<p>Methanation, the production of methane from CO₂ and hydrogen, is attracting increased attention as a measure to reduce carbon dioxide emissions from fossil fuel combustion. To use methanation product gas as city gas, reducing the amount of hydrogen in the methanation product gas remains a key challenge. To achieve this, a catalytic system has been proposed that uses ethanol, a widely used biofuel, and the hydrogen in methanation product gas to drive the ethanol dehydration–hydrogenation reaction. In this study, we found that the Pd/HSiW/SiO₂ catalyst initially exhibited high activity but gradually lost its activity due to reactions with water vapor contained in the reaction gas, as revealed by various measurements. On the other hand, Pd/WO₃/ZrO₂, which initially had relatively low activity and low selectivity, did not degrade after 150&#xa0;h of continuous activity measurement, and the activity and selectivity of the reaction increased during the test. The increase in the activity of WO₃/ZrO₂ after hydrogen pretreatment was investigated by NH₃-TPD, and it was concluded that this increase was due to an increase in the solid acid strength caused by hydrogen in the gas. These results indicate that Pd/WO₃/ZrO₂ is both highly active and highly durable for dehydration–hydrogenation of ethanol and is suitable for practical applications.</p> Graphical Abstract