ASTM D5187-91(2002)
(Test Method)Standard Test Method for Determination of Crystallite Size (Lc) of Calcined Petroleum Coke by X-Ray Diffraction
Standard Test Method for Determination of Crystallite Size (L<sub>c</sub>) of Calcined Petroleum Coke by X-Ray Diffraction
SCOPE
1.1 This test method covers the determination of the mean crystallite thickness of a representative, pulverized sample of calcined petroleum coke by interpretation of a X-ray diffraction pattern produced through conventional X-ray scanning techniques.
1.2 Calcined petroleum coke contains crystallites of different thicknesses. This test method covers the determination of the average thickness of all crystallites in the sample by empirical interpretation of the X-ray diffraction pattern. The crystallite diameter ( La) is not determined by this test method.
1.3 The values stated in SI (metric) units are to be regarded as the standard. The inch-pound units given in parentheses are provided for information purposes only.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
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Standards Content (Sample)
Designation: D 5187 – 91 (Reapproved 2002)
Standard Test Method for
Determination of Crystallite Size (L of Calcined Petroleum
c
Coke by X-Ray Diffraction
This standard is issued under the fixed designation D 5187; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope sample. It is expressed as a linear dimension in angstrom units,
−1
˚
A (10 nm).
1.1 This test method covers the determination of the mean
3.1.3 hkl(002)—the Miller indices of the crystalline planes
crystallite thickness of a representative, pulverized sample of
of graphite corresponding to a lattice spacing (d) of 3.35 Å.
calcined petroleum coke by interpretation of a X-ray diffraction
3.1.4 Q—the glancing angle produced when a parallel beam
pattern produced through conventional X-ray scanning tech-
of uniform X-rays impinges upon a crystalline lattice. This
niques.
angle is measured by the X-ray goniometer and is usually
1.2 Calcined petroleum coke contains crystallites of differ-
expressed in ° 2Q.
ent thicknesses. This test method covers the determination of
the average thickness of all crystallites in the sample by
4. Summary of Test Method
empirical interpretation of the X-ray diffraction pattern. The
4.1 A packed sample pulverized to less than 75 μm is
crystallite diameter (L ) is not determined by this test method.
a
subjected to a monochromatic X-ray beam and rotated to
1.3 The values stated in SI (metric) units are to be regarded
produce a diffraction pattern under specific conditions. The
as the standard. The inch-pound units given in parentheses are
˚
location and shape of the peak with hkl = (002) at d = 3.35; A
provided for information purposes only.
is used to calculate the L by manual interpretation of the peak
c
1.4 This standard does not purport to address all of the
or by computer simulation.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
5. Significance and Use
priate safety and health practices and determine the applica-
5.1 The crystallinity of petroleum coke, as reflected by the
bility of regulatory limitations prior to use.
L value, is a general measure of quality affecting suitability for
c
end use and is a function of the heat treatment.
2. Referenced Documents
5.2 The crystallite thickness is used to determine the extent
2.1 ASTM Standards:
of such heat treatment, for example, during calcination. The
D 346 Practice for Collection and Preparation of Coke
value of the L determined is not affected by coke microporos-
c
Samples for Laboratory Analysis
2 ity or the presence of foreign, non-crystalline materials such as
D 2013 Method for Preparing Coal Samples for Analysis
dedust oil.
D 2234 Test Methods for Collection of a Gross Sample of
Coal
6. Apparatus
D 4057 Practice for Manual Sampling of Petroleum and
6.1 X-Ray Powder Diffractometer, equipped with an X-ray
Petroleum Products
source, a monochromator or filter for restricting the wave-
length range, a sample holder, a radiation detector, a signal
3. Terminology
processor, and readout (chart or computer memory). The
3.1 Definitions of Terms Specific to This Standard:
diffractometer must be capable of rate scanning at 1° per
3.1.1 crystallites—stacks of graphitic carbon platelets lo-
minute or incrementally step scanning at 0.2° per step.
cated parallel to one another.
6.2 Sample Holders, as specified by the manufacturer of the
3.1.2 L —the mean or average thickness of crystallites in a
c
diffractometer that enables packing of a pulverized sample of
sufficient thickness to expose a level, smooth surface to the
X-ray beam.
6.3 Briquetting Press, capable of generating pressures up to
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products and Lubricantsand is the direct responsibility of Subcommittee
10 000 psi (69 MPa).
D02.05.0Don Petroleum Coke Sampling and Procedures.
6.4 Compressible Aluminum Caps, used as a support for
Current edition approved Oct. 15, 1991. Published December 1991.
2 producing a briquetted sample.
Annual Book of ASTM Standards, Vol 05.05.
6.5 Silicon or Quartz Sample, available from National
Annual Book of ASTM Standards, Vol 05.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 5187
Institute of Standards and Technology (NIST). Standards to prepare standard powder diffraction patterns.
Clamp a glass slide over the top face to form a temporary
7. Reagents and Materials
cavity wall. With the holder in a vertical position, drift the
7.1 Purity of Reagents—Reagent grade chemicals shall be
powdered sample into the end opening. If necessary, use a
used in all tests. It is intended that all reagents shall conform to
cardboard pusher cut to fit the cavity to lightly compress the
the specifications of the Committee on Analytical Reagents of
sample so it will remain in the cavity. Return the holder to a
the American Chemical Society where such specifications are
horizontal position and carefully remove the glass slide. Place
available. Other grades may be used, provided it is first
the sample in diffractometer holder.
ascertained that the reagent is of sufficiently high purity to
8.5.4 Briquetting Technique—Weigh out 4.0 g of the sample
permit its use without lessening the accuracy of the determi-
onto a watch glass and pipette exactly 3 mL of the binding
nation.
agent onto the sample and mix thoroughly with a spatula. Place
7.2 Acetone.
the sample under an infrared heat lamp and allow the acetone
7.3 Polyethylene Glycol, (approximate molecular weight of
to evaporate. Typically, about 1 or 2 min will be required to
200).
eliminate the acetone odor from sample. Break up the caked
7.4 Binding Agent—Prepare a 15 mass % solution of
sample with a spatula and transfer to an aluminum cap whose
polyethylene glycol and acetone by adding 15 g of polyethyl-
diameter is compatible with the sample holder of the diffrac-
ene glycol to 85 g of acetone.
tometer. Place the cap in a briquetting press and press at
7000 psi (48 MPa). Transfer the pelletized sample to the
8. Sample Preparation
sample holder and insert into the diffractometer for analysis.
8.1 For recommended practices for obtaining, handling and
preparing coke samples, refer to Test Methods D 2013 and
9. Calibration
D 2234 and Practices D 346 and D 4057. The equipment and
9.1 Calibration consists of ensuring that the diffractometer
procedures for crushing and dividing are also described in
is in correct mechanical and optical alignment and intensities
these test methods.
have been maximized through the procedures described in the
8.2 Reduce and divide the gross sample to obtain a labora-
instrument manufacturer’s documentation. This is best accom-
tory analysis sample.
plished by a service engineer or in-house technician who has
8.3 Divide, by riffling, a minimum of 100 g from the
been well instructed in the correct alignment procedures
laboratory analysis sample.
suggested by the manufacturer.
8.4 Crush 100 g of the test sample such that 98 % will pass
9.2 Proper angles and intensities are monitored by a refer-
through a 75 μm (No. 200) sieve.
ence material such as NIST
...
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