to determine the effect of micro?nano bubbles on the change rule of the viscosity retention rate and structure of HPAM solution, the viscosity retention rate at different aeration conditions was studied, and technologies such as dynamic laser scattering, biological microscopy, and infrared spectroscopy were carried out. Results showed that the viscosity retention rate of HPAM sample, which was prepared with simulated mineralized water after 20 mins circulation of the micro?nano bubbles generator with air as the gas source, decreases the most, and its viscosity average molecular weight is also the lowest. This is attributed to the chemical reaction between oxygen and HPAM molecules in the solution, leading to oxidative degradation. The micro?nano bubbles containing air increase the solubility of oxygen in the solution and generate hydroxyl radicals (·OH), thereby reducing the viscosity retention. In the absence of inflation, micro?nano bubbles are formed in the HPAM solution during the preparation process due to mechanical shear, but the high concentration of the solution hinders the dispersion of micro?nano bubbles, thereby slowing down the decrease in viscosity retention. In addition, micro?nano bubbles have a longer stabilization time in solution than large bubbles, and will affect the particle size distribution of the polymer, resulting in uneven particle size distribution and larger average particle size.
In the process of hydrogen storage by MOFs materials, the low thermal conductivity of the materials leads to heat accumulation,which affects the hydrogen storage performance.In order to improve the thermal conductivity of the adsorbent material and take into account its hydrogen storage capacity, numerical simulation was used to analyze the optimal regulation range of the thermal conductivity of the adsorbent material.The results show that when the thermal conductivity of the adsorbent material is in the range of 0~1.2 W/(m·K), the maximum temperature, average temperature and hydrogen absorption capacity of the hydrogen storage tank are obviously improved with the increase of thermal conductivity.When the thermal conductivity of the material is greater than 1.2 W/(m·K), the improvement effect is significantly weakened; when the material thermal conductivity is greater than 2.0 W/(m·K), the improvement effect almost disappears. Therefore, the optimal thermal conductivity of the adsorbent should be controlled at about 1.2 W/(m·K).
Natural gas hydrates have vast reserves and are considered a new clean energy source for replacing traditional fossil fuels such as coal and oil in the future.The formation, inhibition and decomposition of natural gas hydrate are affected by many factors.When studying the inhibition and acceleration effect of chemical agents on hydrate decomposition,multiple factors should be considered, such as fresh water or sea water, different gas?liquid ratios in the reactor, and pressure. In this paper, hydrate?related simulation experiments were carried out through a self?designed visualization simulation device for hydrate formation,inhibition and decomposition in wellbore. Under a gas?liquid ratio of (150
Layered double hydroxides (LDHs) has simple synthesis process,flexible structure,economy,environmental protection and anion exchange,which strengthen its application range in the field of anti?corrosion coatings.The target properties of LDHs can be achieved by a combination of one or more processes,or chemically modified by surface modification and internal anion replacement,enhancing the applicability of LDHs to meet the needs of different fields of application.This paper mainly focuses on the synthesis method of LDHs,the mechanism of corrosion protection,the practical application of LDHs corrosion protection,and its limitations and prospects.It analyzes the advantages and disadvantages of various synthesis methods,and provides suggestions for future research on the application of LDHs in the field of corrosion protection.
To efficiently remove organics in coking wastewater, this paper prepared an amphiphilic chitosan?loaded bentonite adsorbent (C18CS?BT).The structure and morphology of the adsorbent were characterized by Fourier transform infrared spectroscopy (FT?IR),X?ray diffraction,and scanning electron microscope.By comparing the removal rates of C18CS?BT,unmodified chitosan?loaded bentonite (CS?BT),and bentonite (BT),the study explored the effect mechanism of hydrophobic modified adsorbent on the removal of the organics in coking wastewater.The results show that compared with BT and CS?BT,C18CS?BT features lower dosage, wider application range of pH value,and shorter adsorption equilibrium time.The optimized treatment process is the adsorbent dosage of 1.5 g/L,the adsorption time of 60 min,and the system pH value of 7.0. The COD in coking wastewater after BT, CS?BT and C18CS?BT treatment is reduced from 342 mg/L to 264,218,146 mg/L, and the corresponding removal rates of organics are 22.81%,36.26% and 57.31%, respectively. GC?MS result analysis also confirms that C18CS?BT could remove most of the organics in coking wastewater, especially long?chain alkanes and their derivatives.The hydrophobic modification of the adsorbent can effectively improve the removal performance of organics in coking wastewater.
