Preparation And CO₂ Adsorption Performance Of Biological Carbon-based CO₂ Adsorbent

A large amount of carbon dioxide(CO2)emissions aggravate the greenhouse effect and climate change.In particular,CO2 emissions from the combustion of fossil fuels are considered the major contributors.Therefore,mitigation of CO2 emission is vitally necessary and urgent Up to now,several technologies have proven effectiveness for CO2 capture,including adsorption,absorption,and membrane separation.Above all,adsorption is regarded great promising technology due to its facile operation,low energy consumption,and easy for practical application.The key of adsorption is to obtain adsorbents with good adsorption properties.In this thesis,palm kernel shell-porous carbon have been prepared and their CO2 adsorption properties have been investigated.The summaries of the results are as follows:1.Micro-mesoporous metal-doped porous carbon was prepared by activation and modification of same precursors with different metal nitrates as auxiliary activators and catalysts.After that,the metal-doped porous carbon was treated by acid pickling,which not only removed the residual metal,but also improved the pore structure characteristics,which showed that the pore size distribution was wider and wider.At the same time,its CO2 adsorption capacity can reach 4.64 mmol/g under 1 bar at 25?.It has been confirmed that the high CO2 adsorption performance of metal-doped porous carbon adsorbents not only attributes to the developed porous structure,but also plays an important role in the chemical adsorption of metal doped in the biochar skeleton.In addition,metal-doped porous carbon adsorbents with excellent adsorption performance,excellent CO2/N2 selectivity and stable recycling performance under simulated flue gas conditions,which show strong competitiveness in CO2 capture.2.Nitrogen-rich porous carbon was prepared by one-step simultaneous in-situ N-doping and activation method with waste palm kernel shell as precursor,urea as auxiliary activator and nitrogen source.This mild preparation method not only keeps the conducive nature structure of biomass,but also can improve the efficiency of nitrogen doping.The natural template provided by the silicon-rich raw material was treated by simple acid washing to obtain a hierarchical porous adsorbent with well-developed pore structure.The obtained samples exhibit predominant characteristics with highly developed micropores and a high N content providing an important contribution to CO2 adsorption capacity,which can reach up to 5.29 mmol/g and 2.30 mmol/g under 1 bar at 25 and 60?,respectively.Moreover,the resultant porous carbons also exhibit an excellent cycling stability after 20 cycles.Furthermore,the one-step simultaneous in-situ N-doping and activation mechanism was investigated by the quantitative thermogravimetry-mass spectrometry(TG-MS)method.