4 (part 2) Flashcards
What are the typical gasoline composition percentage of hydrocarbons?
8% alkanes
2-5% alkenes
25-40% isoalkanes
3-7% cycloalkanes
1-4% cycloalkenes
20-50% total aromatics (0.5-2.5% benzene)
The _____ indicates
the “knock resistance” of the
fuel.
octane number
The _____ is defined as the percentage by volume of iso-octane in a mixture of iso-octane and n-heptane that knocks with some intensity as the fuel is being tested.
research octane number (RON)
_____ is the process of transforming C7–C10 hydrocarbons (heavy naphtha) with low octane numbers to aromatics and iso-paraffins which have high octane numbers.
Catalytic reforming
What are the catalytic reforming reactions?
• Naphthene Dehydrogenation of Cyclohexanes
• Paraffin Dehydrogenation
• Dehydrocyclization
_____ is the process in which light straight chain paraffins of low RON (C6, C5 and C4) are transformed with proper catalyst into branched chains with the same carbon number and high-octane numbers.
Isomerization
Two types of isomerization catalysts:
• the standard Pt/chlorinated alumina
with high chlorine content, which is considered quite active
• the Pt/zeolite catalyst
Among the two types of isomerization catalysts, which one has the high chlorine content and which is considered quite active?
Pt/chlorinated alumina
_____ is the name given to breaking up large hydrocarbon molecules into smaller and more useful bits. This is achieved by using high pressures and temperatures without a catalyst, or lower temperatures and pressures in the presence of a catalyst.
Cracking
In _____, high temperatures (typically in the range of 450°C to 750°C) and pressures (up to about 70 atmospheres) are used to break the large hydrocarbons into smaller ones. Thermal cracking gives mixtures of products containing high proportions of hydrocarbons with double bonds -alkenes.
thermal cracking
_____ is a mild thermal cracking of vacuum or atmospheric residues to produce light products and 75–85% cracked material of lower viscosity that can be used as fuel oil.
Visbreaking
What are the two types of visbreakers?
• coil visbreaking (furnace)
• soak visbreaking (soak drum)
_____ is a type of thermal cracking in which the heat required to complete the coking reactions is supplied by a furnace, while coking itself takes place in drums operating continuously on a 24 h filling and 24 h emptying cycles.
The feed to the delayed coker can be any undesirable heavy stream containing high metal content
Delayed coking
_____, also known as petcoke or coke, is a solid byproduct of oil refining that is rich in carbon.
Petroleum coke
The _____ unit is the heart of the refinery and is where heavy low-value petroleum stream such as vacuum gas oil (VGO) is upgraded into higher value products, mainly gasoline and C3/C4 olefins, which can be used in the alkylation unit for production of ultraclean gasoline (C7–C8 alkylates).
fluidized catalytic cracking (FCC)
What are the three primary cracking?
• Olefins - smaller olefins
• Alkylaromatics - Dealkylation
• Alkylaromatics - Side chain cracking
Gasoline formed from primary cracking can undergo further secondary cracking, which is generally caused by hydrocarbon transfer mechanisms such as:
• isomerization
• cyclisation
• coke formation
