The Synthesis Of Mesoporous Silica Nanoparticles With Adjustable Pore Structure And Particle Size And Their Catalytic Propreties

Since the discovery of mesoporous silica nanomaterials(MSN),it has shown excellent performance in drug transport,cell imaging,and heterogeneous catalysis due to its large specific surface area,pore volume and benign biocompatibility.In view of this,a large number of research groups have conducted a series of study and characterization.By changing the amount,type of silicon source,pH of the system,reaction time,and surfactant type,to modulate mesoporous structures(worm-like,stellate,and raspberry-like)and particle sizes(20-1000 nm)is successfully realized.However,many problems have yet to be solved,such as difficult to be synthesized,low yield,and harsh reaction conditions.In this regard,a simple method is put forward to modulate pore size by introducing pore-enlarging agents;in addition,mesoporous silica particles with controllable dimensions of 40-100 nm can be synthesized massively by changing the type of silicon source and the length of the surfactant.In this process,we also unexpectedly realized the modulation of the openness of the mesoporous window,which is an unprecedented discovery.,and which further promotes MSN application in the biomedical field.In the next study,a single-step,simple and large-scale synthesis of nanospheres with a size of 25-50 nm can be successfully achieved by introducing organic alkoxides,avoiding the use of expensive tetramethylorthosilicate(TMOS),as well as avoiding a large water-to-silicon ratio system,this is a major step forward in terms of synthesis.It is well known that mesoporous materials have great potential applications in heterogeneous catalysis due to their special pore structure and large specific surface area,while the current consumption of cyclohexanol and cyclohexanone(KA oil)is huge,and KA oil is mainly prepared by cyclohexane oxidation,so whether MSN could be used in this area has been studied in this paper.By using a simple grinding method,the transition metal(iron,cobalt,manganese,etc.)is incorporated into the mesoporous silica nanoparticles.Due to the material limitation,the metal particles introduced are all around 1-2 nm.Under the oxygen atmosphere,the highest conversion rate of cyclohexane is more than 20% and the selectivity reaches 100%.We proposed a free radical mechanism through the introduction of radical scavenger,and UV characterization,and it provides a theoretical basis for further research.