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Questions and Answers
Why is the water + HCHO + methanol stream sent to a specific section of the absorber and not the top section?
To maximize the removal efficiency of both water and formaldehyde rich solution.
Explain why a light end stripper is used after the absorber.
To remove unwanted components that may have been absorbed by the formaldehyde solution, by gently heating.
Why is pure formaldehyde not produced in the process?
Pure formaldehyde is not stable and tends to produce a trimer or polymer. It is stable only in water.
What is the main function of the absorber in the formaldehyde production process?
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Why is the distillation tower crucial in the production of formaldehyde?
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Study Notes
Formaldehyde
- Formaldehyde is a naturally occurring organic compound with the formula CH2O (H-CHO), also known as methanal.
- It is the simplest of the aldehydes (R-CHO).
- Formaldehyde cannot be shipped over long distances due to stability-associated problems during transportation.
Physical and Chemical Properties
- Formaldehyde is a colorless gas at room temperature and has a clear or water-white liquid appearance.
- It has an irritating odor and is very soluble in water, ether, acetone, benzene, and alcohol.
- Formaldehyde is very reactive, combines with many substances, and polymerizes easily.
- Aqueous formaldehyde is corrosive to carbon steel, but not in the vapor phase.
- It is sold as aqueous solutions (formalin) containing 37 to 50 percent formaldehyde.
Properties
- Chemical formula: HCHO
- Molecular weight: 30.03 g/mol
- Appearance: Colorless gas
- Density: 0.8153 g/cm³ (-20 °C)
- Melting point: -92 °C
- Boiling point: -19 °C
- Solubility in water: 400 g/L
Uses of Formaldehyde
- Used as a disinfectant in industries and as a preservative in some food products.
- Used in the production of car parts, explosives, plastic, resins, chemicals, and other artificial materials.
- Used in sanitary products like paper towels, napkins, and tissues.
- Used in medicine as an antiseptic to kill bacteria and fungi.
- Used in building and construction to manufacture wooden products.
- Used as a preservative in food, paints, and cosmetics.
Formaldehyde Production
- Produced through oxidation, pyrolysis, or undesired reaction of methanol.
- Oxidation reaction: CH3OH + 0.5 O2 → HCHO + H2O
- Pyrolysis reaction: CH3OH → HCHO + H2
- Undesired reaction: CH3OH + 1.5 O2 → 2H2O + CO2
- Distillation tower produces methanol vapor as the top product and the bottom formaldehyde + water product.
Technical Questions
- Water + HCHO + methanol stream is sent to a specific section of the absorber to maximize the removal efficiency of both water and formaldehyde rich solution.
- Light end stripper is used after absorber to remove unwanted light end compounds.
- Pure formaldehyde is not produced in the process because it is not stable and tends to produce a trimer or polymer.
- The absorber functions to absorb any formaldehyde vapor from the reactor product stream and remove inert or unreacted gases.
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Description
Learn about the uses, physical and chemical properties, and production of formaldehyde in the petrochemical industry. Explore the basics of formaldehyde, its formula CH2O, and its significance in various industrial processes.
