Synthesis, characterization and catalytic properties of nitrogen-incorporated ZSM-5 molecular sieves with bimodal pores

Nitrogen-incorporated ZSM-5 molecular sieves with bimodal pores were synthesized by a novel two-step synthesis technique from commercial ZSM-5. The results of structure characterization showed that many mesopores existed in the materials along with micropores inherited from the parent material, and that the mesopore distribution was narrow. The sieves also had obvious nitrogen content and good crystallinity. The results of basicity evaluation showed that these molecular sieves had high activity in the Knoevenagel condensation of benzaldehyde with malononitrile. So these materials offered potential advantage for performing shape-selective base-catalyzed bulky molecular reactions in their pore systems. In addition, desorption traces of carbon dioxide and ammonia showed that stronger basic sites and a small quality of acid sites existed in these nitrogen-incorporated molecular sieves, which still had weak acidic catalytic activity in alkylation of toluene and methanol at a ring position. (C) 2003 Elsevier B.V. All rights reserved.