Novel template confinement derived from polybenzoxazine-based carbon xerogels for synthesis of ZSM-5 nanoparticles via microwave irradiation Uthen Thubsuang a , Hatsuo Ishida b , Sujitra Wongkasemjit a,⇑ , Thanyalak Chaisuwan a,⇑ a The Petroleum and Petrochemical College and Center of Excellence on Petrochemical and Materials Technology, Chulalongkorn University, Bangkok 10330, Thailand b Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, OH 44106, USA article info Article history: Received 25 August 2011 Received in revised form 27 January 2012 Accepted 29 January 2012 Available online 5 February 2012 Keywords: Nanosized ZSM-5 Microwave irradiation Polybenzoxazine Carbon xerogel abstract Polybenzoxazine, a new class of phenolic resin, has been successfully synthesized via a facile quasi- solventless method and used as a starting material for producing nano-porous carbon with pore sizes of about 40–200 nm. This porous carbon is prepared via a sol–gel process, using dioxane as a solvent (CXDI) and is used as a hard template confinement to produce crystalline nanosized MFI or ZSM-5 with a molar composition of 10Na 2 O:200SiO 2 :Al 2 O 3 :20TPABr:12,600H 2 O via hydrothermal microwave irradi- ation technique within 6 h of synthesis time. The XRD patterns show a well-ordered crystalline phase of nanosized ZSM-5. In addition, FTIR result shows the weak absorption band at 550 cm 1 , indicating the presence of nanosized ZSM-5. Particle size distribution obtained from dynamic light scattering and TEM images reveal that the crystal size of ZSM-5 synthesized using CXDI as a hard template (ZSM-5- CXDI) is in the range of 27–70 nm. ZSM-5-CXDI also shows large external surface area of 217 m 2 /g. Ó 2012 Elsevier Inc. All rights reserved. 1. Introduction Zeolite Sieve of Molecular porosity – 5, (structure type MFI – mordenite framework inverted), ZSM-5 has been used in var- ious applications especially as a catalyst in organic syntheses, oil refining, environmental management, and petrochemical industry [1–6], because of its outstanding properties. Some of these proper- ties are: shape-selectivity, surface acidity, well-ordered pore net- work, high thermal stability, and cation-exchange capability. Generally, ZSM-5 is a microporous, aluminosilicate material, hav- ing crystal size in a micrometer range. These properties could influ- ence the catalytic performance for synthesis of large molecules due to a limitation of mass transfer [5,7]. Therefore, many researchers have been interested in synthesizing mesoporous ZSM-5, for the improvement of catalytic properties using carbon aerogel [8–10], polymer [11,12], surfactant [13,14] as a template. Another way to improve the catalytic performance of ZSM-5 is decreasing the crystal size to nanoscale to enable more active sites, resulting in the increased catalytic efficiency [2,15]. Using this ZSM-5 nanocatalyst, Serrano et al. [2] studied the epoxidation rear- rangement reactions and found that nanocrystalline ZSM-5 with the crystal size in the range of 20–50 nm showed higher epoxide conversion than microcrystalline ZSM-5 with the crystal size of 5 lm. Furthermore, ZSM-5 nanoparticles were also used as a mem- brane to effectively separate butane isomers at high temperature [16]. Mesoporous ZSM-5 and ZSM-5 nanoparticles were generally syn- thesized by using resorcinol–formaldehyde (RF)-based carbon aero- gel (or carbon xerogel) as a templating confinement to control the size and the pores of the ZSM-5 crystals [8–10,17,18]. In this work, we proposed a novel hard template derived from polybenzoxazine. Polybenzoxazine (PBZ) was chosen as a starting material to produce carbon aerogel/xerogel since it has many prominent advantages including ring-opening polymerization without added initiators or catalyst, no release of volatiles during polymerization, near-zero volumetric change upon polymerization, and low water adsorption. Of particular interest in the current project is the excel- lent molecular design flexibility of the benzoxazine chemistry by varying types of amines and phenols [19–28] which could tailor the pore structure of PBZ-based organic xerogel and carbon xerogel after carbonization [29–31]. PBZ is easily synthesized by the Man- nich condensation reaction of phenol, formaldehyde, and amine via a quasi-solventless route adapted from the solventless method, proposed by Ishida [32]. PBZ is a cross-linked polymer with addi- tional extensive hydrogen bonded networks which can withstand pore collapse without the need of supercritical CO 2 drying process. The shorter preparation time with fewer steps is required when PBZ is used as a precursor for carbon aerogel/xerogel preparation. A homogeneous orthorhombic MFI zeolite has been successfully synthesized using silatrane, a novel organosilicate material, as a Si source via sol–gel process at 150 °C microwave temperature for 1387-1811/$ - see front matter Ó 2012 Elsevier Inc. All rights reserved. doi:10.1016/j.micromeso.2012.01.035 ⇑ Corresponding authors. Tel.: +66 2 2184143 (T. Chaisuwan), +66 2 2184133 (S. Wongkasemjit). E-mail addresses: dsujitra@chula.ac.th (S. Wongkasemjit), thanyalak.c@hotmail. com (T. Chaisuwan). Microporous and Mesoporous Materials 156 (2012) 7–15 Contents lists available at SciVerse ScienceDirect Microporous and Mesoporous Materials journal homepage: www.elsevier.com/locate/micromeso