Research On Calcium Based High Temperature Carbon Dioxide Adsorbent

The greenhouse effect has become a major issue in the world climate and Carbon dioxide is one of the main greenhouse gases.The global annual emissions is up to 20 billion t.However, fossil fuel emissions accounted for 75% of global carbon dioxide emissions, fossil fuel power plant flue gas emissions accounted for 46% accounts for the largest proportion of all carbon emissions.The main characteristics of flue gas is high flow, high temperature, low content of carbon dioxide ?10%-15%? gas, complex coexistence ?solid particles, SO₂, NO_x, HCl? relatively high difficulty of separation.The traditional separation technology is cooling the flue gas temperature, which will undoubtedly bring great energy loss, so the study of adsorbent under high temperature carbon dioxide adsorption has great significance.In this article, calcium based sorbents are token as the research objects.Using fixed-bed evaluation unit, the influence of the calcining temperature, calcining time and adsorption temperature, adsorbent particle size, gas concentration, gas flow rate on the adsorption breakthrough curve were investigated. The results show that the calcination temperature at 800? for 1h got the best adsorption effect; the best adsorption temperature was 650 ?; the mixed gas flow rate is 60ml/min, the concentration of carbon dioxide is 16%; the adsorbent particle size is 180um-250um. The adsorption capacity of the adsorbent will get the maximum.By using the orthogonal experiment,we get the impact of various factors is as fllows, the mixed gas flow rate> the concentration of carbon dioxide> the adsorption temperature> the adsorbent particle size.For the single metal doping, although the modified adsorption capacity were all decreased, we almost all improve its stability. When the doped Al the adsorption capacity decreased and with the increase of the doping ratio the breakthrough time decreased. After the calcination temperature, ?CaO?₂ ?Al₂O₃?₇ has generated which has a positive effect to improve the cycle stability of the modified adsorbent. Mg modified adsorption has the presence of MgO agent. The reactions of MgO and CO₂ generates to MgCO₃ which can absorb a certain amount of CO₂ But the decomposition temperature of MgCO₃ is 540?, MgCO₃ will quickly decomposed in the reaction process which will not very good at the adsorption of CO₂. Although the La modified adsorbent adsorption capacity declined,the decline is not too much. It is also the good choice of the single metal modified adsorbent of calcium oxide. When the double metal modified, there has an appropriate value metal element proportion. For instance, in this experiment, Al/Zr double metal modified 7:3will be the best proportion. Comparison of the cycle stability of metal doped double agent and the single metal doped, Mg/Zr doped double metal the best ratio is 7:3which has showed good synergistic effect.