تثبيت نانوذرات نقره و روتنيوم بر روي درختسان مغناطيسي حاوي گروه-هاي تيول و بررسي فعاليت كاتاليستي آنها در واكنشهاي تثبيت شيميايي كربن دياكسيد و سنتز بنزايميدازولها

Catalysts are substances that accelerate chemical reactions. In general, catalysts are divided into two categories, homogeneous and heterogeneous catalysts. Each of these catalysts has its own advantages and disadvantages. In order to achieve the advantages of both types of catalysts, homogeneous catalysts are stabilized on supports. This action, in addition to facilitating the separation of catalysts from the reaction mixture, leads to preventing the accumulation of metal nanoparticles. Today, there are many types of supports such as alumina, silica, metal-organic frameworks and dendrimers. Dendrimers are one of the types of supports that can be designed for this purpose. Dendrimers, compounds with tree-like structures, are used in drug delivery, affecting the treatment of brain tumors and designing suitable catalytic supports. One of the important areas of dendrimers is the design of dendrimers with magnetic properties, which enables their easier retrieva‎l in the reaction. Dendrimer-based magnetic iron oxide core provide the possibility of stabilizing different metal nanoparticles in order to catalyze various chemical reactions.Accordingly, in this research, dendrimer structure containing thiol was grown on a magnetic nanoparticle to provide a support for stabilizing silver and ruthenium nanoparticles in addition to using the advantages of magnetic nanoparticles which cause easy separation of the structure. The stabilization of nanoparticles causes more stability, higher dispersion and prevents their accumulation. Two catalysts of silver nanoparticle on magnetic dendrimer support (〖"Fe" 〗_"3" "O" _"4" "@G2-" 〖"Ag" 〗_"np" ) and ruthenium nanoparticle (〖"Fe" 〗_"3" "O" _"4" "@G2" -" 〖"Ru" 〗_"np" ) were investigated by FE-SEM, VSM, XRD,AAS, IR and TGA analysis and were used in two chemical stabilization reactions of carbon dioxide and synthesis of benzimidazole. Investigations show the high performance of〖"Fe" 〗_"3" "O" _"4" "@G2-" 〖"Ag" 〗_"np" catalyst in the CO2 fixation reaction under mild conditions. Also, the catalyst could be recovered 5 times and used again in this reaction without any noticeable decrease in activity. In the case of the 〖"Fe" 〗_"3" "O" _"4" "@G2-" 〖"Ru" 〗_"np" catalyst, after complete tests and investigations, it was found that the 〖"Fe" 〗_"3" "O" _"4" "@G2" support has significant activity in the reaction of benzimidazole synthesis. For this reason, this support was used as a catalyst in this reaction and it maintained its activity after 5 times of recovery.

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