7.1 Industrial Preparation and Use of Alkenes
3 min read•may 7, 2024
Alkenes, like and , are crucial in the petrochemical industry. is the main method for producing these compounds, involving high-temperature reactions that break down larger hydrocarbons into smaller, unsaturated molecules.
The process is influenced by factors such as temperature, pressure, and feedstock composition. Ethylene and propylene serve as building blocks for various plastics, fibers, and chemicals, making them essential in manufacturing everyday products we rely on.
Industrial Preparation of Alkenes
Industrial preparation of ethylene and propylene
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The effect of supported MoO X structures on the reaction pathways of propene formation in the ... View original
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Simulation of a Process Plant for the Production of Propylene View original
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Solution copolymerization of ethylene and propylene by salicylaldiminato-derived [O-NS]TiCl 3 ... View original
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Top images from around the web for Industrial preparation of ethylene and propylene
The effect of supported MoO X structures on the reaction pathways of propene formation in the ... View original
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Simulation of a Process Plant for the Production of Propylene View original
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Solution copolymerization of ethylene and propylene by salicylaldiminato-derived [O-NS]TiCl 3 ... View original
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- Steam cracking primary industrial method for producing ethylene and propylene
- Heats saturated hydrocarbons ( or ethane) to high temperatures (750-950°C) in the presence of steam
- Occurs without oxygen to prevent combustion
- Reaction takes place in a with short residence time (0.1-0.5 seconds)
- Mechanism of steam cracking:
- Initial step: high temperature causes of C-C bonds in saturated hydrocarbons
- Highly reactive form
- Subsequent reactions: free radicals undergo , , and decomposition to form smaller unsaturated hydrocarbons (ethylene and propylene)
- Factors affecting product distribution in steam cracking:
- Feedstock composition impacts product mix
- (higher temperature and longer residence time) favors lighter products
- Higher pressure reduces ethylene and propylene yields
- Diluents (steam) lower partial pressure of hydrocarbons and improve selectivity
Other cracking methods
- : uses catalysts to break down larger hydrocarbons into smaller molecules at lower temperatures
- : uses heat and pressure to break down hydrocarbons without catalysts or steam
Importance of ethylene and propylene
- Ethylene and propylene key building blocks in petrochemical industry
- Ethylene most widely produced organic compound worldwide
- Manufactures (PE) plastics
- (HDPE) used for bottles, pipes, automotive fuel tanks
- (LDPE) used for plastic bags, packaging films, squeeze bottles
- Produces for antifreeze, polyester fibers, surfactants
- Produces for (PVC) plastics
- Produces for styrene monomer used in polystyrene plastics
- Manufactures (PE) plastics
- Propylene second most important petrochemical feedstock
- Produces (PP) for packaging materials, textiles, automotive parts
- Produces for polyurethane foams, propylene glycol
- Produces for acrylic fibers, ABS plastics
- Produces for phenol and acetone
- Ethylene and propylene are examples of , which are important in the production of various
Thermodynamics of steam cracking
- Steam cracking endothermic process
- Requires high temperatures (750-950°C) to overcome activation energy barrier
- Absorbs heat during breaking of C-C bonds in feedstock
- Entropy crucial in thermodynamics of steam cracking
- Cracking reactions increase number of molecules (one large hydrocarbon breaks into multiple smaller molecules)
- More molecules lead to higher entropy ()
- Gibbs free energy () determines spontaneity of steam cracking
- At high temperatures, term becomes more significant
- Positive entropy change () makes more negative, favoring spontaneity of cracking reactions
- Temperature effects on equilibrium of steam cracking reactions
- : higher temperatures shift equilibrium towards endothermic direction (products)
- Higher temperatures favor formation of lighter alkenes (ethylene and propylene) over heavier hydrocarbons
Feedstock and processing
- Various are used in alkene production, including naphtha and ethane
- is used to separate different components of crude oil before cracking processes
Key Terms to Review (28)
Acrylonitrile: Acrylonitrile is a colorless, volatile organic compound with the chemical formula CH2=CHCN. It is an important industrial chemical used in the production of various polymers and copolymers, finding applications in a wide range of industries.
Catalytic Cracking: Catalytic cracking is a crucial industrial process used to convert heavy hydrocarbon feedstocks, such as crude oil, into more valuable and lighter petroleum products like gasoline, diesel, and other fuels. This process utilizes a solid catalyst to break down larger, complex hydrocarbon molecules into smaller, more useful ones through the process of thermal decomposition.
Cracking Severity: Cracking severity refers to the degree of decomposition or fragmentation that occurs during the cracking process, a crucial step in the industrial preparation and use of alkenes. It measures the extent to which larger hydrocarbon molecules are broken down into smaller, more volatile components.
Cumene: Cumene, also known as isopropylbenzene, is an aromatic hydrocarbon compound with the chemical formula C₆H₅CH(CH₃)₂. It is an important industrial chemical used in the production of various compounds and materials.
Dehydrogenation: Dehydrogenation is a chemical reaction that involves the removal of hydrogen atoms from a molecule, typically resulting in the formation of a more unsaturated compound. This process is crucial in the industrial preparation and use of alkenes, as well as in calculating the degree of unsaturation of organic compounds.
Ethylbenzene: Ethylbenzene is an aromatic hydrocarbon compound with the chemical formula C6H5CH2CH3. It is a colorless, flammable liquid with a distinctive petrol-like odor. Ethylbenzene is an important industrial chemical with applications in the production of other organic compounds and the synthesis of various materials.
