| 代蓉,杨冬花,郑子良,吕爱凝,李建华,窦涛,韩培德.EU-1分子筛相邻酸性位的DFT计算和酸性表征[J].分子催化,2014,(5):474-484 |
| EU-1分子筛相邻酸性位的DFT计算和酸性表征 |
| Theoretical Study on the Acidity of Neighboring Acid Sites in EU-1 Zeolite and Its Acidity Characterization |
| 投稿时间：2014-07-14 修订日期：2014-08-12 |
| DOI： |
| 中文关键词: EU-1分子筛 密度泛函理论 相邻酸性位 |
| 英文关键词:EU-1 Zeolite, DFT method, next-nearest-neighbor acid site |
| 基金项目: |
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| 摘要点击次数: 2044 |
| 全文下载次数: 3321 |
| 中文摘要: |
| 利用量子力学中的密度泛函理论(DFT)，对EU-1分子筛中与T1、T2、T3、T6、T7、T8位相邻的骨架铝原子的落位稳定性及酸强度进行理论计算。通过计算得知，双Al原子在EU-1分子筛骨架中优先落位于Al7(Si6-Si7)Al8、Al1(Si2-Si2)Al1、Al2(Si1-Si2)Al2、Al1(Si2-Si2)Al3、Al1(Si2)Al3；根据(Al/Si, H)取代能确定了质子的落位，质子氢较易落位于(O12-H)Al1-(O12-H)Al1、(O12-H)Al1-Al1(O13-H)、(O12-H)Al1-Al1(O12-H)、(O14-H)Al2-(O14-H)Al2、Al2(O12-H)-(O14-H)Al2、Al1(O12-H)-(O15-H)Al3、(O26-H)Al7-Al8(O28-H)；且根据质子亲和势分析知，EU-1分子筛骨架中质子氢落位于NNN位的Br鴑sted酸强度小于NNNN位。借助1H MAS NMR分析合成的不同硅铝比的样品，可知硅铝比低的EU-1分子筛Br鴑sted酸吸收峰的面积增加；由NH3-TPD可知硅铝比低的EU-1分子筛的强酸脱附峰温度降低，酸强度减小。硅铝比低的EU-1分子筛的强酸表现出酸量高、酸强度低的性质。 |
| 英文摘要: |
| The substitution of framework Al pairs at T1, T2, T3, T6, T7 and T8 sites in EU-1 zeolite was calculated by the density functional theory method, and the stability and Brønsted acidity of the neighboring acid sites were theoretically studied. According to the calculated energy, the stable acid sites of EU-1 zeolite were located at Al7(Si6-Si7)Al8、Al1(Si2-Si2)Al1、Al2(Si1-Si2)Al2、Al1(Si2-Si2)Al3、Al1(Si2)Al3. The localization of acidic proton was explored by calculating (Al/Si,H) substitution energy, and the stable proton sites of EU-1 zeolite were at (O12-H)Al1-(O12-H)Al1、(O12-H)Al1-Al1(O13-H)、(O12-H)Al1 -Al1(O12-H)、(O14-H)Al2-(O14-H)Al2、Al2(O12-H)-(O14-H)Al2、Al1(O12-H)-(O15-H)Al3、(O26-H)Al7- Al8(O28-H). The calculation of proton affinity indicated that the Brønsted acid strength of NNNN sites were stronger than the NNN sites. The synthesized products with different SiO2/Al2O3 molar ratio were characterized by MAS NMR, the results showed that the area of Brønsted acid is higher when EU-1 zeolite with lower SiO2/Al2O3 molar ratio. According to NH3-TPD ,the temperature of the desorption and the acid strength were decreased with the decreasing of the SiO2/Al2O3 molar ratio of EU-1 zeolite. |
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