Selective Adsorption Of Dibenzothiophene Research Articles

Fabrication and evaluation of hollow surface molecularly imprinted polymer for rapid and selective adsorption of dibenzothiophene

Rapid and selective recognition and adsorption of dibenzothiophene (DBT) was obtained by a novel hollow surface molecular imprinted polymer (SMIP/HCMS), prepared using α-methacrylic acid (MAA) as the functional monomer and porous magnetic carbon microspheres (p-Fe3O4@C) as the sacrificial support matrix. Some key preparation conditions were systematically optimized. SMIP/HCMS was examined by the characterization of X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, N2 adsorption-desorption isotherms, and thermogravimetric analysis. The adsorption kinetics, adsorption isotherms, selective recognition, and regenerative performance of SMIP/HCMS were also evaluated in detail. The adsorption capacity of SMIP/HCMS for DBT reached 62.06 mg g−1 after 80 min, in comparison with 30.12 mg g−1 of the corresponding non-imprinted polymer and 24.85 mg g−1 of SMIP/p-Fe3O4@C. In addition, the adsorption kinetics and isotherm data of DBT could be well fitted with the pseudo-first-order kinetic model and Langmuir isotherm, respectively. Competitive adsorption experiments demonstrated that SMIP/HCMS possessed a greater affinity towards DBT than other analogue molecules. Finally, SMIP/HCMS could be used eight times without significant loss in the adsorption capacity. This work indicated the potentiality of SMIP/HCMS, combining using p-Fe3O4@C as the support matrix with the hollow surface molecular imprinting technology, in the selective removal of DBT from the oil.

Promoting effect of surface acidities on efficiency of copper modifier for ordered mesoporous carbon-SiO2-Al2O3 nanocomposites in adsorptive desulfurization

The ordered mesoporous carbon-silica-alumina nanocomposites (MCSAs) with different ratios of Si/Al (10, 20 and 100) were synthesized by a multi-component co-assembly method followed by pyrolysis at high temperatures. The Si/Al ratio has an important effect on the acidic characteristics of the nanocomposite. The pyridine FT-IR results show that the nanocomposite with a Si/Al ratio of 100 has maximum amount of Brønsted acid sites. This may be because more non-framework Al-O-Si species are generated in the MCSA samples with lower Si/Al ratio due to the dealumination of the precursor in an acidic media during the surfactant-based assembly procedure and/or partial dealumination occurring during high temperature calcination. The copper-modified MCSAs were prepared by incipient wetness impregnation followed by calcination. The desulfurization performance of the as-prepared adsorbents was evaluated by the selective adsorption of dibenzothiophene (DBT) as a model sulfur compound from model fuels at ambient conditions. The dispersion extent of copper species increases with the increase of Brønsted acid sites, which results in a higher selectivity for DBT in competition with benzene. Compared with our previously prepared ordered mesoporous carbon-silica nanocomposite (MCS), the promotion effect of aluminum incorporation on the desulfurization selectivity is demonstrated. Moreover, the ordered mesoporous carbon-alumina nanocomposite (MCA) was also prepared. Its ordered mesostructure partially collapsed and the micropore volume is increased after copper incorporation, resulting in a good enhancement in sulfur capacity and selectivity.

Enhanced adsorption selectivity of dibenzothiophene on ordered mesoporous carbon-silica nanocomposites via copper modification

In this study, copper-modified ordered mesoporous carbon-silica nanocomposites (MCSs) were synthesized by incipient wetness impregnation of copper nitrate. The desulfurization performance of the as-prepared adsorbents was evaluated by the selective adsorption of dibenzothiophene (DBT) as model sulfur compound from model fuels at ambient conditions. For comparison, the adsorptive desulfurization capacity for copper species supported on pure silica SBA-15 and pure carbonaceous CMK-3 was also investigated, respectively. The results indicate that MCS with 10wt.% of copper performed highest selectivity for DBT in competition with benzene. The significantly enhanced desulfurization performance of MCS could be attributed to its hybrid mesoporous carbon-silica nature which is favorable for high dispersion extent of copper and synergistic effect between the carbon substrate and the supported copper species.

Preparation Cu-Doped Carbon Aerogels and their Adsorptive Desulfurization Performance

Cu-doped carbon aerogels were prepared by the sol-gel polymerization of resorcinol with formaldehyde in aqueous solution to produce organic gels that are supercritically dried in n-hexane and subsequently pyrolyzed in an inert atmosphere, using sodium carbonate as catalyst and copper acetate as copper source. The addition amount of the copper acetate in the initial reaction mixture has a profound effect on the surface morphology and pore texture of the resulting aerogel. It is shown that the introduction of copper lead to generation of ultrafine micropores. The desulfurization performance of the as-obtained carbon aerogels was evaluated by selective adsorption of dibenzothiophene (DBT) as a model sulfur compound and benzene as a competitive aromatic compound. It is found that the adsorption capacity for DBT is related to the volume of micropores. And the selectivity is improved with the increase of copper content, indicating the presence of copper is favorable to DBT retention on the surface via its π-complexation effect.

Synthesis of Potassium Tetratitanate—Based Molecularly Imprinted Polymer for Selective Adsorption of Dibenzothiophene

A potassium tetratitanate-based molecularly imprinted polymer (MIP) was prepared by surface molecule-imprinting technique, which involves coating potassium tetratitanate whiskers with silica and modification with 3-methacryloxypropyltrimethoxysilane. The structural properties of the synthesized MIP were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, nitrogen adsorption and scanning electron microscopy. Adsorption behaviour studies were conducted on the prepared MIP, the results of which showed that it has a porous and large surface area. In addition, the prepared MIP showed good adsorptive capacity and selectivity for dibenzothiophene; the adsorption equilibrium time was 180 minutes and the equilibrium adsorption capacity was 20.86 mg/g at 318 K. The adsorptive behaviour followed the Lagergren pseudo-second-order kinetic model and the Freundlich isotherm model. Thermodynamic parameters demonstrated that the adsorption process was spontaneous and endothermic. Thus, ba...

Removal of Dibenzothiophene with Composite Adsorbent MOF-5/Cu(I)

A new type of composite adsorbent, MOF-5/Cu(I), was prepared by MOF-5 doped with different amount of CuCl using a spontaneous monolayer dispersion technique. These new composite adsorbents were characterized by X-ray diffraction, thermogravimetric analysis, electrondispersion X-ray scope, and N2 adsorption, respectively. The desulfurizaion performance of the prepared adsorbents was evaluated by the selective adsorption of dibenzothiophene from the simulated oils in a fixed-bed breakthrough column at room temperature. From the obtained breakthrough curves, both the breakthrough capacity and the saturation capacity of the adsorbents for sulfur element were determined. The results show that MOF-5/Cu(I) exhibited high desulfurization capacities, which are superior to those reported previously in the literature. In addition, these novel composite adsorbents possessed good durability and affinities for the adsorption of dibenzothiophene in the presence of aromatic components and moisture. The saturated composite adsorbent MOF-5/Cu(I) can be regenerated with nitrogen atmosphere sweeping at 623 K for 4 h. About 97% of the desulfurization capacity was recovered after regeneration.