The large?scale use of fossil fuels has led to excessive CO2 emissions, resulting in a series of problems such as rising temperatures, melting glaciers, and the accumulation of diseases and pests. Using electrochemical reduction of CO2 (CO2RR) to convert CO2 into valuable chemicals and fuels has become a way to realize the carbon cycle. Over the years, good progress has been made in using metals and their oxides, carbon based materials, monatomic catalysts and other electrocatalysts for CO2RR, but rare earth metals as "industrial vitamins" have been rarely reported for CO2RR. This paper summarizes the application of rare earth elements as carriers, main catalysts and cocatalysts in CO2RR, and explores the catalytic performance of rare earth materials in CO2RR, so as to promote practical research of industrial application.
The traditional method for determining the oil content of oily sludge was improved, and the extraction smartphone image colorimetry was established by combining the image colorimetry with the pretreatment method of hot solvent extraction. The effects of RGB value, different color channels, shutter time, sensitivity, white balance and other parameters on the determination of oil content were investigated. Under the premise that the light source was tungsten iodide lamp and the front camera of Samsung A8s mobile phone was used, the best test conditions were finally determined: white balance value was 2 800 K, sensitivity value was 100, shutter time was 1 / 2 000 s. The linear correlation coefficients of the method under the optimal test conditions were more than 0.99 under the optimal test conditions, and the linear range was similar to that of the spectrophotometric method, with the detection limit of 0.06% and the lower limit of 0.24%. The recoveries of 8 groups of parallel standard samples were 96%~103%, and the relative standard deviation was 2.26%, which indicated that the accuracy of this method was relatively high. Compared with the traditional method, this method is more simple and rapid, and its accuracy can meet the needs of conventional oil content measurement, which is expected to realise the rapid on?site determination of oil content of large?scale oil?containing sludge in plants.
Using artificial simulation of diesel contaminated soil, the degradation and remediation ability of functional microbial communities on diesel contaminated soil, as well as changes in microbial diversity and microbial structure composition, were studied. The experimental results of microbial community degradation of diesel in soil showed that after 30 days of degradation, the final degradation rate of microbial community on diesel pollution in soil reached 74.3%.The respiratory intensity of the microbial community in the soil gradually increases within 30 days. When the soil depth changes, the degradation ability of the microbial community gradually weakens with the increase of depth. The results of high throughput sequencing showed that after 30 days of degradation, the microbial diversity and richness in the soil increased compared with the initial degradation, indicating that the microbial community could adapt to the diesel pollution environment well. The initial microbial community for diesel degradation is mainly composed of Proteobacteria, Firmicutes, and a small amount of Bctoidetes. After 30 days of cultivation, the main dominant bacteria in the surface soil are Proteobacteria, while the main dominant bacteria in the deep soil are Firmicutes. Studying the remediation of diesel?contaminated soil by microbial communities and changes in microbial structure and diversity, technical support can be provided for the remediation of diesel?contaminated soil.
While fossil energy is being exhausted day by day,and the problem of environmental pollution needs to be solved urgently.However,the social demand for energy is growing,so the development of green energy has received extensive attention from many scientific researchers.As an efficient energy conversion device,fuel cell has many advantages such as high efficiency, high performance and environmental friendliness.In the choice of fuel cell catalyst,Pt?based catalysts are the preferred materials because of their unique catalytic properties,but their high preparation cost and unstable catalytic properties have hindered the commercialisation of Pt?based catalysts.The working principle of Pt?based catalysts for cathode oxygen reduction reaction of proton exchange membrane fuel cells and the influencing mechanism of catalyst activity are briefly introduced.The research direction of Pt?based catalysts is summarized.Finally,the development direction of future research is prospected.
Pt0.5?Snx/γ?Al2O3 catalysts with different Sn loads were prepared by constant volume sequential impregnation method and ultrasonic shock method to improve metal dispersion. The catalysts were characterized by XRD, BET, H2?TPR, CO?IR and TG, and the effects of Sn content on the active center structure and propane dehydrogenation performance of Pt0.5?Snx/γ?Al2O3 catalysts were investigated. The results showed that adjusting the n（Pt）/n（Sn） by changing the Sn content in the samples would lead to the difference in the spatial distribution of Pt and Sn species, and thus affect the mode of action between Pt and Sn. With the increase of Sn, the interaction between Pt?Sn helps to increase the dispersion of Pt, the number of active sites, the improvement of the reaction activity of the catalyst. However, when excessive Sn is introduced, a Pt?Sn alloy is formed, resulting in the coating of Pt, resulting in a decrease in the number of active sites and a decline in the reactivity.
