Simulation Analysis Of Methane Adsorption By Activated Carbon And Zn-MOF-74 Material

As terms such as "carbon emissions","carbon peaks",and "carbon neutral" frequently appear in people’s daily lives,the Ministry of Ecology and Environment has emphasized the need to put the reduction of carbon emissions in a more prominent and prioritized position.The damage to the ecological environment caused by the greenhouse effect caused by the burning of petroleum fuels and the random emission of low-concentration coal-bed methane during the development of coal-bed methane and the random emission of associated gas from oil wells in oil fields has attracted the attention of the public,which can replace the development and utilization of natural gas.It seems particularly important.At present,the adsorption and storage of natural gas is considered to be one of the most promising CH4 storage methods in the future,and the development of high-efficiency special adsorbents suitable for natural gas storage is an important research direction.Activated carbon materials are widely used in the adsorption of various gases and other substances due to their huge specific surface area,wide pore size distribution and simplicity of preparation.In recent years,new-type metal-organic framework MOFs materials are widely used for gas adsorption and storage due to their large specific surface area,high porosity,and modification of the framework structure and pore size according to target requirements.Therefore,this article uses activated carbon and Zn-MOF-74 as the adsorbent,and methane as the adsorbent.As the experimental analysis method cannot analyze the adsorption mechanism from the micro level and is time-consuming and costly,molecular simulation technology is selected.The construction of activated carbon and Zn-MOF-74 molecular structure model to explain the relationship between adsorbate and adsorbent structure from the molecular level provides a new idea for in-depth exploration of the adsorption performance of the adsorbent.Study the adsorption performance and adsorption behavior of the adsorbent on methane,analyze the adsorption state and adsorption mechanism of methane on the adsorbent.The main results of the research are:(1)Summarize the basic structural parameters of activated carbon according to the literature,and construct basic activated carbon models with different pore sizes of AC-1,AC-2,and AC-3 based on the literature.The model size is 50×50×50(?),which is in line with the inside of the activated carbon.Highly disordered,a certain proportion of five-membered and sevenmembered rings were added in the modeling process,and the characterization of the model has verified its rationality;at the same time,a metal-organic framework Zn-MOF-74 model was constructed.(2)The effects of adsorption conditions on the adsorption performance of activated carbon and Zn-MOF-74 for methane were investigated,and three temperature gradients of 278 K,298K,and 318 K were set to simulate adsorption experiments.The simulation results show that the adsorption performance of AC-2 activated carbon is the best when the temperature is 298 K.An increase in temperature will inhibit the adsorption of methane,but the smaller pore size range AC-3(5-10(?))is significantly less affected by temperature.Zn-MOF-74 can prove that the adsorption effect of Zn-MOF-74 is greater than that of activated carbon from the perspective of adsorption rate and adsorption capacity.(3)The activated carbon and Zn-MOF-74 model were modified with-OH,-NH2,-CH3,-Br functional groups,and the influence of different functional groups on the adsorption performance of activated carbon and Zn-MOF-74 was explored.The results of the study show that at 298 K,basic functional groups such as-OH and-NH2 increase the adsorption performance of AC-2 activated carbon,and the adsorption effect is increased by about 30%;-CH3,-Br functional groups enable the adsorption of Zn-MOF-74 The performance is increased by about 10%,and the modification effect of surface functional groups on activated carbon is more obvious.(4)The adsorption process of activated carbon and Zn-MOF-74 for simultaneous adsorption of methane and carbon dioxide has been studied.The results show that the adsorption capacity of carbon dioxide is much greater than methane at a temperature of 298 K,and the presence of carbon dioxide molecules inhibits the adsorption of methane;In the vicinity of the pressure of 3500-4000 k Pa,it is the most suitable activated carbon material to separate methane and carbon dioxide gas.