Control of copper particles deposition in mesoporous SBA-15 silica by modified CVD method T. Tsoncheva a,⇑ , A. Gallo b,1 , I. Genova a , I. Spassova c , M. Marelli b , M. Dimitrov a , M. Khristova c , G. Atanasova c , D. Kovacheva c , D. Nihtyanova c,d , V. Dal Santo b a Institute of Organic Chemistry with Centre of Phytochemistry, BAS, Sofia, Bulgaria b CNR – Istituto di Scienze e Tecnologie Molecolari, via C. Golgi 19, 20133 Milano, Italy c Institute of General and Inorganic Chemistry, BAS, 1113 Sofia, Bulgaria d Institute of Mineralogy and Crystallography, BAS, 1113 Sofia, Bulgaria article info Article history: Received 23 May 2014 Received in revised form 29 July 2014 Accepted 4 August 2014 Available online 16 August 2014 Keywords: Modified OMCVD Copper deposition on SBA-15 Particles size control Methanol decomposition NO reduction abstract Copper supported SBA-15 catalysts were prepared by modified Organometallic Chemical Vapor Deposi- tion (OMCVD) technique. The materials were characterized by nitrogen physisorption, XRD, TEM, UV–Vis, XPS and temperature programmed reduction. Catalytic reductions of NO with CO and with a mixture of CO and methane as well as methanol decomposition were used as catalytic tests. The modified OMCVD procedure favors the formation of very finely dispersed nanoparticles located deeply into the micropores and the small mesopores of the SBA-15 silica matrix, while larger and predominantly located on the external surface copper species are detected for the materials prepared by conventional wet impregna- tion procedure. Ó 2014 Elsevier B.V. All rights reserved. 1. Introduction Many metallic properties, such as lattice constant, heat capacity, melting point, optical, magnetic, electric, adsorption and catalytic ones significantly change with decreasing of particles size in the nanoscale [1–4]. Mesoporous silicas are considered as good host matrices for nanosized metal particles due to their high surface area, well developed pore volume and tunable pore size, shape and topology [5], but the fine control of metal particles dispersion is still a matter of challenge. Among the various preparation tech- niques, the Organometallic Chemical Vapor Deposition is exten- sively used as solvent free method for the preparation of supported, homogeneously dispersed, metal nanosized particles [6–10]. OMCVD technique is based on the adsorption of a metal pre- cursor from the gas phase on the support followed by its decompo- sition. The main problem with this technique is reaching the desired metal loading due to the undesirable decomposition of pre- cursor on the apparatus walls. In our previous study we proposed a modified OMCVD method for tailored preparation of supported on silica copper nanoparticles [11]. The control of copper loading and particles size was achieved by multi-step deposition of the precur- sor (bis-(hexafluoroacetylacetonate) copper (II) hydrate – Cu(hfac) 2 xH 2 O, x < 1 or x = 1) starting from parent copper material, obtained by simple incipient wetness impregnation technique (WI). This strategy [12,13] allowed copper particles growth by interac- tion of copper precursor with metallic surface according the Eqs. (1) and (2): Hðads: on Cu NPsÞþ CuðhfacÞ 2 ðgÞ! CuðhfacÞðadsÞþ hfacH " ð1Þ CuðhfacÞðadsÞþ 0:5H 2 =Hðads:on Cu NPsÞ! Cuð0Þþ hfacH "; ð2Þ where Cu NPs stay for copper nanoparticles. Alternatively, decomposition of Cu(hfac) 2 on pure silica surface according to Eqs. (3) and (4) was proved [14,15]. CuðhfacÞ 2 ðgÞþ 2SiOHðsurf Þ! SiOðSiOHÞ CuðhfacÞðadsÞþ hfacHðgÞ" ð3Þ SiOðSiOHÞ CuðhfacÞðadsÞþ H 2 ! 2SiOHðsurf :Þ Cuð0Þþ hfacHðgÞ" ð4Þ We also demonstrated that facilitated mass transfer into 3D-ordered mesoporous structure of KIT-6 provides production http://dx.doi.org/10.1016/j.ica.2014.08.008 0020-1693/Ó 2014 Elsevier B.V. All rights reserved. ⇑ Corresponding author. Tel.: +359 029796640. E-mail address: tsoncheva@orgchm.bas.bg (T. Tsoncheva). 1 Current address: Department of Chemical Engineering, University of California, Santa Barbara 93106-5080, USA. Inorganica Chimica Acta 423 (2014) 145–151 Contents lists available at ScienceDirect Inorganica Chimica Acta journal homepage: www.elsevier.com/locate/ica