The Preparation Of Microporous And Mesoporous Materials And Their Capture Performance Toward CO₂

Excessive emissions of greenhouse gases such as CO₂,is one of the main causes of global warming,therefore the CO₂ capture and storage is a scientific and environment problem related to human development.This dissertation is dedicated to broaden research on the preparation and application of N enriched microporous activated carbon and mesoporous MgO/?-Al₂O₃,explore the CO₂ capture performance and adsorption mechanism of N enriched microporous activated carbon and the modification of alkaline earth metal Mg on mesoporous MgO/?-Al₂O₃,the main results are as follows:?1?Using the procambarus clarkii shell as raw material,K₂C₂O₄.H₂O as activator,N enriched activated carbon with micropores were prepared by carbonization and activation through one step method.By using X ray diffraction?XRD?,scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,nitrogen adsorption desorption,Fourier transform infrared spectroscopy?FT-IR?,X ray photoelectron spectroscopy?XPS?characterization methods,the phase,microstructure,pore structure and surface chemical properties of sorbents were investigated and study the effects of the amount of activator,activation temperature on the static,dynamic adsorption of CO₂.When the activator/procambarus clarkii shell mass ratio ranges from 1:1 to 5:1,activation temperature increases from 650°C to 750°C.?1?In a variety of forms containing N?pyridine N,pyrrole N,quaternary N?exist in carbon skeleton.The pyrrole N content is the largest favorable for CO₂ adsorption;?2?The relationships between the textural properties(S_BET,S_tBET,V₀,V_t)and the content of N are not directly related to the adsorption capacity of CO₂.But they play a big role on the adsorption of CO₂ in synergistic effect mechanism.Under static adsorption,the adsorption capacity of CO₂ at 25°C and 0°C were as high as 4.51mmol/g and 6.48mmol/g,respectively.The CO₂/N₂ adsorption selectivity was 52,which simultaneously show the high adsorption capacity and high selectivity.Adsorption heat of samples in the 29-33 kJ/mol still belongs to physical adsorption process.The dynamic adsorption of PK-3-700 in the mixed gas of CO₂/N₂?10:90 v/v?,the CO₂adsorption capacity is 0.79 mmol/g,which coincides the value of pure CO₂ gas in the partial pressure of 0.1bar under static adsorption.In addition,the material in 15 times circulation only slightly decreased thus exhibited excellent regeneration cycle.?2?Using cheap inorganic aluminum salt Al?NO₃?₃.9H₂O as aluminum source,inorganic Mg?NO₃?₂.6H₂O as source of magnesium,NaAlO₂ as both aluminum source and the precipitating agent,P123 as template,MgO/?-Al₂O₃ adsorbents were synthesized by one pot double hydrolysis method.By using XRD,SEM,TEM,nitrogen adsorption desorption,diffuse Fourier transform infrared spectroscopy?DRIFTS?,CO₂ temperature programmed desorption?CO₂-TPD?characterization methods,the adsorbent phase,microstructure,pore structure,physical and chemical properties,alkaline surface were inverstigated.The static adsorption amount of Mg/Al-0??-Al₂O₃?,Mg/Al-0.1,Mg/Al-0.2,and Mg/Al-0.3 were as high as 1.53mmol/g,1.22 mmol/g,1.14 mmol/g and 1.08 mmol/g,this change trend coincided with their surface area,which may be attributed to the adsorption capacity of CO₂mainly by Van der Waals force and hydrogen bond adsorption dominated under low temperature and low pressure.In dynamic adsorption;the determination of CO₂adsorption in simulated flue gas.By changing the amount of Mg,the experimental results show that MgO/?-Al₂O₃ sorbents have 3 kinds of basicity sites during CO₂adsorption in forms of bicarbonate,bidentate and monodentate carbonate,respectively.When the Mg/Al molar ratio is 0.2,in atmospheric at 60°C reached maximum CO₂adsorption capacity of 1.6mmol/g,because of the number of basic sites of Mg/Al-0.2is the highest,with the introduction of water vapor,the adsorption capacity increased up to 2.1 mmol/g,which is mainly due to the formation of more carbonate.In addition,the material can be cycled 11 times before slightly decreased,showing excellent recycling performance.