Controlling carbon dioxide output from an ODH process

A method for controlling the carbon dioxide output from an oxidative dehydrogenation process comprising the steps of:

• i) introducing a gas mixture comprising ethane and oxygen, and optionally one or more of steam and inert diluent, into at least one ODH reactor containing an ODH catalyst, provided that if more than one ODH reactor is present then each reactor may contain the same or different ODH catalyst and at least one of the ODH catalysts is capable of utilizing carbon dioxide as an oxidizing agent, under conditions to produce a product stream from the at least one ODH reactor comprising ethylene, and optionally one or more of unreacted ethane, unreacted oxygen, carbon dioxide, carbon monoxide, inert diluent, and acetic acid;
• ii) measuring a carbon dioxide level in the product streams;
• and
• either:
• a. introducing steam, or increasing an amount of steam introduced, into the at least one ODH reactor in an amount sufficient to decrease carbon dioxide levels if the measured carbon dioxide level is above a predetermined target carbon dioxide level;
• b. decreasing the flow rate of steam introduced into the at least one ODH reactor to increase the carbon dioxide level if steam was introduced in step i) and the measured carbon dioxide level is below a predetermined target carbon dioxide level;
• c. increasing the volumetric ratio of oxygen to ethane in the gas mixture introduced into the at least one ODH reactor to a degree sufficient to decrease the carbon dioxide level if the measured carbon dioxide level is above a predetermined target carbon dioxide level;
• or
• d. decreasing the volumetric ratio of oxygen to ethane in the gas mixture introduced into the at least one ODH reactor to a degree sufficient to increase the carbon dioxide level if the measured carbon dioxide level is below a predetermined target carbon dioxide level.