Modeling of NH 3 –NO–SCR reaction over CuO/c-Al 2 O 3 catalyst in a bubbling fluidized bed reactor using artificial intelligence techniques Muhammad Faisal Irfan a,⇑ , Farouq S. Mjalli b , Sang Done Kim c a Department of Chemical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia b Petroleum and Chemical Engineering Department, Sultan Qaboos University, 123 Muscat, Oman c Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, 305-701 Daejeon, Republic of Korea article info Article history: Received 6 August 2010 Received in revised form 16 September 2011 Accepted 19 September 2011 Available online 1 October 2011 Keywords: SCR NO removal ANN Mechanistic model abstract Comparative study of the artificial neural network and mechanistic model was carried out for NO removal in a bubbling fluidized bed reactor. The effects of temperature, superficial gas velocity and ammonia/nitric oxide ratio on the NO removal efficiency were determined and their optimum conditions were estimated by the experimental study, the artificial neural network and mechanistic models as well. The optimum values of ammonia/nitric oxide ratio, temperature and superficial gas velocity for the max- imum NO removal efficiency were found to be 1.5, 300 °C and 0.098 m/s, respectively. A mechanistic model was implemented in our previous study [Muhammad F. Irfan, Sang Done Kim and Muhammad R. Usman, 2009] and it was found that this model fitted well only at specific condition i.e. maximum con- version temperature (300 °C). However, it failed to perfectly match with rest of the experimental data points at other temperatures and parametric conditions as well. To improve this, an artificial neural net- work modeling strategy was applied and its predictions were evaluated which were favorably matched with the experimental data rather than the mechanistic model. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Selective catalytic reduction process is a well known process for the NO reduction using nitrogen containing compounds such as ammonia or urea. Different catalysts have been studied and used for this process such as Cu-zeolite and oxide based catalysts [1–7], vanadium based catalysts [8,9], cobalt based catalysts [10]. The vanadium based catalysts have been used for more than 20 years for the SCR process [11]. However, porous anatase re- quired was found difficult to prepare and it has also high cost [12]. On the contrary, CuO is cheaper in cost, highly active and can simultaneously remove SO 2 and NO x and thus provide a wider roam for further study [13,14]. Otto et al. [15] reported that the CuO based catalysts containing Cu-zeolite have a high activity for the reaction of NO with NH 3 . Chmielarz et al. [2,3] studied the NO reduction with NH 3 process over Al 2 O 3 and TiO 2 pillared mont- morillonites modified with Cu or Co active metals. They claimed that Ti-modified clays were found to be significantly more active in DeNO x process than Al-sample. Moreover, introduction of Cu into Ti and Al samples activates them much more effectively in the low temperature region (25–450 °C) than Co based samples which are much better at high temperature region (T > 400 °C). Chmielarz et al. [5] reported the CuO/Al 2 O 3 catalyst surface proper- ties and reaction mechanism by in situ diffuse reflectance infrared fourier transform spectroscopy to understand the catalyst’s surface acid sites, the nature of catalytic sites and the SCR mechanism. Also, CuO/zeolite catalyst has a distinct advantage of decrease of NH 3 oxidation over other catalysts to remove NO x [16]. Chmielarz et al. [3] compared the NH 3 oxidation by O 2 at high temperature over modified Cu and Co based catalysts and they observed that NH 3 oxidation was occurred on modified Cu based catalyst how- ever, no oxidation of NH 3 took place over the titania-pillared clay modified with Co catalyst in the studied temperature region i.e. 50–450 °C. The reaction mechanism in the SCR of NO with NH 3 in the presence of O 2 over CuO/c-Al 2 O 3 catalyst was summarized by Centi et al. [17]. They reported that CuO/c-Al 2 O 3 catalyst might have two possible reaction pathways of NO reduction to N 2 , one via a nitrosoamide like intermediate and second via an ammonium nitrate like intermediate or their equivalent Cu complexes [NO– Cu–NH 2 and NO 2 –Cu–NH 4 respectively]. As NH 3 oxidation is one of the side reactions during SCR process and it does affect on NO reduction hence numerous studies have also been conducted for this process over Cu based catalysts [13,18,19]. Blanco et al. [13] developed CuO/NiO based catalysts and they claimed that these catalysts helped in reducing NH 3 slip up to great extent due to NH 3 oxidation and the optimum active phase content found was [CuO] = 6.3 wt.% and [NiO] = 0.6 wt.%. Jones et al. [18] developed a reaction mechanism to satisfactorily describe the NH 3 oxidation 0016-2361/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.fuel.2011.09.043 ⇑ Corresponding author. Tel.: +60 3 7967 5206; fax: +60 3 7967 5319. E-mail address: muhammadfipk@um.edu.my (M.F. Irfan). Fuel 93 (2012) 245–251 Contents lists available at SciVerse ScienceDirect Fuel journal homepage: www.elsevier.com/locate/fuel