Determination of Hydrogen Content in Hydrocarbons Using minispec NMR Method

Hydrogenation is a process used for refining vegetable oils and hydrocarbons. Hydrogen consumption presents a significant cost issue in a refinery, whereas percentage hydrogen content serves as a key indicator of refining progress. One major specification that needs to be met for diesel and jet fuel is hydrogen content at the endpoint.

In order to keep hydrogen consumption as low as possible and also to demon­strate compliance to official specifications, a reliable and accurate analytical method is definitely needed. The minispec NMR is one such method that is developed to meet speed, precision and accuracy requirements for process control. The instrument features a robust design, requiring minimal service. The minispec can be easily operated and does not call for skilled personnel.

Other reasons for hydrogen content analysis

  • Higher hydrogen content means better petrol combustion and higher quality
  • Thermal radiation, exhaust smoke and soot deposits increase with decreasing hydrogen content

ASTM* D 7171 is an International Standard Method based on Pulsed TD-NMR

Hydrogen content by TD-NMR

  • QA/QC measurement
  • Fast, non-destructive, solvent free
  • Simple calibration using a few number of commercially available compounds
  • All Official International Standard Methods supported (ASTM D 3701, ASTM D 7171 and ASTM D 4808)
  • Minimum sample preparation
  • Excellent reproducibility
  • High return on investment
  • Dedicated analyzer with perfectly adapted software

*ASTM: American Society for Testing and Materials

According to ASTM pure hydrocarbons can be used for instrument calibration.

According to ASTM pure hydrocarbons can be used for instrument calibration.

minispec Calibration

There are two viable calibration methods:

  • With reference values and samples as supplied by the user
  • With pure hydrocarbons − like dodecane − as available from chemical suppliers

Sample Handling and Tube Sizes

This method typically uses two tube sizes: either 40 mm or 18 mm diameter tubes. PTFE plugs with rod are also provided which prevent sample evaporation. Metal block thermostats are largely used for sample pre-tempering, because they only require electricity – even for permanent operation.

Typical measurement time

Strong NMR signals are exhibited by the samples, allowing a good signal to noise ratio and leading to a short measurement time of just one minute.

Further applications of minispec in petrochemical industry

  • Total hydrogen content in coal
  • Oil content determination in oil shale and oil sands
  • Oil content determination in paraffin/wax
  • Relaxation time analysis on rock cores
  • Viscosity determinations of oils

All types of hydrocarbons can be examined, from light distillates up to residua, gas oils as well as aviation turbine fuels

All types of hydrocarbons can be examined, from light distillates up to residua, gas oils as well as aviation turbine fuels

International Methods

The International Standard methods propose calibration with pure hydrocarbons. The recent ASTM D 7171 method includes a list of proposed calibration substances with related hydrogen content values.

Percent Hydrogen Calculation

In addition, the compounds’ hydrogen content can be measured directly, since the chemical formula is well-recognized and the substance purity is extremely high.

List of International Methods

  • ASTM D 3701 (Aviation Turbine Fuels)
  • ASTM D 4808 (Light and Middle Distillates, Gas Oils and Residua)
  • ASTM D 7171 (released 2005, based on pulsed NMR) for Middle Distillate Petroleum Products

Using the pulsed NMR minispec instead of the origi­nal cw-NMR instruments can ful­fill and even exceed the ASTM methods D 4808 and D 3701. The pulsed NMR method is faster, more accurate and more sensitive, also allowing more applications.

Typical System Configuration(s): Jet fuel or Diesel (homogenous fractions/low viscosity liquids)

mq-one Hydrogen Analyzer

  • Dedicated to hydrogen content application
  • Sample diameter: 18 mm

minispec mq20

  • Hydrogen content application
  • Sample diameter: 18 mm
  • For more applications, see 'Further minispec Applications in Petro­chemical Industry'

Heavy Fractions/Distillates, (non-homogenous samples, viscose liquids and more)

minispec mq10

  • Hydrogen content application
  • Sample diameter: 40 mm
  • For more applications, see 'Further minispec Applications in Petro­chemical Industry'

Remark: For more heavy frac­tions, sometimes tempering and measuring the samples at a higher temperature is reasonable, like for instance at 50 °C. For this applica­tion, variable temperature probes are available.

The mq-one Analyzer Comes in a Package with

  • 18 mm Ø PTFE plugs
  • 18 mm Ø glass tubes
  • minispec Plus Software
  • Sample preparation block

minispec Plus Software for mq-one

  • Easy to use, multi-lingual and 21CFRPart11 compliant software
  • Pre-defined method for determination of hydro­gen content
  • User rights for administration (full access), calibration & mea­surement, and measurement only

About Bruker BioSpin - NMR, EPR and Imaging

Bruker BioSpin offers the world's most comprehensive range of NMR and EPR spectroscopy and preclinical MRI research tools. The Bruker BioSpin Group of companies develop, manufacture and supply technology to research establishments, commercial enterprises and multi-national corporations across countless industries and fields of expertise.

Bruker microCT formerly known as SkyScan develops and produces wide range of high-end microtomography instruments for life science, material research and in-vivo preclinical studies.

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Last updated: Mar 6, 2019 at 6:56 AM

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