5988 7929EN HTR 5
User Manual: HTR-5
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Page Count: 6
Author
Allen K. Vickers
Agilent Technologies, Inc.
91 Blue Ravine Road
Folsom, CA 95630
Abstract
Improved GC columns have been developed that now
permit operation up to 430 °C and can be used to perform
simulated distillations covering the range from C
5
to C
110
.
They exhibit excellent inertness and low bleed at high
temperatures.
Introduction
Data derived from high-temperature simulated dis-
tillation (HTSD) analysis provides valuable infor-
mation to refiners of heavy crude oils, helping
them improve yields and minimize vacuum tower
residues. The method is also precise enough to
determine if a crude oil was adulterated, for exam-
ple, by blending pitch (1000 °F+) into the crude [1].
The American Society for Testing and Materials
(ASTM) has established guidelines for simulated
distillation (SimDist) analyses, which include sam-
ples that have atmospheric equivalent boiling
points (AEBP) in the range of about –44 to 1139 °F
(–42 to 615 °C). These include ASTM Methods
D2887 and D3710 [2]. For analysis of heavier sam-
ples, such as crude oils, HTSD method D6352 [2]
extends the AEBP distribution to temperatures
upwards of 1300 to 1380 °F (704 to 749 °C).
Higher-Temperature Simulated Distillation
with DB-HT Sim Dis Columns
Application
HTSD methods require a robust GC column with
high upper temperature limits. For this purpose,
Agilent Technologies, Inc. provides a metal
column, DB-HT Sim Dis, deactivated by a propri-
etary process, offering excellent performance and
exceptional durability.
Method Considerations
Typically, capillary GC SimDist analyses are per-
formed using a bonded 100% dimethylpolysiloxane
stationary phase in 0.53-mm id columns with rela-
tively thick films (>3 µm). The thick film aids in
preventing sample overload while giving adequate
retention to the early-eluting fractions of the
sample and extending the low end of the boiling
point distribution range down to propane (with
cryogenic conditions). However, the increased
retention of higher-boiling hydrocarbons and inter-
ferences from stationary phase bleeding limit the
upper end of the distribution curve achievable
with thicker films. ASTM Method D2887 has an
upper temperature limit for petroleum products
with a final boiling point of 1000 °F
(538 °C) at atmospheric pressure.
To extend the boiling point distribution range for
analyzing heavy crudes, it is necessary to use a
thin film column. With film thicknesses of 0.09 to
0.15 µm in a 0.53-mm id column, it is possible to
elute materials equivalent to C
110
and higher at GC
oven temperatures that are 500–600 °F (260–316 °C)
below their AEBP.
Hydrocarbon Processing
The polymer bonding and crosslinking processes
used to manufacture the DB-HT Sim Dis column
(5 m ×0.53 mm id ×0.15 µm film of 100%
dimethylpolysiloxane)1generate a “low bleed” pro-
file, critical for accurate quantitative results at the
upper temperature extremes.
The limited sample capacity of a thin stationary
phase coating requires care in the dilution of the
standards and sample matrices (about 0.1%–2% wt/wt)
as well as special sample introduction techniques.
Cool-on-column injection techniques can be used
to prevent analyte discrimination, but programma-
ble temperature vaporization (PTV) injectors have
a definite advantage with regards to automation,
reproducibility, and flexibility, and are generally
preferred for this analysis.
The extremely high temperatures used in HTSD
make it an especially challenging analytical proce-
dure, pushing the limits of all GC system compo-
nents including the GC column. Standard fused
silica columns cannot withstand the extreme oven
temperatures encountered (up to about 430 °C).
Advances in surface deactivation [3] have made it
possible to use capillary-dimensioned, stainless
steel tubing as the starting point for WCOT
columns. The metal tubing does not show the prob-
lems of brittleness and short lifetime encountered
with high-temperature polyimide-coated and
aluminum-clad fused silica columns.
The high quality of the proprietary J&W brand
deactivation process as well as polymer bonding
and crosslinking for DB-HT Sim Dis produces an
exceptionally durable column for HTSD.
