Support interaction of Ni nanocluster based catalysts applied in CO 2 reforming Subhasis Das a , Sharvani Thakur a , Arijit Bag b , Manveer Singh Gupta a , Prasenjit Mondal c , Ankur Bordoloi a,⇑ a Refinery Technology Division, CSIR—Indian Institute of Petroleum, Dehradun 248005, India b Chemical Science Division, IISER Kolkata, Mohanpur, Nadia, West Bengal, India c Department of Chemical Engineering, Indian Institute of Technology, Roorkee, India article info Article history: Received 7 April 2015 Revised 4 June 2015 Accepted 11 June 2015 Keywords: C–H activation Surface-modified alumina Dry reforming Density functional theory calculations Reaction kinetics abstract Surface-tuned mesoporous alumina has been prepared using a template-assisted solvo thermal method, and Ni nanoclusters (4–5 nm) have been synthesized on this support using a very facile organic matrix decomposition approach to dry reforming of methane. The catalyst system demonstrates very good catalytic activity toward CH 4 and CO 2 conversion (>90%), with a H 2 /CO ratio in syngas of almost unity, remarkable stability for more than 100 h, and is proven to be a very interesting catalyst system in dry reforming with methane. Both fresh and spent catalyst have been thoroughly characterized using differ- ent techniques such as N 2 physisorption studies, X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, temperature-programmed reduction, scanning elec- tron microscopy, energy-dispersive X-ray spectroscopy, and thermogravimetric analysis to determine the structure–activity relationship. Characterization results show that Ni nanoclusters are highly dis- persed on the surface of modified alumina. In addition, an excellent metal-support interaction evolves that clearly enhances the stability of the Ni clusters, providing better resistivity toward sintering. The presence of balanced acidic and basic sites in the surface-modified alumina drastically lowers coke for- mation and enhances the catalyst lifetime. The structures of adsorbed methane and carbon dioxide on the catalyst surface and the corresponding energy of adsorption have been computed using density functional theory calculations. It has been found that CO 2 is adsorbed and dissociated into CO and O, while methane is adsorbed as CH 3 / and H / on the catalyst system. Ó 2015 Elsevier Inc. All rights reserved. 1. Introduction Depletion of petroleum feedstock and the urgent need to reduc- ing carbon footprints to combat global warming necessitate the human race’s exploration of alternative fuel resources that are eco- logically and economically acceptable and can also limit the dependency on crude oil. Methane and carbon dioxide, the two major greenhouse gases, can be utilized to generate valuable prod- ucts and reduce global warming. One of such processes is carbon dioxide reforming with methane (DRM), in which carbon dioxide and methane produces synthesis gas (syngas), a mixture of carbon monoxide and hydrogen with a molar ratio near unity. Syngas is a crucial ingredient for many fuels and chemicals such as methanol and FT products through direct or indirect routes. Furthermore, the reaction is usually considered as a chemical energy transmission system (CETS) that can transform solar energy or nuclear energy into comprehensible chemical energy [1,2]. Supported noble metals (Ru, Rh, Pd, Ir, Pt, W), as well as transi- tion metals (Co, Ni, Cu, Fe), have been extensively reported in the literature as catalysts for carbon dioxide reforming with methane [3]. However, very limited success has been observed for most of the reported catalyst systems due to deposition of carbonaceous species on active sites of the catalyst and pore blocking, resulting in an increase in pressure in reformer reactor tubes [4] and sinter- ing of active species. Noble metals show promising catalytic activ- ity and higher coke resistivity; however, high cost and limited availability restrict their use in large-scale processes. Carbon depo- sition on an active catalyst depends upon several parameters, such as the nature of the metal, the crystalline structure of the metal, the metal-support interaction, and support acidity–basicity [5]. It is an established fact that the modification of Ni-based catalysts with different supports and promoters, as well as controlling the size of the particle, is an effective way to reduce carbon deposition http://dx.doi.org/10.1016/j.jcat.2015.06.010 0021-9517/Ó 2015 Elsevier Inc. All rights reserved. ⇑ Corresponding author. E-mail address: ankurb@iip.res.in (A. Bordoloi). Journal of Catalysis 330 (2015) 46–60 Contents lists available at ScienceDirect Journal of Catalysis journal homepage: www.elsevier.com/locate/jcat