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Industry: petrochemical · EPR

Vanadium, radicals and catalyst deactivation

Vanadyl species in crude oils and asphaltenes, and radicals on catalysts and in coke precursors, studied directly on small samples.

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What it tells you

Metals and radicals in heavy oils

Crude oils and residues contain vanadium, much of it as vanadyl, which poisons catalysts in refining. The asphaltenes, the heaviest fraction, contain stable radicals. EPR (electron paramagnetic resonance) sees both, in the same measurement and on a small sample, as they are.

First-derivative EPR spectrum with eight lines from vanadyl species and one sharp line from a radical of the asphaltenes
EPR spectrum of a crude oil. Schematic illustration.
Typical samples

Where it is used

  • Crude oils, residues and asphaltenes
  • Catalysts before, during and after use
  • Coke and coke precursors
  • Lubricants, where the radical level can indicate the remaining life of the oil

Typical tasks are measuring the vanadyl content of feeds, following the build-up of vanadium and radicals on a catalyst, and understanding why a catalyst loses activity.

How it works

A pattern for the metal, a line for the radical

Vanadyl gives a pattern of eight lines, and the size of the pattern is the amount of vanadyl. The radicals of the asphaltenes give a single sharp line. The signals are compared with a calibration to give amounts. Followed over the life of a catalyst, the signals show how vanadium and coke accumulate while the activity falls.

Catalyst activity falling over time on stream while the vanadium and coke radical signals on the catalyst rise
Catalyst deactivation followed by EPR. Schematic illustration, not measured data.
Why EPR

What it adds

  • Sees vanadyl and radicals directly and selectively
  • A small sample is enough, and the measurement works on dark, viscous or solid samples
  • Links the loss of activity to what is on the catalyst
  • Benchtop instruments make it practical to run regularly in a process laboratory
Good to know

Points that matter in practice

  • Only the paramagnetic forms are seen. Other metals, such as nickel or iron, give different signals or none, so EPR is not a full elemental analysis
  • The amount is calibrated against a reference such as an element analysis of the same samples
  • The signal of the asphaltene radical depends on the temperature and on the history of the sample, so a defined pre-treatment is part of the method
  • Compare samples that were measured in the same way, with the same tube and position
How MSY Consulting helps

From your question to a routine method

Send or bring representative samples. MSY Consulting runs feasibility measurements, plans the calibration and the pre-treatment with you, and trains your team until the method is part of your routine.

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Contact

Let's talk about your application

Send an email describing your instrument and your application, and you will get a reply.

contact@msyconsulting.eu

MSY CONSULTING SAS · Wissembourg, France · LinkedIn