Dimethyl ether synthesis from methanol over diatomite catalysts modified using nitric acid was investigated. The catalytic performance of diatomite was tested in a fixed-bed reactor under atmospheric pressure and within the temperature range of 250–350°C. It was discovered that high acidity of the catalyst yielded a higher methanol conversion rate. Moreover, it was revealed that the acidity of the catalyst surface was controlled by Al<sup>(IV)</sup> ions whereas basicity of the catalyst surface was determined by Al<sup>(V)</sup> and Al<sup>(VI)</sup> ions. From this finding, the authors were able to propose the mechanism of DME synthesis from methanol over treated diatomite.