Ethylene: Ethylene is a colorless, flammable gas with the chemical formula C₂H₄. It is the simplest alkene and is widely used in the chemical industry for the production of various organic compounds and polymers. Ethylene is a key term that connects to several important topics in organic chemistry, including the structure of alkenes, chemical bonding, and industrial applications.
Ethylene Dichloride: Ethylene dichloride, also known as 1,2-dichloroethane, is a colorless, volatile liquid chemical compound widely used in industrial processes. It is a key intermediate in the production of vinyl chloride, which is then polymerized to make polyvinyl chloride (PVC) plastic.
Ethylene Oxide: Ethylene oxide is a colorless, flammable gas that is widely used in industrial and medical applications. It is a cyclic ether with the chemical formula C₂H₄O, and it serves as a key intermediate in the production of various chemicals and materials.
Fractional Distillation: Fractional distillation is a separation technique used to purify and isolate different components from a complex mixture, such as crude oil, by taking advantage of their varying boiling points. It is a crucial process in the industrial preparation and use of alkenes.
Free Radicals: Free radicals are highly reactive chemical species that possess one or more unpaired electrons in their outer shell. These unstable molecules are capable of initiating chain reactions and can have significant impacts on various chemical processes, including those encountered in organic chemistry.
High-Density Polyethylene: High-density polyethylene (HDPE) is a type of polyethylene plastic characterized by its high density, strength, and durability. It is widely used in various industrial and consumer applications due to its unique properties and versatility.
Homolytic Cleavage: Homolytic cleavage refers to the breaking of a covalent bond in a molecule in a way that results in the formation of two neutral radical species, each retaining one of the shared electrons from the original bond. This process is a key feature in radical reactions and is central to understanding the industrial preparation and use of alkenes, as well as the preparation of alkyl halides from both alkanes and alkenes.
Hydrocarbon Feedstocks: Hydrocarbon feedstocks are the raw materials, typically derived from fossil fuels, that are used as the primary input for various industrial processes and chemical productions. They serve as the fundamental building blocks for the synthesis of a wide range of organic compounds and fuels.
Isomerization: Isomerization is a chemical process in which a molecule is transformed into one or more structural isomers - compounds with the same molecular formula but different arrangements of atoms in space. This rearrangement can result in changes to the physical and chemical properties of the substance.
Le Chatelier's Principle: Le Chatelier's principle states that when a system at equilibrium is subjected to a change in one of the factors (concentration, temperature, or pressure) determining the equilibrium, the system will shift to counteract the change and establish a new equilibrium. This principle helps predict the direction of a system's response to disturbances.
Low-Density Polyethylene: Low-density polyethylene (LDPE) is a type of thermoplastic polymer derived from the polymerization of ethylene. It is a versatile material widely used in various industrial and consumer applications due to its unique properties and cost-effectiveness.
Naphtha: Naphtha is a volatile, flammable liquid hydrocarbon mixture derived from the distillation of crude oil. It is a key component in the industrial preparation and use of alkenes, which are unsaturated hydrocarbons with carbon-carbon double bonds.
Olefins: Olefins, also known as alkenes, are a class of unsaturated hydrocarbons containing at least one carbon-carbon double bond. They are an important group of organic compounds with diverse industrial applications, particularly in the context of the industrial preparation and use of alkenes.
Petrochemicals: Petrochemicals are a class of chemicals derived from the processing and refining of crude oil, natural gas, and their byproducts. They serve as the building blocks for a wide range of products, including fuels, plastics, pharmaceuticals, and synthetic materials, making them essential in the industrial preparation and use of alkenes.
Polyethylene: Polyethylene is a thermoplastic polymer made from the polymerization of ethylene. It is one of the most widely used and versatile plastics, with applications ranging from packaging to construction materials.
Polypropylene: Polypropylene is a thermoplastic polymer derived from the monomer propylene. It is widely used in a variety of industrial and consumer applications due to its unique properties, making it an important material in the context of both the industrial preparation and use of alkenes, as well as the structure and physical characteristics of polymers.
Polyvinyl Chloride: Polyvinyl chloride (PVC) is a widely used thermoplastic polymer that is produced by the polymerization of vinyl chloride monomers. It is a versatile material with a wide range of applications, particularly in the context of industrial preparation and use of alkenes.
Propylene: Propylene, also known as propene, is a colorless, flammable gas that is an important industrial chemical. It is a key building block for a variety of products and plays a crucial role in the production of many common materials and fuels.
Propylene Oxide: Propylene oxide is a colorless, flammable liquid that is widely used in the production of various chemicals and materials. It is a key intermediate in the industrial preparation and use of alkenes, which are important organic compounds with diverse applications.
Pyrolysis Furnace: A pyrolysis furnace is a specialized type of industrial furnace used for the thermal decomposition of organic materials in the absence of oxygen. This process, known as pyrolysis, is a key step in the industrial preparation and use of alkenes, a class of unsaturated hydrocarbons.
Steam Cracking: Steam cracking is a crucial petrochemical process used to produce alkenes, particularly ethene and propene, from heavier hydrocarbon feedstocks. It involves the thermal decomposition of larger hydrocarbon molecules into smaller, more valuable olefins through the application of high temperatures and steam.
Thermal Cracking: Thermal cracking is a refining process used in the petrochemical industry to break down large, complex hydrocarbon molecules into smaller, more valuable ones. It involves the application of heat and pressure to crude oil or other hydrocarbon feedstocks to induce chemical reactions that cleave carbon-carbon bonds, resulting in the production of lighter, more volatile products.