The Tb coordination complex [Tb(H2O)8]?(L)?2(4,4'?bipy)?3H2O（complex 1） was synthesized by hydrothermal reaction of sodium 1,3,6?naphthalene trisulfonate (Na3L) and 4,4'?bipy (4,4'?bipy) with Tb(NO3)3?6H2O. The molecular structure and composition of complex 1 were characterized by single crystal X?ray diffraction, FT?IR spectroscopy, thermogravimetric analysis and elemental analysis. Thermal stability and fluorescence emission properties of complex 1 were also evaluated. The results indicate that Tb3+ is eight?coordinated in a tetragonal antiprismatic coordination configuration and coordinates with eight H2O molecules to form [Tb(H2O)8]3+.L3- does not coordinate with metal ion, but only balances the positive charge in the molecule. The formation of hydrogen bonds between the sulfonic acid group of the L3- and the coordinating H2O molecule connects the [Tb(H2O)8]3+ and the L3- to form a one?dimensional chain structure,which in turn expands into a two?dimensional lamellar structure.The fluorescence emission peaks of complex 1 at 395，453 nm are the characteristic peaks of Na3L, and the emission peaks at 545,601，641 nm are the characteristic peaks of Tb3+.
The preparation of activated carbon from residue of a distillation reactor is an efficient and economical strategy for the utilization of hazardous waste resources.However,the prepared activated carbon is generally powdered,which is difficult to meet the requirements of industrial application.In this work,the activated carbon microspheres were prepared based on the rectification residue activated carbon from the powders,using deionized water as the solvent and polyacrylic acid (PAA),sodium alginate (SA) and Ca2+ as the additives.The effects of SA,Ca2+ and PAA amount on the structure and mechanical strength of the activated carbon microspheres were investigated.X?ray diffraction,Fourier transform infrared spectroscopy and Raman spectroscopy were used to investigate the shaping mechanism of activated carbon microspheres.The activated carbon microspheres were applied in the tetracycline adsorption,and the maximum adsorption capacity of tetracycline was up to 257.8 mg/g.At the same time,after 9 months of water stability test,the activated carbon microspheres still had good adsorption performance and mechanical strength. This shaping strategy adopted green and economical raw materials,which could effectively solve the problems of powder shaping and poor performance of microspheres,and provide the effective solution for the industrial application of high?performance materials.
To prevent accidents like the "3?12" explosion and fire incident in the hydrogenation unit of a petrochemical enterprise in Jiujiang, Jiangxi Province, this study proposes the application of Hazard and Operability Analysis (HAZOP) and Safety Integrity Level (SIL) classification in the basic design phase of the emergency cut?off function hazards control project for a refining and chemical enterprise. HAZOP analysis adopts a workflow based on the parameter preference method while SIL classification is based on the LOPA (Layers of Protection Analysis) method, following the ALARP (As Low As Reasonably Practical) principle. HAZOP & SIL classification was carried out for a coking steam kerosene hydrorefining unit, a hydrogenation combined diesel hydrorefining unit and an ethylbenzene unit in a refining enterprise. A total of 12 accident scenarios were identified and 6 recommended measures were put forward. The results demonstrate that HAZOP & SIL classification can effectively assist the refining and chemical enterprise in managing the risks of intermingling pressures, maintaining control over safety production, reducing intermingling pressure risks to an acceptable level, or eliminating them promptly, thereby preventing accidents caused by intermingling pressures and ensuring the inherent safety of the refining and chemical enterprise.
