Non Hydrocarbon Intermediates
INTRODUCTION
From natural gas, crude oils, and other fossil materials such as coal, few intermediates are produced that are not hydrocarbon compounds. The important intermediates discussed here are hydrogen, sulfur, carbon black, and synthesis gas.
Synthesis gas consists of a nonhydrocarbon mixture (H2,CO) obtain- able from more than one source. It is included in this chapter and is fur- ther noted in Chapter 5 in relation to methane as a major feedstock for this mixture. This chapter discusses the use of synthesis gas obtained from coal gasification and from different petroleum sources for produc- ing gaseous as well as liquid hydrocarbons (Fischer Tropsch synthesis).
Naphthenic acids and cresylic acid, which are extracted from certain crude oil fractions, are briefly reviewed at the end of the chapter.
HYDROGEN
Hydrogen is the lightest known element. Although only found in the free state in trace amounts, it is the most abundant element in the uni- verse and is present in a combined form with other elements. Water, nat- ural gas, crude oils, hydrocarbons, and other organic fossil materials are major sources of hydrogen.
Hydrogen has been of great use to theoretical investigation. The struc- ture of the atom developed by Bohr (Nobel Prize Winner 1922) was based on a model of the hydrogen atom. Chemically, hydrogen is a very reactive element. Obtaining hydrogen from its compounds is an energy- extensive process. To decompose water into hydrogen and oxygen, an energy input equal to an enthalpy change of +286 KJ/mol is required1:
111
H2O r H2 + 1/2O2 ∆H = +286 KJ/mol
Electrolysis, and thermochemical and photochemical decomposition of water followed by purification through diffusion methods are expensive processes to produce hydrogen.
The most economical way to produce hydrogen is by steam reforming petroleum fractions and natural gas (Figure 4-1).2 In this process, two major sources of hydrogen (water and hydrocarbons)
From natural gas, crude oils, and other fossil materials such as coal, few intermediates are produced that are not hydrocarbon compounds. The important intermediates discussed here are hydrogen, sulfur, carbon black, and synthesis gas.
Synthesis gas consists of a nonhydrocarbon mixture (H2,CO) obtain- able from more than one source. It is included in this chapter and is fur- ther noted in Chapter 5 in relation to methane as a major feedstock for this mixture. This chapter discusses the use of synthesis gas obtained from coal gasification and from different petroleum sources for produc- ing gaseous as well as liquid hydrocarbons (Fischer Tropsch synthesis).
Naphthenic acids and cresylic acid, which are extracted from certain crude oil fractions, are briefly reviewed at the end of the chapter.
HYDROGEN
Hydrogen is the lightest known element. Although only found in the free state in trace amounts, it is the most abundant element in the uni- verse and is present in a combined form with other elements. Water, nat- ural gas, crude oils, hydrocarbons, and other organic fossil materials are major sources of hydrogen.
Hydrogen has been of great use to theoretical investigation. The struc- ture of the atom developed by Bohr (Nobel Prize Winner 1922) was based on a model of the hydrogen atom. Chemically, hydrogen is a very reactive element. Obtaining hydrogen from its compounds is an energy- extensive process. To decompose water into hydrogen and oxygen, an energy input equal to an enthalpy change of +286 KJ/mol is required1:
111
H2O r H2 + 1/2O2 ∆H = +286 KJ/mol
Electrolysis, and thermochemical and photochemical decomposition of water followed by purification through diffusion methods are expensive processes to produce hydrogen.
The most economical way to produce hydrogen is by steam reforming petroleum fractions and natural gas (Figure 4-1).2 In this process, two major sources of hydrogen (water and hydrocarbons)