Synthesis of Dense High-Silica Zeolite Beta Membranes with Controllable Orientation for n-Butanol Recovery from Dilute Aqueous Solution

The dense high-silica zeolite beta (HSZB) membranes with controllable orientation were fabricated on randomly oriented seed layers using a secondary growth method. It was found that the higher H2O/SiO2 ratio could facilitate the growth of HSZB crystals along the (00l)-direction. Consistent with the competitive growth model, the as-synthesized HSZB membrane with the preferential (h0l)-orientation was obtained when the H2O/SiO2 ratio was 4, whereas the c-oriented HSZB membrane was prepared with the H2O/SiO2 ratio of 7. The formation process of HSZB membranes with preferred orientation was investigated during an evolutionary growth process. The (h0l)-oriented HSZB membrane exhibited high fluxes up to 1.45 and 1.05 kg m–2 h–1 with respect to 1 and 5 wt % n-butanol/water mixtures, while the corresponding separation factors were 36.5 and 32.5, respectively. Compared with available zeolite membranes reported in the literature, the synthesized (h0l)-oriented HSZB membranes would be more promising for n-butanol recovery from dilute aqueous solution due to high fluxes with relatively high separation factors. The orientation of membranes could be controlled by adjusting the composition of synthesis solutions on randomly oriented seed layers, which provides a new insight into fabricating oriented zeolite and metal–organic framework membranes.