Template removal from AFI aluminophosphate molecular sieve by Pd/SiO2 catalytic hydrocracking at mild temperature

Abstract

Pd/SiO2 catalytic hydro-cracking is applied to remove triethylamine template in an AFI type MnMgAlPO-5 molecular sieve. The triethylamine template reacts with spillover hydrogen inletting from the Pd/SiO2 catalyst, and is hydro-cracked to small molecules at a mild temperature (613K). This behavior is distinguish to the conventional template removal method of calcination above 823K, and consistently proved by H2-TPR/MS, TG/MS, and N2-isotherms results. The catalytic hydro-cracking method does not damage the crystal structure of MnMgAlPO-5, indicated by XRD characterization. Its novelty is suggested as reserving the local symmetric structure of MnMgAlPO-5 (i.e., keeping framework Mn and Mg), consistently verified by EPR, UV–vis, and Raman spectra. This provides an alternative option for the template removal from molecular sieves.