Study On Preparation Of Magnesium Oxide Adsorbent And Its Adsorption Of CO₂

With the increase of carbon dioxide emissions,the greenhouse effect is becoming more and more serious,and the treatment of carbon dioxide emission reduction is urgent.Coal-fired power plants are the primary source of concentrated carbon dioxide emissions.For power plants that are currently under construction and have been put into production,post-combustion capture technology is the most useful and economical measure to control carbon dioxide emissions.The metal oxide adsorption material is an ideal CO₂ adsorbent for the power plant flue gas temperature?about50⁹0??,low CO₂ partial pressure,and certain relative humidity in the flue gas.In the metal oxide-based adsorbent material,the MgO adsorbent adsorbs the CO₂temperature below 200?,and the adsorption temperature of the magnesium oxide is in the temperature range of the flue gas.At the same time,MgO is suitable for adsorbing CO₂ from coal-fired flue gas containing a certain relative humidity.In addition,MgO is usually present in large quantities in the form of magnesite,which is convenient for large-scale and low-cost manufacturing.Considering comprehensively,magnesium oxide is an adsorbent that is very suitable for capturing CO₂ in flue gas from coal-fired power plants.In view of the current poor performance of MgO adsorbent and the unclear adsorption performance of adsorbent under coal-fired flue gas conditions,the adsorbent performance and influencing factors of magnesium oxide under the conditions of MgO adsorbent preparation and coal-fired flue gas respectively And other aspects of research.The main research contents and conclusions are as follows:The porous structure and adsorption properties of MgO adsorbents prepared by different kinds of precursors were studied.According to scanning electron microscopy?SEM?,X-ray diffraction?XRD?and nitrogen adsorption desorption curve,the results show that the surface morphology of MgO adsorbent is affected by the morphology of the precursor and is similar to the morphology of the precursor.The porous magnesium oxide adsorbing material is prepared by calcining the precursor in the decomposition process by the release of by-product water and carbon dioxide.The MgO adsorbent prepared by calcining a magnesium oxalate precursor having a relatively high average molecular weight has a large specific surface area.The adsorption of carbon dioxide by MgO adsorbent is mainly chemical adsorption,accompanied by a small amount of physical adsorption.Therefore,the amount of MgO adsorbed by CO₂ is related to the specific surface area.Magnesium oxide prepared by three precursors of magnesium hydroxide,basic magnesium carbonate and magnesium oxalate has a specific surface area of 136.5m²/g,125.3m²/g,and160.1m²/g,respectively.Among them,the magnesium oxide material prepared by magnesium oxalate has a large specific surface area and a large amount of adsorption to carbon dioxide.By studying the effects of various factors on the adsorption of carbon dioxide by magnesium oxide,the primary and secondary factors affecting the adsorption amount were obtained by orthogonal test.The order of the primary and secondary is the relative humidity of the flue gas,the gas flow rate,and the reaction temperature;the optimum process conditions are combined to a relative humidity of 50%,a gas flow rate of 150 ml/min,a reaction temperature of 50?,and the maximum amount of carbon dioxide adsorbed by the magnesium oxide.The amount was 3.52 mol/kg.