Applied Catalysis A: General 466 (2013) 137–141 Contents lists available at SciVerse ScienceDirect Applied Catalysis A: General j ourna l h om epage: www.elsevier.com/locate/apcata Development of gallium incorporated mesoporous silica catalysts for the selective removal of BTX Azhagapillai Prabhu ∗ , Ahmed Al Shoaibi, Chandrasekar Srinivasakannan Department of Chemical Engineering, The Petroleum Institute, Abu Dhabi, United Arab Emirates a r t i c l e i n f o Article history: Received 20 May 2013 Received in revised form 27 June 2013 Accepted 28 June 2013 Available online xxx Keywords: Mesoporous silica Ga-KIT-6 Adsorption of BTX compounds Surface acidity Surface area a b s t r a c t Three-dimensional mesoporous gallium KIT-6 with different Si/Ga molar ratios have been prepared by using P123 as a structure directing agent under acidic medium in hydrothermal conditions. The syn- thesized Ga-KIT-6 materials were characterized using small angle X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), nitrogen sorption analyzer, UV–visible diffuse reflectance spectroscopy (UV–vis DRS), X-ray fluorescence spectroscopy (XRF), Fourier transform infrared spectroscopy (FT-IR) and thermo gravimetric analysis (TGA). The developed mesoporous gallium KIT-6 material possesses a high surface area of 892 m 2 g −1 and pore volume of 1.24 cm 3 g −1 . The mesoporous structure of the catalyst together with the presence of gallium in the silica framework, which confers acidity for better adsorption. Adsorption of BTX over the different Si/Ga molar ratios of cubic Ia3d (Ga- KIT-6) materials were studied and found that the better adsorption on Ga-KIT-6 (5). Interestingly, this material showed excellent adsorption capacity of BTX in aqueous solution. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Mesoporous molecular sieves represent a new class of inor- ganic materials. An over increasing scientific interest has been initiated since mesoporous molecular sieves such as hexagonally ordered MCM-41 were discovered by Mobil corporation scien- tists in 1992 [1,2]. The new type of ordered mesoporous material (SBA) was achieved by using a triblock copolymer as structure- directing agent under strongly acidic conditions [3,4]. SBA-15 usually has wider pores than MCM-41 (SBA-15 pores range from 5 to 30 nm), and higher pore volume. Moreover, in compari- son with other mesostructured silica materials, SBA-15 exhibits thicker pore walls which provide high hydrothermal stability [5,6]. Among copolymer-directed mesostructures, particularly interest- ing are large-pore cage-like mesoporous silica materials [5,7–11]. Their 3-D interconnected pore structures facilitates mass transfer and are less susceptible for pore blockage, making these materi- als more attractive for applications in catalysis, selective sorption and separation processes. They can also serve as model systems for adsorption behavior and diffusion studies in cage-like pores [12–15]. The further mesoporous silica material with Fm3m sym- metry, designated as KIT-5, has been reported by Kleitz et al. [16]. Another new large pore mesoporous silica KIT-6 was prepared by ∗ Corresponding author. Tel.: +971 2 6075651; fax: +971 2 6075200. E-mail addresses: prabhu.au@gmail.com, aprabhu@pi.ac.ae (A. Prabhu). Kim et al. [17]. It provides highly opened spaces for direct access to guest species without pore blockage due to their unique 3D channel networks. Benzene, toluene and xylene (BTX) are some of the most com- mon air pollutants that are released by chemical, petrochemical, and related industries. BTX are the main components of automobile exhaust gases from gasoline engines. VOCs in the form of ben- zene derivatives are especially harmful to the environment and human health [18]. There exist several methods such as conden- sation, absorption, adsorption, contact oxidation and incineration that are employed for an efficient removal and recovery of organic vapors. The most commonly used process is adsorption for which adsorbents with high surface areas, pore volume, pore size distri- bution, pore surface chemistry and reusability is required. Many researchers have proposed high surface area of activated carbon; nevertheless, this material involves some problems including the fact that the adsorbed molecule are not destroyed or decomposed (through irreversible dissociative chemisorption) but instead it is only weakly held at the surface. The most widely utilized adsorbent for environmental cleaning is high surface area mesoporous sili- cates such as MCM and SBA [19]. KIT-6 exhibits three dimensional cubic Ia3d symmetric structures with interpenetrating bicontinu- ous network of channels [20]. Mesoporous cubic Ia3d KIT-6 silica materials with various pore diameters and their application in biomolecule immobilization [21]. Several studies dealing with the incorporation of transition metals like Al, V, Ce and Ti into the KIT- 6 host via direct synthesis [22–26]. Shim et al. [27] reported the 0926-860X/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.apcata.2013.06.050