Coal-based activated carbons (CAC) were prepared from coal in Xinjiang China by microwave-assisted activation. The effects of preparation conditions on adsorption capabilities of CAC for methylene blue (MB) and iodine were investigated. The microwave activation was carried out with coal activator ratio of 1:3 for 12 min at 700 W of power, the adsorption capacities of the prepared CAC achieved the maximal values of 312 and 1048.19 mg/g for MB and iodine. The increasing of CAR, activation time, and microwave power reduced the surface functional groups and improved the pH PZC of CAC. The BET surface area and total pore volume of CAC prepared were identified as 1770.49 m 2 /g and 0.99 cm 3 /g, respectively. Hence, the work demonstrates that the use of microwave heating for preparing CAC is more rapid, cheaper and efficient. The adsorption behaviors of typical polycyclic aromatic hydrocarbons (PAHs) in ethanol aqueous solution on CAC were also explored. Equilibrium data were favorably described by the Langmuir and Freundlich isotherms, and adsorption kinetics was fitted to the pseudo-second-order model well. The equilibrium adsorption amounts were 117.17 mg/g for pyrene, 111.39 mg/g for phenanthrene, and 78.18 mg/g for naphthalene. Thus, CAC prepared by microwave activation could have a very effective application in removal of these PAHs.
Yong Qu,Jingmei Liu,Xiaodong Zhou,Lang Liu,Ruitao Ma,Yongguo Su,Chunmei Ma,Pengtao Sun
Low-temperature coal tar (LTCT) is the preferred raw material for the catalytic hydrogenation of coal tar. In order to study and popularize the technology of preparing fuel oil by hydrogenation of LTCT, it is necessary to research its composition and structural characteristics. Heavy hydrogenated coal tar (HHCT) from a company in Xinjiang, which is a mixture of hydrorefined tail oil distillate (>350 °C) and hydrotreated circulating tail oil (>350 °C). To make scientific and customized use of HHCT, the chemical composition and molecular structure characteristics of HHCT and its subcomponents were investigated by using elemental analysis (EA), infrared analysis (FT-IR), and nuclear magnetic resonance (1H NMR and 13C NMR) through fraction separation. Compared to other low-temperature coal tar (LTCT), the content of saturates (SA) in HHCT is 95.01 wt %, considerably higher than other LTCT samples, and the content of aromatics (AR), resins (RE), and asphaltenes (AS) is all much lower than other LTCT samples. Compared with the basic properties, elemental content, and refining performance of other crude oils, HHCT is good-quality oil with relatively small density, high H/C ratio, fewer heteroatoms, and low metal impurities, and is easy to refine and process. FT-IR and NMR results show that HHCT and SA are primarily constituted of long-chain n-alkanes possessing longer aliphatic chains and fewer branched chains. Aromatics are predominantly present in AR and mainly encompass bicyclic and tricyclic aromatics. HHCT and other fractions contain a small quantity of aromatic structures.
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