Al-modified mesoporous silica for efficient conversion of methanol to dimethyl ether

The aim of this work was to design efficient mesoporous heterogeneous catalysts for the reaction of conversion of methanol to dimethyl ether (DME). Mesostructured silica and aluminosilicate solids were synthesized using an original synthesis procedure enabling the elaboration of structurally homogeneous solids at atmospheric pressure and using a food grade templating agent. The prepared solids consisted of mesoporous silica and aluminosilicates with aluminium contents of 0.76, 1.11 and 1.60 wt%. These solids were characterized by XRD, N₂-physisorption and TEM. Their efficiency in the catalytic reaction of conversion of methanol to DME was subsequently correlated with their structural and acidic properties. The sample exhibiting a pore diameter of 2.2 nm for a Si/Al ratio of 27 showed remarkable performances with a methanol conversion as high as 80% at 598 K (7.5 vol% MeOH; 50 mg of catalyst; GHSV = 26,000 cm³ h^-1 g^-1) and a total selectivity to DME.