| Gas adsorption separation technology can recycle and purify hydrogen,carbon dioxide,carbon monoxide and other gases from various kinds of mixture and industrial waste gas,which has been widely used and development in recent years because of the characteristics of low energy consumption and obvious comprehensive utilization effect.Gas adsorption separation,successful or not,largely depends on the choice of selective adsorption capability.The separation selectivity of the adsorbent was mainly through molecular size and the adaptability of pore diameter,which was given priority to the selectivity of shapes,so having uniform ultramicropore should be the most important thing of adsorbent for gas separation.In this thesis,ultramicroporous activated carbon is a carbonaceous product which is derived by controlling pyrolysis of Shannxi Shenmu semi-coke under part of the water vapor circumstance with thimbleful KOH impregnation.The properties of activated carbon were characterized by using N2 adsorption-desorption techniques,iodine adsorption and methylene blue adsorption,Boehm titration,TG/DTG,XRD,TEM and H2 adsorption capacity test,etc.Optimization of activated carbon performance was established in relation to pretreatment of raw material,activation method and conditions for the controlling pyrolysis.The effects of activated carbon as an adsorbent for adsorption separation was also discussed.Adsorptive property of activated carbon prepared by different temperature program under the condition of the same condition had a greater different.The properties of activated carbon were the best which was prepared at room temperature,heating up to 370?,keep in 1h and continuing to heat up to the predetermined activation temperature.The atmosphere components also had an influence on the pore structure and surface properties of activated carbon.The BET surface area,total pore volume and microporosity of activated carbon prepared under N2 atmosphere with a mixture of water vapor displayed 598.5m2/g,0.31cm3/g and 68.7%,which were greater than the property of activated carbon prepared under pure water vapor atmosphere and pure CO2 atmosphere.The number of pores,specific surface area and total volume of activated carbon were increased by low concentration KOH impregnation.Ultramicroporous activated carbon can be prepared by controlling pyrolysis under part of the water vapor circumstance after impregnatd at room temperature by 5-15wt% KOH with KNO3 as the oxidant.An orthogonal design was employed and the optimized conditions were obtained at the activation temperature 900?,activation time 1h,KOH concentration15% and impregnation time 24 h.The results indicated that the iodine sorption value of the resulting activated carbons under the optimum condition was 840.0mg/g.BET surface area was 725.8m2/g,medium pore diameter was 0.51 nm.Microporous entrance space contributions accounted for 70.8 percent of total pore volume.The samples were given priority to ultramicropores,Pore diameter are mainly distributed in between 0.48?0.52 nm,ultramicropores had the concentrated distribution.Experiments of hydrogen pressure swing adsorption showed that the adsorption quantity and the biggest test pressure displayed 96.9Bar and 35.30cm3/g in the process of the actual test.According to the theory of Langmuir,the maximum adsorption quantity of the samples and Langmuir pressure displayed 76.86cm3/g and 113.6Bar.So the ultramicroporous activated carbon prepared in this study is the most suitable alternative adsorben to apply in pressure swing adsorption about purification of hydrogen gas from coke oven gas.Activated carbon can be prepared under part of the water vapor circumstance from semi-coke oxidation pretreated by the concentration of 10?30% nitric acid dipping ratio 1:1.Regarding the iodine adsorption,showed a peak value with the increase of concentration of nitric acid.The methylene blue adsorption showed the trend of rising.The yield fell slightly.Its content of acidic oxygen containing functional groups increased rapidly.BET surface area,micropore volume and total pore volume of activated carbon oxidized by HNO3 were ranked only second to activated carbon impregnated by KOH.The adsorption of hydrogen effect is worse than the latter,but its content of acidic oxygen containing functional groups was much more than the latter,which could be suitable for different purposes... |
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