Enhancement in propane aromatization with Ga2O3/HZSM-5 catalysts

Abstract

A strong enhancement in the propane aromatization activity of Ga/HZSM-5 catalysts may be achieved by mechanically mixing Ga203 with HZSM-5 and activating the catalyst by either hydrogen pretreatment or long term exposure to a propane reactant.

Enhanced magnetism of Fe3O4 nanoparticles with Ga doping

“…Although good agreement in peak position of a high energy peak occurs (dashed line at 1128.2 eV in Fig. 1) differences of the Ga XAS of (Ga x Fe 1Àx ) 3 O 4 suggest that the actual local Ga bonding is not identical to the b-Ga 2 O 3 structure, but more likely a substitution into Fe sites in the host Fe 3 O 4 spinel structure, similar to that determined in coprecipitation studies. 1 A definitive determination of the site occupancy of the Ga cannot be made from the Ga XAS spectra alone.…”

“…The mixture was gradually heated to 200 C and allowed to anneal for 24 h. The reaction mixture was then cooled to room temperature, and the particles were precipitated in ethanol, centrifuged, and dried. Gallium doped magnetite nanoparticles, (Ga x Fe 1Àx ) 3 O 4 were synthesized by substitution of Ga(acac) 3 for the Fe(acac) 3 . TEM measurements determined their size to be 8.5-9 nm.…”

“…Gallium doped iron oxide, (Ga x Fe 1Àx ) 3 O 4 , is interesting as it exhibits an energy-dependent photoabsorption as a function of Ga concentration in bulk samples. 1 This property could be advantageous in nanoparticles providing utility for applications.…”

“…Bulk (Ga x Fe 1Àx ) 3 O 4 magnetic trends have not been fully studied, but Ga is typically present as a 3þ valence ion so it is likely to be present as a 3þ valence ion given the two options in the spinel structure. 1 The effect on the magnetic properties of doping Fe 3 O 4 with other nonmagnetic transition metals of similar ionic radii, such as Zn, show that Zn preferentially substitutes for Fe 3þ as Zn 2þ in the tetrahedral coordination.…”

“…Additionally, Ga-based mixed oxides have shown interesting catalytic behavior, an application that nanoparticles are known to be exceptional for due to their large surface-to-volume ratio. [2][3][4] Furthermore, the doping of magnetic nanoparticles can have behaviors distinct from bulk alloys, including changes in dopant site occupation and different variations of moment and anisotropy with doping concentration, making them interesting from a purely scientific standpoint.…”