This work is devoted to a study of the life cycle of silica gel adsorbents of the ASM brand used in natural-gas purification, as well as to establishing the factors affecting their catalytic activity under the conditions of methanol conversion to dimethyl ether. The elemental and phase composition, specific surface area, and pore volume of commercial adsorbents have been established by X-ray fluorescence, X-ray phase, synchronous thermal analysis, and low-temperature nitrogen adsorption, and relationships with their catalytic activity have been studied. The dependences of the yield of dimethyl ether on the time of operation of adsorbents at gas-treatment gas-transportation units (GTUs) have been studied. It is shown that the phase state of the original, spent, and regenerated adsorbents does not change during their operation. A decrease in the thermal catalytic activity of the adsorbent under the conditions of the conversion of methanol to dimethyl ether over time during the operation of GTUs was found, which is due to a decrease in their specific surface area and specific pore volume, as well as the accumulation of various organic components (turbine oil) and sulfur.