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.

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.

Organic sulfides widely exist in natural resources such as petroleum and coal,which have abundant resource reserves.In the petroleum refining industry,the cleavage of C-S bonds is usually required for the desulfurization of petroleum fractions. Among them,the transition metal?catalyzed cleavage reactions of C-S bonds have attracted the attention of researchers owing to the advantages of high efficiency,mild conditions,and low pollution.This review summarizes the progress in transition metal?catalyzed C-S bond cleavage reactions of different types of organic sulfides,and provides insights into Pd,Cu,Ni and Fe catalytic systems and mechanisms.Moreover,the development of such reactions is proposed.

Asymmetric supercapacitors(ASCs) have the merits of rapid charge and discharge,high power density,and long?term cyclic stability.The properties of electrode materials determine the performance of ASCs.Cation substitution is an effective method to tune the structure and properties of electrode materials and optimize energy storage performance accordingly.This paper prepared MCo₂S₄(M=Co,Ni,or Cu) nanosheet arrays on the surface of a nickel foam substrate.For this purpose,it controlled the cationic components of the spinel sulfide and employed a hydrothermal method.Due to the differences in the radius and electronegativity of metal irons,the lattice structure of Co₃S₄ underwent strain when Ni²⁺ or Cu²⁺ ions were introduced into Co₃S₄ to obtain NiCo₂S₄ or CuCo₂S₄.The result was reinforced reactivity of the metal sites.The charge transfer and ion diffusion resistances of NiCo₂S₄ are respectively 48.6% and 28.7% lower than those of Co₃S₄,indicating favorable electrochemical properties achieved.The specific capacity of NiCo₂S₄ is 1 128.8 F/g under a current density of 1 A/g.The capacity retention is 59.8% under a current density of 10 A/g.The retention of the initial specific capacity is 60.2% after 8 000 cycles.

Taking the gas storage tank in a gas?liquid linkage actuator of a gas transmission pipeline as an example, the software Ansys Fluent was used to establish a 3D model with the same proportion, to simulate the change of pressure and temperature with continuous heat input when external fire occur. Aspen Hysys was used to calculate the minimum PSV diameter required for safe discharge under fire conditions. The results show that the temperature and pressure of the tank rise sharply, reaching to the steel tank collapse temperature and design pressure in a very short time, when the external fire occurs. The time to reach the collapse temperature of steel tank is lagged behind the time to reach the design pressure of the gas tank. From a security perspective, the PSV should be set, which can also help to reduce the damage of the accidents even if the tanks collapse. The minimum diameter of the PSV calculated by Aspen Hysys is 0.13 cm², and the recommended diameter of the PSV is no less than 0.15 cm².