P. Da Costa et al., Novel phosphorus-doped alumina-supported molybdenum and tungsten carbides:synthesis, characterization and hydrogenation properties, CATAL LETT, 72(1-2), 2001, pp. 91-97
The effect of atomically dispersed phosphorus on Mo2C- and WC-supported gam
ma -Al2O3 has been studied. Phosphorus was introduced via molybdenum or tun
gsten heteropolyanions. Mo- and W-based heteropolyanions were used to synth
esize supported materials. Propene and tetralin hydrogenation were used as
molecular probe reactions to test the activity and selectivity of the alumi
na-supported molybdenum or tungsten carbides. The effect of phosphorus on t
he hydrogenation activity of materials was also considered. Catalysts were
characterized by X-ray diffraction, transmission electron microscopy (TEM),
energy-dispersive spectroscopy (EDS) and CO chemisorption. Phosphorus was
found to increase significantly the activity of molybdenum and tungsten car
bides. Supported molybdenum carbides are highly dispersed. Tungsten carbide
particles are well dispersed with sizes ranging from 2 to 4 nm. To check t
he stability of carbides they were characterized after catalytic runs.