Processes Not So Common to Energy Refineries
Octane Enhancement Processes
The octane enhancement processes detailed in this book are the alkylation process
and the isomerization process. These processes are usually proprietary and are
provided to refiners under license.
The alkylation process treated here is the HF process which uses hydrogen
fluoride as the catalyst which is used to convert unsaturated C 4 s and iC 4 to highoctane alkylate. The unit’s recovery side is the aspect dealt with in some detail
together with a descriptive item on the safe handling of hydrogen fluoride. An
alternative alkylation process uses sulfuric acid, H 2 SO 4 , instead of HF.
The isomerization process has a similar configuration to the catalytic reformer
plant. This process uses hydrogen in its conversion of low-octane hydrocarbons to
higher-octane isomers.
Both these processes are described and discussed in detail in the chapters on
“▶ Alkylation in Petroleum Processing” and “▶ Isomerization in Petroleum
Processing.”
Oxygenated Gasolines
The concentration of vehicles on the roads in most of the cities in the modern world
has increased dramatically over the last two decades. The emission of pollutants
from these vehicles is causing a significant addition to the already critical problem
of atmospheric pollution. The problem is now so acute that governments of most
developed countries are seeking legislation to curb and minimize this pollution and
most countries will see further implementation of “Clean Air” acts.
Petroleum refining companies have been working diligently for many years to
satisfy the requirements of “Clean Air” legislation already in place. This began in
the 1970s with the elimination of tetraethyl lead from most gasoline applications.
Processes such as isomerization and polymerization of refinery streams were
developed together with a surge in the use of the alkylation process. However,
the further decrease of pollutants now requires a move away from the traditional
gasoline octane enhancers such as the aromatics and the olefins.
Catalytic reforming produces gasoline streams to meet octane requirements
mainly by converting cycloparaffin to light aromatics. Fluid catalytic cracking
also produces gasoline blending stocks by cracking paraffins to light olefins and
the products from these two processes still make up the bulk of a refinery’s gasoline
pool. Unfortunately the aromatics are “dirty compounds” because they produce a
sooty exhaust emission – unacceptable in meeting the “Clean Air” requirements
and the aromatics are considered “toxics”. Considerable work has been done with
alcohol to take the place of aromatics and as octane enhancers and meeting other
Introduction to Crude Oil and Petroleum Processing
41
Octane Enhancement Processes
The octane enhancement processes detailed in this book are the alkylation process
and the isomerization process. These processes are usually proprietary and are
provided to refiners under license.
The alkylation process treated here is the HF process which uses hydrogen
fluoride as the catalyst which is used to convert unsaturated C 4 s and iC 4 to highoctane alkylate. The unit’s recovery side is the aspect dealt with in some detail
together with a descriptive item on the safe handling of hydrogen fluoride. An
alternative alkylation process uses sulfuric acid, H 2 SO 4 , instead of HF.
The isomerization process has a similar configuration to the catalytic reformer
plant. This process uses hydrogen in its conversion of low-octane hydrocarbons to
higher-octane isomers.
Both these processes are described and discussed in detail in the chapters on
“▶ Alkylation in Petroleum Processing” and “▶ Isomerization in Petroleum
Processing.”
Oxygenated Gasolines
The concentration of vehicles on the roads in most of the cities in the modern world
has increased dramatically over the last two decades. The emission of pollutants
from these vehicles is causing a significant addition to the already critical problem
of atmospheric pollution. The problem is now so acute that governments of most
developed countries are seeking legislation to curb and minimize this pollution and
most countries will see further implementation of “Clean Air” acts.
Petroleum refining companies have been working diligently for many years to
satisfy the requirements of “Clean Air” legislation already in place. This began in
the 1970s with the elimination of tetraethyl lead from most gasoline applications.
Processes such as isomerization and polymerization of refinery streams were
developed together with a surge in the use of the alkylation process. However,
the further decrease of pollutants now requires a move away from the traditional
gasoline octane enhancers such as the aromatics and the olefins.
Catalytic reforming produces gasoline streams to meet octane requirements
mainly by converting cycloparaffin to light aromatics. Fluid catalytic cracking
also produces gasoline blending stocks by cracking paraffins to light olefins and
the products from these two processes still make up the bulk of a refinery’s gasoline
pool. Unfortunately the aromatics are “dirty compounds” because they produce a
sooty exhaust emission – unacceptable in meeting the “Clean Air” requirements
and the aromatics are considered “toxics”. Considerable work has been done with
alcohol to take the place of aromatics and as octane enhancers and meeting other
Introduction to Crude Oil and Petroleum Processing
41