Methanol and desalinated water are mixed in a certain proportion and preheated by a heat exchanger before being sent to the vaporization tower. The vaporized water methanol vapor is superheated by the heat exchanger and enters the reactor for catalytic cracking and transformation reaction in the catalyst bed, producing cracking gas containing about 74% hydrogen and 24% carbon dioxide. After heat exchange, cooling and condensation, it enters the water washing absorption tower. The tower kettle collects unconverted methanol and water for recycling, and the top gas is sent to the pressure swing adsorption device for purification. According to different requirements for product gas purity and trace impurity components, the purity can reach 99.9-99.999%. The carbon dioxide in the cracked gas can be purified to food grade using a pressure swing adsorption device, which is used in the beverage and alcohol industries. This can greatly reduce production costs. The process is set to first separate carbon dioxide through a pressure swing adsorption device, and then the cracked gas rich in hydrogen is pressurized and sent to the pressure swing adsorption device for purification. Widely used in industries such as chemical, steel, non-ferrous, powder, etc