ABSTRACT
Two kinds of NiO/ZnO-TiO2 adsorbents were prepared by equal volume impregnation (NiO/ZnO-TiO2-1) and kneading (NiO/ZnO-TiO2-2) methods. The adsorbents were characterized by X-ray diffraction, mercury intrusion porosimetry, scanning electron microscopy, energy dispersive X-ray spectroscopy, H2 temperature-programmed reduction, and H2 temperature-programmed desorption. It was found that NiO/ZnO-TiO2-2 had a smaller average pore diameter and a larger specific surface area as well as a more uniform distribution of the nickel element. Additionally, more Ni0 active sites together with a stronger interaction between the active component and the support were detected on the surface of NiO/ZnO-TiO2-2, which was beneficial to the inhibition of olefin saturation during desulfurization. The desulfurization performance of the adsorbents was investigated in a fixed bed reactor with fluid catalytic cracking light gasoline as a feed oil. The evaluation results confirmed NiO/ZnO-TiO2-2 with a better desulfurization performance with less olefin saturation. It could reduce the total sulfur content from 300 ppmw to less than 5 ppmw, and the breakthrough time and breakthrough sulfur capacity were 91 h and 6.71% (67.1 mg S/g adsorbent), respectively.
ABSTRACT
We evaluate the fullerene C60 binding effect; through the metal (Al) and through the ligand (Pc,TPP), on the photophysical and charge transport properties of M-porphyrin(TPP)/phthalocyanine(Pc) (M = Al(III), Zn(II)). We perform density functional theory (DFT) and time-dependent DFT calculations for the macrocycle-C60 dyads, showing that all systems studied are thermodynamically favorable. The C60 binding effect on the absorption spectrum is a red-shift of the Q and Soret (B) bands of TPPs and Pcs. The Pc-dyads show longer λ for Q bands (673 nm) than those with TPP (568 nm). AlTPP-C60 and ZnTPP-C60 show a more favorable electron injection to TiO2 than the analogs Pcs, and the regeneration of the dye is preferred in AlTPP-C60 and AlPc-C60. Zero-bias conductance is computed (10-4-10-7 G0) for the dyads using molecular junctions with Au(111)-based electrodes. When a bias voltage of around 0.6 V up to 1 V is applied, an increase in current is obtained for AlTPP-C60 (10-7 A), ZnTPP-C60 (10-7 A), and AlPc-C60 (10-8 A). Although there is not a unique trend in the behavior of the dyads, Pcs have better photophysical properties than TPPs and the latter are better in the charge transport. We conclude that AlTPP(ZnTPP)-C60 dyads are an excellent alternative for designing new materials for dye-sensitized solar cells or optoelectronic devices.
ABSTRACT
Deep desulfurization is a key process for the production of high value-added products from C5 distillates. In this work, different potassium salt modified gamma-Al2O3 adsorbents were prepared by an incipient-wetness impregnation method and characterized by N2 adsorption-desorption, SEM-EDS, TEM, CO2-TPD, XRD, FT-IR, and IC. The C5 distillate with a 1200 µg mL-1 sulfur content is desulfurized to less than 10 µg mL-1 within 24 hours by the static adsorption method. For the desulfurization in the fix-bed reactor, the breakthrough sulfur capacity of K2CO3-decorated gamma-Al2O3 reaches 0.76 wt% under the optimized conditions, viz., at 30 °C, with a sulfur content of 50 µg mL-1 in the raw oil, and a liquid hourly space velocity of 1 h-1. The desulfurization activity of the exhausted adsorbent can be recovered after regeneration. Selective adsorption of CS2 includes three processes: adsorption, hydrolysis, and oxidation. CS2 is first adsorbed on the adsorbent and hydrolyzed to form H2S. H2S is further oxidized to form S/SO4 2-, and then deposits on the surface of the adsorbent. Adsorption, hydrolysis, and oxidation all play essential roles in the removal process of CS2.
ABSTRACT
A new natural product named longanlactone was isolated from Dimocarpus longan Lour. seeds. Its structure was determined as 3-(2-acetyl-1H--pyrrol-1-yl)-5-(prop-2-yn-1-yl)dihydrofuran-2(3H)-one by spectroscopic methods and HRESIMS.
