Published: March 16, 2011 r2011 American Chemical Society 437 dx.doi.org/10.1021/cs1001509 | ACS Catal. 2011, 1, 437–445 RESEARCH ARTICLE pubs.acs.org/acscatalysis Performance of TS-1-Coated Structured Packing Materials for Styrene Oxidation Reaction Xiaobin Wang, † Xiongfu Zhang,* ,† Yao Wang, † Haiou Liu, † Jieshan Qiu,* ,† Jinqu Wang, † Wei Han, ‡ and King Lun Yeung* ,‡ † State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, P.R. China ‡ Department of Chemical and Biomolecular Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, S.A.R.-P.R. China 1. INTRODUCTION Multiphase reactions involving a solid catalyst and liquid reactants are important in chemical synthesis. 1,2 The TS-1- catalyzed hydroxylation of aromatic molecules using hydrogen peroxide as liquid oxidant is of academic and industrial interest. 3,4 It is considered an economical, clean, and safe production process. 5 The use of powder catalyst poses a problem in product separation and catalyst reuse. Efforts were made to form the TS-1 powder into beads and pellets, but the results were unsatisfactory because of the sensitivity of the reaction to the inorganic and organic binders used in the forming process. 6,7 Structured supports and packing are commonly used to improve transport processes in separations and reactions. 8,9 They promote mixing and contact by providing a large interfacial area. Solid catalysts were deposited on packing materials by Dechaine and co- workers 10 and used for reactive distillation of acetone to diace- tone alcohol. This work investigates the use of TS-1-coated stainless steel packing materials for selective oxidation of styrene to phenyla- cetaldehyde and benzaldehyde using hydrogen peroxide. Thin TS-1 films were grown on glasses, 11,12 solid and porous stainless steel, 13,14 and ceramics 15À18 by both conventional and micro- wave heating methods. 19 TS-1 films were also prepared on silica and carbon nanofibers 20,21 and even within the microchannels of silicon and stainless steel microreactors. 22À25 Indeed, zeolites had been deposited on surfaces by methods ranging from self- assembly to highly ordered, close-packed layer 26,27 and defect- free membranes capable of molecular sieving separation. 28À30 Prior works 15À17 by the authors reported the preparation and reaction performance of TS-1 catalytic membrane contactors prepared by growing thin TS-1 films on porous tubes seeded with zeolite nanoparticles by either dip-coating or slip-casting techni- ques. The purpose of this work is to examine the preparation of thin TS-1 zeolite film coating on substrates of complex geometry. The TS-1 coating was achieved by, first, self-assembling the zeolite seeds using organic linkers, followed by regrowth to obtain a uniform catalyst layer. The thin adherent TS-1 layer was examined by electron microscopy and analyzed by X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), ultravioletÀvisible spectroscopy (UVÀvis), and X-ray photoelectron spectroscopy (XPS). The TS-1-coated stainless steel packing materials were tested in a batch reactor for selective oxidation of styrene to phenylacetaldehyde and benzaldehyde by hydrogen peroxide. 2. EXPERIMENTAL SECTION 2.1. Materials. The stainless steel packing rings (SSR) were supplied by the Shanghai Research Institute of Chemical In- dustry and consisted of coiled stainless steel wire of 0.1 mm diameter. The stainless steel packing rings come in two sizes and shapes: SSR1 have a diameter of 1 mm and height of ∼60 mm, and SSR2 have a diameter of 1.5 mm and height of ∼60 mm. Tetraethyl orthosilicate (98%, Tianjin Kermel), tetrabutyl ortho- titanate (98.5%, Beijing Xingjin), and laboratory-synthesized Received: December 18, 2010 Revised: March 11, 2011 ABSTRACT: Titanium silicalite-1 (TS-1)-coated on stainless steel packing rings of complex geometries provided a large interfacial contact area for improving mass transport processes. Zeolite seeds were assembled using organic linker, and a thin uniform layer of TS-1 catalyst was deposited on the surface by hydrothermal regrowth. The chemical, structural, and catalytic properties of the TS-1 layer were examined. An order of magnitude higher styrene conversion rate was obtained from the TS-1-coated substrates compared with powder. The catalyst was sensitive to pretreatment, and heat treatment in nitrogen provided a 30% higher conversion rate than the air-calcined samples. The N 2 -pretreated catalyst displayed lower activity loss and better regenerability. KEYWORDS: TS-1, packing rings, film, contact area, styrene oxidation