بررسی پایداری ساختاری و خواص عبوردهی اکسیژن از غشاء پروسکایتی Ba0.5 Sr0.5 Co0.8 Fe 0.2O3- δ

نوع مقاله: مقاله پژوهشی

چکیده

 
مـواد پروسـکایتی
(Ba
0/5 Sr 0/5 Co 0/8 Fe 0/2 O3- δ (BSCF
و
(Sr Co
0/8 Fe 0/2 O3- δ (SCF
با استفاده از روش تشکیل کمپلکس با سیترات-EDTA سنتز شد. ساختار کریستالی، پایداری ساختاری و ریز ساختار این مواد با آنالیزهایی چون پراش اشعه ایکس (XRD) و میکروسکوپ الکترونی(SEM) مورد بررسی قرار گرفت. همچنین میزان عبوردهی اکسیژن برای غشاء های ساخته شده از این مواد بر حسب دما در محدوده700oC تا 950oCبا استفاده از یک دستگاه دما بالا، اندازه‌گیری شد. نتایج XRD نشان داد این مواد دارای ساختار خالص مکعبی پروسکایتی می‌باشند. میزان عبوردهی بالایی برای این مواد (حدود cc/min.cm22 در دمای 950oC) حاصل شد. نتایج نشان می‌دهد که در محدوده وسیعی از دما، میزان عبوردهی BSCF از SCF بیشتر می‌باشد. همچنین اثر فشار جزئی اکسیژن جریان بالادستی در محدوده atm 1-0،
بر شار عبور اکسیژن در دماهای مختلف بررسی شد. افزایش فشار جزیی اکسیژن به شدت باعث افزایش میزان عبوردهی می‌شود که استفاده عملی از این غشاها را در مقیاس صنعتی جذاب می‌نماید. با آنالیز انرژی اکتیواسیون محاسبه شده می‌توان گفت که میزان عبور دهی غشاء پروسکایتی SCF در دماهای پایین نسبت به BSCF به دما حساس‌تر است و این موضوع در دماهای بالاتر بر عکس می‌باشد. همچنین نتایج نشان می دهد که سرعت عبور اکسیژن توسط هر دو عامل، مرحله نفوذ توده و تبادل سطحی کنترل می‌شود. الگوی پراش اشعه ایکس بعد از عملیات جذب و دفع اکسیژن، حاکی از آنست که بر خلاف SCF، مواد پروسکایتی BSCF، دارای پایداری ساختاری خوبی در شرایط دمایی بالا و فشار جزئی پایین اکسیژن می‌باشند.
 

کلیدواژه‌ها


عنوان مقاله [English]

An Investigation on Structural Stability and Oxygen Permeation Properties of Dense Membrane Perovskite Ba0.5Sr0.5Co0.8Fe0.2O3-δ

چکیده [English]

In this study, perovskite Ba0.5Sr0.5Co0.8Fe0.2O3−δ and SrCo0.8Fe0.2O3−δ were synthesized by EDTA and citrate complexing methods. The microstructural studies were carried out using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) to investigate the crystal structure and also structural stability. Oxygen permeation through BSCF and SCF membranes were measured at elevated temperatures (700oC to 950oC). XRD results showed that both specimens possess perovskite and cubic structure. A relatively high permeation value (2 cc/min.cm2 at 950oC) were reported for both specimens. The results indicated that oxygen permeation of BSCF is higher than that of SCF through a wide range of temperature. Also, the effect of upstream partial pressure of oxygen (0-1 atm) on oxygen flux was studied at various temperatures. The increase in oxygen partial pressure significantly increases the oxygen flux which suggests that these membranes may be used for industrial application. Activation energy results revealed that permeation of SCF membrane at low temperatures is more sensitive to temperature than BSCF which is contrary to observations at high temperatures. It was concluded that Oxygen permeation flux is controlled by both surface exchange kinetics and bulk diffusion. XRD patterns after (adsorption-desorption treatment) indicated that BSCF has a more stable structure at high- temperatures than SCF and also possesses lower oxygen partial pressures.

کلیدواژه‌ها [English]

  • Membrane
  • Permeation
  • Perovskite
  • stability

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