Research On 3D Printing Silicon-based Porous Solid Acid/base Catalyst And Its Application

In the research of our work,SiO₂ was used as the raw material combined with advanced 3D printing technology to prepare a porous structure with controllable structure.The effects of 3D printing ink composition,printing parameters,and post-processing technology on structure formation were explored.A graded volatile ink was developed during this process,and experiments have shown that the printing ink has good moldability.In order to make the carrier have proper strength,the carrier is subjected to gradient heat treatment.SEM showed that the SiO₂ matrix was locally sintered after heat treatment;XRD showed that the crystal form of the SiO₂ matrix had changed from amorphous to cristobalite phase;FT-IR showed that the hydroxyl groups on the surface of the SiO₂ matrix had substantially decreased;in addition,the strength of the structure increased with The increase in voids decreases.Under the optimized ink composition and printing parameters,a porous structure with a diameter and height of 14 mm × 10 mm and a pore diameter of 900 ?m was prepared and processed to obtain the corresponding carrier.Subsequently,the printed porous cylinder was used as a catalytic support to prepare a porous solid base catalyst.First,different base molecules were grafted on the carrier and they were compared by preliminary screening.After selecting the optimal base molecule,diethylenetriamine,the target solid base catalyst was prepared,and its microscopic morphology was observed by SEM.In addition to macroscopically visible pores,the surface of the material is rough,which is conducive to a wide range of catalytic active sites distributed.FTIR verified that the characteristic peaks of the modified molecules appeared at 3300,2920,2870,1450,and 1388 cm^-1.TGA showed the thermogravimetric loss of alkali molecules.Subsequently,by using benzaldehyde and malononitrile as a model reaction,the effects of various solvents on the catalytic efficiency of the catalyst were discussed,and the results showed that the catalyst had the best catalytic effect in a 95% ethanol solution.The catalytic performance of the catalyst on a series of aldehydes was discussed.The results showed that the catalyst had high catalytic activity on a series of aldehydes,and the yield of the product could reach more than 90% in 30 minutes.In addition,the catalyst can be recycled at least 10 times and still has high catalytic activity.Finally,the FTIR,¹H NMR and melting point of the product were measured to confirm that the product obtained by the catalyst was indeed the target product.Then,a sulfonic acid group was introduced which was based on the base catalyst to prepare a functional solid acid catalyst.The micro-morphology was observed by SEM.Before and after acid functionalization,the color of the material changed from white to light yellow,and the catalyst surface became black after catalyzing 1-octanol.The successful grafting of the sulfonic acid group was verified by FTIR,and the pyrolysis of the material was analyzed by thermal TGA to indicate that the catalyst was modified.Subsequently,p-hydroxybenzyl alcohol and 2,3-dihydropyran were used as model reactions,and the effects of each solvent on the catalytic efficiency of the reaction were discussed.The results showed that the catalyst had the best catalytic effect when dichloromethane was used as a solvent.In addition,the catalytic effect of the catalyst on a series of aldehydes can reach more than 89% in 30 minutes.The product was verified by FTIR and¹H NMR,and the recycling ability of the catalyst was evaluated.The catalyst can efficiently catalyze at least 12 times.In a word,we successfully prepared a structure-controllable silicon-based porous acid / base catalyst through 3D printing technology.The catalyst showed high catalytic efficiency and could be reused which offered a new idea for preparing the porous catalyst.