The Synthesis Of Mesoporous Activated Carbon And The Basic Research On Separation Of N₂/CH₄Mixtrue Gas By Hydrate

With the global economic development and the population growth, the energy problems and environmental pollution abstract human’s attention. It makes human being to find out an appropriate alternative fuel to release the pressure on petroleum demand. As natural gas is a kind of clean energy, and it is abundant and cheap, so it will play an important roll in the future framework of energy. The greenhouse effect of methane is very strong. The coal-bed gas resources of China is rich. The direct emissions of coal-bed gas not only is a waste of resources, but also pollute the environment. Therefore it is necessary to enhance the separation and utilization of methane in coal-bed gas. As a way of methane storing, the advantages of nature gas hydrate (NGH) are high adsorption capacity, the low required pressure, mild temperature and low cost, however the disadvantages of NGH are the slow formation rate and low water utilization. NGH is in the development stage now. In this paper, we try the way of combining activated carbon and additives to increase the formation rate and water utilization.At first, we prepared the activated carbon with the KOH activation method. After characterizing the surface physical properties, we chose the activated carbon prepared under the conditions of carbon materials grinding and sieving, carbon-base ratio is4.0:1, roasting temperature is780℃and roasting time is90min. The specific surface area of activated carbon is2373m2/g, and the pore volume if1.427mL/g.On the impact study of various additives to gas hydrate formation in activated carbon hole, we carried on the experiments under conditions of different Rw and different additives. Under the condition of Rw=2.0, type I methane hydrate has formed, the jump pressure was4Mpa, adsorption capacity was high and water utilization was high, but the induction time was long and the formation rate was slow. In the experiments of different additives, the addition of300ppm SDS had the better promoting effect, not only the maximum capacity was higher, but also the induction time (60min) was shorter than the induction time(550min) without additives. With the addition of20%THF, the methane adsorption isotherms would be formed of two adsorption platforms, which was due to THF could be reacted with water to form THF hydrate, which made the methane hydrate converte to hydrate type II. As the Rw and THF concentration was at certain condition, the temperature would have effect on pressure of the jump point, and no effect on the capacity of methane adsorption. By calculating, we proved that the appearance of jump point was due to the formation of methane hydrate. In the experiment of nitrogen adsorption, nitrogen and methane adsorption isotherms were significantly different, that made the method of methane hydrate to separate methane and nitrogen possible.