Industrial Chemistry 1: Chapter 3 - Chemicals Based on Ethylene PDF

Industrial Chemistry 1 Chapter 3 Chemicals based on Ethylene Dr. OSAMAH ALGHAZWAT 1  Outline Brief introduction of ethylene Properties of ethylene List of major products of ethylene Discussion of products obtained from ethylene Ethyle...

Industrial Chemistry 1 Chapter 3 Chemicals based on Ethylene Dr. OSAMAH ALGHAZWAT 1  Outline Brief introduction of ethylene Properties of ethylene List of major products of ethylene Discussion of products obtained from ethylene Ethylene Glycol Acetaldehyde 2  Ethylene – An Introduction Ethylene is a hydrocarbon with a chemical formula C2H4 3 Ethylene – Properties Colorless, flammable gas with a sweet and musky odor in its pure form Simple structure High reactivity Relatively inexpensive Produces less by-products, during reactions with other compounds, as compared to other olefins 4 Ethylene – Properties (contd.) Raw material for various chemicals and polymers e.g., ethanol and polyethylene Easily produced from any hydrocarbon source through steam-cracking Molecular weight – 28.05 g/mol Density - 1.178 kg/m3 at 15 °C,gas At standard conditions, Melting point is −169.2 °C or 104.0 K Boiling point is −103.7 °C or 169.5 K 5 Major Chemicals & Polymers produced form Ethylene 6 Products of Ethylene (A) ETHYLENE OXIDE 7  Ethylene Oxide A precursor for many important commercial chemicals such as, Ethylene glycol Ethanolamines Polyesters 8 Ethylene Oxide - Production Main reaction is controlled oxidation (either using oxygen or air) of ethylene over a silver catalyst Reaction is exothermic and heat content should be controlled 9 Ethylene Oxide - Production (contd.) Ethylene Oxide 10 Ethylene Oxide - Production (contd.) 11  Ethylene Oxide - Production (contd.) Compressed oxygen, ethylene, and recycled gas are fed to a multi- tubular reactor The temperature of oxidation is controlled by boiling water in the shell side of the reactor Effluent gases are cooled and passed to the scrubber where ethylene oxide is absorbed as a dilute aqueous solution Un-reacted gases are recycled Epoxidation reaction occurs at approximately 200–300°C with a short residence time of one second 12 Products of Ethylene (B) ACETALDEHYDE 13 Acetaldehyde A colorless liquid with a pungent odor A reactive compound with no direct use except for the synthesis of other compounds e.g., raw material for production of acetic acid 14 Acetaldehyde - Production Old Technique: Silver-catalyzed oxidation or chromium activated copper- catalyzed dehydrogenation of ethanol (reaction temperature for oxidation is approximately 500 °C whereas for dehydrogenation is approximately 250 °C ) New Technique: Oxidation of ethylene using a homogeneous catalyst (Wacker catalyst and reaction temperature of 130 °C ) 15 Acetaldehyde – Production (contd.) Ethylene oxidation is carried out through redox reactions The overall reaction is exothermic Acetaldehyde 16 Acetaldehyde – Production (contd.) The Wacker Process The process employs an aqueous solution of palladium(II) chloride, copper(II) chloride catalyst system Pd2+ ions are reduced to Pd metal, and ethylene is oxidized to acetaldehyde 17 Acetaldehyde – Production (contd.) The Wacker Process (contd.) Pd° is re-oxidized by action of Cu(II) ions, which are reduced to Cu(I) ions The reduced Cu(I) ions are re-oxidized to Cu(II) ions by reaction with oxygen and HCl 18 Acetaldehyde – Production (contd.) The oxidation reaction may be carried out in a single- stage or a two stage process In the single-stage, ethylene, oxygen, and recycled gas are fed into a vertical reactor containing the catalyst solution. Heat is controlled by boiling off some of the water. The reaction conditions are approximately 130°C and 3 atmospheres In the two-stage process, the reaction occurs under relatively higher pressure (approximately 8 atmospheres) to ensure higher ethylene conversion. The reaction temperature is approximately 130°C 19 Acetaldehyde – Production (contd.) The yield of acetaldehyde from either process is about 95% By-products from this reaction include acetic acid, ethyl chloride, chloroacetaldehyde, and carbon dioxide 20 Conclusion Ethylene is indeed one of the most important raw materials for manufacturing of various chemicals and polymers It is sometimes referred to as the “king of petrochemicals” It has great commercial importance and thus improvements should be continuously made in its manufacturing, in order to increase production of various other petrochemicals 21