Formaldehyde manufacturing technologies have developed some of the process methods for production of formalin based on raw materials,
- Reduction of carbon oxides process
- Hydrocarbon gases conversion
- Oxidation of methane
- Oxidative – dehydrogenation process
- Pure oxidation process
Physical Properties of Formaldehyde:
1. Pure formaldehyde solutions are colorless and clear. Opalescence or cloudiness is caused by polymer precipitation.It has an irritating odor
2. It is soluble in water, alcohol and polar solvents, slightly soluble in hydrocarbons, chloroform, ether.
3. Various grades of formaldehyde are CP gas, 37% aqueous solutions, trioxane polymer (CHO), Para formaldehyde, (CHO)n . nH2O, where n=10-50.
4. Molecular weight = 30.03
5. Boiling point = -190C
6. Melting point = -1180C
7. Refractive index = 1.3773.
8. Toxicity limits = 10ppm
9. Density = 37% formaldehyde containing 9.2% methanol at 180C is 1.0895.
10. Lower explosive limit = 7 vol. % in air
11. Upper explosive limit = 73 vol. % in air
12. Solutions containing 15% methanol, of specific gravity 1.0775 at 15 to 23.70C has a
dielectric constant of 45.0.
13. Expansion coefficient of formaldehyde = 0.00057
14. Flash point of formaldehyde (37wt %) = 640C
15. Partial Pressure of formaldehyde (37 wt %) at 350C = 4.2mm Hg.
16. Resistivity of commercial formaldehyde solution at 300C = 35000 to 37000 ohms.
17. Absolute viscosity of formaldehyde at 250C = 2.58 centi poise.
18. Heat of combustion = 134.1 Kcal/gmol.
19. Heat of formation = -27.70 Kcal/gmol.
20. Free energy = -26.266 Kcal/gmol.
21. Heat capacity = 8.461 cal/gmol 0C.
22. Entropy = 8.461 cal/gmol 0C.
23. Heat of vaporization at boiling point (19.2 0C) = 5.570 Kcal/gmol.
24. Heat of solution = 15 kcal/gmol.
25. Heat of dilution = 0.45 Kcal/gmol.