Delivered by Publishing Technology to: Purdue University Libraries IP: 186.216.249.223 On: Fri, 18 Mar 2016 09:03:37 Copyright: American Scientific Publishers RESEARCH ARTICLE Copyright © 2012 American Scientific Publishers All rights reserved Printed in the United States of America Journal of Nanoscience and Nanotechnology Vol. 12, 9142–9147, 2012 Nickel Metal with Various Morphologies: Synthesis and Performances for Catalytic Carbon Dioxide Reforming with Methane Nopporn Teabpinyok 1 , Sutheerawat Samingprai 2 , and Metta Chareonpanich 1 3 ∗ 1 Faculty of Engineering, Department of Chemical Engineering, Center for Petroleum, Petrochemical, and Advanced Materials, Kasetsart University, Bangkok 10900, Thailand 2 Innovation and Technology Department, PTT Global Chemical Public Company Limited, Bangkok 10900, Thailand 3 Faculty of Engineering, Department of Chemical Engineering, Center for Advanced Studies in Nanotechnology and Its Applications in Chemical, Food and Agricultural Industries, Kasetsart University, Bangkok 10900, Thailand In this research, nickel metal of three different morphologies including nanostar, icosahedra, and microsphere structures were synthesized. It was found nanostar nickel revealed the Ni(111) crys- tallographic plane with particle size in the range of 150–200 nm and BET surface area of 13 m 2 /g. The icosahedra nickel also showed the Ni(111) crystallographic plane with larger particle size (300–400 nm) and BET surface area of 20 m 2 /g, whereas microsphere nickel exhibited the relatively large cluster size (approximately 3 m) and BET surface area (114 m 2 /g) as a result of an aggrega- tion of Ni(101) nanoplates. The obtained nickel catalysts were tested for the activity in carbon dioxide reforming with methane. Based on the similar specific surface area of catalysts, nanostar nickel showed the highest carbon dioxide and methane conversions due to its crystallographic structure. At 700  C, nanostar nickel catalyst exhibited the highest carbon dioxide and methane conversions of 17.6 and 10.5 times higher than those of microsphere nickel catalyst, respectively. Keywords: Nanostar, Icosahedra, Microsphere, Dry Reforming, Nickel Catalysts. 1. INTRODUCTION Carbon dioxide reforming with methane (CO 2g + CH 4g ↔ 2CO g + H 2g H =+247 kJ/mol) is a promis- ing reaction that offers advantages such as a potential reduction of major greenhouse gases (CO 2 and CH 4  and a low CO/H 2 ratio of synthesis gas product which is suit- able for the syntheses of hydrocarbon and oxygenated compounds. 1–4 Various types of catalysts and reaction con- ditions have been examined in the fixed bed reactor to achieve high carbon dioxide and methane conversion from this highly endothermic reforming reaction. 3–6 Among metal catalysts, an available and low cost nickel catalyst shows high activity for carbon dioxide reform- ing with methane. 2 4–6 However, the deactivation rate of nickel catalyst is relatively high due to the carbon depo- sition on the active surface of the catalyst, compared to that of the noble metal. 1 7 In order to achieve higher activity for carbon dioxide reforming with methane, high energy is required to enhance the methane decomposition rate and overcome the thermodynamic stability of methane ∗ Author to whom correspondence should be addressed. molecular structure. 8 9 The active surface area of nickel cat- alyst also potentially impact the decomposition of methane or CH x species. 10 In order to clarify the effect of metal morphology on the structure-reactivity of nickel catalysts, nickel catalysts with different morphologies were synthesized by using various techniques 11–13 and applied without the supports. Accordingly, the smaller-size, narrow particle size distri- bution, non-agglomerated nickel nanostar was synthesized by hydrazine reduction technique. 11 The perfect structure, icosahedral metallic nickel was synthesized via polyol reduction technique, 12 whereas nickel hydroxide with hier- archical structure and high surface area was synthesized via hydrothermal technique. 13 In this present work, these 3 kinds of nickel nanopar- ticles with different textural morphologies including nanostar, icosahedra, and microsphere have been synthe- sized following the techniques reported by Jung et al. 11 Bai et al. 12 and Kuang et al. 13 respectively. The effects of nickel morphology on catalytic activity and deactivation by carbon deposition were examined through carbon dioxide reforming with methane using a fixed bed reactor under various reaction temperatures. The conversions of carbon 9142 J. Nanosci. Nanotechnol. 2012, Vol. 12, No. 12 1533-4880/2012/12/9142/006 doi:10.1166/jnn.2012.6742