Malaysian Journal of Analytical Sciences Vol 20 No 5 (2016): 1073 - 1083

DOI: http://dx.doi.org/10.17576/mjas-2016-2005-12

 

 

 

EFFECT OF pH ON THE PHYSICOCHEMICAL PROPERTIES AND REDUCIBILITY OF MoVTeNbOx CATALYSTS

 

(Kesan pH Terhadap Sifat Fizikokimia dan Kebolehturunan Mangkin MoVTeNbOx)

 

Syazwani Mohd Noor¹, Irmawati Ramli^1,2*, Taufiq Yap Yun Hin^1,2, Norhazlin Zainuddin²

 

¹Centre of Excellence for Catalysis Science and Technology, Faculty of Science

²Department of Chemistry, Faculty of Science

Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia

 

*Corresponding author: irmawati@upm.edu.my

 

 

Received: 17 August 2015; Accepted: 25 August 2016

 

 

Abstract

A range of MoVTeNbOx catalysts were synthesised by slurry method assisted with a microwave irradiation. The pH of the synthesis solution was varied at pH = 1, 3, 5, and 7 and the obtained solid were calcined in air at 553 K for 1 hour and followed in N₂ at 873 K for 2 hours. The calcined samples were characterised and their reduction properties were evaluated. The pH of the synthesis solution was shown to affect the physicochemical properties where the formation of orthorhombic M1 phase was obtained for catalysts prepared at pH 1 and 3. The reducibility of the catalyst is improved for catalyst prepared at pH 3 as compared to those prepared at pH 1. Although higher synthesised pH (5 and 7) gave much higher reducibility of the metal oxides, however the removable oxygen could be of the unselective ones.

 

Keywords:  MoVTeNbOx catalysts, pH, reducibility, propane, acrylic acid

 

Abstrak

Satu siri mangkin MoVTeNbOx telah disintesis menggunakan kaedah buburan dibantu oleh radiasi gelombang mikro. Nilai pH bagi larutan sintesis telah dikaji pada pH = 1, 3, 5, dan 7 dan pepejal yang diperolehi telah dikalsin dalam udara pada 553 K selama 1 jam dan diikuti dalam nitrogen pada 873 K selama 2 jam. Sampel terkalsin telah dicirikan dan sifat kebolehturunan telah dikaji. Di dapati, pH bagi larutan sintesis memberi kesan kepada ciri fizikokimia di mana pembentukan fasa ortorombik M1 telah terjadi bagi mangkin yang disediakan pada pH 1 dan 3. Kebolehturunan mangkin ini dipertingkatkan bagi mangkin yang disediakan pada pH 3 berbanding yang disediakan pada pH 1. Walaupun mangkin yang disediakan pada pH yang lebih tinggi (5 dan 7) memberikan kebolehturunan logam oksida lebih tinggi, namun penyingkiran oksigen mungkin menjadi tidak selektif.

 

Kata kunci:  mangkin MoVTeNbOx, pH, kebolehturunan, propana, asid akrilik

 

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