| CBM is an efficient and clean energy and in recent years the governments have constant attention on it. United States, Australia, have launched related work, and have made significant achievements. China has always paid attention on the development and utilization of coal-bed methane, but because of special conditions, many coal mines directly emit large quantities of low concentration CBM. This action not only caused a huge waste of resources, but also caused serious environmental pollution. Therefore, the effective use of low concentrations of coal-bed methane is an important subject of coalbed methane development. In the utilization of low concentrations of coalbed methane, the deoxygenation is a key factor, in addition to the nitrogen is an important step. MOFs is potential porous material, who has shown a huge advantage in these two areas. However, MOFs materials are not stable, how to solve this problem has become an important topic.This article selected M-BTC as a material object, under different conditions synthesized sample Cu-BTC, Cr-BTC, in subsequent trials examined in detail the synthesis temperature, reaction time, material ratio on the samples synthesized to obtain the optimum reaction conditions. And powder X-ray diffraction(PXRD), N2 adsorption analysis have also been used. The main contents and conclusions include the following:(1) Optimum conditions of synthesis metal-organic framework compound Cr-BTC is: Cr(CO) 6, 1.09 g(5 mmol); 1,3,5- benzenetricarboxylic acid, 0.623 g(3 mmol); N N-dimethylformamide, 50 ml; heating temperature of 393 K, reaction time 48 h.(2) Cr-BTC oxygen adsorption-desorption properties. After repeated adsorption-desorption of oxygen, Cr-BTC can maintain oxygen uptake capacity, but it occurred some changes. Temperature performance has little effect of Cr-BTC oxygen uptake, only at higher temperatures, which the oxygen uptake will be decreased. Cr-BTC-deoxy is mainly effected by the pressure and temperature. Oxygen can not be desorbed under high pressure, when the pressure reaches about 0.05 bar, oxygen began to be desorbed. Deoxy overall rate increase with increasing temperature, and the desorption rate of oxygen continues to decrease with time.(3) The stability of Cu-BTC and Cr-BTC is investigated under oxygen atmosphere, water vapor environment, O2-H2 O environment. In the oxygen atmosphere, Cu-BTC and Cr-BTC structure are destroyed. In the water vapor environment, structural damage of Cu-BTC and Cr-BTC is higher than the oxygen environment. In the O2-H2 O environment, specific surface area of Cr-BTC and Cu-BTC dramatically changed. O2-H2 O environment is the most influential environmental in the three environments of this paper.(4) Organic molecules of different functional groups, different carbon atoms have different influence on the stability of Cr-BTC. When the organic molecules contain the same functional group, the stability increases with the number of carbon atoms, when it reaches three carbon atoms, it is most stable. When the number of carbon atoms is the same, different functional groups can affect the stability of Cr-BTC. Bromides are most stable, followed by an amine, an alcohol again. When the organic molecules have two identical functional groups, the stability of Cr-BTC greatly reduced. |
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