| Sulfur-containing compounds are widely present in the fuels, which can produce SOX upon combustion causing the catalysts in the emission control system poisoned, reduceing the efficiency of automobile exhaust treatment. After combining with water, these materials are converted into acid rain, which can make buildings corroded. At the same time, sulfur compounds in fuels also corrode the mechanical equipment and oil pipeline used in factories. Therefore, it is very important to remove sulfur compounds before exposing the fuel or its combustion products to the environment. At present, the most widely used in industry is hydrodesulfurization (HDS), which needs high temperature and pressure conditions as well as hydrogen as a reactant increasing the cost. In recent years, some new desulfurization technologies have emerged, in which the adsorption desulfurization has been paid more attention because of its simple operation, mild conditions, high selectivity and easy to recycle.Metal organic frameworks (MOFs) are a genre of hybrid organic-inorganic polyporous materials with highly ordered multidimensional network structure formed by the metal cation and the multi-functional organic ligand. Compared with other traditional adsorbents, MOFs feature with higher porosity, larger specific surface area, pore size and shape easy to adjust. However, it is difficult to recycle because of powder state of MOFs. To solve this problem, we think of an idea, namely, supporting MOFs on carriers. Millimeter-sized mesoporous ?-Al2O3 beads are good carrier materials which feature high mechanical strength, low price, especially easy to recycle with decantation.In this paper, MOFs were successfully supported on the ?-Al2O3 beads and their adsorption performance of thiophene compounds in model oil were researched, the main results are described as follows:(1) Synthesized MOF-5@?-Al2O3 and IRMOF-3@?-Al2O3 composite materials by solvothermal method. The composite materials were characterized by IR, XRD, SEM, XRF. Loading amounts of MOF-5 and IRMOF-3 on the carrier were 13.4% and 16.3% respectively. MOF-5@ ?-Al2O3 and IRMOF-3@?-Al2O3 composite materials were used to adsorption desulfurization from model oil for BT, DBT,3-MT and 4,6-DMDBT. Effect of time, temperature and MMOFS@?-Al2O3/Moil on the adsorption desulfurization performance were researched, getting the best conditions for desulfurization:time,60 min, temperature,30?, M MOFs@?-Al2O3/MOii=1:40. Adsorption performance of MOF-5@?-Al2O3 and IRMOF-3@?-Al2O3 composite materials is better than MOF-5 and IRMOF-3, and adsorption desulfurization capacity of IRMOF-3@?-Al2O3 significantly higher than that of MOF-5@?-Al2O3. This is due to the -NH2 as electron donor group, increasing the electron cloud density of benzene ring, enhancing the conjugation effect between MOFs and sulfides.At the same time, in MOFs, the conjunction of the aromatic ring and the lone pair electron of nitrogen make the hydrogen in the amino group more electropositive, and this results in the hydrogen being more easily attracted to the sulfur atom with its lone pair electron, forming hydrogen-bonded. Adsorption kinetic and thermodynamic parameters were also calculated. The results indicated that adsorption rate of MOF-5@?-Al2O3 and IRMOF-3@?-Al2O3 composite materials match well with the versatile pseudo-second-order kinetic model. And the thermodynamic parameters indicated that the adsorption process was spontaneous and endothermic, and increasing of entropy is the main driving force of the adsorption desulfurization.(2) Synthesized HKUST-1@?-Al2O3 composite materials by solvothermal method with different amounts of ?-Al2O3 beads added in the mother liquor of HKUST-1. The composite materials were characterized by IR, XRD, SEM and elemental analysis. The results demonstrated that HKUST-1 was successfully loaded on ?-Al2O3 beads, and loading amount of HKUST-1 is lower with adding more ?-Al2O3 beads, but the the raw material utilization rate is higher. Different loading amounts of HKUST-1@?-Al2O3 composite materials were used to adsorption remove dibenzothiophene from model oil. The results showed that with HKUST-1 loading amounts decreasing, adsorption desulfurization capacity of HKUST-1@?-Al2O3 composite materials increases first and then tends to balance. When the loading amount of HKUST-1 was 12.1%, the adsorption desulfurization performance is the best, with adsorption desulfurization capacity of 64.2 mg S/g MOF. It reveals that the HKUST-1 is more close to the monolayer distribution with the decrease of the loading amount, and the exposed active site is increased. With this loading amount of HKUST-1@?-Al2O3 composite material for deep desulfurization, sulfur content in the model oil reduced from 35 ppmws to 7.8 ppmws at Madsorbent/Moii=50%. The crushing strength of HKUST-1@?-Al2O3 composite materials are higher than that of ?-Al2O3 beads. Performance for reuse of adsorbent was also researched. After five times reuse, adsorption desulfurization capacity of HKUST-1 reduced from 49.1 mg S/g MOF to 43.6 mg S/g MOF, that reduction rate is 11.2%. Compared with HKUST-1, HKUST-1@?-Al2O3 composite material is more simple to recycle and after five times reuse, adsorption desulfurization capacity reduced from 64.2 mg S/g MOF to 58.5 mg S/g the MOF, that reduction rate is only 8.9%. Therefore, HKUST-1@?-Al2O3 composite material synthesized by adding 6 g ?-Al2O3 beads, is not only to improve the utilization of raw materials, but also improve adsorption desulfurization performance. |
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