Application Note
AN #: 04_013_11_003
Market: Industrial
Subcategory: Petrochemical
Product: HI902C, HI5110B, HI5311,
HI7072L
Determination of Organic Chlorine in Crude
Oil with the HI902C Potentiometric Titration
System According to ASTM D4929
Description
Crude oil is a term for unrefined petroleum, a
naturally occurring liquid found in geological
formations beneath the earth’s surface.
Crude oil can be refined into several valuable
types of fuel including petrol, jet, and diesel
fuels. Crude oil is ideal for the production
of these high-energy fuels, as it contains
a large quantity of hydrocarbons. The
combustion of these hydrocarbons with
oxygen produce the energy needed to operate
boilers, engines and other machinery.
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While crude oil contains high amounts of
hydrocarbons, it also contains water, chloride
salts and other impurities. A desalting process
can remove many of the impurities. This process
involves the addition of water to dissolve the
salts and other impurities from the crude oil
feedstock. The mixture is then separated;
the water goes to an industrial wastewater
treatment facility and the refined petroleum is
developed into different petroleum products.
The desalting process removes the majority
of chloride salts, which if present in the oil
at high temperatures can form hydrochloric
acid. The hydrochloric acid formed can
readily corrode equipment throughout the
refining process. As a result, the desalting
process is crucial to crude oil refining.
Organic chlorides are compounds which
contain a carbon-chlorine bond. Examples
of these compounds include chloroform and
chlorobenzene. Organic chlorides present
a more significant problem in crude oil
refineries as compared to inorganic chlorides
since they are not removed through the
desalting process. While these compounds
are generally not present naturally, the oil
can be adulterated when additives, cleaning
solutions or chemicals for oil recovery are
used. As a result, refineries typically do not
accept crude oil that contains more than 5
parts per million (µg/g) of organic chloride.
Organic chlorides are determined through
potentiometric titration per Standard Method
ASTM D4929. This method utilizes a sodium
biphenyl reduction of the organic chlorides to
yield inorganic chlorides. The chlorides are then
extracted from the petroleum sample into an
aqueous phase and titrated with silver nitrate.
Application
An oil refinery contacted Hanna to determine the
organic chloride content of incoming crude oil.
AN #: 04_013_11_003
Application Note continued
Market: Industrial
Subcategory: Crude Oil
Product: HI902C, HI5110B, HI5311,
HI7072L
The customer required that the titrator
conformed specifically to the specifications
outlined in the their standard operating
procedure, based on ASTM D4929. Hanna
offered the HI902C Potentiometric Titration
System. In order to accommodate the standard
method, the 5mL burette was supplied in
place of the 25mL burette. The HI5110B
ORP Half Cell for Argentometric Titration and
HI5311 Reference Electrode with HI7072L
KNO₃ reference electrolyte were used since
the method specified a silver billet-type halfcell electrode and reference electrode. The
customer appreciated the support offered by
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Hanna Instruments to ensure that all materials
would be supplied for their titration to take
place. Although the titrator was supplied with
only one burette, the customer was considering
expanding their testing to include methods
such as acid number (AN), so the option for a
second pump and burette to be attached was
appreciated. The customer also appreciated
the potential for an autosampler expansion
on the titrator in the event that their in-house
testing needs grew. Overall, the HI902C
provided a comprehensive solution to the
customer’s current and future testing needs.