بررسی اثرات دمای پیرولیز آئروژل آلی و نحوه نشاندن فلز کبالت بر روی آن بر خصوصیات فیزیکی و شیمیایی کربن آئروژل

در این تحقیق برای نخستین بار، اثر دمای پیرولیز بر ساختار کربن آئروژل سنتز شده در شرایط محیطی به عنوان پایه و نحوه نشاندن فلز کبالت به عنوان جزء فعال بر آن، بررسی شده است. کربن آئروژل توسط پیش‌سازنده‌های رزورسینول و فرمالدئید در دماهای پیرولیز 550، 700 و c° 900 تولید و کبالت به سه روش مختلف  (الف) تلقیح کبالت بر روی کربن آئروژل، (ب) تلقیح کبالت بر روی آئروژل آلی رزورسینول فرمالدئید، (ج) افزودن پیش سازنده کبالت به مخلوط اولیه رزورسینول-فرمالدئید پیش از فرایند پلیمریزاسیون کربن آئروژل، بر روی کربن آئروژل نشانده شد. نتایج نشان داد که پیرولیز در دمای c° 700 منجر به تولید کربن آئروژلی مزوحفره با سطح ویژه m2/g 8/483 می‌شود. در روش تلقیح، کبالت به خوبی بر روی پایه پراکنده شده و کنترل پذیری اندازه ذرات وجود دارد، در حالی که در روش سوم، پیش‌سازنده کبالت فرایند پلیمریزاسیون را کاتالیز کرده و منجر به تولید میکروذرات می‌گردد.

investigating the effects of pyrolysis temperature and cobalt-doped methods in organic aerogel on the physical and chemical properties of carbon aerogel

introduction carbon aerogels (ca) are sponge-like carbon materials obtained by carbonizing organic aerogels. the term aerogel refers to the replacement of air instead of liquid within a solid nanostructure without structural shrinkage [1]. depending on the type of precursor, drying methods and carbonization conditions of the aerogel, the volume of micro and meso pores of carbon aerogels can be controlled [2].in order to remove the gelation solvent, there are several methods, which can be referred to as solvent replacement, supercritical drying, and freeze drying. in recent years, due to the high costs of the mentioned methods, drying in environmental conditions is used to improve the chances for large-scale application [3]. carbonization is usually carried out in tube furnaces under inert gas in the temperature range of 550-2100 °c, and the optimal carbonization temperature is selected depending on the intended application [4].in the present study, carbon aerogel was synthesized at pyrolysis temperatures of 550, 700 and 900 °c and the effect of pyrolysis temperature on the structure of carbon aerogel have been investigated., cobalt was then doped on the ca support using various methods, and physicochemical properties have been investigated.materials and methodscarbon aerogel synthesiscarbon aerogel was synthesized in ambient condition by resorcinol and formaldehyde precursors with polycondensation (sol-gel chemistry) and then carbonized under nitrogen flow at temperatures of 550, 700 and 900 °c for 120 min. ca samples carbonized at the above temperatures will be referred to as ca-550, ca-700, and ca-900, respectively.cobalt-doped carbon aerogel synthesiscobalt-doped ca was synthesized by the following three main strategies: (i) cobalt impregnation on the carbon aerogel, (ii) cobalt impregnation on the organic resorcinol-formaldehyde aerogel, and (iii) addition of cobalt to the initial resorcinol-formaldehyde mixture before precursors polymerization. in all these methods, the precursor co(no3)2.6h2o is used, and cobalt is deposited on the carbon aerogel with a weight percentage of 15%. cobalt precursor impregnated on carbon aerogel, cobalt-doped resorcinol-formaldehyde aerogel and cobalt added to resorcinol-formaldehyde solution will be referred to as co-ca-a, co-ca-b, and co-ca-c, respectively.results and discussioneffect of pyrolysis temperaturethe pore size distribution (psd) of ca-550, ca-700, and ca-900 samples evaluated using the bjh model, and the nldft method showed that increasing the pyrolysis temperature of the organic aerogel reduces the pore volumes and increases the pore size.