Methods for processing hydrocarbon feedstocks
Methods for processing a hydrocarbon feedstock may include cracking at least a portion of the hydrocarbon feedstock by contacting the hydrocarbon feedstock with a modified zeolite in the presence of hydrogen to form an intermediate cracked product and steam cracking at least a portion of the intermediate cracked product to form a steam cracked product. The intermediate cracked product may include at least 30 wt. % of one or more linear alkanes. The modified zeolite may include a microporous framework. The microporous framework may include at least silicon atoms and oxygen atoms. The modified zeolite also includes a plurality of Group 4-6 metal atoms each bonded to four bridging oxygen atoms, wherein each of the bridging oxygen atoms bonded to the Group 4-6 metal atoms bridges one of the plurality of the Group 4-6 metal atoms and a silicon atom of the microporous framework.
1 . A method of processing a hydrocarbon feedstock, the method comprising:
cracking at least a portion of the hydrocarbon feedstock by contacting the hydrocarbon feedstock with a modified zeolite in the presence of hydrogen to form an intermediate cracked product, wherein:
the hydrocarbon feedstock comprises at least 20 wt. % of one or more alkanes;
the intermediate cracked product comprises at least 30 wt. % of one or more linear alkanes; and
the modified zeolite comprises:
a microporous framework comprising a plurality of micropores having diameters of less than or equal to 2 nm, wherein the microporous framework comprises at least silicon atoms and oxygen atoms; and
a plurality of Group 4-6 metal atoms each bonded to four bridging oxygen atoms, wherein each of the bridging oxygen atoms bonded to the Group 4-6 metal atoms bridges one of the plurality of the Group 4-6 metal atoms and a silicon atom of the microporous framework; and
steam cracking at least a portion of the intermediate cracked product to form a steam cracked product.
2 . The method of claim 1 , wherein the intermediate cracked product is not processed as to change its composition before being steam cracked.
3 . The method of claim 1 , wherein the intermediate cracked product is not reverse isomerized before being steam cracked.
4 . The method of claim 1 , wherein the hydrocarbon feedstock comprises at least 90 wt. % C 15 to C 100 alkanes.
5 . The method of claim 1 , wherein the hydrocarbon feedstock comprises from 20 wt. % to 60 wt. % paraffinic hydrocarbons; from 20 wt. % to 60 wt. % naphthenic hydrocarbons; and from 1 wt. % to 10 wt. % aromatic hydrocarbons.
6 . The method of claim 1 , wherein contacting the hydrocarbon feedstock with the modified zeolite occurs at a temperature from 100° C. to 450° C.
7 . The method of claim 1 , wherein contacting the hydrocarbon feedstock with the modified zeolite occurs under a partial pressure of hydrogen from 0.5 mbar to 1.5 mbar.
8 . The method of claim 1 , wherein the hydrocarbon feedstock and the modified zeolite are contacted in a reactor at a liquid hour space velocity from 0.02 hr −1 to 10 hr −1 .
9 . The method of claim 1 , wherein the intermediate cracked product comprises at least 50 wt. % linear alkanes.
10 . The method of claim 1 , wherein the steam cracked product comprises from 20 wt. % to 75 wt. % ethylene.
11 . The method of claim 1 , wherein the Group 4-6 metal atoms are selected from titanium, hafnium, zirconium, and combinations thereof.
12 . The method of claim 1 , wherein the Group 4-6 metal atoms comprise titanium.
13 . The method of claim 1 , wherein the modified zeolite comprises a plurality of mesopores having diameters of greater than 2 nm and less than or equal to 50 nm.
14 . The method of claim 13 , wherein the plurality of mesopores are ordered with cubic symmetry.
15 . The method of claim 1 , wherein the modified zeolite has a total acidity from 0.15 mmol/g to 0.55 mmol/g.
16 . The method of claim 1 , wherein the modified zeolite comprises from 0.01 mmol/g to 0.45 mmol/g of the Group 4-6 metal.
17 . The method of claim 1 , wherein the mesopores are ordered with cubic symmetry having an Ia-3d, Fm-3m, Pm-3n, Pn-3m or Im-3m space group.
18 . The method of claim 1 , wherein the microporous framework further comprises aluminum atoms, and a ratio of silicon atoms to aluminum atoms is from 1.5 to 1500.
19 . The method of claim 1 , wherein a surface area of the modified zeolite is from 200 m 2 /g to 1500 m 2 /g and a total pore volume of the modified zeolite is from 0.01 to 1.5 cm 3 /g.
20 . The method of claim 1 , wherein the modified zeolite further comprises silicon hydride moieties each bonded to bridging oxygen atoms.