Results
Users report hundreds of temperature cycles, to
430 °C, with minimal performance degradation
caused by phase loss (bleed), making DB-HT Sim
Dis the column of choice for this application. For
reference, Table 1 shows the atmospheric equiva-
lent boiling points (AEBP) for normal paraffins
with carbon numbers from 2 to 120.
2
Table 1: AEBP for Normal Paraffins with Carbon Numbers
from 2 to 120
Carbon no. Boiling point (°F)* Carbon no. Boiling point (°F)*
2 -127.5 46 1033
3 -44 48 1051
4 32 50 1067
5 97 52 1083
6 156 54 1098
7 209 56 1112
8 259 58 1126
9 303 60 1139
10 345 62 1152
11 385 64 1164
12 421 66 1175
13 455 68 1186
14 489 70 1197
15 520 72 1207
16 549 74 1216
17 576 76 1227
18 601 78 1238
20 651 80 1247
22 696 82 1258
24 736 84 1267
26 774 86 1276
28 808 88 1283
30 840 90 1292
32 871 92 1299
34 898 94 1306
36 925 96 1314
38 948 98 1321
40 972 100 1328
42 993 110 1355
44 1013 120 1382
*AEBP (Atmospheric Equivalent Boiling Point) as described in API Project 44.
1Part no. 145-1001
3
An example of a n-paraffin standard analysis using
a PTV inlet is shown for a DB-HT Sim Dis column
in Figure 1. This chromatogram is of the “raw”
output—that is the background signal has not been
altered. Figure 2 is a boiling point distribution
curve for DB-HT Sim Dis. The polydimethylsiloxane
column has an effective distribution range of
156 °F (69 °C) to 1355 °F (735 °C).
1400
1200
1000
800
Boiling point (˚F)
600
400
200
0
0 5 10 15 20 25
Retention time (min)
30 35 40 45 50
Figure 2. Boiling point vs. retention time for n-paraffins on the DB-HT Sim Dis using the conditions shown in Figure 1.
Figure 1. n-paraffin standard showing SimDist results from C
6
to C
110
on the DB-HT Sim Dis.
6
7
8
9
10
1112
14
16
18
20 24 2830
32
40
50
60
70
80 90 110
0 5 10 15 20 25 30 35 40 45 50
Time (min)
Column: DB-HT Sim Dis
5 m × 0.53 mm id, 0.15 µm
J&W Part no.: 145-1001
Carrier: Helium at 18 mL/min, measured at 35 ˚C
Oven: -30_430 ˚C at 10 ˚/min
430
˚C for 5 min
Injector: PTV
55_450 ˚C at 2 ˚/sec
0.5 µL of about 2% n-paraffins in CS2
Detector: FID, 450
˚C
Nitrogen makeup gas at 15 mL/min
4
Analyses of two reference oils with DB-HT Sim Dis
are shown in Figures 3 and 4. Both chromatograms
show a sharp return to baseline at the end of the
run for each of the oils indicating the final boiling
point of the respective oil.
Figure 3. Simulated distillation of a midrange reference crude oil (HTST_REF).
Final Bp
0 5 10 15 20 25 30 35 40 45 50
Time
(
min
)
Column: DB-HT Sim Dis
5 m × 0.53 mm id, 0.15 µm
J&W Part no.: 145-1001
Carrier: Helium at 18 mL/min, measured at 35 ˚C
Oven: -30_430 ˚C at 10 ˚/min
430
˚C for 5 min
Injector: PTV
55_450 ˚C at 2 ˚/sec
0.5 µL of about 2% OB_HTR crude oil in CS2
Detector: FID, 450 ˚C
Nitrogen makeup gas at 15 mL/min
Final Bp
0 5 10 15 20 25 30 35 40 45 50
Time
(
min
)
Column: DB-HT Sim Dis
5 m × 0.53 mm id, 0.15 µm
J&W Part no.: 145-1001
Carrier: Helium at 18 mL/min, measured at 35 ˚C
Oven: -30_430 ˚C at 10 ˚/min
430
˚C for 5 min
Injector: PTV
55_450 ˚C at 2 ˚/sec
0.5 µL of about 2% OB_HTR crude oil in CS2
Detector: FID, 450
˚C
Nitrogen makeup gas at 15 mL/min
Figure 4. Simulated distillation of a full range reference crude oil (OB_HTR).
