No abstract

No abstract

No abstract

No abstract

No abstract

Samples of V 2 O 5 catalysts supported on nanostructures of TiO 2 and γ-Al 2 O 3 were synthesized through the hydrothermal method and used for the oxidative dehydrogenation of propane (ODHP) to propylene. The TiO 2 support was utilized in both commercial microstructure and synthesized nanostructure forms. Moreover, the γ-Al 2 O 3 support was synthesized through chemical and precipitation methods. The vanadium catalyst was then deposited onto the hybrid of the TiO 2 and γ-Al 2 O 3 materials. All prepared catalysts were characterized through the BET, FESEM, FTIR, XRD and TPR techniques. Performances of the synthesized catalysts were subsequently examined in a fixed-bed reactor. The main products were propylene, ethylene and CO x . The prepared catalysts over TiO 2 and γ-Al 2 O 3 were evaluated under reactor test conditions of 500 °C, feed of C 3 H 8 /air with molar ratio of 0.6, and total feed flow rate of 90 mL min -1 . These resulted in optimum values of 35.53 and 23.88 % for the propylene selectivity and propane conversion, respectively 6 h after the start of the reaction. The comparison of performances made between the synthesized materials and those available in the open literature for the ODHP reaction was indeed satisfactory.

In this research, the equilibrium and dynamic adsorption studies of the CO2 upon the MIL-101­(Cr) metal–organic framework (MOF) as well as its GNP hybrid composites, the MIL-101­(Cr)/GNP, were performed. First, the hybrid composite samples were synthesized by adding various amounts of GNP in an in situ manner during the preparation of the MIL-101­(Cr). The prepared materials were characterized through several physicochemical analyses, including powder X-ray diffraction (PXRD), adsorption of nitrogen at 77.4 K, Fourier transfer infrared (FT-IR) spectroscopy, thermal analysis (DTG), and field emission scanning electron microscopy (FESEM). It was demonstrated that the synthesized MIL-101­(Cr)/GNP possessed a nearly similar crystal structure and morphology compared with those of the virgin sample. Next, the CO2 adsorption studies upon these sorbents were performed through a volumetric adsorption apparatus at 298 K and CO2 pressures of up to 40 bar using an in-house made rig. It was shown that the CO2 adsorption capacity was enhanced by about 43% (i.e., from 14.38 to 20.62 mmol·g–1) for the hybrid composite containing 10 wt % of the GNP compared to the virgin MIL at 298 K and 40 bar. This enhancement in the CO2 adsorption capacity was attributed to the effect of the GNP embedded into the internal MIL-101­(Cr) pores giving rise to stronger interactions between the walls of this species and CO2 molecules. Furthermore, increase of the specific surface area as well as total and micropore volumes of the MIL-101­(Cr) was rationalized to be due to this GNP addition. Ultimately, in order to mechanistically understand the adsorbents’ behaviors, several kinetic and isotherm models were studied. It was revealed that the FL-PFO and dual site Toth relationships outstandingly described the CO2 adsorption upon the sorbents.

No abstract