Article No : a11_619
Formaldehyde
GU¨ NTHER REUSS, BASF Aktiengesellschaft, Ludwigshafen, Federal Republic of Germany
WALTER DISTELDORF, BASF Aktiengesellschaft, Ludwigshafen, Federal Republic of Germany
ARMIN OTTO GAMER, BASF Aktiengesellschaft, Ludwigshafen, Federal Republic of Germany
ALBRECHT HILT, Ultraform GmbH, Ludwigshafen, Federal Republic of Germany
1. Introduction...... 735 6. Quality Specifications and Analysis ..... 751 2. Physical Properties ...... 736 6.1. Quality Specifications...... 751 2.1. Monomeric Formaldehyde...... 736 6.2. Analysis ...... 751 2.2. Aqueous Solutions ...... 737 7. Storage and Transportation...... 752 3. Chemical Properties ...... 739 8. Uses ...... 753 4. Production ...... 740 9. Economic Aspects ...... 754 4.1. Silver Catalyst Processes ...... 740 10. Toxicology and Occupational Health .... 755 4.1.1. Complete Conversion of Methanol (BASF 11. Low Molecular Mass Polymers ...... 756 Process) ...... 742 11.1. Linear Polyoxymethylenes ...... 756 4.1.2. Incomplete Conversion and Distillative 11.2. Cyclic Polyoxymethylenes ...... 759 Recovery of Methanol ...... 743 11.2.1. Trioxane ...... 759 4.2. Formox Process ...... 744 11.2.2. Tetraoxane ...... 762 4.3. Comparison of Process Economics...... 745 11.2.3. Higher Cyclic Polyoxymethylenes ...... 762 4.4. Distillation of Aqueous Formaldehyde 12. Formaldehyde Cyanohydrin ...... 762 Solutions ...... 747 References ...... 763 4.5. Preparation of Liquid Monomeric Formaldehyde ...... 747 5. Environmental Protection ...... 748
1. Introduction even in cigarette smoke. Formaldehyde is an important industrial chemical and is employed Formaldehyde occurs in nature and is formed in the manufacture of many industrial products from organic material by photochemical process- and consumer articles. More than 50 branches of es in the atmosphere as long as life continues on industry now use formaldehyde, mainly in the earth. Formaldehyde is an important metabolic form of aqueous solutions and formaldehyde- product in plants and animals (including containing resins. In 1995, the demand for form- humans), where it occurs in low but measurable aldehyde in the three major markets – Northern concentrations. It has a pungent odor and is an America, Western Europe, Japan – was 4.1 irritant to the eye, nose, and throat even at a low 106 t/a [1]. concentration; the threshold concentration for History. Formaldehyde was first synthesized odor detection is 0.05 – 1 ppm. However, form- in 1859, when BUTLEROV hydrolyzed methylene aldehyde does not cause any chronic damage to acetate and noted the characteristic odor of the human health. Formaldehyde is also formed resulting solution. In 1867, HOFMANN conclusive- when organic material is incompletely com- ly identified formaldehyde, which he prepared by busted; therefore, formaldehyde is found in com- passing methanol vapor and air over a heated bustion gases from, for example, automotive platinum spiral. This method, but with other vehicles, heating plants, gas-fired boilers, and catalysts, still constitutes the principal method