Process control, hydrogen damage

Naturally white, but slightly yellowed fur skins from sheep and lambs are reduction bleached, most commonly with dithionite or/and in combination with hydrogen peroxide in a weakly alkaline medium. A true bleach in the sense of destroying the natural pigments in the hair can only be achieved by means of oxidation with, e g., hydrogen peroxide, catalyzed by iron(n) salts. This exothermic process is very difficult to control and must be monitored carefully. In addition, the skin must not be chrome tanned, as this could cause serious damage. 

The reduction of double bonds is an exothermic reaction. Heat control is important during hydrogenation to avoid damage to the product and the equipment. Also, the capture of heat and its reuse to bring subsequent hydrogenation runs up to reaction temperatures is a significant aspect in overall process economics. 

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