Highly efficient and greener synthesis of TS-1 in a flow system by recycling the mother liquid

In this work, a highly efficient synthetic route for TS-1 zeolites has been developed in a flow system, a greener preparation method is further proposed by recycling the mother liquid. The prepared TS-1 by recycling the mother liquid contained no extraframework Ti species with uniform size and high crystallization as well as excellent catalytic performance for cyclohexanone ammoximation in the flow system containing a tubular reactor and an autoclave. As the fast heating rate of flow chemical process, the crystallization time was shortened to 20 min at 175 degrees C. Due to the short crystallization, hardly TPAOH participated in the Hofmann elimination reaction except for the structure-directing usage. The full recycle of remained TPAOH in the mother liquid was reused after being concentrated via vacuum distillation, and this novel recycling technology could have 98.5% TPAOH utilization as well as 98.3% TS-1 yield. These results indicate that the flow chemical process plays a key role in the new greener approach for the TS-1 synthesis.