DOI: 10.1002/cctc.201100281 Synthesis of Titanium Chabazite: A New Shape Selective Oxidation Catalyst with Small Pore Openings and Application in the Production of Methyl Formate from Methanol Einar AndrØ Eilertsen, [a] Silvia Bordiga,* [b] Carlo Lamberti, [b] Alessandro Damin, [b] Francesca Bonino, [b] Bjørnar Arstad, [c] Stian Svelle, [a] Unni Olsbye, [a] and Karl Petter Lillerud* [a] Isomorphous substitution of a small fraction of titanium(IV) in the tetrahedral sites of zeolitic frameworks provides materials with excellent catalytic properties for partial oxidation reac- tions with H 2 O 2. [1] The original TS-1 [2] material performs with an enzyme like activity and selectivity and is of great industrial im- portance in partial oxidation reactions of small organic sub- strates. [3] Titanium incorporation in silicates has been extensive- ly studied both on amorphous phases [4] (dispersed in micropo- rous silica and grafted to mesoporous molecular sieves), in lay- ered delaminated zeolite precursors [5] and in zeolitic frame- works; [6] such as Ti-Beta, TS-2, Ti-ZSM-48, Ti-MWW, and Ti-MTF. Here we report the synthesis of Ti-CHA zeolites with and without aluminum and demonstrate their activity in partial oxi- dation reactions with H 2 O 2 . The pores in most titanium silicates are medium to large; however in this material they are 8-mem- bered rings. This opens up new possibilities within shape-se- lective oxidation catalysis. CHA is a zeolite topology with a 3- dimensional pore structure comprising an elongated cage with 8-ring windows. Different CHA materials (SAPO-34 and SSZ-13) have been studied as catalysts in the methanol-to-olefin process due to their shape selective properties. [7] The CHA topology is rare in that it contains only one crystal- lographic independent T site and is, therefore, an interesting model material to study Ti insertion in the framework, as testified by previous theoretical periodic studies. [8] It was recently reported that CHA zeolites can be prepared over a wide range of sili- con/aluminum ratios, including the purely siliceous. [9] This cre- ates new doping options, for example in Ti-CHA and Ti-Al-CHA, in which both redox and acidic properties can work together. For example, a possible application of the Ti-Al-CHA material is in the production of methyl formate from methanol. Methyl formate is of great importance as an intermediate in the pro- duction of chemicals such as formamide, dimethyl formamide, and formic acid. Formic acid alone is produced in several hun- dred thousands of tons per year. [10] In contrast to the conven- tional synthetic route, this method operates at very mild condi- tions, making it economically and environmentally advantageous. Detailed results are reported for two Ti-containing samples (Ti-CHA with Si/Ti = 246 and Ti-Al-CHA with Si/Ti = 95 and Si/ Al = 17) with comparison to their respective blank matrices (pure siliceous- and Al-CHA with Si/Al = 20). The elemental analysis reported in Table 1 shows that the Ti loading is low, as already observed in other Ti-containing zeolites, and that Ti in- corporation occurs to a much greater extent in Ti-Al-CHA than in Ti-CHA. Analysis of the powder X-ray diffraction data reported in Figure 1 confirms that all samples are of the CHA topology, highly crystalline, and without impurities. SEM images (please see Supporting Information) show uniform particle sizes of 4 mm for Ti-CHA and 1.5 mm for Ti-Al-CHA, whereas 27 Al magic- angle spinning (MAS) NMR spectroscopy (see Supporting Infor- mation) shows that the Ti-Al-CHA material contains only tetra- hedral Al centers. The isomorphous substitution of Si by Ti has been confirmed using Raman, UV/vis, and X-ray absorption near-edge spectros- copy (XANES), with data similar to other Ti zeolites. The IR spectra are more complex, owing to the very broad bands of [a] E. A. Eilertsen, Prof. S. Svelle, Prof. U. Olsbye, Prof. K. P. Lillerud SMN/inGAP/Department of Chemistry University of Oslo Pb.1033 Blindern, 0315 Oslo, Norway Fax: + 47-22855457 E-mail : kpl@kjemi.uio.no [b] Prof. S. Bordiga, Prof. C. Lamberti, Dr. A. Damin, Dr. F. Bonino Dipartimento di Chimica IFM, NIS centre of excellence, University of Torino, and INSTM reference centre Via. Quarello 11, I-10135 Torino, Italy Fax: + 39011-6707855 E-mail : silvia.bordiga@unito.it [c] Dr. B. Arstad SINTEF Materials and Chemistry Department of Hydrocarbon Process Chemistry Pb. 124 Blindern, 0314 Oslo Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/cctc.201100281. Table 1. Catalyst elemental analysis and catalytic activity. In gel In solid Ti incorporated Conversion of H 2 O 2 Selectivity Material Si/Ti Si/Ti Si/Al [%] [%] Ethylene oxide [%] Methyl formate [%] Ti-CHA [a] 75 246 1 31 10 69 N/A TS-1 [a] 75 79 1 96 93 62 N/A Ti-Al-CHA [b] 75 95 17 78 65 N/A 85 Al-TS-1 [b] 75 74 21 100 94 N/A 55 [a] Reaction conditions for Ti-CHA and TS-1: batch reactor, 16 g H 2 O, 2.6 g H 2 O 2 (30 wt %), 0.2 g catalyst, p ethene = 0.4 MPa, T = 60 8C, t = 6 h. [b] Reaction conditions for Ti-Al-CHA and Al-TS-1: 16 g methanol, 2.6 g H 2 O 2 (30 wt %), 0.2 g catalyst. T = 60 8C. t = 6 h. ChemCatChem 2011, 3, 1869 – 1871  2011 Wiley-VCH Verlag GmbH& Co. KGaA, Weinheim 1869