Treatment of air to a catalyst regenerator to maintain catalyst activity

A process of regenerating a spent SAPO or AlPO molecular sieve catalyst comprising:

• a) introducing a spent SAPO or AlPO molecular sieve catalyst into a regeneration vessel;
• b) introducing a flow of dried and purified gas into said regeneration vessel, wherein said gas comprises about 10 to 500 ppb alkali metal salt and wherein said gas contains at least 50% less water than prior to being subjected to a drying and purification step wherein said drying and purification step comprises passing said gas in an axial direction through a rotary adsorbent contactor to remove impurities including water and said alkali metal salt and then sending a purified gas flow to said regeneration vessel;
• and
• c) heating said spent SAPO or AlPO molecular sieve catalyst for a sufficient period of time and at a sufficient temperature to regenerate said molecular sieve catalyst.