Simulation On The Self-assembly Behavior Of Ordered Mesoporous Carbons And Their Performance In Adsorption

Ordered Mesoporous Carbons （OMCs） hold significant potential applications inseparation, adsorption, catalysis, energy storage and electrochemistry, due to their uniqueproperties such as uniform pore sizes, large surface areas and porosity, specific channels,structural regularity, chemical and thermal stability. The channel connectivity and porestructure of ordered carbon materials are crucial for the mass transportation processes such asadsorption and separation. However, there are still plenty of obstacles in the strict test oftheoretical concepts, restricted by complicated multicomponent mixture, environmentalconditions, experimental methods etc. In order to endow the products with specificphysicochemical properties, and attain the needs of practical applications, a rationalmodification is expected. Based on precise theoretical models for accurate theoreticalcalculation, computer simulation opens a new door in investigating character of structures,dynamics behaviors and physiochemical performance of materials, so as to predict thepotential performance.In the present work, Dissipative Particle Dynamics （DPD） method was applied tosimulate the self-assembly process and phase transmission of liner triblock copolymer（PEO-PPO-PEO type） as well as OMCs by using F108as template and phenolic resin ascarbon precursor in ethanol solution. In addition, the adsorption behavior of benzene onOMCs was investigated in the molecular level.Firstly, we presented the Gaussian chain model of liner triblock copolymer withPEO-PPO-PEO type and DPD parameters employed in the following study.Then, the affect of the length of EO chain and concentration of components on theself-assembled structure and phase transmission were investigated in detail. With differentcompositions of different components, different kinds of morphologies in ethanol, such asspherical, hexagonal packed cylinders, body-centered-cubic and alternating lamellarmesostructures have been observed. We also analyzed the cooperative self-assembly processof forming micelles under the fixed concentration of the components.Afterward, we established stabe structural model of OMCs. After geometr optimization,the total energy of this model was319655kcal/mol, and we found its structure wasconvergent. And the dynamic simulation also proved it has been steady.In addition, we studied adsorption behavior of benzene on structural model. At the fixedpressure of3.5kPa, the adsorption capcity of benzene on OMC-30model went up rapidly atthe beginning and then increase slowly. In the sorption isotherm of OMC-30at323K, 10^-54.6kPa, we found the maximum adsorption capcity of151benzene atoms per cell at4.6kPa where isosteric heat was39kcal/mol. There was only one adsorption site under thiscondition.Contrast to adsorption isotherms of different size of structural models, theadsorption capacity and rate in turn was proportional to the size. All of them got close toadsorption saturation, indicating that OMCs were not so sensitive to the conditions of low-pressure.