Most commercial nitro group hydrogenation processes are related to fine chemistry and pharmaceutical chemistry, but in terms of product quantity the most important process is the hydrogenation of dinitrotoluene (DNT) to toluenediamine (TDA). TDA is an intermediate in the production of polyurethanes. TDA is converted with phosgene to toluenediisocyanate (TDI) which is mainly used, together with polyether polyols, for the production of flexible PU foams for furnishing, packaging foam, mattresses, and auto seatings, which together constitute some 90 % of its usage.

There are four technologies established for the hydrogenation of DNT using different types of catalysts:

• Nickel catalysts supported on silica
• Activated Base Metal Catalysts (Nickel)
• Precious metal catalysts supported on activated carbon
• Precious metal catalysts supported on carbon black

Evonik offers all catalyst systems listed above except silica supported nickel catalysts. You can find detail information on catalyst types and reaction conditions under Reactions and Products.

Apart from tailor made TDA catalysts, Evonik provides technical support and inhouse testing of catalysts. Through collaborations with engineering companies, we keep in touch with the latest technology. We have an elaborated testing concept for TDA catalysts that starts with a high throughput pre-screening, includes batch tests and ends with testing under customer identical conditions in a semi-continuous mini plant.