| Due to the abundant volumes of micropore, homogeneous pore structure and favorable chemical stability of carbon molecular sieve (CMS), it exhibits wide application in some fields of petrochemical industry and environmental protection. For instance, CMS can separate and purify gas mixture and water. Besides, it also can serve as catalyst or catalytic carrier. Coal contains high level of fixed carbon and organic matters, thus, its application in producing CMS has long been researched. However, its low quality and performance have limited its development. Therefore, developing the coal based CMS with high quality is the key to solve these problems in China.Anthracite and bituminous coal in high deterioration were chosen as raw materials to produce coal based carbon molecular sieve. The process of this study was as follows:First of all, analyzed the raw materials, and particularly, researched the pyrolytic reaction of anthracite to get its heat treatment temperature range. Furthermore, studied raw materialstechnical parameter of carbonization and activation to investigate whether coal types, their particle sizes and activation condition would influence the productsstructure and adsorbability. Moreover, produced the target material i.e. CMS from anthracite, and indicated its structure and adsorbability.According to our study, we gained some valuable information. Anthracite is suitable to make CMS, owing to its ash and volatile matter in low grade and fixed carbon in high grade. The pyrolytic reaction of anthracite mainly occurs between500～1000℃. Especially, there are two gas-producing temperature ranges concentrated at650℃and800℃, respectively. Different from anthracite, bituminous coal possesses low fixed carbon and high volatile matter content. Nevertheless, it also can be used in preparing CMS. Its pyrolytic reaction mainly occurs between500-900℃. And two gas-producing temperature ranges were concentrated at500℃and750℃, respectively. Based on the above data, we could find two phases of carbonization:initial heating at600℃and terminal heating at800℃. The evaporation of volatile matter needs long soaking time, and that can benefit for the following treatment of producing pore and activation.The main gases released from coal in the pyrolysis process were H2, CH4, CO2and SO2, and they came from decomposition of the organic groups including-CH3、-CH2、-CH and C=C from the fatty hydrocarbon and aromatic hydrocarbon in the coal.As for CMS from anthracite, raw material with small particle size was prone to show high loss in ignition after carbonization and activation, slightly high porosity in CMS, and good adsorbability for methyl orange (MO). Furthermore, high activating temperature could result in high loss in ignition, high porosity initially and good adsorbability for MO. Compared with carbonization treatment, activating treatment was in favor of loss in ignition, porosity and adsorbability. The influence tendency of treatment temperature on CMS from bituminous coal was similar to CMS from anthracite. Above all, bituminous coal exhibited better activating performance than anthracite.In the study, anthracite was activated into CMS via heating at800℃with activator CO2. Study on the target materials structure and isothermal adsorption-desorption curves and pore size distribution curve showed that its specific surface area is195.92m2/g, and micropore surface area accounts for87.5%of the total specific surface area, and micropore capacity accounts for85.2%of the total volume. This showed the CMS sample mainly contains micropores.We tried to prepare CMS using anthracite as raw material by activation treatment of KOH, it was found that when the mass ratio of anthracite and KOH is1, the CMS samples pore proves to be strong, showing good adsorbability of MO. With activation temperature rising, there is a trend that the adsorption rates of CMS firstly rise and then decrease. So, the CMS sample has the best adsorbability when anthracite was heated to900℃and kept for1hour in the activation process. |
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