100
oxides, which react with acidic metal complexes and precipitate them in the form of
stable silicates or sulfates [40].
7 Propylene Maximization
The world’s automotive fuel demand has been experiencing a slow decline along the
recent years. With the emergence of efficient engines, sustainable alternate energy
sources, and migration to electric power and fuel cells, it is predicted that the automotive fuel market will decline sharply in the coming years. At the same time, the
consumption of oil for petrochemical manufacture will soon overtake that of automotive fuels according to a study by IEA [11]. By 2030, petrochemicals will contribute to more than a third in the world’s oil demand. The key driver behind this is
the ever-increasing demand for plastics and fertilizer, which has overtaken the
requirement of other bulk materials like steel, aluminum, and cement. Hence, refiners are gradually shifting their priorities toward manufacturing raw materials for
petrochemical synthesis.
C2/C3 olefins are the most significant contributors to petrochemical synthesis,
and their demand has increased in the recent 10 years [12]. Steam or naphtha cracking is still the major provider of ethylene and propylene, contributing more than
70% of the world’s supply. The FCC unit produces an average 5 wt% propylene on
a fresh feed basis, but efforts are being made to increase this quantity and propylene
recovery units are installed to obtain propylene of high purity for polymer manufacture. Existing FCC units can be optimized to obtain a higher propylene yield (15 wt
%), or a dedicated cracking unit developed on the principles of the FCC unit can be
commissioned to obtain high amounts of propylene (20 wt%) [13].
7.1 Operational Modifications for Propylene Manufacture
In an FCC unit, hydrocarbon feeds (VGO), when subjected to cracking conditions
for a long residence time, end up as dry gas or coke. Propylene is an intermediate
compound, which is formed during carbenium ion cracking of gasoline range olefins as discussed earlier. However, among the secondary reactions such as hydrogen
transfer, isomerization, oligomerization, and aromatization reactions, hydrogen
transfer, in particular, depletes most of the light olefins formed by cracking. The
degree of hydrogen transfer can be tracked using hydrogen transfer index (HTI)
(Figs. 22 and 23) [27].
HTI i C yield total C in LPG
= - 4
4
/
.
A. R. Khande et al.
oxides, which react with acidic metal complexes and precipitate them in the form of
stable silicates or sulfates [40].
7 Propylene Maximization
The world’s automotive fuel demand has been experiencing a slow decline along the
recent years. With the emergence of efficient engines, sustainable alternate energy
sources, and migration to electric power and fuel cells, it is predicted that the automotive fuel market will decline sharply in the coming years. At the same time, the
consumption of oil for petrochemical manufacture will soon overtake that of automotive fuels according to a study by IEA [11]. By 2030, petrochemicals will contribute to more than a third in the world’s oil demand. The key driver behind this is
the ever-increasing demand for plastics and fertilizer, which has overtaken the
requirement of other bulk materials like steel, aluminum, and cement. Hence, refiners are gradually shifting their priorities toward manufacturing raw materials for
petrochemical synthesis.
C2/C3 olefins are the most significant contributors to petrochemical synthesis,
and their demand has increased in the recent 10 years [12]. Steam or naphtha cracking is still the major provider of ethylene and propylene, contributing more than
70% of the world’s supply. The FCC unit produces an average 5 wt% propylene on
a fresh feed basis, but efforts are being made to increase this quantity and propylene
recovery units are installed to obtain propylene of high purity for polymer manufacture. Existing FCC units can be optimized to obtain a higher propylene yield (15 wt
%), or a dedicated cracking unit developed on the principles of the FCC unit can be
commissioned to obtain high amounts of propylene (20 wt%) [13].
7.1 Operational Modifications for Propylene Manufacture
In an FCC unit, hydrocarbon feeds (VGO), when subjected to cracking conditions
for a long residence time, end up as dry gas or coke. Propylene is an intermediate
compound, which is formed during carbenium ion cracking of gasoline range olefins as discussed earlier. However, among the secondary reactions such as hydrogen
transfer, isomerization, oligomerization, and aromatization reactions, hydrogen
transfer, in particular, depletes most of the light olefins formed by cracking. The
degree of hydrogen transfer can be tracked using hydrogen transfer index (HTI)
(Figs. 22 and 23) [27].
HTI i C yield total C in LPG
= - 4
4
/
.
A. R. Khande et al.