Technique for synthesizing methanol by hydrogen and carbon dioxide

The invention discloses a technological method for synthesizing methanol by using hydrogen and carbon dioxide. The method mainly comprises the following steps that the hydrogen and the carbon dioxide are subjected to catalytic reaction which is the first step in a first reactor under the action of copper-based hydrogenation catalyst, so as to obtain methanol, water and carbon monoxide; separation is performed in a gas-liquid separator; liquid methanol and water are separated out; gaseous carbon monoxide, hydrogen and carbon dioxide enter a second reactor; and under the action of a methanol synthesis catalyst, synthesis reaction which is the second step is carried out, so as to obtain crude methanol and water. The method has the advantages that the method uses the hydrogen and the carbon dioxide as raw materials to synthesize the methanol, can fully utilize carbon dioxide resource which is generally regarded as waste gas to be discharged to synthesize the methanol easily, is low in reaction temperature, high in carbon dioxide conversion rate, simple in technological process, low in energy consumption and easy to realize industrialization, and develops a new way to produce methanol raw materials while reducing carbon dioxide emission into atmosphere.