Please cite this article in press as: A.P.C. Ribeiro, et al., J. Mol. Catal. A: Chem. (2016), http://dx.doi.org/10.1016/j.molcata.2016.07.015 ARTICLE IN PRESS G Model MOLCAA-9949; No. of Pages 7 Journal of Molecular Catalysis A: Chemical xxx (2016) xxx–xxx Contents lists available at ScienceDirect Journal of Molecular Catalysis A: Chemical journal homepage: www.elsevier.com/locate/molcata The influence of multiwalled carbon nanotubes and graphene oxide additives on the catalytic activity of 3d metal catalysts towards 1-phenylethanol oxidation Ana Paula C. Ribeiro a , Emmanuele Fontolan a,b , Elisabete C.B.A. Alegria a,c,∗ , Maximilian N. Kopylovich a , Roberta Bertani b , Armando J.L. Pombeiro a,∗∗ a Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Universidade de Lisboa, Portugal b Department of Industrial Engineering, University of Padova, Padova, Italy c Chemical Engineering Departament, Instituto Superior de Engenharia de Lisboa, Instituto Politécnico de Lisboa, Portugal a r t i c l e i n f o Article history: Received 25 April 2016 Received in revised form 28 June 2016 Accepted 6 July 2016 Available online xxx Dedicated to Prof. Georgiy B. Shul’pin on the occasion of his 70th birthday as a recognition for his relevant scientific achievements. Keywords: Carbon nanotubes Mechanochemistry Catalysis Oxidation Alcohols a b s t r a c t 3d metal (Cu, Fe, Co, V) containing composite catalysts for the solvent-free microwave-assisted trans- formation of 1-phenylethanol to acetophenone with tert-butyl hydroperoxide (TBHP) as oxidant were prepared by ball milling. The influence of multiwalled carbon nanotubes (CNTs) and graphene oxide (GO) additives on the catalytic activity of the catalysts was studied. CNTs or GO were mixed by ball milling with the metal salts (CoCl 2 ), oxides (CuO, Fe 2 O 3 , V 2 O 5 ) or binary systems (Fe 2 O 3 -CoCl 2, CoCl 2 -V 2 O 5 , CuO- Fe 2 O 3 ). For CoCl 2 -based catalytic systems, addition of small amounts (0.1–5%) of CNTs or GO leads to significant improvement in catalytic activity, e.g. 1% of the CNTs additive allows to rise yields from 28 to 77%, under the same catalytic conditions. The CoCl 2 -5%CNTs composite is the most active among the studied ones with 85% yield and TON of 43 after 1 h. © 2016 Elsevier B.V. All rights reserved. 1. Introduction The design and synthesis of micro- and nanoscale materials with specific shapes, sizes and morphologies are one of the most promising directions in chemical technology. Due to their small sizes, micro- and nanocatalysts have high surface-to-mass ratio and exposed active sites, and thus they can exhibit unique prop- erties, in particular a high catalytic activity [1–8]. However, in many instances, high cost, fast deactivation and difficult recovery of the dispersed catalysts make their practical application prohibitive [1,2]. In this respect, the following points should be addressed towards the development of new (micro, nano) dispersed catalytic ∗ Corresponding author at: Chemical Engineering Department, Instituto Superior de Engenharia de Lisboa, Instituto Politécnico de Lisboa, Portugal. ∗∗ Corresponding author at: Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Universidade de Lisboa, Lisboa, Portugal. E-mail addresses: ebastos@deq.isel.ipl.pt (E.C.B.A. Alegria), pombeiro@tecnico.ulisboa.pt (A.J.L. Pombeiro). systems: (i) how to decrease the price of the catalysts and improve their stability; (ii) how to recover the catalysts by a cheap and effec- tive way. The usage of cheap and available starting materials and simple synthetic procedures can be proposed as a response for point (i), while magnetic recovery can be an answer for the (ii) challenge [9,10]. One of the well-known approaches to construct smart materi- als is the preparation of composites from compounds of various classes [11,12]. Carbon nanomaterials, such as carbon nanotubes or graphene, can -interact with aromatic substituents of a sub- strate and facilitate electron transfer in catalysis [13], while the inorganic component of composite, e.g. a transition metal, can be responsible for performing a redox or another transformation of substrate [14]. If the overall action is synergistic, a significant improvement in activity can occur [14]. As result, the prepara- tion of catalytic systems composed of transition metals and carbon nanomaterials is of great potential. For example, a sandwich-like N-doped graphene/Co 3 O 4 hybrid catalytic system was prepared by solvothermal method and applied for selective oxidation of http://dx.doi.org/10.1016/j.molcata.2016.07.015 1381-1169/© 2016 Elsevier B.V. All rights reserved.