Cao Based High Temperature Carbon Dioxide Adsorbent Carbonate Reaction Kinetics Study

Since the20th century, the emission of the greenhouse effect gas has increased heavily with the globally use of the fossil energy. At the same time, the severe climate disaster has been brought about following the global warming. The emission of CO2as the main greenhouse effect gas becomes more and more with the development of the economic, which draws more attention of human beings. The main emission source of CO2is the burning of fossil energy, and the power sector is included. The characteristic of the CO2emission of the power sector is high temperature, while the present recovery technology of CO2is conducted at low temperature, which makes the cost increasing. So it is a hot spot to develop a CO2trapping and recover technology to reduce the emission of greenhouse effect gas. The CaO-based CO2adsorbent at high temperature becomes a hot spot at present because of its advantages such as low cost, cycle use, convenient regeneration and so on. But its reaction process with CO2is influenced by a lot of factors, such as the grain diameter, the concentration of the reactant gas, reaction temperature, and its adsorption process is influenced by reaction kinetics, diffuse kinetics and thermodynamics. So it is very important to improve the cycle number of uses and adsorption property by studying the reaction kinetics of carbonation at high temperature.In this article, the CaO adsorbents preparated by high temperature melt method of solid were divided into three grain diameter as the object of study. I studied how the concentration of reaction gas, adsorbent grain and heating rate influenced the carbonation reaction by thermal analysis method. I found that the chemical reaction control stage is not influenced by the increasing of the concentration of reaction gas, while the diffusion coefficient of ash content layer and the carbonation degree of CO2is increased by increasing the concentration of reaction gas at the ash content layer diffusion control stage. From the experiment of the CaO carbonation influenced by heating rate, I found that the weightlessness peak of thermoanalysis DTG curve is retruded with the increasing of heating rate for the same grain diameter adsorbent, and the reaction temperature higher, the reaction rate corresponding the weightlessness peak is lower. From the experiment of the CaO carbonation influenced by grain diameter, the weightlessness peak of thermoanalysis DTG curve has the same reaction temperature corresponding the weightlessness peak at the same heating rate, and the grain diameter smaller, the reaction rate corresponding the weightlessness peak value and the maximum chemical reaction rate larger. I analyzed the dynamics of the carbonation process to study its reaction character. I found that the kinetic parameter is influenced heavily by the ash content layer diffusion with the increasing of percent conversion at the carbonation reaction progress. The apparent activation energy is dropped with the increasing of the carbonation reaction degree. And the grain diameter bigger, the drop severer. The adsorption penetrate experiment was conducted at the constant temperature for the different grain diameter by fixes bed. All of the adsorbents with different grain diameter have the longest breakthrough time at600℃. And the breakthrough time is longer while the grain diameter is smaller. The experiment of concentration of reaction gas shows that the breakthrough time is longer with the increasing of the gas concentration.