Dibenzothiophene (DBT, a typical sulfur compound) and dibenzothiophene sulfone (DBTO2, an oxidation product of DBT) were chosen as the model compounds, and their adsorption over a mesoporous silica (MCM-41) and a mesoporous carbon (CMK-3) were conducted under the exact same conditions. The adsorption amounts of DBTO2 over both adsorbents were enhanced compared to the DBT adsorption amounts, which clearly demonstrated that a combination of oxidation and adsorption is better than direct adsorption to achieve a better desulfurization performance. Besides, it was found that CMK-3 performed better for DBT removal compared to MCM-41, but the adsorption amount of DBTO2 over MCM-41 exceeded the corresponding value over CMK-3 (1.60 vs 0.88 mgS/g in p-xylene). Moreover, model fuels with varied hydrocarbon compositions were employed to investigate the impact of arene amounts. Finally, jet and diesel fuels were oxidized and treated with MCM-41, resulting in 85.6% and 81.4% sulfur removal, respectively. In contrast, when the fuels were directly treated with MCM-41, the corresponding sulfur removal amounts were only 19.8% and 40.9%. The results with real fuels further verified the necessity of the oxidation process. A simple washing method was found to be effective for regeneration of the adsorbent.

•In comparison with the parent HZSM-5, Zr-ZSM-5, Ag-ZSM-5, and the regenerated HZSM-5 can promote light olefins production.•Enhancement of hydride transfer promoted n-pentane catalytic cracking accompanied with a proximate stability.•Dehydrogenation and redox cracking selectively promoted alknenes formation that accelerated n-pentane protolytic cracking.•The selective enhancement of alkenes accelerated coke formation and thus catalyst deactivation.Insights into reaction mechanism were vital to direct naphtha catalytic cracking process to produce light olefins. In order to reveal influences of reaction pathways modulation on light olefins production, Zr-ZSM-5, Ag-ZSM-5, and the regenerated HZSM-5 (ZSM-5(R2)) were prepared and employed in n-pentane catalytic cracking. It was found that light olefins yield obtained over Zr-ZSM-5, Ag-ZSM-5, and ZSM-5(R2) at 500 °C was 58%, 81%, and 113% higher than that over the parent HZSM-5 (12.0%), respectively. Promotion on light olefins production caused by Zr-incorporation can be attributed to the enhancement of hydride transfer reactions increasing the utilization of Brønsted acid sites and the catalytic activity accompanied with the proximate stability compared to the parent HZSM-5. Different from Zr-ZSM-5, Ag-ZSM-5 and ZSM-5(R2) respectively introduced dehydrogenation cracking and redox cracking to n-pentane catalytic cracking, which selectively promoted the formation of light olefins and significantly enhanced n-pentane protolytic cracking. However, both Ag-ZSM-5 and ZSM-5(R2) went through a rapid deactivation at 550 °C, which was probably due the selective enhancement of alkenes accelerating the side reactions to coke formation.Download high-res image (109KB)Download full-size image

Activated carbons derived from hydrothermal carbonization of sucrose and subsequent KOH activation have been prepared and tested for the adsorptive removal of refractory thiophenic compounds. Textural and chemical properties of the carbons and their corresponding impacts on adsorption rates and capacities were discussed in detail. The optimum carbon possessed high adsorption capacity (41.5 mgS/g for 300 ppmwS model oil), fast adsorption rate (97% saturated within 5 min) as well as relatively good selectivity for the adsorption of thiophenic compounds due to the abundant small micropores, suitable mesopore fraction and various oxygen functionalities present in the carbon. Combined with the economic and environmental merits of the preparation procedure, the sucrose-derived activated carbons are promising candidates for potential practical applications.Keywords: Activated carbon; Adsorption; Desulfurization; Dibenzothiophene; Sucrose;

TiO2 and ZnO are extensively used photocatalysts, but their activity needs improvement due to rapid charge recombination. Herein, we designed and synthesized a novel structure of a TiO2–ZnO composite sphere decorated with ZnO clusters by a one-pot solvethermal method. TEM and EDX characterizations show this structure contains a TiO2 core, TiO2–ZnO composite (type II heterojunction) surface layer, and surface c-axis ZnO clusters. The in situ Au and PbO2 photodeposition shows that the photoinduced electrons and holes are driven to ZnO clusters and TiO2, respectively, attributed to the synergy of the type II heterojunction of TiO2–ZnO and high electron mobility of ZnO. The PL spectra confirm that such a structure is much more efficient in retarding the charge recombination than the sole TiO2–ZnO sphere. Importantly, this structure shows higher photoactivity in degradation of rhodamine B and isomerization of norbornadiene than pure TiO2, ZnO, and TiO2–ZnO composite spheres.

•Carbon nitride with simultaneous porous network and O-doping was “one-pot” fabricated.•It shows significantly enhanced optical absorption and charge transfer and separation.•It shows hydrogen evolution with AQE of 7.8% at 420 nm.•Synergetic interaction of porous network and O-doping is disccused.Efficient charge separation and broaden light absorption are of crucial importance for solar-driven hydrogen evolution reaction (HER), and graphitic carbon nitride (g-C3N4) is a very promising photocatalyst for this reaction. Here we report a facile precursor pre-treatment method, by forming hydrogen bond-induced supramolecular aggregates, to fabricate g-C3N4 with simultaneous novel porous network and controllable O-doping. Experimental and DFT computation identified that O doping preferentially occurs on two-coordinated N position, and the porous network and O-doping synergetically promote the light harvesting and charge separation. As a result, this material shows 6.1 and 3.1 times higher HER activity (with apparent quantum efficiency of 7.8% at 420 nm) than bulk and even 3D porous g-C3N4. This work highlights that simply pre-treating the precursor can not only control the architecture but also introduce helpful foreign atoms or monomer in the matrix, which provides a useful strategy to design and fabricate highly efficient g-C3N4 photocatalyst.This paper describes a facile precursor pre-treatment method, by forming hydrogen bond-induced supramolecular aggregates, to fabricate g-C3N4 with simultaneous novel porous network structure and O-doping. Experimental and DFT computation confirm simultaneous porous network structure and O-doping have synergetic promotion on light harvesting and charge separation. As a result, it shows remarkably higher HER activity (AQE=7.8% at 420 nm) than bulk and even 3D porous g-C3N4.

In the new generation of aircraft, jet fuel will serve as both an energy source and a heat sink for cooling through endothermic fuel reactions. Catalytic cracking of hydrocarbon fuel has proved to be potential for endothermic reaction. For this application, we have prepared ZSM-5 membranes as catalyst on the surface of stainless steel by secondary growth method. An optimized activation procedure of ZSM-5 membrane for catalytic cracking reaction is established by combining the results of catalytic reaction with thermal analysis (TGA and DSC). Taking n-dodecane as a model compound, the influence of silica alumina ratio (SAR = nSiO2/Al2O3) of initial gel on the activity of hydrocarbon cracking reaction were studied. The results also demonstrate that the conversion of catalytic cracking reaction is much higher than that of pyrolysis during supercritical state. In addition, hydrogen molar ratio in gas production decreases with increasing the reaction temperature. Besides that, the optimum temperature for coke removal and the reduction of zeolite catalysts is between 550 °C and 600 °C.