摘要
LTA (Linde Type A) molecular sieve has widely used in adsorption and separation due to its regular pore structure, high thermal stability and chemical stability. Copper-exchanged LTA (Cu-LTA) zeolite membranes with enhanced water flux of ethanol dehydration were developed through copper ion exchange of Na-LTA zeolite membrane. In the first step, a thin and well intergrown Na-LTA zeolite membrane was prepared on macroporousα-Al2O3 tube which was modified by 3-aminopropyltriethox-ysilane (APTES). Afterwards, copper exchange of the as-synthesized Na-LTA zeolite membranes was done to prepare Cu-LTA zeolite membrane. According to characterizations of XRD, FESEM, and XPS, both the morphology and structure of the Cu-LTA zeolite membranes are identical to those of the Na-LTA zeolite membranes, and there are no cracks and pinholes are found in the membrane layer. Attributing to a wider pore diameter because two sodium ions of Na-LTA framework are replaced by one copper ion, the Cu-LTA zeolite membrane displays a higher water flux in the separation of ethanol/water mixture than Na-LTA membranes. At 75 °C, the water flux of the Cu-LTA zeolite membrane is 3.52 kg m^-2 h^-1 with water/ethanol separation factor of 3591, while the water flux of the Na-LTA zeolite membrane is only 1.65 kg m^-2 h^-1 with water/ethanol separation factor of 4082.
LTA（Linde Type A）molecular sieve has widely used in adsorption and separation due to its regular pore structure,high thermal stability and chemical stability.Copper-exchanged LTA（Cu-LTA）zeolite membranes with enhanced water flux of ethanol dehydration were developed through copper ion exchange of Na-LTA zeolite membrane.In the first step,a thin and well intergrown Na-LTA zeolite membrane was prepared on macroporous α-Al2 O3 tube which was modified by 3-aminopropyltriethoxysilane（APTES）.Afterwards,copper exchange of the as-synthesized Na-LTA zeolite membranes was done to prepare Cu-LTA zeolite membrane.According to characterizations of XRD,FESEM,and XPS,both the morphology and structure of the Cu-LTA zeolite membranes are identical to those of the Na-LTA zeolite membra nes,and the re are no cracks and pinholes are found in the membrane laye r.Attributing to a wider po re diameter because two sodium ions of Na-LTA framework are replaced by one copper ion,the Cu-LTA zeolite membrane displays a higher water flux in the separation of ethanol/water mixture than Na-LTA membranes.At 75℃,the water flux of the Cu-LTA zeolite membrane is 3,52 kg m 2 h 1 with water/ethanol separation factor of 3591,while the water flux of the Na-LTA zeolite membrane is only1.65 kg m 2 h 1 with water/ethanol separation factor of 4082.
基金
financially supported by the National Natural Science Foundation of China (Nos. 21761132003, 21606246)
Ningbo Science and Technology Innovation Team (No. 2014B81004)
