Study On Modification Of Activation Carbon Fibers And Their Adsorption And Desorption Performance Of Gasoline

In the process of petroleum products loading,unloading,storage,transportation,or distribution,a great deal of the petroleum vapor are evaporated and emitted from the tanks to air,which will not only bring on serious petroleum loss,but do harm to the environment and the health of people.So it is very important to carry out the research of gasoline vapors recovery.Till now,adsorption has been the most widely used method to recover gasoline vapors,during which the adsorbent is the key.Though activated carbon is the commonly used adsorbent,it still has some disadvantages,such as low adsorption capacity,poor wearing quality and high temperature in fixed bed.Activated carbon fiber,as a novel adsorption material,has the disadvantages of high adsorption capacity,excellent wearing quality and low temperature in fixed bed,which has a broad application prospect in gasoline recovery.However,there are few studies on the application of activated carbon fiber as adsorbent for gasoline recovery.This paper firstly investigated the performances of adsorption and desorption of activated carbon fiber in the process of gasoline recovery under different operating conditions,which the activated carbon fiber is used as the adsorbent.Then the activated carbon fiber is modified by potassium hydroxide and high temperature heat treatment,through a variety of characterization methods to investigate the modification of pore structure and surface groups of the effects of activated carbon fiber,then the modified samples are used in the process of gasoline recovery.Finally,analyze the adsorption property of modified activated carbon fiber combined with dynamic adsorption experiments.The results show:In the process of dynamic adsorption experiments,the bigger the inlet concentration of gasoline is,the better adsorption properties of gasoline the activated carbon fibers show,and the higher temperature the bed rise,but the less the breakthrough time and saturation time is.The amount of activated carbon fiber has little effect on the adsorption performance,but the amount of activated carbon fiber and the penetration time is proportional to.Therefore,in the research and practical application,we can maintain a certain adsorption desorption cycle by controlling the inlet gasoline concentration and the amount of adsorbents,which can also effectively control the temperature rise of the adsorption bed to prevent accidents.The desorption rate of activated carbon fiber is different with different desorption methods.In addition,the adsorption performance of activated carbon fiber decreased with the increase of the number of desorption regeneration,and finally the stabilized.During the vacuum desorption,the lower the vacuum degree is and the longer the desorption time is,the better the desorption effect is,the highest desorption rate was 39.2%,and the breakthrough adsorption amount of activated carbon fiber is almost unchanged after 20 cycles,which is reduced to 37%of the original sample.During the heat desorption,the higher the heating temperature is,the better the desorption effect is,the highest desorption rate was 52.9%,the breakthrough adsorption amount of activated carbon fiber is almost unchanged after 12 cycles,which is reduced to 51.2%of the original sample.During the high temperature N₂ desorption,the higher the temperature of the N₂ blowing is and the longer the desorption time is,the better the desorption effect is,the highest desorption rate was 72.1%,and the breakthrough adsorption amount of activated carbon fiber is almost unchanged after,which was reduced to71.7%of the original sample.The main factors that affect the adsorption performance of ACF on gasoline are the number of micropore and the number of surface oxygen-containing functional groups.The more the micropore,the less the surface oxygen-containing functional groups,especially the acidic oxygen-containing functional groups,the better the adsorption performance of the ACF on gasoline.After the modification of KOH,the number of micropore of ACF increased slightly,while the number of acidic oxygen functional groups on the surface is obviously reduced,therefore,the adsorption performance of the modified ACF on gasoline is increased,the breakthrough adsorption capacity increased by 23.2%compared to the original sample.After the modification of high temperature heat treatment,the number of micropore the modified ACF is significant increased,and the amounts of acidic oxygen-containing functional groups also greatly reduced,therefore,the adsorption performance of the modified ACF on gasoline is greatly increased,the breakthrough adsorption capacity increased by 37.2%compared to the original sample.