Control of the crystal morphology of VOHPO4·0.5H2O precursors prepared via light alcohols-assisted solvothermal synthesis and influence on the selective oxidation of n-butane

Publication date: September 2019Source: Journal of Catalysis, Volume 377Author(s): M.T. Nguyen Dinh, T.L. Nguyen, M.D. Phan, L. Nguyen Dinh, Q.D. Truong, E. Bordes-RichardAbstractThe catalytic performance of vanadyl pyrophosphate (VPP) catalysts in the oxidation of n-butane to maleic anhydride (MA) depends strongly on the display of the active and selective {0 0 1} faces, that may be controlled during the preparation of VOHPO4·0.5H2O precursor by solvothermal technique using C2 to C4 alkanoic alcohols. Intercalated metastable vanadyl-alkyl-phosphates were formed when linear alcohols (ethanol, n-butanol) were used, at variance with iso-alcohols. {0 0 1} platelets of VOHPO4·0.5H2O yielded {2 0 0} platelets to (VO)2P2O7 in nitrogen or in situ in the reactor, as revealed by structural analyses. The catalysts prepared in ethanol or n-butanol in situ activated at 440 °C were more active and selective to MA than in iso-alcohols, but if the equilibration was performed at 380 °C the influence of alcohol was mitigated. The highest MA yield was obtained with the ethanol-derived catalyst, which exhibited the smallest platy crystallites of (VO)2P2O7, as well as surface V5+ species as seen by XPS.Graphical abstract

Source: Journal of Catalysis - August 25, 2019 Category: Chemistry Source Type: research