Catalytic Cracking

1 - 19 . (canceled)

20 . A process for producing a catalyst additive for an FCC catalytic cracking process comprising:

providing an aluminosilicate selected from MFI aluminosilicate, MEL aluminosilicate and combinations thereof, wherein the aluminosilicate comprises an aluminosilicate silicon/aluminium atomic ratio of from 10 to 250;

de-aluminating the aluminosilicate by extracting from 20 wt. % to 40 wt. % of alumina therefrom to form de-aluminated aluminosilicate;

combining the de-aluminated aluminosilicate with a binder; and

calcining the combination of the de-aluminated aluminosilicate and the binder at elevated temperature to produce a catalyst additive.

21 . The process of claim 20 , wherein the de-aluminated aluminosilicate comprises an de-aluminated aluminosilicate silicon/aluminium atomic ratio of from 11 to 1000.

22 . The process of claim 20 , wherein the de-aluminated aluminosilicate comprises an de-aluminated aluminosilicate silicon/aluminium atomic ratio that is increased over the aluminosilicate silicon/aluminium atomic ratio.

23 . The process of claim 20 , wherein the aluminosilicate silicon/aluminium atomic ratio is from 10 to 30.

24 . The process of claim 20 , wherein the aluminosilicate is an MFI-type crystalline silicate of the ZSM-5 type.

25 . The process of claim 20 , wherein the binder is selected from aluminium oxide, silicon oxide, phosphates, clays and combinations thereof.

26 . The process of claim 20 , wherein the catalyst additive comprises from 25 wt. % to 75 wt. % de-aluminated aluminosilicate and from 75 wt. % to 25 wt. % binder.

27 . The process of claim 20 , wherein the de-aluminating comprises heating the aluminosilicate in steam and then contacting the aluminosilicate with a complexing agent for aluminium to remove aluminium therefrom.

28 . The process of claim 20 , wherein the de-aluminating comprises heating the aluminosilicate in steam and then contacting the aluminosilicate with a phosphorous-containing mineral acid to remove aluminium therefrom and to deposit phosphorous in the de-aluminated aluminosilicate.

29 . The process of claim 28 , wherein the phosphorous-containing mineral acid comprises phosphoric acid.

30 . The process of claim 28 , wherein the de-aluminated alumonosilicate upon contact with the phosphorous-containing mineral acid comprises from 0.1 wt. % to 10 wt. % phosphorous.

31 . The process of claim 20 , further comprising combining the catalyst additive with a Y-type zeolite to produce a composite catalyst for fluidised catalytic cracking of a hydrocarbon feedstock, wherein the composite catalyst comprises from 50 wt. % to 99.5 wt. % of a Y-type zeolite containing catalyst and from 0.5 wt. % to 50 wt. % of the catalyst additive.

32 . The process of claim 31 , wherein the composite catalyst comprises from 1.5 wt. % to 15 wt. % of the de-aluminated aluminosilicate and from 98.5 wt. % to 85 wt. % of the binder and the Y-type zeolite.

33 . A composite catalyst formed by the process of claim 31 .

34 . The catalyst of claim 33 comprising from 1.5 wt. % to 5 wt. % de-aluminated aluminosilicate and from 98.5 wt. % to 95 wt. % binder and Y-type zeolite.

35 . A composite catalyst for fluidised catalytic cracking of a hydrocarbon feedstock comprising:

from 50 wt. % to 99.5 wt. % of a Y-type zeolite;

from 0.5 wt. % to 50 wt. % of a de-aluminated aluminosilicate catalyst comprising a de-aluminated MFI or MEL aluminosilicate having a silicon/aluminium atomic ratio of from 11 to 300; and

a binder, wherein the composite catalyst comprises from 1.5 wt. % to 5 wt. % of the de-aluminated aluminosilicate and from 98.5 wt. % to 95 wt. % of the binder and the Y-type zeolite.

36 . A process for the fluidised catalytic cracking of a hydrocarbon feedstock comprising:

contacting a hydrocarbon feedstock with the composite catalyst of claim 35 to produce an effluent containing propylene.

37 . The process of claim 36 , wherein the contacting step is carried out in an FCC reactor at an inlet temperature of from 500 to 650° C.