Mineral oils: processes and products – Chemical conversion of hydrocarbons – Reforming
Reexamination Certificate
1999-12-29
2002-10-01
Yildirim, Bekir L. (Department: 1764)
Mineral oils: processes and products
Chemical conversion of hydrocarbons
Reforming
C208S141000, C208S017000, C208S150000
Reexamination Certificate
active
06458265
ABSTRACT:
The present invention relates to a highly paraffinic (at least 50% C
10
to C
20
paraffins) diesel fuel having a very high iso-paraffin to normal paraffin mole ratio.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 4,594,468 teaches that it is desirable to have a low iso
ormal ratio of paraffins in gas oils made from Fischer Tropsch catalysts. The examples show normal/iso ratios of from 2.7:1 to 7.5:1 (iso
ormal ratios of from 0.13:1 to 0.37:1) in conventional processes and from 9.2 to 10.5:1 (iso
ormal ratios of from 0.095:1 to 0.11:1) for examples of its invention.
U.S. Pat. No. 5,135,638 discloses isomerizing a waxy feed over a catalyst comprising a molecular sieve having generally oval 1-D pores having a minor axis between 4.2 Å and 4.8 Å and a major axis between 5.4 Å and 7.0 Å, with at least one group VIII metal. SAPO-11, SAPO-31, SAPO-41, ZSM-22, ZSM-23 and ZSM-35 are disclosed as examples of useful catalysts.
U.S. Pat. No. 5,689,031 teaches a clean distillate useful as a diesel fuel, produced from Fischer-Tropsch wax. The isoparaffin
ormal paraffin ratio is given as being from 0.3:1 to 3.0:1, preferably from 0.7:1 to 2.0:1.
U.S. Pat. No. 5,866,748 teaches a solvent (not a diesel fuel) produced by hydroisomerization of a predominantly C
8
-C
20
n-paraffinic feed. The isoparaffin
ormal paraffin ratio is given as being from 0.5:1 to 9.0:1, preferably from 1:1 to 4:1.
Two papers, “Studies on Wax Isomerization for Lubes and Fuels”
Zeolites and Related Microporous Materials: State of the Art
1994 Studies in Surface Science and Catalysis, Vol. 84, Page 2319 (1994), and “New molecular sieve process for lube dewaxing by wax isomerization” Microporous Materials 2 (1994) 439-449, disclose dewaxing by a catalytic (Pt-SAPO-11) wax isomerization process. These papers disclose isomerization selectivity for n-hexadecane of from 93% to 84% at 89% to 96% conversion, respectively, for iso
ormal ratios of from 7.4:1 to 20.7:1. A third paper, “Wax Isomerization for Improved Lube Oil Quality,” Proceedings, First International Conference of Refinery Processing, AlChE Natl. Mtg, New Orleans, 1998, discloses isomerization selectivity for n-C
24
lube oil of from 94% to 80% at 95% to 99.5% conversion, respectively, for iso
ormal ratios of from 17.8:1 to 159:1.
SUMMARY OF THE INVENTION
The present invention provides a highly paraffinic (at least 50% C
10
to C
20
paraffins) diesel fuel having a very high iso-paraffin to normal paraffin mole ratio. The diesel fuel must have an iso-paraffin to normal paraffin mole ratio of at least 21:1, most preferably at least about 30:1.
In both embodiments, preferably the diesel fuel has a total paraffin content of at least 90%. The term “total paraffin content” refers to the percentage of the diesel fuel that is any type of paraffin (iso-paraffin or normal paraffin). Preferably, the diesel fuel is derived from a Fischer-Tropsch catalytic process.
The diesel fuel can be produced by contacting a highly paraffinic feed in an isomerization reaction zone with a catalyst comprising at least one Group VIII metal and a molecular sieve having generally oval 1-D pores having a minor axis between 3.9 Å and 4.8 Å and a major axis between 5.4 Å and 7.0 Å. The molecular sieve can be selected from the group consisting of SAPO-11, SAPO-31, SAPO-41, ZSM-22, ZSM-23, ZSM-35, and mixtures thereof. More preferably, it is selected from the group consisting of SAPO-11, SAPO-31, SAPO-41, and mixtures thereof. Most preferably, it is SAPO-11. Preferably, the Group VII metal is selected from the group consisting of platinum, palladium, and mixtures thereof.
Preferably, the process is carried out at a temperature of from 200° C. to 475° C., a pressure of from 15 psig to 3000 psig, and a liquid hourly space velocity of from 0.1 hr
−1
to 20 hr
b−1
. More preferably, it is carried out at a temperature of from 250° C. to 450° C., a pressure of from 50 to 1000 psig, and a liquid hourly space velocity of from 0.1 hr
−1
to 5 hr
−1
. Most preferably, it is carried out at a temperature of from 340° C. to 420° C., a pressure of from 100 psig to 600 psig, and a liquid hourly space velocity of from 0.1 hr
−1
to 1.0 hr
−1
.
Preferably, the process is carried out in the presence of hydrogen. Preferably, the ratio of hydrogen to feed is from 500 to 30,000 standard cubic feet per barrel, more preferably from 1,000 to 10,000 standard cubic feet per barrel.
Preferably, the feed has at least 80% C
10+
normal paraffins, more preferably at least 90% C
10+
normal paraffins. Preferably, the feed is derived from a Fischer-Tropsch catalytic process.
REFERENCES:
patent: 4594468 (1986-06-01), Minderhoud et al.
patent: 5135638 (1992-08-01), Miller
patent: 5689031 (1997-11-01), Berlowitz et al.
patent: 5866748 (1999-02-01), Wittenbrink et al.
patent: 5916433 (1999-06-01), Tejada et al.
patent: WO 98/56876 (1998-12-01), None
Dahlberg Arthur John
Krishna Kamala R.
Krug Russell R.
Miller Stephen J.
Burns Doane Swecker & Mathis L.L.P.
ChevronTexaco Corporation
Yildirim Bekir L.
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