The continuous increase in carbon emissions and the escalating severity of environmental issues, it has become a global focus of attention to explore feasible solutions. Converting CO2 into useful fuels or chemicals through photocatalysis and electrocatalysis has garnered significant interest. TiO2 is highly favored for its stable chemical properties, high catalytic activity, low cost, non?toxicity, and environmental friendliness. This review provides an overview of the reaction mechanisms involved in photocatalytic CO2 reduction and electrocatalytic CO2 reduction. It emphasizes the key applications and advantages of TiO2 in these processes, investigates the influence of different surface modification technologies on the catalytic performance of TiO2, explores how different morphologies of TiO2 affect the catalytic activity and selectivity of CO2 reduction, and discusses strategies for enhancing the catalytic performance of TiO2?based. The overview not only contributes to the existing body of knowledge through additional experimental and theoretical research on the mechanism of titanium dioxide but also provides a scientific basis for the achievement of sustainable carbon conversion processes.
Asphaltene is the most associative component in crude oil and residual oil.Asphaltene can easily aggregate with each other through charge transfer,hydrogen bond and dipole interaction.Asphaltene may congregate and settle when external conditions or composition change,which poses a challenge to the petroleum industry.Asphaltene dispersants can effectively inhibit the agglomeration of asphaltene.In this paper,the research progress of asphaltene dispersants is reviewed from the aspects of asphaltene structure,dispersant types and dispersant mechanism,and the future development trend of asphaltene dispersants is analyzed.
In recent years, many oil wells in Mahu oil fields have experienced scaling on the pipe wall, which leads to wellbore blockage and seriously affects the production effect. In this paper, the structure and composition of scale in Mahu oilfield were studied, and the mechanism of scale formation was investigated by using OLI?ScaleChem simulation method and the interaction experiments between fluid and rock matrix. The results show that the main fouling is CaCO3, and the deeper the well is, the larger the amount of scale is. In addition, the wellbore temperature, pressure and pH of the fluid all have certain influence on scaling. According to the results of fluid rock reaction, it is inferred that CaCO3 scale is the reaction product of highly mineralized fluid and calcium?rich minerals under the condition of acidic well fluid, and forms into balls under the action of polymer, resulting in hole and wellbore plugging. The results of the study are of great significance in guiding the proposal of subsequent scaling prevention and treatment measures in the oilfield.
Transporting hydrogen?blended natural gas (HBNG) through existing natural gas pipelines can significantly reduce the cost of hydrogen transportation. To evaluate the risk of HBNG pipeline leakage, a high?pressure pipeline small?hole leakage model and a Gaussian plume model are combined, taking into account the lifting height caused by the initial momentum of the jet. The calculation results of the Gaussian plume model are compared with the existing experimental data. Then, the influence of the hydrogen mixing ratio, pipeline pressure, wind speed, and leakage hole diameter on the explosion risk area caused by the leakage of the natural gas pipeline is analyzed. The research results indicate that the calculation results of the Gaussian plume model are in good agreement with the experimental data. The hydrogen mixing ratio is approximately linearly negatively correlated with the maximum distance from the methane hazardous area, and linearly positively correlated with the maximum distance from the hydrogen hazardous area. The maximum distance between methane and hydrogen hazardous areas is approximately linearly positively correlated with pipeline pressure, negatively correlated with wind speed, and approximately proportional to the diameter of the leakage hole.
To study the explosion risk associated with the use of wearable devices in oil transfer stations, research was conducted through the investigation of explosion accidents at oil transfer stations and fire and explosion accidents involving wearable devices. Additionally, experimental tests were carried out on the maximum surface temperature of wearable devices, their electromagnetic radiation power, and calculations were done to analyze the explosion risk of the devices' batteries. It was found that there have been no reported cases of explosion accidents at oil transfer stations caused by the use of smart wearable devices. The ignition risks associated with wearable devices in oil and gas locations mainly include: the risk of ignition due to device overheating, the risk of battery combustion and explosion, and the risk of sparks from device radio frequency. During the use of smart wearable devices, it is virtually impossible for temperatures to exceed 200.0 ℃, thus mitigating the risk of oil and gas ignition due to heated surfaces. The maximum electromagnetic radiation power tested for wearable smart devices is far too low to ignite petroleum vapors. Consequently, the risk of oil and gas combustion or explosion accidents caused by wearable devices catching fire or exploding within oil transfer stations is minimal or even negligible, falling within an acceptable range of safety risks.
