Cellulose acetate manufacture

Eastman-Halcon A process for making acetic anhydride from syngas. The basic process is the carbonylation of methyl acetate. Methanol is made directly from the carbon monoxide and hydrogen of syngas. Acetic acid is a byproduct of the cellulose acetate manufacture for which the acetic anhydride is needed. The carbonylation is catalyzed by rhodium chloride and chromium hexacarbonyl. 

Uses In textile dyeing and printing solvent for cellulose acetate manufacturing methylstyrene. 

Typical Analysis of Cellulose Used for Cellulose Acetate Manufacture ... 

Practically all cellulose acetate manufactured at the present time is the acetone-soluble product, ranging from 37% to 41% acetyl content. Cellulose mixed esters now produced in quantity include cellulose acetate propionate of 33% propionyl content, cellulose acetate butyrate of 16% butyryl content, both of which are used largely for protective coatings and films, and cellulose acetate butyrate of 36% butyryl content used for plastics. 

A simple example will indicate the scope of the operation and some of its characteristics. Acetic acid is produced by methanol carbonylation or oxidation of acetaldehyde, or as a by-product of cellulose acetate manufacture. In all three cases, a mixture of acetic acid and water must be separated to give glacial acetic acid (99.8 wt%, min). Separation by distillation is expensive because of the need to vaporize large amounts of water with its very high heat of vaporization. Accordingly, an alternative, less expensive liquid-liquid extraction process is often used. 

The cellulose acetate manufacturer receives the cellulose in rolls or bales. For wood pulp, the bales consist of sheets of pulp. However, for cotton linters the bales can consist of sheets or cellulose in bulk form. The most important chemical properties are cellulose purity, intrinsic viscosity (IV), and cellulose reactivity. The most important physical properties are sheet density and moisture content. 

Cellulose acetate was stable, not readily flammable, and water repellent, so it was a suitable substitute for cellulose nitrate. Further, in its soluble form, cellulose acetate could be applied by simply painting the fabric as had been done with cellulose nitrate. However, cellulose acetate manufacture would require large quantities of acetic anhydride, and there was no good way to produce acetic anhydride other than the existing neutralization of calcium acetate with sulfuric acid. What ensued would be one of those creative bursts that occur sporadically in the chemical industry. 

If one looks at the overall process as it is integrated to cellulose acetate manufacture (equations [21] through [26]) the attraction of this process becomes apparent. By instituting a methyl acetate carbonylation, Eastman Chemical Company was able to replace the very energy intensive ketene process with a nearly thermodynamically neutral esterification as a method to remove water and subsequent exothermic carbonylation in the manufacture of cellulose acetate. 

Acetone is an important solvent in textile manufacture where it is used in large quantities in the dry extrusion process of cellulose acetate manufacture. The filtered solution of cellulose acetate and acetone is passed... 

Aceta n. Cellulose acetate, manufactured by Bayer, Germany. 

Cellon n Cellulose acetate. Manufactured by Dynamit Nobel, Germany. 

The greatest use of acetic anhydride is in esterifying cellulose to cellulose acetate for application as cigarette filter tow and in textiles. In the United States, acetic anhydride is manufactured by cellulose acetate manufacturers and largely used internally. Other products using acetic anhydride as a raw material are mostly mature with low growth rates they include triacetin, plastic modifiers and intermediates for pharmaceuticals, herbicides, pesticides, and dyes for polyolefins. Growth in production was projected to be 2.1 percent/year in the United States and less in Western Europe and Japan from 1988 to 1995. 

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