Production of olefins

1. A process for converting a carbon containing feedstock to provide an effluent containing light olefins, the process comprising:

forming a catalyst, wherein the catalyst is formed by

supplying an MEL crystalline silicate catalyst;

steam treating the MEL crystalline silicate catalyst;

after steam treating, contacting the MEL crystalline silicate catalyst with a complexing agent for aluminum;

after contact with the complexing agent, reducing the sodium content of the MEL crystalline silicate catalyst by subjecting the MEL crystalline silicate catalyst to ion exchange with a salt;

calcining the MEL crystalline silicate catalyst after reducing the sodium content of the MEL crystalline silicate catalyst;

passing a feedstock containing carbon containing compounds consisting essentially of C 1 to C 6 aliphatic hetero compounds selected from the group consisting of alcohols, ethers, carbonyl compounds and mixtures thereof and containing steam in an amount up to 80 weight % of said feedstock, through a reactor containing the catalyst to produce an effluent including propylene which is recovered from the reactor, wherein the feedstock is passed over the crystalline silicate at a reactor inlet temperature of about 550° C.

2. A process according to claim 1 wherein the carbon containing feedstock contains at least one hetero compound selected from the group consisting of methanol, ethanol, dimethyl ether, diethyl ether and mixtures thereof.

3. A process according to claim 1 wherein the carbon containing feedstock is passed over the crystalline silicate at a WHSV of from 0.5 to 30 h −1 ,the WHSV being based on the weight of the at least one C 1 to C 6 aliphatic hetero compound in the feedstock.

4. A process according to claim 3 wherein the partial pressure of the at least on C 1 to C 6 aliphatic hetero compound in the feedstock when passed over the crystalline silicate is from 20 to 400 kPa.

5. The process of claim 1 wherein said feedstock comprises methanol and said reactor is operated under conversion conditions comprising an inlet temperature within the range of 450-550° C.

6. The process of claim 5 wherein said reactor is operated under conversion conditions providing a product containing propylene and ethylene and having a propylene/ethylene ratio which is greater than the propylene/ethylene ratio of a conversion product produced by the conversion of a methanol-containing feedstock operated at an inlet temperature in said reactor of 400° C.

7. The process of claim 5 wherein said reactor is operated under conversion conditions providing a product containing propylene and propane and having a propylene/propane ratio which is greater than the propylene/propane ratio of a conversion product produced by the conversion of a methanol-containing feedstock operated at an inlet temperature of 400° C.

8. The process of claim 1 , wherein the effluent comprises a propylene/ethylene weight ratio ranging from 2 to 10.

9. The process of claim 1 , wherein the effluent comprises a propylene/ethylene weight ratio ranging from 2 to 5.

10. The process of claim 1 , wherein the salt comprises ammonium ions.

11. The process of claim 1 , wherein the complexing agent comprises an acid in an aqueous solution, a salt of the acid in aqueous solution, or combinations thereof.

12. The process of claim 1 , wherein the propylene yield is above 35wt %.

13. The process of claim 12 , wherein the time on stream is about 61 minutes.

14. The process of claim 12 , wherein the time on stream is about 123 minutes.

15. The process of claim 12 , wherein the time on stream is about 185 minutes.