The sol-gel method was applied to prepare a novel Ag-SiO_2-Al_2O_3 catalyst which showed high activity in the reaction of direct dehydrogenation of methanol to formaldehyde. The influence of silver loading, calcination temperature and reaction temperature on the catalytic activity was investigated, respectively. XRD patterns show that there are no sharp diffraction peaks before reaction, but after reaction, a set of sharp peaks corresponding to Ag(lll), Ag(200), Ag (220), Ag(311) and Ag(222) are observed. SEM results accord well with those from XRD. The special structure of the novel Ag-SiO_2-Al_2O_3 catalyst may lead to its excellent catalytic performance (95.0% of conversion of methanol and 81.2% of HCHO yield), which is the best of all the previous results.

Key words: METHANOL, SOL-GEL PROCESS, SILVER, SILICON OXIDE, ALUMINIUM OXIDE, CATALYTIC ACTIVITY, DEHYDROGENATION, METHANOL, SEM, XRD