Patent ID: 7741528

Claim:
A method for forming and separating an olefin fraction which comprises the following steps: i) contacting oxygenate with metalloaluminophosphate molecular sieve catalyst to form an olefin stream; ii) cooling the olefin stream in a quench system to form a first fraction comprising olefin and a second fraction comprising condensed water and entrained catalyst, wherein the quench system is comprised of an iron oxide-containing surface structure; iii) injecting an acid or base into the quench system in an amount to maintain a zeta potential of the entrained catalyst in the second fraction and an effective zeta potential of the surface of the quench system contacting the condensed water both in a positive range or both in a negative range with an absolute value of 2 mV; and iv) separating at least a portion of the second fraction from the olefin fraction.