Controllable synthesis of polyoxymethylene dimethyl ethers by ionic liquids encapsulated in mesoporous SBA-16

The promising combustion and emission properties of polyoxymethylene dimethyl ethers (PODEn) are of significant interest. However, the synthesis of PODEn products with desired chain lengths is still a problem facing synthetic PODEn. Herein, a series of unique IL@SBA-16-Cx solid catalysts are prepared by encapsulation of ionic liquids (ILs) within the nanocage of SBA-16 through a silylation method. The structure of the encapsulated catalyst was characterized by UV–vis spectra, Fourier transform infrared (FT-IR), N2 adsorption–desorption isotherms, Powder X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Elemental analysis. The encapsulated catalysts show similar catalytic activity to the homogeneous counterparts and display higher selectivity to the targeted PODE3–5 products than their homogeneous counterparts in the synthesis of PODEn from methanol (MeOH) and trioxymethylene (TOM). The encapsulated catalysts exhibit a superior PODE3–5 selectivity and could be the promising catalysts for PODEn synthetic reaction.