کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
10142382 | 1646098 | 2018 | 29 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Hierarchical AlPO4-5 and SAPO-5 microporous molecular sieves with mesoporous connectivity for water sorption applications
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی مواد
فناوری نانو (نانو تکنولوژی)
پیش نمایش صفحه اول مقاله

چکیده انگلیسی
Herein, we report the synthesis of hierarchical AlPO4-5 and SAPO-5 molecular sieves that exhibit varying degrees of mesoporous interconnectivity by controlling the amount of triethylamine (TEA) (used as the structure directing agent) and the Si-to-Al ratio (Si/Al); the gel mixture had a composition of (1â¯ââ¯y) Al2O3:y SiO2:1.3 P2O5:x TEA:200 H2O. The molecular sieves were characterized by X-Ray powder Diffraction (XRD) and Scanning Electron Microscopy/Energy Dispersive X-Ray Spectroscopy (SEM/EDX), and their sorption properties were studied by N2 adsorption-desorption at 77â¯K and water adsorption at 316â¯K. In the synthesis gel with xâ¯=â¯1.6 ((1â¯ââ¯y) Al2O3:y SiO2:1.3 P2O5:1.6 TEA:200 H2O), SAPO-5 and AlPO4-5 exhibit high Brunauer-Emmett-Teller specific surface areas of ~380â¯m2â¯gâ1 and 325â¯m2â¯gâ1, respectively. SAPO-5, having a composition of Si0.46Al0.6P0.804, exhibits significant water uptake at low relative pressures (3.4â¯mmol/g at P/P0â¯=â¯0.03 vs. 0.2â¯mmol/g for pure AlPO4-5) attributed to the contribution of hydrophilic Brønsted acid sites, arising from the charge imbalance created by the isomorphic substitution of Si into the aluminophosphate structure predominantly via the SM2 mechanism. Furthermore, SAPO-5 exhibited a hierarchical pore structure having distinct pore size distributions centred on 0.7â¯nm and 15.8â¯nm, attributed to the AFI framework and the induced mesoporosity, respectively. At higher relative pressures, SAPO-5 exhibited the highest total water adsorption capacity of 14.1â¯mmol/g at a relative pressure of 0.38, compared to 11â¯mmol/g for AlPO4-5. The higher overall capacity of SAPO-5 is attributed to capillary condensation into the relatively large mesopore volume.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Surface and Coatings Technology - Volume 353, 15 November 2018, Pages 378-386
Journal: Surface and Coatings Technology - Volume 353, 15 November 2018, Pages 378-386
نویسندگان
Georgia Basina, Dana AlShami, Kyriaki Polychronopoulou, Vasileios Tzitzios, Vaithilingam Balasubramanian, Fadi Dawaymeh, Georgios N. Karanikolos, Yasser Al Wahedi,