The invention provides a method for preparing a high-performance B-ZSM-5
molecular sieve membrane in a dilute synthesis solution. According to the method, B-ZSM-5
zeolite molecular sieves of different sizes are adopted as seed crystals and a thin and dense
seed crystal layer is formed directly on the surface of a macroporous carrier tube. After that, the seed crystals and the
seed crystal layer are subjected to hydro-thermal synthesis in a dilute synthesis solution, wherein the ratio of H2O to SiO2 is 200-1200. Finally, a high-performance B-ZSM-5
molecular sieve membrane is formed on the surface of a macroporous carrier. According to the method,
boron is led into a
zeolite framework in the isomorphism manner, so that the separation performance of the B-ZSM-5
molecular sieve membrane is greatly improved. The
pervaporation performance of the prepared B-ZSM-5 molecular
sieve membrane is tested in an
ethanol / water
system, wherein the weight ratio of
ethanol to water is 5 to 95. The result of the test shows that, at 60 DEG C, the
permeation flux and the separating factor of the B-ZSM-5 molecular
sieve membrane are respectively 2.60 kg / m<2>*h, and 54.98. Due to the adoption of the dilute synthesis solution, the application amounts of a
silicon source and a template agent for synthesizing the membrane are reduced. Therefore, the method is suitable for the
recovery of fuel
ethanol during the
fermentation-based ethanol production process.