| With the growing environmental issues and the lack of fossil fuels, developing the use of H2, CH4and other clean energy to reduce energy consumption and pollution, has become an urgent task today. In addition, CH4is a long-lived greenhouse gases, its global warming potential (GWP) is21times of CO2. Therefore, the rational use of CH4can not only ease the energy crisis, but also control the greenhouse effect. CH4coexist with CO2and other gases in the wide sources, such as natural gas, biogas, landfill gas and coal bed methane. The CO2reduces the heat of combustion of CH4, and cause corrosion in the transport pipeline at the same time. In fact, CO2is an important resource in many fields such as preservation of agricultural products, beverage processing, and supercritical extraction. In short, the separation of CH4/CO2mixture gas is very important.There are many methods for separating these mixture gases, such as adsorption, chemical absorption, membrane separation, cryogenic separation and chemical conversion. The adsorption have the many advantages, so more and more cholars focus on this method. In the adsorption separation process, adsorbent is a key factor. So far, almost all of the adsorbents, such as zeolite, activated carbon, mesoporous silica, silica gel and MOFs, are used in this field. Two modification methods (ion-exchange and grafting of amine groups) are often applied to enhance the separation performance of the adsorbents.In our study, adsorption isotherms is measured via the volumetric method. Adsorption equilibrium is a very slow process, so we have to spend a lot of time to determine the adsorption isotherm. In order to improve work efficiency and shorten time of the test, we have designed a highly efficient static adsorption equipment, by which isotherms of multi-samples could were tested at the same time.The key question of this study is the removal of high concentrations of carbon dioxide, and the core of pressure swing adsorption process is adsorbent. Before synthetize adsorbent, we need to design characteristics of adsorbent. In this work, two aspects (chemical essence and the pore structure) was designed. We get same conclusion:the chemical essence of aluminosilicate, mesoporous structure and small specific surface area are conducive to the separation CO2/CH4mixture gas, so we think that mesoporous aluminosilicate is best choose for separation of CO2/CH4. The two types of mesoporous aluminosilicate were synthesized via different routes and conditions, same conclusion were obtained:(1) Al-MCM-41:the best crystallization temperature is100℃and secondary crystallization could enhance ion exchange performance of Al-MCM-41; K-Al-MCM-41b obtained from secondary crystallization and ion exchange have better separation performance than K-Al-MCM-41a obtained once crystallization. Potassium ions play an important role in enhancing separation performance of the Al-MCM-41; the separation factor of Al-MCM-41is from2to3, and this type material did not achieve the desired goals.(2) The mesoporous aluminosilicate synthetized via using zeolite seed as precursor:excellent separation performance of this type mesoporous aluminosilicate was obtained and separation factor is from80to1000; the optimum synthesis conditions are that:pH=11, crystallization time=5hours, Si/Al=0.5-3. |
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