Ammonium heptamolybdate was dissolved in water or oxalic acid solution,and then compounded with TiO2 to prepare MoO x ?TiO2 support,and the VO x /MoO x ?TiO2 catalysts were obtained after loading vanadium by impregnation method.The structure and properties of the catalysts were characterized by XRD,SEM,BET,XPS,H2?TPR and NH3?TPD,and its denitration activity and high temperature aging performance were investigated.The results showed that the denitrification efficiency of VMoTiO?F prepared by oxalic acid?assisted dissolution of (NH4)6Mo7O24 was greater than 80.0% at 210 ~ 510 °C,which was better than that of VMoTiH?F prepared by water dissolution.Because there was more MoO x on the surface of VMoTiO?F,the interaction with VO x was enhanced,which promoted the production of more low?valence VO x and surface chemisorbed oxygen (Oα) active species on the surface of the catalyst.At the same time,the interaction between VO x and MoO x could also improve the low?temperature redox performance and facilitate the electron transfer in the catalytic process.After high temperature aging,VMoTiH?F had more MoO x into the TiO2 lattice than VMoTiO?F,which was helpful to improve the thermal stability of TiO2.However, anatase TiO2 in VMoTiO?A was seriously sintered or even partially transformed into inert rutile crystal during high temperature aging,resulting in the loss of surface acid sites and the reduction of redox properties.Therefore,the denitrification performance of VMoTiH?A catalyst was significantly higher than that of VMoTiO?A.
Sn additives can effectively improve the propylene selectivity of propane dehydrogenated Pt?based catalysts and inhibit the generation of carbon deposition,but the effect of Sn additives is still unclear.Therefore,in this paper,different PtSn action systems were constructed by co?impregnation method and sol?gel method to modulate the introduction of PtSn,and the effect of Sn introduction methods on the dehydrogenation performance of propane of Pt?based catalysts was systematically explored.XRD and BET were used to characterize the texture properties of the catalyst,H2?TPR,TEM and CO?IR were used to distinguish the Sn structure of the additives,and the propane dehydrogenation reaction evaluation and carbon deposition analysis of the catalysts were carried out.The results show that compared with the PtSn/γ?Al2O3 catalyst prepared by co?impregnation method,the Pt/Sn?γ?Al2O3 catalyst prepared by sol?gel method has a lower specific surface area and higher pore size,which can promote the interaction between PtSn clusters and carriers to achieve high metal dispersion.More active sites give the Pt/Sn?γ?Al2O3 catalyst higher propane conversion and propylene yield,and the larger pore size of the carrier also significantly reduces the carbon deposition of the catalyst.
Using ammonium metatungstate and copper acetate as raw materials,the precursors with different morphology were synthesized by a simple hydrothermal method by controlling the doping ratio.Then,combined with high temperature annealing method,the in?situ growth of Cu?WN?5∶1 was successfully realized on carbon paper.The morphology and structure of the samples were characterized by SEM,TEM,XRD and XPS,and then the hydrogen evolution performance of the catalyst was evaluated by electrochemical testing methods.The results show that the doping ratio of W and Cu (n(W)/n(Cu)） has a significant effect on the hydrogen evolution performance of the catalyst,in which the optimal hydrogen precipitation activity is achieved when n(W)/n(Cu) is 5∶1.The successful doping of Cu increases the number of active sites by changing the electronic structure of WN,accelerates the charge transfer rate in the catalytic process,which in turn improves the HER activity of the material.The required overpotential of Cu?WN?5∶1 at 1.0 mol/L KOH with a current density of 10 mA/cm2 is 195 mV,and the Tafel slope is 192 mV/dec,which indicates that Cu?WN?5∶1 has a fast kinetic rate of electrochemical hydrogen precipitation reaction;the material has been continuously reacted for 36 h under the condition of 1.0 mol/L KOH,and it exhibits excellent long?term stability.
Proton exchange membrane fuel cell (PEMFC) is characterized by high efficiency and environmental protection, and has great potential for development in solving energy and environmental problems.Proton exchange membrane (PEM) is one of the key components of PEMFC, which affects the performance and cost of the cell. Existing commercial Nafion type PEMs have a problems in balance of high cost, conductivity and mechanical properties. PEMs with low cost and excellent performance can improve the performance and commercialization of fuel cells. To address the compatibility problem of conductivity and mechanical properties of PEMs, researchers have designed a variety of enhanced PEM materials in terms of membrane constituent materials and microcosmic nano structures. Here, the requirements of PEMFC for PEM are briefly introduced, and the preparation methods of novel PEM based on doped nanomaterials, composite resin cross?linking and porous skeleton are mainly analyzed. The characteristics of membrane properties before and after modification are compared, and the problems in the preparation process of PEM are briefly analyzed, and the future research directions of PEM are further prospected.
As a new class of materials, tin pyrophosphate stands out due to its high specific capacity and suitable lithium insertion potential. Carbon?coated SnP2O7 particles anchored on a carbon framework (SPO/C@C) have been synthesised by an environmentally friendly approach using phytic acid as a phosphorus and carbon source, with polyethylene oxide (PEO) as an additional carbon source. Experimental results show that the addition of extra carbon layer effectively mitigates the volume expansion of the material and reduces the charge transfer resistance, thereby improving the electronic conductivity and the capacitance contribution ratio. That the SPO/C@C sample with 1.36 g of PEO exhibits excellent dispersion and electrochemical performance. At a current density of 0.5 A/g, the discharge specific capacity is 351.3 mA·h/g after 250 cycles, and at a scan rate of 2.0 mV/s, the capacitance contribution ratio is 60.8%.
