Journal of Molecular Catalysis A: Chemical 223 (2004) 339–345 Effect of method of preparation of copper – magnesium oxide catalyst on the dehydrogenation of cyclohexanol B.M. Nagaraja, V. Siva Kumar, V. Shashikala, A.H. Padmasri, S. Sreevardhan Reddy, B. David Raju ∗ , K.S. Rama Rao ∗ Catalysis and Physical Chemistry Division, Indian Institute of Chemical Technology, Tarnaka, Hyderabad 500 007, India Received 10 February 2003; received in revised form 12 November 2003; accepted 21 November 2003 Available online 15 September 2004 Abstract The superior catalytic activity in the dehydrogenation of cyclohexanol to cyclohexanone of Cu/MgO coprecipitated catalyst over corre- sponding impregnated and solid–solid wetting catalysts is ascribed to the higher Cu metal area and interaction between the microcrystals of CuO and MgO associated with coprecipitated catalyst. Further, the effect of Cu loading on the activity of Cu/MgO coprecipitated catalysts indicates that the catalyst comprising of ∼16 wt.% Cu exhibits higher activity. The catalysts have been characterized by different techniques, viz. X-ray diffraction (XRD), atomic absorption spectroscopy (AAS), temperature programmed reduction (TPR), BET-surface area measure- ments and N 2 O decomposition for measuring Cu metal surface areas and the results have been correlated with the activities of catalysts where ever possible. © 2004 Elsevier B.V. All rights reserved. Keywords: Dehydrogenation; Cyclohexanol; Cyclohexanone; N 2 O decomposition; Co precipitation; Impregnation; Solid–solid wetting 1. Introduction Catalytic dehydrogenation of cyclohexanol to cyclohex- anone is an industrially important reaction in the manufacture of nylon because the two major raw materials in produc- ing polyamide fiber are caprolactum and adipic acid, both of which can be obtained from cyclohexanone [1,2]. However, the conventional dehydrogenation process is severely con- strained by thermodynamic equilibrium apart from sintering of Cu metal beyond 280 ◦ C [3,4]. The commercial catalysts for the dehydrogenation of cyclohexanol are either Cu-Zn- Al or Cu-Mg catalysts, for which the method of preparation is very crucial to obtain the equilibrium conversions of cy- clohexanol, which are in the range of 50–60% in the tem- perature range of 220–260 ◦ C. Modification of Cu–Al 2 O 3 interaction by carbon coverage of Al 2 O 3 and its influence on ∗ Corresponding authors. Fax: +91 40 271 60921. E-mail addresses: david@iict.ap.nic.in (B. David Raju), ksrama- rao@iict.ap.nic.in (K.S. Rama Rao). the cyclohexanol dehydrogenation activity has been reported [5]. In the catalytic dehydrogenation of cyclohexanol, the dependence of Cu oxidation state on the catalytic properties of Cu/MgO catalysts has been reported [6]. In the present investigation, we are reporting the influence of method of preparation of Cu/MgO catalysts and the loading of Cu metal on the characteristics and the cyclohexanol dehydrogenation activity. 2. Experimental 2.1. Preparation of Cu/MgO catalysts Three Cu/MgO catalysts with 16 wt.% of Cu have been prepared by coprecipitation, impregnation and solid–solid wetting methods. An aqueous solution containing requisite amounts of Cu (NO 3 ) 2 ·3H 2 O (M/S. Loba Chemie Ltd., In- dia), Mg (NO 3 ) 2 ·6H 2 O (M/S. Loba Chemie Ltd., India) with their concentration of 1 M each, have been simultane- 1381-1169/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.molcata.2003.11.046