TY  - THES
T1  - Catalytic oxidative dehydrogenation of propane by AMoVNbOx (A = Ni, Co, Pt) synthesised via impregnation method
A1  - Wong, Mei Sam
LA  - English
YR  - 2013
UL  - http://discoverylib.upm.edu.my/discovery/Record/oai:psasir.upm.edu.my:67694
AB  - Propane is a natural gas that is found abundant and low cost material in
petroleum industry. In order to upgrade the value of propane, catalytic oxidative
dehydrogenation of propane has been carried out to form propylene which is
widely used as chemical intermediate in manufacturing process. Thus, Ni, Co
and Pt-doped MoVNbOx catalysts were prepared by using impregnation method.
These catalysts were used for oxidative dehydrogenation reaction of propane to
propylene. The catalysts prepared were characterized by X-ray diffraction
(XRD), Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES),
Brunauer-Emmett-Teller (BET) Surface Area Measurement, SBET, Scanning
Electron Microscopy (SEM), and Temperature Programmed Reduction in
Hydrogen (H2-TPR). From the XRD data, it has been found that all doped
catalysts showed the presence of tetragonal Mo5O14-like phases with a much better crystallite formation as compared to the undoped MoVNbOx. The particle
crystallinity increases as the amount of dopant loaded increases. ICP-OES
analysis displayed that the atomic ratio of Mo/V/Nb was 1/0.24/0.13, agreeing
well with the theoretical ones. However, the amount of dopant was a bit less
especially for Pt doped catalysts. Doping of Ni, Co and Pt lowered the surface
area value as compared to undoped MoVNbOx catalysts (8.8 m2/g). This
confirmed the incorporation of dopants occur in the catalytic system.
Furthermore SEM images supported this claim by showing the particles
developed into c-direction which supported high crystallinity of doped catalysts
and the role of dopants as structural promoter. Therefore, the reputed active site
(i.e. Mo5O14-like phase) improved when dopants were added, eventually affecting
the catalytic performance. H2-TPR showed the reducibility of the catalyst
confirming the existence of lattice oxygen of high reaction temperature. Catalytic
test of Pt-MoVNbOx catalysts gave the highest activity (13.4 % for aPtMoVNbOx
and 23.4 % for bPtMoVNbOx) in propane conversion but 0 % selectivity towards
propylene due to the poisoning of Pt site by COx. Meanwhile Ni-MoVNbOx
catalysts have relatively lower activity (7.5 % for aNiMoVNbOx) than Pt-
MoVNbOx catalysts but higher selectivity for propylene production (44.0 % for
aNiMoVNbOx). For Co-MoVNbOx catalysts, the higher activity for propane
conversion is found for lower loading of dopants, while high selectivity for
propylene is observed for high loading of dopants.
KW  - Dehydrogenation
KW  - Oxidation
KW  - Catalysis
ER  -