Studies On The Ionothermal Synthesis Of Aluminophosphate Molecular Sieves And Their Hydroisomerization Performance Of N-Alkanes

Owing to the widely application of molecular sieves in much scientific area, it is of great importance to investigate the synthesis and applications of molecular sieves. Recently, a very promising method, ionothermal synthesis, for preparing materials has been developed by Morris et al. In this work, the ionothermal synthesis of aluminophosphate molecular sieves has been studied. Several MeAPO molecular sieves have been synthesized ionothermally and their catalytic performance in the hydroisomerization of n-alkane has been evaluated.The ionothermal synthesis of molecular sieves in 1-butyl-3-methylimidazolium bromide ionic liquid has been studied for the first time. The results indicate that the structure of ionic liquid has a major influence on the products structure. In the presence of amine, the dynamics of the ionothermal crystallization process is changed, leading to the formation of pure AFI structure. This shows that the amine have a structure-directing effect in the ionothermal synthesis of aluminophosphate molecular sieves.In addition, another pure ATV structure can be synthesized ionothermally at 280°C with the addition of amine. This finding extends the temperature range of ionothermal synthesis. The ionothermal synthesis of molecular sieves was also carried out under microwave conditions, namely the microwave-enhanced ionothermal synthesis of molecular sieves, which combines the advantages of both microwave heating and ionothermal synthesis.Four different MeAPO-11(Me=Mg, Si, Zn, Mn) have been successfully prepared using the ionothermal synthesis for the first time. The hydroisomerization performance of the Pt/MeAPO-11 catalysts has been investigated. The results show that the hydroisomerization activity of Pt/MgAPO-11 is the highest.The influence of the reaction variables on the hydroisomerization performance of MgAPOs was studied. It was found that the structure, BET area, acidity, and hydroisomerization performance can be affected by increasing the Mg content and the addition of amine. The Pt/MgAPO-11 catalyst with the best catalytic performance was obtained by optimization, whose selectivity is 94% at a 92.8% conversion of n-dodecane at 280°C (H2/n-C12(mol)=15.0, WHSV=0.3h^-1, Ptotal=1atm).