TY - JOUR
T1 - Effect of crystallographic phase (beta vs. gamma) and surface area on gas phase nitroarene hydrogenation over of Mo2N and Au/Mo2N
AU - Perret, Noemie
AU - Cardenas-Lizana, Fernando
AU - Lamey, Daniel
AU - Laporte, Vincent
AU - Kiwi-Minsker, Lioubov
AU - Keane, Mark A.
PY - 2012/10/1
Y1 - 2012/10/1
N2 - The catalytic action of Mo2N and Au/Mo2N has been assessed in the selective gas phase hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN). The nitrides were synthesised via temperature programmed treatment of MoO3 in H-2 + N-2 and Au introduced by deposition-precipitation with urea. We have examined the influence of nitride crystallographic phase (tetragonal beta-Mo2N vs. cubic gamma-Mo2N) and surface area (7-66 m(2) g(-1)) on the catalytic response. Catalyst activation by temperature programmed reduction has been monitored and the reduced catalysts characterised in terms of BET area/pore volume, H-2 chemisorption/temperature programmed desorption (TPD), powder X-ray diffraction (XRD), elemental analysis, scanning (SEM) and transmission (TEM) electron microscopy and X-ray photoelectron spectroscopy (XPS) measurements. The formation of beta- and gamma-Mo2N was confirmed by XRD and TEM. gamma-Mo2N exhibits a platelet morphology whereas beta-Mo2N is characterised by an aggregation of small crystallites. Hydrogen chemisorption and TPD analysis have established a greater hydrogen uptake capacity (per unit area) for beta-Mo2N relative to gamma-Mo2N, which is associated with surface nitrogen deficiency, i.e. higher surface Mo/N for beta-Mo2N. Incorporation of Au on both nitrides resulted in an increase in surface hydrogen. The Au phase takes the form of nano-scale particles with a mean size of 7 and 4 nm on beta-Mo2N and gamma-Mo2N, respectively. Both beta-Mo2N and gamma-Mo2N promoted the exclusive hydrogenation of p-CNB to p-CAN where the beta-form delivered a higher specific (per m(2)) rate; the specific rate for gamma-Mo2N was independent of surface area. The inclusion of Au on both nitrides served to enhance p-CAN production.
AB - The catalytic action of Mo2N and Au/Mo2N has been assessed in the selective gas phase hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN). The nitrides were synthesised via temperature programmed treatment of MoO3 in H-2 + N-2 and Au introduced by deposition-precipitation with urea. We have examined the influence of nitride crystallographic phase (tetragonal beta-Mo2N vs. cubic gamma-Mo2N) and surface area (7-66 m(2) g(-1)) on the catalytic response. Catalyst activation by temperature programmed reduction has been monitored and the reduced catalysts characterised in terms of BET area/pore volume, H-2 chemisorption/temperature programmed desorption (TPD), powder X-ray diffraction (XRD), elemental analysis, scanning (SEM) and transmission (TEM) electron microscopy and X-ray photoelectron spectroscopy (XPS) measurements. The formation of beta- and gamma-Mo2N was confirmed by XRD and TEM. gamma-Mo2N exhibits a platelet morphology whereas beta-Mo2N is characterised by an aggregation of small crystallites. Hydrogen chemisorption and TPD analysis have established a greater hydrogen uptake capacity (per unit area) for beta-Mo2N relative to gamma-Mo2N, which is associated with surface nitrogen deficiency, i.e. higher surface Mo/N for beta-Mo2N. Incorporation of Au on both nitrides resulted in an increase in surface hydrogen. The Au phase takes the form of nano-scale particles with a mean size of 7 and 4 nm on beta-Mo2N and gamma-Mo2N, respectively. Both beta-Mo2N and gamma-Mo2N promoted the exclusive hydrogenation of p-CNB to p-CAN where the beta-form delivered a higher specific (per m(2)) rate; the specific rate for gamma-Mo2N was independent of surface area. The inclusion of Au on both nitrides served to enhance p-CAN production.
U2 - 10.1007/s11244-012-9881-4
DO - 10.1007/s11244-012-9881-4
M3 - Article
SN - 1022-5528
VL - 55
SP - 955
EP - 968
JO - Topics in Catalysis
JF - Topics in Catalysis
IS - 14-15
ER -