Synthesis Of Mesoporous（Fe、Co） Aluminophosphate In The Presence Of Compressed CO₂

Green chemistry and chemical technology meeting with the economic and social sustainable development are more and more attractive in recent years. And the supercritical fluid is a promising field in green chemistry. Supercritical or compressed CO2has received much attention because of its various advantages, which has been widely used in different fields, such as extraction and fractionation, chemical reactions and material science. To date, it becomes a hot topic that use of compressed CO2in the preparation of porous materials.The first synthesis of aluminophosphate molecular sieve AlPO-n in the1980s was an important milestone in the history of molecular sieves. The AFI type of aluminophosphate molecular sieve AlPO and their derivatives became the most active members in the family. But their relatively small and uniform micropores strongly affect the mass transfer of reactants and products, thus reducing the catalytic conversion of bulky molecules. One solution for this problem is to prepare mesoporous zeolites.This thesis mainly includes two parts.In the first part, we synthesized AFI type of aluminophosphate molecular sieve AlPO in the compressed CO2system. Compared to conventional hydrothermal synthesis of AlPO for48h, it was found that the crystallization time of the sample AlPO was shortened to28h in the presence of compressed CO2. Moreover, mesopores are successfully introduced without use of any mesoscale templates.In the second part, in order to get oxidation catalysts, metal such as Fe, Co salts were introduced into the synthesis systems, and metal substituted aluminophosphate MeAlPO (Me=Fe, Co) were fabricated. Meanwhile, the traditional hydrothermal syntheses of MeAlPO (Me=Fe, Co) samples were made for comparison. It was found that the crystallization time in the compression CO2was shortened to28h. In addition, mesopores are successfully introduced without use of any mesoscale templates. The catalytic activities in the reactions of styrene and cyclohexene oxidation were investigated. It showed that the MeAlPO (Me=Fe, Co) samples displayed better catalytic performances than conventional MeAlPO zeolites, which was attributed to the fast diffusions of reactants and products in the mesopores formed. Furthermore, the influences of different metal loadings are studied, Me:A1:P=O.12:0.88:1is the best optimum for the catalytic conversions. Herein, we successfully synthesized AFI type aluminumphosphate A1PO and the metal substituted aluminophosphate MeAlPO with mesoporsity without using any mesoscale template in the presence of compressed CO2for the first time. The developed compressed CO2route provides a simple, green and economic procedure for synthesis of mesoporous zeolites, which are of great importance to industrial applications for bulky molecules.