Lesson 1, Topic 1
In Progress


Abdulaziz July 8, 2020

// Non-Hydrocarbon

  • 1. Non HC
    • High level of organic sulfur and organic nitrogen can cause pollution
    • Oxidation product of sulfur and nitrogen are corrosive in nature
  • 2. Sulfur
    • Two groups of sulfur:
      • Organosulfur
      • Inorganic sulfur- hydrogen sulfide; H2S harmful and corrosive
    • Two class of organosulfur:
      • acidic  – thiols (mercaptans)
      • Non-acidic:
        • thiophene
        • sulfides
        • disulfides
    • Sour crude:
      • Contain high % of H2S
      • Many organic sulfur compounds are not thermally stable, hydrogen sulfide
      • is often produced during crude processing.
      • High-sulfur crudes are less desirable because treating the different refinery streams for acidic hydrogen sulfide increases production costs.
      • Q: How can these sulfur compounds be removed from petroleum streams?
graph of desnity and sulfur content of selected crude oils, as explained in the article text
Changing quality mix is affecting crude oil price differentials and refining decisions
  • 3. Nitrogen
    • Simple heterocyclic form
      • pyridine ; C5H5N
      • pyrrole; C4H5N
    • Complex stucture – porphyrin
    • Nitrogen content in most crudes is very low and does not exceed 0.1 wt%.
    • In some heavy crudes, however, the nitrogen content may reach up to 0.9 wt %.
    • more thermally stable than sulfur compounds
    • Concentrated in heavier petroleum fractions and residues.
    • Light petroleum streams may contain trace amounts of nitrogen compounds, which should be removed because they poison many processing catalysts.
    • Classified into two groups:
      • Basic nitrogen compounds -mainly those having a pyridine ring,
      • Non-basic nitrogen compounds – have a pyrrole structure.
    • Both pyridine and pyrrole are stable compounds due to their aromatic nature.
  • 4. Oxygen
    • more complex than the sulfur types.
    • However, their presence in petroleum streams is not poisonous to processing catalysts.
    • Two groups of oxygen compound in CO;
      • Weakly acidic
      • Non acidic – Many of the oxygen compounds found in crude oils are weakly acidic.
    • Acidic oxygen compound
      • They are carboxylic acids, cresylic acid, phenol, and naphthenic acid.
      • Naphthenic acids are mainly cyclopentane and cyclohexane derivatives having a carboxyalkyl side chain.
      • Naphthenic acids in the naphtha fraction have a special commercial importance and can be extracted by using dilute caustic solutions.
      • The total acid content of most crudes is generally low, but may reach as much as 3%, as in some California crudes
    • Non-acidic oxygen compound
      • less abundant compared to acidic compound
      • e.g. esters, ketones, and amides
      • no commercial value.