Malaysian Journal of Analytical Sciences Vol 21 No 1 (2017): 119 - 126

DOI: http://dx.doi.org/10.17576/mjas-2017-2101-14

 

 

 

ROLE OF ACTIVE CHROMIUM SPECIES ON DIFFERENT SUPPORT FOR DEHYDROGENATION OF PROPANE

 

(Peranan Spesies Kromium Aktif pada Penyokong yang Berbeza dalam Tindak balas Penyahhidrogenan Gas Propana)

 

Wan Nor Roslam Wan Isahak^1,2*, Zatil Amali Che Ramli², Ibdal Satar², Mohamed Wahab Mohamed Hisham³,

Mohd Ambar Yarmo³

 

¹Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment

²Fuel Cell Institute

³School of Chemical Sciences and Food Technology, Faculty of Science and Technology

Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

 

*Corresponding author: wannorroslam@ukm.edu.my

 

 

Received: 21 October 2015; Accepted: 14 June 2016

 

 

Abstract

Dehydrogenation of propane (DHP) was studied over a series of Cr₂O₃–Al₂O₃ and Cr₂O₃-SiO₂ catalysts, prepared by incipient wetness impregnation and sol gel (SG) method, respectively, to gain a better understanding of the nature and distribution of chromium (Cr) species and their catalytic function. To this end, the catalysts were characterized by N₂-physisorption and X-ray diffraction (XRD). N₂-physisorption analysis of Cr₂O₃-SiO₂ showed the relatively higher surface area of 391.1 m²/g, compared with Cr₂O₃-Al₂O₃ of 224.3 m²/g. The combination method of sol gel and sonothermal also produced smaller particles size of catalyst with higher microporosity of 23.5% and smaller pores size of 6 nm. The good surface properties of Cr₂O₃-SiO₂ enabled the high conversion of propane of 55% at 550 °C. At higher temperature of 600 °C, the Cr species might be reduced into lower oxidation state and inhibit the catalytic behavior to produce hydrogen.

 

Keywords:  chromium (II) oxide, thermodynamic consideration, sonothermal, catalytic behavior, hydrogen energy

 

Abstrak

Tindak balas penyah-hidrogenan gas propana (DPP) telah dikaji menggunakan beberapa siri mangkin Cr₂O₃–Al₂O₃ dan Cr₂O₃-SiO₂ yang dihasilkan melalui kaedah impregnasi basah dan sol gel (SG) method, untuk memahami sifat dan serakan spesies logam Cr dan fungsi pemangkinannya. Dalam kajian ini, mangkin diciri menggunakan kaedah jerapan gas N₂ dan pembelauan sinar X (XRD). Analisis jerapan N₂ bagi mangkin Cr₂O₃-SiO₂ menunjukkan ia mempunyai luas permukaan yang paling tinggi sebanyak 391.1 m²/g, berbanding mangkin Cr₂O₃-Al₂O₃ sebanyak 224.3 m²/g. Kombinasi kaedah sol gel (SG) dan sonotermal menghasilkan mangkin yang bersaiz lebih kecil dengan keporosan mikro sebanyak 23.5% dan saiz liang sebanyak 6 nm. Ciri-ciri permukaan yang baik ditunjukkan oleh mangkin Cr₂O₃-SiO₂ menyumbang kepada aktiviti tindak balas yang baik dengan peratus penukaran propana yang tinggi sebanyak 55% pada suhu 550 °C. Pada suhu tindak balas 600 °C pula, spesies logam Cr boleh terturun kepada keadaan pengoksidaan yang lebih rendah dan merencat tindak balas pemangkin bagi menghasilkan gas hidrogen sebagai produk utama.

 

Kata kunci:  kromium (II) oksida, pendekatan termodinamik, sonotermal, sifat pemangkinan, tenaga hidrogen

 

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