The Synthesis And Catalytic Performance Of Sulfonic Acid Groups Functionalized Nanoporous Carbon Spheres

Nanoporous carbon spheres?NCS?have been widely applied in energy storage and conversion devices,catalysis and biomedical research owing to their high chemical stability,excellent electrical conductivity,low cost,high specific surface area caused by porous structure,controllable porous structures and pore diameter.And NCS with different structures are available in many fields especially in some special fields.Thus numerous attempts have been focused on the synthesis of NCS and some important breakthroughs have been made.In this paper,by changing surfactants with different lengths of carbon chains,we successfully synthesize mesoporous carbon nanospheres?MCN?with different structures and dendritic MCN?Particle Size Distribution,PSD<120 nm?,realize the transformation of MCN from hollow structure to dendritic structure according to literature and our group's previous work.This paper mainly focuses on the synthesis,formation mechanism and functionalization of MCN.The obtained results are listed below:1.The transformation of MCN from hollow structure to dendritic structure has been successfully realized by changing surfactants with different lengths of carbon chains when using TEAH₃ as alkali source.By tracing the pH value in the synthetic process,we find that the micelles composed by the surfactants with different lengths of carbon chains have different concentration and covering degree of silicon species caused by the difference of adsorbed alkali.This is a key factor in the synthesis of MCN with various structures.2.When using MCN as carrier,it can be concluded that gas-phase sulfonated method outperform other sulfonated methods.By sulfonating the obtained MCN and using the alkylation reaction of m-cresol with tert-butanol as probe reaction,we investigate the catalytic performance of MCN-SO₃H with different carbonization temperatures and structures and find that the catalytic performance of MCN under different carbonization temperatures is ascribed to the different structures of MCN.3.We detailedly inquire the reason of the inferior cycled performance of MCN-SO₃H in the alkylation reaction.Reasons are as follows:?1?the channels of MCN-SO₃H are blocked by the reactants in the alkylation reaction.?2?The MCN are synthesized by the reaction of resorcinol with methanol and the solvents of probe reaction are m-cresol and tertiary butanol.The hydroxyl of resorcinol in MCN can react with the hydroxyl in m-cresol and tertiary butanol and the products are prone to block the channels of MCN.Meanwhile,the loss of catalysts results in the less products in the alkylation reaction.?3?The-SO₃H groups of catalysts may fall off under high temperature in the presence of water in the reactive solvents.Besides,we sulfonate MCN with alcohols of different chain lengths,realize the adjustment of hydrophilia and hydrophobicity of catalysts and investigate their catalytic performance in the alkylation reaction.In addition,the catalysts with different hydrophilic-hydrophobic properties may exhibit robust catalytic performance in low temperature aldol reaction of nonanal with glycol.