Synthesis Of Calcium Based Absorbent And Its CO₂Circulation Absorption Performance

There is a widespread concern over the issue that the global warming is gettingworse in recent years. It has greatly affected the production and living of people. Asone of the main greenhouse gases, the emission load of carbon dioxide (CO2) increasegradually and must take action to control it. On the other hand, it has been usedwidely in industry. If the CO2can be captured and applied by appropriate method, itwill have very high environmental and economic value. So CO2capture has become amajor theme in research.The emission of CO2mainly comes from the burning of fossil fuels and otherchemical process, which is accompanied by a high temperature state. So the absorbentof CO2at high temperature becomes a major theme. There are two kinds of material:Lithium-based absorbent and calcium-based absorbent. Besides of large absorption,calcium-based sorbent not only has wide source of raw materials, but also has lowprice. However, the disadvantage of calcium-based sorbent is that it will generatesintering phenomenon among the process of CO2cycle adsorption-desorption, whichwill decrease its adsorptive capncity. In order to improve the absorption in the processof multiple cycles, this paper researched the technology of calcium-based sorbent bycalcined calcium carbonate which prepared by carbonization method using limestoneas raw materials. X-Ray Diffraction (XRD), scanning electron microscope (SEM), thedevice of CO2absorption/desorption and so on were used to characterize the size andmorphology of sample’ particle and the performance of CO2cycleadsorption-desorption. Based on the above research, some results were obtained asfollows:The loss on ignition of limestone materials which was calcined1h at900oC was42.8%which closed to the theoretical value; the absorption of lime which calcined1hat600oC in CO2atmosphere is larger. In the process of synthesis of calcium carbonate,the lower the carbonization temperature, the smaller the calcium carbonate particles.And the shortest time of the synthesis of calcium carbonate is40oC. As CO2concentration in the mixed gases raised, the synthesis time of calcium carbonate was shortened and its particle size increased slightly. In the process of synthesis ofcalcium carbonate by using carbonization, adding crystal-growing controlling agentof ethylenediamine tetraacetic acid, hexadecyl trimethyl ammonium bromide, zincsulfate, citric acid into reaction, calcium carbonate was prepared with a spindle, cube,spherical particles, irregular shape.Compared with the calcium-based sorbent of raw material calcined, the calciumbased sorbents obtained by carbonation method have better CO2cycle absorptionperformance. Added crystal-growing controlling agent of ethylenediamine tetraaceticacid, hexadecyl trimethyl ammonium bromide, citric acid into carbonation reaction,the30cycle CO2absorption rate of corresponding calcium based sorbent were41.9%,30.9%and43%. Among these, the calcium based absorption of adding citric acid hadthe best performance, which circulation absorption15times of CO2absorption ratewas as high as75.5%. But, the calcium based absorption of adding zinc sulfate wasgreatly reduced of CO2absorption performance.Compared with the calcium based sorbent of raw material calcined, the first CO2absorption rate of the calcium based sorbent which mixed strontium carbonate oraluminium nitrate is reduced to78.1%and75.6%from80.3%. But the absorptionrate decreased slowly with the rise of number of cycle. After30cycle absorption, theabsorption rate of the calcium based sorbent which mixed strontium carbonate/aluminium nitrate increased to32.9%and49.9%from31%.