Study On The Adsorption And Separation Law Of Gas By Modified Carbon Nanospheres

Methane gas is an associated energy source for coal.my country is rich in coal resources,but the gas utilization rate is low,and coal mine gas emissions rank first in the world.Most of the higher-concentration gas can be used directly,but a large amount of air will be mixed in during the drainage process,and it will be transformed into low-concentration gas that cannot be directly used.The purification and utilization of low-concentration gas has multiple implications for the environment and resources.Low-concentration gas separation and purification technologies continue to develop.Among them,pressure swing adsorption technology is widely used due to the advantages of high device reliability and low economic cost.Therefore,this thesis explores the influencing factors of the optimized preparation ofcarbon nanospheres and penetration column adsorption and separation of gas,as the basic experimental research of pressure swing adsorption.First of all,carbon nanospheres have the advantages of rich pore size and high stability,and are widely used in water purification,gas adsorption and other fields.In this paper,glucose is used as the carbon precursor,and the carbon nanospheres prepared by the hydrothermal synthesis method have low selectivity for gas adsorption.Therefore,through physical activation method,KOH chemical activation method,and metal ion loading surface modification methods,thecarbon nanospheres were activated respectively,and the samples were measured with the help of several modern analysis techniques such as SEM,XRD,FTIR,BET and XPS The morphology,structure,and the use of a multi-component gas competitive adsorption analyzer to test the adsorption selectivity ofcarbon nanospheres to methane gas.The change of hydrothermal synthesis conditions has a great influence on the morphology ofcarbon nanospheres,but the separation performance of gas gas is very poor.After various activation methods,thecarbon nanospheres have a rich microporous structure,and the gas adsorption selectivity is greatly improved.Among them,the specific surface area of the carbon nanospheres treated with KOH chemical activation reached1066 m²/g,and the adsorption selectivity for CH₄/N₂was the best.Secondly,with the help of a multi-component gas competitive adsorption analyzer,the influence of the types of adsorbents,the size of the adsorption column,the flow rate and concentration of the feed gas on the law of gas adsorption and separation were explored.By comparing the penetration curves of four adsorbents:carbon nanospheres,activated carbon,carbon molecular sieve,and 5A molecular sieve,the modified carbon nanospheres have the strongest adsorption selectivity for CH₄/N₂/O₂,and carbon molecular sieve has the best O₂separation effect.The influence of the size of the adsorption column on the penetration law is considered in three aspects:(1)In the same adsorption column,the adsorbents of different masses(different aspect ratios)are filled.The greater the penetration and separation of CH₄/N₂.(2)In the adsorption columns of different sizes,the adsorbent is filled to the same aspect ratio.The larger the diameter of the adsorption column,the greater the packing quality and the greater the adsorption and separation of gas.(3)Adsorption columns of different sizes are filled with adsorbents of the same mass.The smaller the length-diameter ratio of the packed adsorbents,the greater the adsorption and separation of gas.The greater the flow rate of the feed gas,the shorter the contact time between the adsorbent and the adsorbate,and the worse the adsorption and separation of the gas.In the raw gas components,the CH₄concentration increases and the CH₄breakthrough time is advanced,which makes the breakthrough curve steeper,which is not conducive to the adsorption and separation of gas gas.Through the above basic experimental research,it can provide guidance for the setting of pressure swing adsorption parameters.Take this experimental system as an example.KOH-CS-1-900 is selected as the best adsorbent for CH₄/N₂separation,and carbon molecular sieve is used as the adsorbent for separating O₂from gas.The adsorbent with the largest packing mass(the maximum allowable packing capacity of the adsorption column volume)in the adsorption column with a volume of 100 m L and a diameter of 2.4 cm has the best purification effect on gas.The smaller the feed gas flow rate(the total feed gas flow rate is 50 m L/min)and the smaller the concentration of CH₄,the stronger the selective adsorption performance for methane gas.The thesis has 39 pictures,36 tables,and 82 references.