Seed-assisted synthesis of high silica ZSM-35 through interface-induced growth over MCM-49 seeds

High-silica ZSM-35 has been successfully synthesized by adding non-calcined MCM-49 seeds to the initial gel without the help of organic structure-directing agents (OSDAs). This is the first report of seed-assisted synthesis without the common composite building units (CBUs) contained in the seeds and products. High solid yields of 65-85% have been achieved, which are the highest values ever reported for the seed-assisted synthesis. Alkaline treatment and hyperpolarized Xe-129 NMR are employed to study the ZSM-35 products, and an interface-induced growth mechanism is proposed, in which ZSM-35 grows over partially dissolved MCM-49 through interface connection. It is supposed that similarity in the local atomic connection between the seeds and target zeolites, even without the common CBUs, would have the possibility to lead to a successful synthesis. The catalytic performance of H-ZSM-35 is tested in the dimethyl ether (DME) carbonylation, which shows excellent stability and high selectivity towards methyl acetate (MA). (C) 2014 Elsevier Inc. All rights reserved.