Adsorption desulfurization performance of PdO/SiO2@graphene oxide hybrid aerogel: Influence of graphene oxide.

Preparation of PdO/SiO2@graphene oxide (GO) hybrid aerogels were carried out sol-gel method combined with atmospheric drying technology to study their adsorption performance for thiophenics and compared with PdO/SiO2. Scanning electron microscope (SEM), N2 adsorption-desorption isotherms, X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy (XPS), and fourier transformation infrared spectroscopy (FT-IR) for samples were performed. The adsorption performance of PdO/SiO2@GO for thiophene were better than that of PdO/SiO2, attributed to that incorporation of GO increased the specific surface area and the Pd incorporation rate, where Pd2+ ions acted as the π-complexation and sulfur-metal (SM) bond adsorption active centers, as well as GO adsorbed thiophene by the π-π stacking effect. The adsorption capacities of PdO/SiO2@GO-1.0 for thiophene (TH), benzothiophene (BT) and dibenzothiophene (DBT) were 8.89, 9.3 and 12.6 mg-S/gads, respectively. The addition of GO in aerogels could improve the inhibition effect of toluene, cyclohexene and pyridine while decreased the inhibition effect of MTBE and H2O for the adsorption of thiophene, due to the π-π stacking effect and the hydrophobicity of GO, respectively. The adsorption process was spontaneous and exothermic, be well fitted by the apparent second-order kinetic model and dominated by chemical interaction. Pd/SiO2@GO-1.0 had a good solvent elution regeneration performance.

The effect of Fe2O3 crystal phases on CO2 hydrogenation.

The effect of Fe2O3 crystal phases on their performance in CO2 hydrogenation was studied. α-Fe2O3 crystal was prepared by precipitation method from Fe(NO3)3·9H2O and (NH4)2CO3, and γ-Fe2O3 was prepared by grinding Fe(NO3)3·9H2O and L(+)-Tartaric acid in agate mortar completely. The crystal phases of Fe2O3 influence the distribution of promoter Zn, K and Cu on catalysts. The dispersity of K on γ-Fe2O3 surface is higher than α-Fe2O3. On the contrary, Cu and Zn are more dispersive on α-Fe2O3 surface than γ-Fe2O3. The catalyst in γ-Fe2O3 phase is easily reduced relative to the catalyst in α-Fe2O3 phase. The former presents higher CO2 conversion and C2+ hydrocarbon selectivity than the latter in CO2 hydrogenation.

Effects of Weak Surface Modification on Co/SiO2 Catalyst for Fischer-Tropsch Reaction.

A weak surface modification is applied to Co/SiO2 catalyst by hydrothermal treatment at 180°C for 5 h. Aluminum is introduced to Co/SiO2 catalysts during the surface modification. The effects of surface modification on Co/SiO2 catalyst are studied by changing the operating sequences of surface modification and cobalt impregnation in the catalyst preparation. Surface modification before cobalt impregnation makes Co3O4 particle small and dispersed into the deep part of enlarged pore in SiO2, while surface modification after cobalt impregnation does not obviously change the particle size of Co3O4. The improved amplitude of catalytic activity is similar for the two kinds of catalysts, but they are benefited from different factors. The content of iso-hydrocarbons in the products is increased by the surface modifications.