دراسة المراكز الطاقية على سطح الزيوليت AlPO4 - 5
Abstract
يوجد عدد كبير من المراكز الطاقية على سطح المركب فوسفات الألمنيوم البلوري المكرومساميAlPO4-5 . يحتوي هذا المركب على نوعين من المراكز الحمضية
(مراكز لويس والمراكز البروتونية). تكون هذه المراكز مسؤولة عن الفعالية الحفزية للزيوليت الذي يمكن استخدامه في تكسير النواتج النفطية وفي كثير من الصناعات الكيميائية. يمتلك المركب الفوسفاتي AlPO4-5 صفات حمضية قوية وفعالية حفزية كبيرة.
أجريت دراسة توزع المراكز الفعالة على سطح الزيوليت بواسطة الإمتزاز الكيميائي بطريقة المج في درجات حرارة مبرمجة Temperature Programmed Desorption(TPD) والمج الحراري برفع درجات الحرارة Stepwise Thermal Desorption(STD) , وقد تبين أنه توجد مراكز طاقية على سطح الزيوليت وأن بعض هذه المراكز يكون ذات فعالية قوية والأغلبية ذات فعالية ضعيفة.
There are many energy sites on the surface of microporous crystalline AlPO4-5 . This compound possesses two types of acidic centers (Lewis and protonic). Acidic centers are responsible for catalytic activity for zeolite AlPO4-5 . The number of these centers are low compared to others zeolits .
AlPO4-5 possesses acidic properties and catalytic activity stronger than amorphous aluminium phosphate .
The measurments were caried out chemical adsorption of pyridin with temperature-programmed Desorption (TPD) and stepwise thermal desorption (STD) methods . The number of strong acidic centers are less than the number of weake acidic centers .
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