Example 1
An Arab light crude oil with an API gravity of 33.0 and a sulfur content of 1.6 wt. % was fractionated in a distillation column to form a light stream and a heavy stream. Properties of the feed crude oil stream and the resulting fractions (based on their percent composition in the crude oil fractions) are given in Table 1 below.
TABLE 1
Stream NameBoiling RangeNi (ppm)V (ppm)S (wt. %)N (ppm)
Hydrocarbon3.414.521.6444
Feed
Light StreamLess than<1<10.213
370° C.
Heavy StreamGreater than 4.414.21.4431
370° C.
Details of the un-hydrotreated heavy stream are shown below in Table 2, where the heavy stream is designated EX-1(A).
The same Arab light crude oil used in Example 1 was directly cracked in the same cracking reactor and under the same conditions as was used in Example 3(A), results are designated CE-1. Specifically, the temperature was 675° and the TOS was 75 seconds.
TABLE 4
3(A)3(B)3 (Combined)CE-1
(wt. %)(wt. %)(wt. %)(wt. %)
Dry Gas9.876.438.0610.80
Light Olefins39.1151.6743.4634.89
Ethylene11.8210.0610.6910.41
Propylene18.3425.7621.0516.51
Butylene8.9615.8411.727.96
Gasoline Range33.1224.6028.3824.21
Products
Coke4.926.615.5113.86
Conversion91.1494.4689.8687.38
As can be seen in Table 4, the combined yields of total light olefins from the present methods are significantly higher than the yields from the comparative methods. Further, each of examples 3(A), 3(B), and 3(Combined) show significantly decreased levels of coke formation relative to the comparative example CE-1.
Example 2
The heavy stream from Example 1 was hydrotreated in a three-stage hydrotreater. The reaction conditions were: a weighted average bed temperature of 400° C., a pressure of 150 bar, a liquid hourly space velocity (LHSV) of 0.5 h−1, an Hz/oil ratio 1200:1(v/v), an oil flowrate of 300 ml/h, and an H2 flowrate of 360 L/h.
The first stage of the hydrotreater used a KFR-22 catalyst from Albemarle Co. to accomplish hydro-demetallization (HDM). The second stage of the hydrotreater used a KFR-33 catalyst from Albemarle Co. to accomplish hydro-desulfurization (HDS). The third stage of the hydrotreater used a KFR-70 catalyst from Albemarle Co. to accomplish hydro-dearomatization (HDA). The first, second, and third stages were discrete beds placed atop one another in a single reaction zone. The heavy stream flowed downward to the first stage, then to the second stage, and then to the third stage. Properties of this hydrotreated heavy stream are shown in Table 2 below and are designated EX-2.
TABLE 2
EX-1(A)EX-2
Kinematic viscosity at 100° C. (mm2/s)6
Density (g/ml)0.9650.8402
Nitrogen (ppm)120868.5
Sulfur (wt. %)3.10.007
Ni (ppm)10<1
V (ppm)32<1
Aromatics68.625.6
The hydrotreated heavy stream from Example 2 was fed to the advanced cracking evaluation unit. A TOS of 75 seconds, a residence time of from 1 to 2 seconds, and a temperature of 645° C. was used. Characterization of the product is given in Table 5 below.
TABLE 5
CE-13(B)
Temp. ° C.645645
T.O.S.(s)7575
Steaming Cond.810° C. for 6 hours
CAT/OIL6.488.00
Conversion (%)82.7794.46
Yields (wt. %)
H2 (wt. %)0.600.93
C1 (wt. %)4.823.71
C2 (wt. %)2.741.79
C2═ (wt. %)8.0710.06
C3 (wt. %)2.262.25
C3═ (wt. %)17.1625.76
iC4 (wt. %)0.671.58
nC4 (wt. %)0.550.69
t2C4═ (wt. %)2.393.92
1C4═ (wt. %)1.672.78
iC4═ (wt. %)3.596.01
c2C4═ (wt.%)1.903.14
1,3-BD (wt. %)0.010.63
Total Gas (wt. %)46.4463.25
Gasoline (wt. %)18.0924.60
LCO (wt. %)9.843.95
HCO (wt. %)7.381.59
Coke (wt. %)18.246.61
Groups (wt. %)
H2—C2 (dry gas)16.2416.49
C3—C4 (LPG)30.1946.77
C2═−C4═ (Light34.7952.30
olefins)
C3═+C4═26.7142.24
C4═ (Butenes)9.5516.48
Molar Ratios
mol/mol)
C2═/C23.156.03
C3═/C37.9711.97
C4═/C48.067.52
iC4═/C4═0.380.36
iC4═/iC45.513.94
As can be seen in Table 5, utilizing a hydrotreated heavy stream as the feed to the catalytic reactor results in higher conversion; greater yield of C2, C3, and C4 olefins; greater yield of gasoline; and significantly decreased coke formation, among other advantages.
Example 3
The respective fractions of Arab light crude were cracked at the conditions described below. A catalyst with the composition shown in Table 3 below as used in all of the reactions.
TABLE 3
ComponentWeight %Notes
ZSM-520Phosphorus impregnated at 7.5 wt. %
P2O5 on zeolite
USY21Lanthanum impregnated at 2.5 wt. %
La2O3 on zeolite
Alumina8Pural SB from Sasol
Clay49Kaolin
Silica2Added as colloidal silica Ludox TM-40
An Advanced Cracking Evaluation (ACE) unit was used to simulate a commercial FCC process. The reaction was run two times with fresh catalyst to simulate two separate FCC reaction zones in parallel.
Prior to each experiment, the catalyst is loaded into the reactor and heated to the desired reaction temperature. N2 gas is fed through the feed injector from the bottom to keep catalyst particles fluidized. Once the catalyst bed temperature reaches within ±2° C. of the reaction temperature, the reaction can begin. Feed is then injected for a predetermined time (time-on-stream (TOS)). The desired catalyst-to-feed ratio is obtained by controlling the feed pump. The gaseous product is routed to the liquid receiver, where C5+ hydrocarbons are condensed and the remaining gases are routed to the gas receiver. After catalyst stripping is over, the reactor is heated to 700° C., and nitrogen was replaced with air to regenerate the catalyst. During regeneration, the released gas is routed to a CO2 analyzer. Coke yield is calculated from the flue gas flow rate and CO2 concentration. The above process was repeated for each of Examples 3(A) and 3(B). The weight ratio of catalyst to hydrocarbons was 8.
It should be understood that time-on-stream (TOS) is directly proportional to residence time.
The light stream from Example 1 was fed to the advanced cracking evaluation unit. A time-on-stream (TOS) of 75 seconds, a residence time of from 1 to 2 seconds, and a temperature of 675° C. was used.
The hydrotreated heavy stream from Example 2 was fed to the advanced cracking evaluation unit. A TOS of 75 seconds, a residence time of from 1 to 2 seconds, and a temperature of 645° C. was used. Characterization is shown in both Table 4 and Table 5.
The streams of Examples 3(A) and 3(B) were combined to form a single stream. The single stream simulates the output of processing a whole crude according to the methods of the present disclosure.
Example 3(Combined) is a weighted average of Examples 3(A) and 3(B). Example 3(A) represented 53 wt. % of Example 3(Combined). Example 3(B) represented 44 wt. % of Example 3 (Combined).
