Contents lists available at ScienceDirect Energy Conversion and Management journal homepage: www.elsevier.com/locate/enconman Thermodynamic and experimental analysis on ethanol steam reforming for hydrogen production over Ni-modified TiO 2 /MMT nanoclay catalyst Muhammad Tahir a, ⁎ , William Mulewa a,b , Nor Aishah Saidina Amin a , Zaki Yamani Zakaria a a Chemical Reaction Engineering Group (CREG), Department of Chemical Engineering, Faculty of Chemical & Energy Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia b Technical University of Mombasa, 90420, Mombasa 80100, Kenya ARTICLE INFO Keywords: Thermodynamics Montmorillonite Ni/TiO 2 Ethanol steam reforming H 2 production Stability performance ABSTRACT Catalytic ethanol steam reforming (ESR) offers a sustainable and attractive route for hydrogen production, which can be utilized as a substitute for fossil fuels. ESR for hydrogen production involves complex reactions and yield of hydrogen depends upon several process variables such as temperature, molar feed ratio and pressure. In this study, a thermodynamics analysis coupled with experimentation for ESR toward hydrogen production has been investigated. The structured montmorillonite (MMT) nanoclay and TiO 2 supported catalyst incorporated by nickel (Ni) was developed via a sol-gel and impregnation methods. The catalyst samples were characterized by XRD, FE-SEM, EDX, BET and TGA to understand crystallinity, surface morphology, pore structure and stability. Initially, thermodynamic analysis was employed to study the effect of reaction conditions on equilibrium pro- duct distribution of ESR. The equilibrium concentrations of different compounds were calculated by the method of direct minimization of the Gibbs free energy. Optimum conditions for ESR were found to be; atmospheric pressure, temperatures between 600 and 700 °C and steam to ethanol (S/E) feed molar ratio of 10:1, at which highest hydrogen can be produced with minimum coke formation. Next, catalytic performance of NiO/MMT- TiO 2 catalyst for enhanced ESR for hydrogen production was conducted in a tubular fixed bed reactor at 500 °C and atmospheric pressure. Noticeably, Ni-promoted TiO 2 NPs found efficient for selective hydrogen production, yet MMT-supported Ni/TiO 2 gave much higher ethanol conversion with improved hydrogen yield. Using 12% Ni-10% MMT/TiO 2 catalyst, ethanol conversion of 89% with H 2 selectivity and yield of 61 and 55%, respectively were obtained. The stability test revealed MMT-supported catalysts maintained activity even after 20 h. By comparing results, it was possible to explain deviations between thermodynamic analysis and experimental results regarding carbon deposition and selective hydrogen production. 1. Introduction Among the renewable fuels, hydrogen (H 2 ) as an energy carrier has the long-term potential of reducing dependency on fossil fuels and ex- hibits zero carbon emissions since its oxidation reactions produce water vapor [1,2]. However, overall environmental impact and energy effi- ciency of H 2 depend on its sources and means of production. H 2 can be produced from a variety of feedstocks, including fossil fuels such as natural gas (NG), oil and coal and renewable sources like biomass [3,4]. Steam reforming (SR) of hydrocarbons (HCs), especially NG is the most common method for H 2 production, yet it is not attractive approach due to its fossil-fuel derived feedstock [5]. Recent research has dwelt on oxygenated HCs, including; bio-oil [6,7], glycerol [8–10], and methanol [11–13], yet ethanol (EtOH) reforming is considered another attractive and low cost renewable feedstock due to high H 2 content and can be produced renewably from biomass through fermentation [14,15]. Since, the boiling point of EtOH is lower than H 2 O, thus EtOH reformed can be conducted through three main techniques; partial oxidation (POX), auto-thermal reforming (ATR) and steam reforming (ESR) [16]. POX reaction requires lower energy input for fuel evaporation compared to ATR and ESR because water is absent as a reactant. Air can be used as an oxidant substitute for O 2 in the reaction, making POX more economical as explained in Eq. (1) [17–19] + → + =− C H OH 3 2 O 2CO 3H ΔH 554 kJ/mol 2 5 2 2 2 (1) However, the maximum theoretical yield of POX is 3 mol H 2 per http://dx.doi.org/10.1016/j.enconman.2017.10.042 Received 18 May 2017; Received in revised form 21 September 2017; Accepted 14 October 2017 ⁎ Corresponding author at: Chemical Reaction Engineering Group (CREG), Department of Chemical Engineering, Faculty of Chemical & Energy Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia. E-mail addresses: mtahir@cheme.utm.my, bttahir@yahoo.com (M. Tahir). Energy Conversion and Management 154 (2017) 25–37 0196-8904/ © 2017 Elsevier Ltd. All rights reserved. MARK