Bromine Number of Petroleum Distillates
The bromine number is a measure of olefins in a petroleum distillate boiling up to
600
F. The number is a supporting evidence of the purity of the product with
respect to its olefin content.
ASTM D1159
The apparatus used in this test is any apparatus that can perform titration to a preset
end point. Such an apparatus may include an electrical meter with two polarized
electrodes of sufficient voltage to indicate the end point. The titration vessel is a
jacketed glass vessel about 120 mm high and with 45 mm internal diameter. The
sample contained in the vessel will be kept at 32–45
F. The burette will be a
normal titration burette capable of measuring the titration reagent in graduations of
0.05 ml or smaller. Place 10 ml of 1,1,1-trichloroethane or dichloromethane in the
titration vessel, and introduce the test specimen as indicated in Table 17.
Fill the titration vessel to the mark with the selected solvent. Mix the contents
well. Titrate the sample with the standard bromine–bromate solution – stir the
specimen well during the titration. The end point is noted by a sudden change in
potential on an electrometric end point indicator due to the presence of bromine.
The bromine number is calculated by the following equation
Bromine number ¼
A À B
ð
Þ M 1
ð Þ 15:98
ð
Þ
W
where
A = milliliters of bromide–bromate solution required for titration of the test sample
B = milliliters of bromide–bromate solution required for titration of the blank
M 1 = molarity of the bromide–bromate solution, as Br 2
W = grams of the test specimen
The olefin content of the test sample can be calculated from the bromine number
by the equation
Olefin mass % ¼ f BM=160
ð
Þ
where
Table 17 Weight of test
specimen vs. predicted
bromine number
Predicted bromine number
Specimen weight, grams
0–10
20–16
Over 10–20
10–8
Over 20–50
5–4
Over 50–100
2–1.5
Over 100–150
1–0.8
Over 150–200
0.8–0.6
678
D.S.J. Jones
The bromine number is a measure of olefins in a petroleum distillate boiling up to
600
F. The number is a supporting evidence of the purity of the product with
respect to its olefin content.
ASTM D1159
The apparatus used in this test is any apparatus that can perform titration to a preset
end point. Such an apparatus may include an electrical meter with two polarized
electrodes of sufficient voltage to indicate the end point. The titration vessel is a
jacketed glass vessel about 120 mm high and with 45 mm internal diameter. The
sample contained in the vessel will be kept at 32–45
F. The burette will be a
normal titration burette capable of measuring the titration reagent in graduations of
0.05 ml or smaller. Place 10 ml of 1,1,1-trichloroethane or dichloromethane in the
titration vessel, and introduce the test specimen as indicated in Table 17.
Fill the titration vessel to the mark with the selected solvent. Mix the contents
well. Titrate the sample with the standard bromine–bromate solution – stir the
specimen well during the titration. The end point is noted by a sudden change in
potential on an electrometric end point indicator due to the presence of bromine.
The bromine number is calculated by the following equation
Bromine number ¼
A À B
ð
Þ M 1
ð Þ 15:98
ð
Þ
W
where
A = milliliters of bromide–bromate solution required for titration of the test sample
B = milliliters of bromide–bromate solution required for titration of the blank
M 1 = molarity of the bromide–bromate solution, as Br 2
W = grams of the test specimen
The olefin content of the test sample can be calculated from the bromine number
by the equation
Olefin mass % ¼ f BM=160
ð
Þ
where
Table 17 Weight of test
specimen vs. predicted
bromine number
Predicted bromine number
Specimen weight, grams
0–10
20–16
Over 10–20
10–8
Over 20–50
5–4
Over 50–100
2–1.5
Over 100–150
1–0.8
Over 150–200
0.8–0.6
678
D.S.J. Jones