Polyoxymethylene dimethyl ethers (PODEn, CH3O(CH2O)(n),CH3, where n >= 1) are receiving much attention as ideal diesel fuel additives because they can significantly reduce the emission of smoke and engine exhaust during combustion. PODEn are synthesized over acid catalysts. In this work, highly efficient sulfate titania catalysts were prepared by impregnation for the synthesis of PODEn from dimethoxymethane (DMM) and paraformaldehyde (PF). XPS and XRF were used to determine the spatial distribution of S, and NH3-TPD and Pyridine-IR were used to measure acid properties. The concentration of the precursor solution had an important effect on the catalyst activity. The spatial distribution of S influenced the acid properties and catalyst activity. A catalytic mechanism based on Bronsted and Lewis acid sites was proposed, which explained the synergistic effect of Bronsted and Lewis acid sites in the reaction for the first time. (C) 2017 Elsevier Inc. All rights reserved.