24
The Chemistry and Technology of Petroleum
tar, in waterproofing roofs and other structures, and to make electrodes. Wood tar pitch is a bright,
lustrous substance containing resin acids; it is used chiefly in the manufacture of plastics and insulating materials and in caulking seams. Pitch derived from fats, fatty acids, or fatty oils by distillation are usually soft substances containing polymers and decomposition products; they are used
chiefly in varnishes and paints and in floor coverings.
Pitch lake is the name that has been applied to large surface deposit of bitumen. Guanoco Lake
in Venezuela covers more than 1,100 acres (445 ha) and contains an estimated 35,000,000 bbl of
bitumen. It was used as a commercial source of asphalt from 1891 to 1935. Smaller deposits occur
commonly where Tertiary marine sediments outcrop on the surface; an example is the tar pits
at Rancho La Brea in Los Angeles (brea and tar have been used synonymously with bitumen).
Although most pitch lakes are fossils of formerly active seeps, some, such as Pitch Lake on the
island of Trinidad, continue to be supplied with fresh crude oil seeping from a subterranean source.
Pitch Lake covers 115 acres and contains an estimated 40,000,000 bbl of bitumen.
1.5.5 Coke
Coke is the solid carbonaceous material produced from petroleum during thermal processing. It is
often characterized by having a high carbon content (95%+ by weight) and a honeycomb type of
appearance. The color varies from gray to black, and the material is insoluble in organic solvents.
1.5.6 syntHetIC Crude oIl
Coal, oil shale, bitumen, and heavy oil can be upgraded through thermal decomposition by a variety of processes to produce a marketable and transportable product. These products vary in nature,
but the principal product is a hydrocarbon that resembles conventional crude oil: hence the use of
the terms synthetic crude oil and syncrude. The synthetic crude oil, although it may be produced
from one of the less conventional conversion processes, can actually be refined by the usual refinery
system.
By comparison, the unrefined synthetic crude oil from bitumen will generally resemble petroleum more closely than either the synthetic crude oil from coal or the synthetic crude oil from oil
shale. Unrefined synthetic crude oil from coal can be identified by a high content of phenolic compounds, whereas the unrefined synthetic crude oil from oil shale will contain high proportions of
nitrogen-containing compounds.
1.6 DERIVED MATERIALS
1.6.1 AsPHAltenes, CArBenes, And CArBoIds
All the petroleum-related materials mentioned in the preceding sections are capable of being separated into several fractions (Chapter 9) that are sufficiently distinct in character to warrant the application of individual names (Pfeiffer, 1950).
Treatment of petroleum, residua, heavy oil, or bitumen with a low-boiling liquid hydrocarbon
results in the separation of brown to black powdery materials known as asphaltenes (Figure 1.1).
The reagents for effecting this separation are n-pentane and n-heptane, although other low molecular weight liquid hydrocarbons have been used (Van Nes and van Westen, 1951; Mitchell and
Speight, 1973).
Asphaltenes separated from petroleum, residua, heavy oil, and bitumen dissolve readily in
benzene, carbon disulfide, chloroform, or other chlorinated hydrocarbon solvents. However, in
the case of the higher molecular weight native materials or petroleum residua that have been
heated intensively or for prolonged periods, the n-pentane-insoluble for n-heptane-insoluble
fraction may not dissolve completely in the aforementioned solvents. Definition of the asphaltene
The Chemistry and Technology of Petroleum
tar, in waterproofing roofs and other structures, and to make electrodes. Wood tar pitch is a bright,
lustrous substance containing resin acids; it is used chiefly in the manufacture of plastics and insulating materials and in caulking seams. Pitch derived from fats, fatty acids, or fatty oils by distillation are usually soft substances containing polymers and decomposition products; they are used
chiefly in varnishes and paints and in floor coverings.
Pitch lake is the name that has been applied to large surface deposit of bitumen. Guanoco Lake
in Venezuela covers more than 1,100 acres (445 ha) and contains an estimated 35,000,000 bbl of
bitumen. It was used as a commercial source of asphalt from 1891 to 1935. Smaller deposits occur
commonly where Tertiary marine sediments outcrop on the surface; an example is the tar pits
at Rancho La Brea in Los Angeles (brea and tar have been used synonymously with bitumen).
Although most pitch lakes are fossils of formerly active seeps, some, such as Pitch Lake on the
island of Trinidad, continue to be supplied with fresh crude oil seeping from a subterranean source.
Pitch Lake covers 115 acres and contains an estimated 40,000,000 bbl of bitumen.
1.5.5 Coke
Coke is the solid carbonaceous material produced from petroleum during thermal processing. It is
often characterized by having a high carbon content (95%+ by weight) and a honeycomb type of
appearance. The color varies from gray to black, and the material is insoluble in organic solvents.
1.5.6 syntHetIC Crude oIl
Coal, oil shale, bitumen, and heavy oil can be upgraded through thermal decomposition by a variety of processes to produce a marketable and transportable product. These products vary in nature,
but the principal product is a hydrocarbon that resembles conventional crude oil: hence the use of
the terms synthetic crude oil and syncrude. The synthetic crude oil, although it may be produced
from one of the less conventional conversion processes, can actually be refined by the usual refinery
system.
By comparison, the unrefined synthetic crude oil from bitumen will generally resemble petroleum more closely than either the synthetic crude oil from coal or the synthetic crude oil from oil
shale. Unrefined synthetic crude oil from coal can be identified by a high content of phenolic compounds, whereas the unrefined synthetic crude oil from oil shale will contain high proportions of
nitrogen-containing compounds.
1.6 DERIVED MATERIALS
1.6.1 AsPHAltenes, CArBenes, And CArBoIds
All the petroleum-related materials mentioned in the preceding sections are capable of being separated into several fractions (Chapter 9) that are sufficiently distinct in character to warrant the application of individual names (Pfeiffer, 1950).
Treatment of petroleum, residua, heavy oil, or bitumen with a low-boiling liquid hydrocarbon
results in the separation of brown to black powdery materials known as asphaltenes (Figure 1.1).
The reagents for effecting this separation are n-pentane and n-heptane, although other low molecular weight liquid hydrocarbons have been used (Van Nes and van Westen, 1951; Mitchell and
Speight, 1973).
Asphaltenes separated from petroleum, residua, heavy oil, and bitumen dissolve readily in
benzene, carbon disulfide, chloroform, or other chlorinated hydrocarbon solvents. However, in
the case of the higher molecular weight native materials or petroleum residua that have been
heated intensively or for prolonged periods, the n-pentane-insoluble for n-heptane-insoluble
fraction may not dissolve completely in the aforementioned solvents. Definition of the asphaltene