Pressure swing adsorption apparatus for high purity hydrogen purification from ammonia decomposition and hydrogen purification method using the same

A hydrogen purification method using a pressure swing adsorption apparatus, comprising:

• providing the pressure swing adsorption apparatus comprising:
• a raw material feed pipe for supplying a mixed hydrogen gas produced after ammonia decomposition;
• a plurality of adsorption towers including a guard bed unit disposed at a lower position and a hydrogen purification unit disposed at an upper position;
• a vacuum pump connected to the plurality of adsorption towers to maintain the plurality of adsorption towers under vacuum pressure;
• and
• a plurality of valves configured to open and close pipes connecting the plurality of adsorption towers and the vacuum pump,
• wherein each adsorption tower of the guard bed unit is packed with a first adsorbent and a second adsorbent arranged in layers to selectively remove moisture and ammonia, respectively, from the mixed hydrogen gas,
• wherein each adsorption tower of the hydrogen purification unit is packed with a third adsorbent to selectively remove nitrogen from the mixed hydrogen gas, and
• wherein during operation a lowest pressure reached in each adsorption tower of the guard bed unit is not less than one fourth of a raw material feed pressure;
• feeding the mixed hydrogen gas produced after ammonia decomposition into an adsorption tower of the guard bed unit through the raw material feed pipe;
• selectively adsorbing and removing moisture by allowing the fed mixed hydrogen gas to pass through the first adsorbent packed at a lower layer region of the adsorption tower in the guard bed unit;
• selectively adsorbing and removing ammonia by allowing the mixed hydrogen gas free of moisture to pass through the second adsorbent packed at an upper layer region of the adsorption tower in the guard bed unit;
• feeding the mixed hydrogen gas free of moisture and ammonia into an adsorption tower of the hydrogen purification unit;
• and
• selectively adsorbing and removing nitrogen by allowing the fed mixed hydrogen gas free of moisture and ammonia to pass through the third adsorbent packed in the adsorption tower in the hydrogen purification unit to acquire purified hydrogen.