Catalytic properties of fluorinated alumina for the production of dimethyl ether

Fluorination by NH4F solution was used to modify the acidity of alumina. The textural and acidic properties of the parent alumina and modified alumina were studied by N2 adsorption and NH3-TPD. It was disclosed that both surface area and acidity of alumina are enhanced by the treatment with 0.1 mol/l NH4F solution, while modification with more concentrated NH4F solutions leads to the decrease in surface area of alumina and thereby weakens its acidity. The catalytic properties of these alumina samples were subsequently investigated in the production of DME. Sample AF1, treated by 0.1 mol/l NH4F solution, performed best in both methanol dehydration and the STD process (syngas to dimethyl ether) because of its strongest acidity.