5
Superior Performance with the DB-HT
Sim Dis—A Customer Example
The DB-HT Sim Dis outperforms and outlasts
another manufacturer’s metal column (Figure 5).
Figure 5 shows the failure of the Brand R metal
column (of equivalent dimensions) while in use at
a customer’s laboratory (top chromatogram). The
Brand R column was installed in an Agilent 6890
GC, and initially performed well. After only 276
injections under harsh analytical conditions (oven
temperature cycling from –20 to 425 °C), this
column exhibited loss of retention and poor peak
0.0 2.5 5.0 7.5 10.0 12.5
0
200
400
600
800
Time (Min)
C12
C20
C8
Brand R column
After 276 oven cycles
0.0 2.5 5.0 7.5 10.0 12.5
0
100
200
300
400
500
600
700
800
900
Signal (pA) Signal (pA)
Time
(
Min
)
DB-HT Sim Dis
After 377 oven cycles
C7 C12
C20
Figure 5. Customer data comparing two high temperature metal columns after injections of n-paraffin calibration standards.
shape due to rapid phases degradation. Needing a
column to perform their SimDist samples, the cus-
tomer reinstalled a previously “retired” DB-HT Sim
Dis (retired after 376 injections) into the same
6890 GC. With the same samples and temperature
conditions, the DB-HT Sim Dis column showed
superior performance even after 377 injections
(bottom chromatogram). At this point, the DB-HT
Sim Dis had outlived the competition’s column by
35%. The results of the analysis are shown, not
only in the bottom chromatogram of Figure 5, but
also for the entire analysis, up to C
100
at 425 °C, in
Figure 6.
Agilent shall not be liable for errors contained herein or for incidental or consequen-
tial damages in connection with the furnishing, performance, or use of this
material.
Information, descriptions, and specifications in this publication are subject to change
without notice.
© Agilent Technologies, Inc. 2002
Printed in the USA
October 31, 2002
5988-7929EN
www.agilent.com/chem
n-C5n-C6
n-C7
n-C8
n-C9
n-C10
n-C11
n-C12
n-C13
n-C14
n-C15
n-C16
n-C17
n-C18
n-C20
n-C22
n-C24
n-C26
n-C28
n-C30
n-C32
n-C34
n-C36
n-C38
n-C40
n-C42
n-C44
n-C46
n-C48
n-C50
n-C52
n-C54
n-C56
n-C58
n-C60
n-C62
n-C64
n-C66
n-C70
n-C72n-C74
n-C76n-C78
n-C80 n-C82
n-C84 n-C86
n-C88 n-C90
n-C92 n-C94
n-C96 n-C98
n-C100
n-C68
0 5 10 15 20 25 30
DB-HT Sim Dis
After 377 oven cycles
Figure 6. Customer's full chromatogram for the 377th injection showing performance of the "previously retired" DB-HT Sim Dis
column for an extended hydrocarbon mixture up to C
100
. The front section of this chromatogram is shown in larger format
in Figure 5 (bottom).
Conclusions
The DB-HT Sim Dis column is the column of choice
for performing ASTM Method D6352, The Standard
Test Method for Boiling Range Distribution of
Petroleum Distillates in Boiling Range from 174 to
700 °C by GC.
References
1. D. C. Villalanti, D. Janson, and P. Colle,
“Hydrocarbon Characterization by High Tem-
perature Simulated Distillation (HTSD),” Distil-
lation Session, Distillation Column Design and
Operation-IV: Advances in Distillation Modeling
and Simulation, AIChE1 995 Spring National
Meeting, March 19–23, Institute of Chemical
Engineers, New York, 1995.
2. American Society for Testing and Materials,
100 Barr Harbor Drive, West Conshohocken, PA
19428-2959; http://www.astm.org
3. A. K. Vickers, Mitch Hastings, Dean Rood, and
Roy Lautamo, “An Improved Deactivation
Process for Metal Tubing Used in Capillary Gas
Chromatographic Columns,” Presented at the
Pittsburgh Conference and Exposition, New
Orleans, LA, March 5–10, 1995.
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