Malaysian Journal of Analytical Sciences Vol 20 No 2 (2016): 382 - 387
Temperature
Programmed Reduction and X-Ray
Diffractometry Studies of MoO3 Reduction by Different ConcentrationS of Carbon Monoxide
(Kajian
Penurunan Suhu Berprogram dan Pembelauan Sinar-X Terhadap Penurunan MoO3
Menggunakan Kepekatan Karbon Monoksida Berbeza)
Alinda
Samsuri1, 2*, Tengku Shafazila Tengku Saharuddin1, Fairous
Salleh1, Rizafizah Othaman1,
Mohamed
Wahab Mohamed Hisham1, Mohd. Ambar Yarmo1
1Catalysis Research Group, School of Chemical Sciences
and Food Technology,
Faculty
of Science and Technology,
Universiti
Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan, Malaysia.
2Centre for Defence
Foundation Studies,
Universiti Pertahanan
Nasional Malaysia, Kem Sungai Besi, 57000 Kuala Lumpur, Malaysia
*Corresponding author: alindasamsuri@gmail.com
Received: 24 February 2015; Accepted: 27 October 2015
Abstract
Reduction of
molybdenum trioxide, MoO3 to molybdenum dioxide, MoO2 by using
carbon monoxide, CO has been studied by temperature programmed reduction (TPR)
and X-ray diffraction spectroscopy (XRD). The influence of carbon monoxide
concentration on the reduction of MoO3 have been investigated by
comparing the reduction behaviour of MoO3 to MoO2 with 20
vol.% and 40 vol.% of CO concentration. The XRD results show that by using 20% of CO, reduction to MoO2 takes
place at 700°C in 60 minutes. However, by using 40% of CO, complete reduction
to MoO2 takes place at 700°C in only 30 minutes. Moreover, excess of
CO results in the formation of molybdenum carbide, Mo2C. It is suggested that by using CO, complete reduction
from MoO3 to MoO2 gives two-steps reduction (MoO3
→ Mo4O11 → MoO2) with Mo4O11
as an intermediate product. It can be
concluded that the reducing behavior of MoO3 is strongly dependent
on the concentration of CO and reaction time.
Keywords: molybdenum trioxide, molybdenum
dioxide, molybdenum carbide, carbon monoxide
Abstrak
Penurunan molibdenum trioksida,
MoO3 kepada molibdenum dioksida, MoO2 dengan menggunakan
karbon monoksida, CO telah dikaji menggunakan suhu penurunan berprogram (TPR)
dan spektroskopi pembelauan sinar-X (XRD). Kesan kepekatan karbon monoksida terhadap
penurunan MoO3 telah dikaji dengan membandingkan kesan penurunan MoO3
kepada MoO2 menggunakan kepekatan karbon monoksida di antara 20 %
dan 40 %. Keputusan XRD menunjukkan bahawa dengan menggunakan 20 % kepekatan
CO, penurunan kepada MoO2 berlaku pada suhu 700 °C dalam masa 60
minit. Walau bagaimanapun, dengan menggunakan 40 % kepekatan CO, penurunan
lengkap kepada MoO2 berlaku pada suhu 700 °C dalam masa hanya 30 minit.
Selain itu, pendedahan kepada CO berlebihan akan menyebabkan pembentukan molibdenum
karbida, Mo2C. Adalah dicadangkan bahawa dengan menggunakan CO, penurunan
lengkap daripada MoO3 kepada MoO2 terdiri daripada dua peringkat penurunan (MoO3
→ Mo4O11 → MoO2) dengan menghasilkan Mo4O11
sebagai produk perantara. Ini boleh disimpulkan bahawa kelakuan penurunan
MoO3 adalah amat bergantung kepada kepekatan CO dan tempoh masa
tindak balas.
Kata
kunci: molibdenum
trioksida, molibdenum dioksida, molibdenum karbida, karbon monoksida
References
1.
Manukyan, K., Davtyan, D.,
Bossert, J. and Kharatyan, S. (2011). Direct reduction of ammonium molybdate to
elemental molybdenum by combustion reaction. Chemical Engineering Journal,
168 (2): 925 – 930.
2.
Enneti, R. K. and Wolfe, T. A. (2012). Agglomeration during
reduction of MoO3. International
Journal of Refractory Metals and Hard Materials, 31: 47 – 50.
3.
Wang, J., Ren, Z., Liu, W., Gao, F. and Zhou, M. (2009). Effects
of RE2O3 doping on the reduction behavior of molybdenum
oxide and properties of molybdenum powder. International
Journal of Refractory Metals and Hard Materials, 27 (1): 155 – 158.
4.
Saghafi, M., Heshmati-Manesh, S., Ataie, A. and Khodadadi, A.
A. (2012). Synthesis of nanocrystalline molybdenum by hydrogen reduction of
mechanically activated MoO3. International
Journal of Refractory Metals and Hard Materials, 30 (1): 128 – 132.
5.
Saghafi, M., Ataie, A. and Heshmati-Manesh, S. (2011). Effects
of mechanical activation of MoO3/C powder mixture in the processing
of nano-crystalline molybdenum. International
Journal of Refractory Metals and Hard Materials, 29 (4): 419 – 423.
6.
Satyajeet Chaudhury, V. V., Mukerjee, S. K. and Vaidya, V. N.
(1997). Kinetics and mechanism of carbothermic reduction of MoO3 to
Mo2C. Journal Alloys Compounds, 261: 105 – 113.
7.
Dang, J., Zhang, G.-H., Chou, K. C., Reddy, R. G., He, Y. and
Sun Y. (2013). Kinetics and mechanism of hydrogen reduction of MoO3
to MoO2. International Journal
of Refractory Metals and Hard Materials, 41: 216 – 223.
8.
Lalik, E. (2011). Kinetic analysis of reduction of MoO3
to MoO2. Catalysis Today, 169: 85 – 92.
9.
Claridge, J. B., York, A. P. E., Brungs, A. J., Marquez-Alvarez,
C., Sloan, J., Tsang, S. C. and Green, M.
L. H. (1998). New Catalysts for the Conversion of Methane to Synthesis Gas :
Molybdenum and Tungsten Carbide. Journal of Catalysis, 180: 85 – 100.