A new method for the synthesis of esters by C=C bond breaking in olefins has been realised using cobalt nanoparticles (Co?NC?900) as catalysts and oxygen as oxidant.The catalytic system has a wide range of substrate applications and functional group compatibility.A diverse set of mono? and multi?substituted aromatic and aliphatic alkenes could be effectively cleaved and converted into the corresponding esters by C=C bond cleavage. In addition, the catalyst can be recycled up to six times without significant loss of activity.Characterization analysis revealed nanostructured nitrogen?doped graphene?layer coated cobalt nanoparticleis possibly responsible for excellent catalytic activity.Mechanistic studies revealed that alcohols or ketones derived from olefins under oxidative conditions are formed as intermediates,which subsequently are converted to esters through a tandem sequential process.
Under the hydrothermal synthesis,an organic?inorganic hybrid compound was prepared through the self?assembly process by using phosphomolybdic acid as a polyoxometallate (polyacid for short) building block and triphenylphosphine as an organic ligand.Its molecular formula was determined by X?ray single?crystal diffraction technique as H15{(PMo12O40)2[MoO4?(PPh3)4]2?[NaO3?(PPh3)3][(H2O?PPh3)3]（compound 1),which is a novel inorganic?organic hybrid material formed by electrostatic interactions between [PMo12O40]3-,[MoO4?(PPh3)4]2-,[NaO3?(PPh3)3]5- and H2O?PPh3 building blocks.The IR spectrum,luminescence spectra and cyclic voltammetric characteristic curves of compound 1 were also tested,focusing on the photocatalytic degradation of methylene blue(MB).The good ability of compound 1 to degrade organic dyes was demonstrated by photodegradation analysis experiments.
Chiral epichlorohydrin is obtained by kinetic resolution of racemic epichlorohydrin through hydrolysis. Chiral epichlorohydrin is a valuable intermediate which is widely used in the synthesis of medicine and material. Salen refers to a base formed by the condensation of two identical aldehyde molecules and a diamine molecule, and the complex formed by its combination with metals is called Salen metal complex, which is often used in the synthesis of chiral epichlorohydrin. In this paper, the development of Salen metal complex catalysts and their application in chiral epichlorohydrin synthesis are reviewed. At the same time, the deactivation mechanism of catalyst in the process of hydrolytic kinetic resolution was investigated and the application prospect of synthesis of chiral epichlorohydrin using Salen metal complex catalysts was prospected.
Highstrength polymer materials with excellent mechanical properties and wear?resistance have been widely used in water pumps, electric generator and other fields as a new generation of bearing materials. A high performance polyurethane/carbon fiber composite （PUE/CF） was prepared by combining chopped carbon fiber (CF) with polyurethane elastomer (PUE), and the effects of carbon fiber content on the mechanical and tribological properties of the composites were investigated. The results show that the hardness of the composite can reach 60 ~ 68 HD, the tensile strength and elongation at break can reach 54 MPa and 298% respectively. Under dry friction condition, 0.16 of friction coefficient and 0.570% of wear rate can be obtained. Under water friction condition, 0.02 of friction coefficient and 0.129% of wear rate can be obtained. In summary, the composite prepared in this paper can meet the application requirements of polymer bearing bush and have broad application prospects in the field of automobile and ship.
The Ruddlesden?Popper (RP) perovskitetype composite cathode material was prepared by a sol?gel method,and the performance of using it as a SOFC cathode was evaluated.XRD result shows that the composite material calcined at 1 200 ℃ was (La2/3Sr4/3)FeO4?(La4/3Sr8/3)Fe3O10 (LSF).At 400 ℃,the highest conductivity of the sample is 57.0 S/cm in air.At 800 ℃,the interfacial polarization resistance of the LSF electrode on La0.9Sr0.1Ga0.8Mg0.2O3-δ (LSGM) electrolyte is 0.198 Ω·cm2.Based on a single cell supported by a 300?μm?thick LSGM,the peak power density of the sample when used as a cell cathode was up to 670 mW/cm2 when used as the cathode of the cell, with no performance degradation for 50 h of continuous operation.Experiments show that the LSF cathode has excellent and stable electrochemical performance,and is a very promising cathode material for SOFC.
After the application of a non?ionic polyether clear water agent in an oilfield in the Bohai Sea,the difficulty of dewatering crude oil in the downstream terminal treatment plant increased,and the water content of the outgoing crude oil frequently exceeded the standard.The Effect of nonionic polyether water clarifier on crude oil dehydration was researched,the reasons of difficulty in dewatering were analysed,and the emulsion could not be treated by conventional polyether demulsifier.Polyamines were synthesised from dimethylamine,dodecyl dimethyl tertiary amine and epichlorohydrin,while polyethylene?polyamines were used as cross?linking agents to synthesise polyamine copolymer emulsion breakers.The emulsion breaker can reduce the water content of the external crude oil to less than 0.5% at a concentration of 80 mg/L,and reduce the static dewatering time of the crude oil from more than 120 h to less than 48 h.This effectively solves the problem of excessive water content in the external crude oil of the terminal treatment plant.
