Atomic Layer Deposition of ZnO Thin Films on ZSM-5 Zeolite and Its Catalytic Performance in Chichibabin Reaction

A series of ZnO thin film modified ZSM-5 zeolites was prepared by atomic layer deposition (ALD) method with different ALD cycle numbers. These samples were characterized by nitrogen adsorption-desorption, ICP-AES, XPS, TEM and NH3-TPD techniques. The results of these characterizations showed that the thin film was ZnO, which was deposited on the surface of ZSM-5, especially the edge. The surface and pores of ZSM-5 was covered progressively by the increase of ALD cycles. By relating the Zn content of each cycle to the characters of ALD method, a deposition model of ZnO on ZSM-5 substrate was deduced. The surface acidity of the prepared samples can be tuned by adjusting the ALD cycle number as well. The catalytic properties of these samples were evaluated in Chichibabin reaction of acetaldehyde and ammonia. They could not only highly enhance the total yield of pyridine bases, but also could change the product distribution.