Simulation of the operation of the gas refrigerator recurrent complicated ethylene polymer deposits

The work based on the methods and equations of mechanics of multiphase media, the resulting system of ordinary differential equations, describing hydrodynamic and heat and mass transfer processes in counterflow heat exchangers type “pipe in pipe”, where the inner tube flows a mixture of ethylene and polyethylene, and in the annular space counter-current moves water. For gas mixtures is complicated by the “sticking” of liquid polyethylene on the walls of the pipe. In describing the process of formation of the polymer film is considered one of the possible mechanisms for the admission of liquid polyethylene particles from the turbulent core to the surface of the pipe, the turbulent diffusion. The results of studies on the dynamics of accumulation of the plastic film on the inner surface of gas refrigerator returnable ethylene. It is established that the formation of the profile of sediments is complex: the maximum film thickness is shifted to the output section of the channel.

Synthesis and Catalytic Performances of a Novel Zn-MOF Catalyst Bearing Nickel Chelating Diimine Carboxylate Ligands for Ethylene Oligomerization

A novel Zn-MOF[Zn3(OH)2L2] was synthesized from dicarboxylate ligands with diimine groups (1,4-bis(4-CO2HC6H4)-2,3-dimethyl-1,4-diazabutadiene). The physicochemical properties of the material were characterized by a series of technologies including XRD, SEM, and ICP. In order to adapt to the ethylene oligomerization process, a catalyst[Zn3OH2L1Ni2](denoted as Cat.A) possessing active Ni2+centers was prepared by a postsynthetic treatment method using dichloride nickel as a nickel source in this work. For comparison,α-diimine ligands with/without dicarboxylic acid groups reacted with dichloride nickel to obtain homogenous Cat.B and Cat.C, respectively. The effects of reaction parameters, includingn(Al)/n(Ni), temperature, and pressure on the oligomerization activities and oligomers distribution were investigated. The results demonstrated that all of catalysts used with diethylaluminum chloride were active for the ethylene oligomerization. Among them, Cat.A and Cat.B showed higher catalytic activities and higher selectivities to low-carbonα-olefins at atmospheric pressure. The Cat.A exhibited the optimal catalytic activity [6.7 × 105 g/(mol·Ni·h·atm)] for C4 (91.8%) under the conditions of Al/Ni = 1500,P= 1.0 atm, T = 20°C. In addition, Cat.A and Cat.B presented large amount of ethylene polymer, while Cat.C had a higher catalytic activity of ethylene oligomerization at high pressure.

Continuous flow photolysis of aryl azides: Preparation of 3H-azepinones

Photolysis of aryl azides to give nitrenes, and their subsequent rearrangement in the presence of water to give 3H-azepinones, is performed in continuous flow in a photoreactor constructed of fluorinated ethylene polymer (FEP) tubing. Fine tuning of the reaction conditions using the flow reactor allowed minimization of secondary photochemical reactions.