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.

 




Previous                    Content                    Next