摘要
以四乙基溴化铵为模板剂 ,硅溶胶和铝酸钠分别为硅源和铝源 ,用水热合成法在氧化铝载体上合成出丝光沸石膜 .用扫描电镜、X射线衍射和核磁共振等手段对所制得的沸石膜进行了表征 ,证明其交联良好、覆盖完全、附着强度高 .通过采用晶化母液老化的方法 ,可使丝光沸石晶体的大小从 2 0～ 30 μm减小到 4～ 5 μm .小晶粒丝光沸石膜的渗透分离性能与大晶粒丝光沸石膜相比有较大的提高 ,其H2 /N2 的理想分离系数从 3 82提高到 9 80 .丝光沸石膜在醇 /水混合体系中能选择性地透过水 ,对水 /甲醇、水 /乙醇、水 /正丙醇和水 /异丙醇体系的最大分离系数分别为 2 6 0 0 (水的摩尔分数xw=5 0 % ,T =32 3K) ,5 5 0 0 (xw=5 0 % ,T =343K) ,6 0 0 0 (xw=15 % ,T =343K)和 6 80 0 (xw=5 0 % ,T =343K)
The mordenite membrane was prepared on an alpha-Al2O3 tube by in situ hydrothermal synthesis with tetraethylammonium bromide (TEABr) as the template agent. Silica sol (40% SiO2) and sodium aluminate (43% Al3O3) were used as the sources of silica and alumina, respectively. A clear synthesis solution used in this study has a molar composition of 11.4Na(2)O: 1.5Al(2)O(3):40SiO(2):2500H(2)O:1.5TEABr. The mordenite powders and mordenite membrane were characterized by SEM, XRD and NMR. It has been proven that the mordenite membrane is of excellent intergrowth, full coverage and little impurity. By the application of aging process of the parent solution, the size of mordenite crystals can be remarkably reduced from 20 similar to 30 mum (without aging) to 4 similar to 5 mum. The small crystal mordenite membrane has higher performance for pure gas permeation than the big crystal mordenite membrane. The ideal selectivity of H-2/N-2 over the small crystal mordenite membrane is 9.80, which is much higher than 3.82 over the big crystal mordenite membrane. The membrane displays high water-permselective performance toward alcohol/water mixtures in the pervaporation test. The highest separation factors achieved toward water/methanol, water/ethanol, water/n-propanol and water/i-propanol are 2 600 (molar fraction of water x(w) = 50%, T = 323 K), 5500(x(w) = 50%, T = 343 K), 6000(x(w) = 15%, T = 343 K) and 6800 (x(w) = 50%, T = 343 K), respectively.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
2002年第2期145-149,共5页
