Development of modified KIT-6 and SBA-15-spherical supported Rh catalysts for N 2 O abatement: From powder to monolith supported catalysts Murid Hussain a,b , Debora Fino a , Nunzio Russo a,⇑ a Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, Torino 10129, Italy b Department of Chemical Engineering, COMSATS Institute of Information Technology, MA Jinnah Building, Defence Road, Off Raiwind Road, Lahore 54000, Pakistan highlights  Improved hydrothermal stability of KIT-6, SBA-15-S by post salt addition.  Moderate acidic sites on KIT-6 or SBA-15-S surfaces by Al incorporation.  N 2 O decomposition by modified silica supported Rh powder catalysts at lab-scale.  Inhibitors or promoters effects on the catalytic activity, and stability tests.  Activity of optimized powder catalysts on monolith by lab-scale pilot-plant reactor. article info Article history: Available online 24 June 2013 Keywords: Mesoporous silica modification Powder Monolith Rh N 2 O decomposition abstract In the chemical industry, nitric acid and adipic acid plants are the main producers of nitrous oxide (N 2 O), a greenhouse gas that damages the ozone layer and leads to environmental problems. In this work, mes- oporous silica KIT-6 and SBA-15-spherical, materials have been modified by post salt addition and the incorporation of aluminum (Al), in order to increase their stability and produce more acidic sites on the surface. The potential of these modified mesoporous silica supported Rh (1 wt.%) powder catalysts has been examined in a small laboratory scale reactor under specific N 2 O decomposition conditions to investigate the properties of these materials for this kind of application. Modified KIT-6 or SBA-15-spher- ical supported Rh catalysts not only showed better activity, but also very good stability compared to the non-modified mesoporous silica supported Rh catalysts that were investigated. The higher catalytic activ- ity was due to the improved acidic sites on the supports and the long-term stability might be due to the thicker wall of the materials caused by the post salt addition. The role of O 2 , CO and NO has also been explored to establish the promoting or inhibiting effect on these catalysts. It has been found that O 2 and NO inhibited and suppressed the activity, whereas CO promoted the N 2 O decomposition activity at lower temperatures. The final optimized catalysts (Rh/Al-KIT-6 post salt treated and Si/Al = 5, and Rh/Al-SBA-15-S post salt treated and Si/Al = 20) have also shown better activity than the commercial alu- mina supported Rh catalysts. Finally, the optimized powder catalysts were deposited on a cordierite type monolith and tested in a laboratory-scale pilot-plant reactor, also showed good activity and hydrother- mal stability, which means they can be considered promising candidates for this application. Ó 2013 Elsevier B.V. All rights reserved. 1. Introduction Nitrous oxide, N 2 O, has recently received a great deal of atten- tion by scientists because of its possible environmental effects [1].N 2 O lasts a long time (approximately 150 years) in the atmo- sphere, contributes to the destruction of stratospheric ozone and is considered a greenhouse gas [1–3].N 2 O is produced by natural as well as anthropogenic sources. The primary natural sources of N 2 O are the biological processes that take place in soils and oceans. Fertilizers, nitric acid, adipic acid, caprolactam and glyoxal produc- tion, fossil fuels and biomass combustion, as well as sewage treat- ment are the main contributors of the anthropogenic sources [3–5]. However, nitric acid production is thought to be the largest industrial source with a global annual emission of 400 kt of N 2 O [4] and present in the tail-gas (NO x : 100–3500 ppm; N 2 O: 300–3500 ppm; O 2 : 1–4 vol.%; H 2 O: 0.3–2 vol.%) at the outlet of the NO 2 absorber in the nitric acid plant. It has therefore been 1385-8947/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.cej.2013.06.032 ⇑ Corresponding author. Tel.: +39 011 0904710; fax: +39 011 0904699. E-mail address: nunzio.russo@polito.it (N. Russo). Chemical Engineering Journal 238 (2014) 198–205 Contents lists available at SciVerse ScienceDirect Chemical Engineering Journal journal homepage: www.elsevier.com/locate/cej