Synthesis Of Mesoporous Aluminosilicates By Composite Templates And Mother Liquor Recycling Method

Poor hydrothermal stability of traditional mesoporous aluminosilicates due to their amorphous walls limited their application.Precursor assembly technique which favors the introduction of primary and secondary structural units into the walls of mesophase,could improve the hydrothermal stability of mesoporous aluminosilicates greatly.However,how to obtain hydrothermally stable mesoporous aluminosilicates with enhanced templates utilization and decreased amount of water,remains a great challenge.Seed-assisting method can significantly increase template utilization because of the role of directing structure.But it is difficult to control the synthesis rate and product morphology,and repeatability is poor.Then,templates in mother liquor can be reused by mother liquor recycling method,which would reduce the water consumption and improve template utilization.However,high synthetic costs due to the complex operation processes and high demand for equipment.Composite templates P123/SDMBS?sodium dodecyl dimethyl-benzenesulfonate?was employed in this article to solve the above problems.The critical micelle concentration?CMC?and cloud point?CP?of the composite templates increased greatly,resulting in the formation of well-ordered mesophase at high template concentrations.Enhanced hydrophilicity of PEO moiety due to the introduction of SDMBS would improve the solubility of P123 and decrease the micelle aggregation number.As a result,the template consumption was 1.09 g/g MAs,29.3%lower than that of conventional synthesis?1.50 g/g MAs?;the water consumption was 27.5 g/g MAs,32%that of conventional method?86 g/g MAs?;the synthetic cost was 26,773 yuan/ton MAs,58.4%that of conventional method?45,842 Yuan/ton MAs?.After hydrothermal treatment at 800 ?,100%water vapor for 10 h,BET surface area and total pore volume were 237 m²·g^-1 and 0.45 cm3·g-1,and the retaining ratio value of BET surface area and total pore volume were 30.5%and 52.9%,respectively.As a comparison,similar properties were exhibited(the BET surface area and total pore volume of conventional synthesized samples were 223 m²·g^-1 and 0.45 cm3·g-1,and the corresponding reserved ratio value were 30.2%and 38.1%),indicating the high hydrothermal stability of MAs synthesized by composite templates method.The mesoporous aluminosilicates were synthesized with the composite templates in 10 L crystallization vessel.As a consequence,surface area and pore volume of samples were 266.4 m²·g^-1 and 0.34 cm3·g-1.Retaining ratio value of surface area and pore volume is 34.3%and 29.4%,respectively,indicating that samples had high hydrothermal stability.It is shown that this method is characterized by improved template utilization and reduced water consumption.These advances shed a light on the practical application on the MAs.