Binary γ-Al2O3–α-Ga2O3 as supports of NiW catalysts for hydrocarbon sulfur removal

Abstract

A series of γ-Al2O3–α-Ga2O3 binary mixed supports with different Ga2O3 content (labeled AlGa-x, where x is the wt.% of Ga2O3) were synthesized by a one-step precipitation method and calcination. These supports were used to prepare NiW catalysts and later tested in the hydrodesulfurization (HDS) reactions of gasoline and diesel model sulfur compounds. Morphology, surface and electronic properties of AlGa-x samples changed considerably depending on Ga2O3 content. Amorphous alumina and low gallium oxide content samples showed higher WS2 dispersion when compared with the gallium-free sample by HRTEM analysis. All materials displayed excellent catalytic activity in the 3-methyl-thiophene (3MT) and dibenzothiophene HDS reactions. The best catalytic performance for both tests was obtained with the NiW/AlGa-25 sulfided catalyst. Furthermore, hydrogenation capacity was clearly modified by the presence of GaAl2O4 spinels as well as α-Ga2O3. In the 3MT HDS reaction, the presence of isoprene among the reaction products showed that, using the NiW/AlGa-x catalyst, this reaction may be successfully conducted by the desulfurization pathway. Noteworthy was the formation of well-defined microcrystals in samples with the highest gallium oxide content. Results from this work reveal that the binary γ-Al2O3–α-Ga2O3 mixed oxides have great potential as support for hydrocarbon sulfur removal catalysts.