Classic esterification reactions between a carboxylic acid and alcohol (Fischer Esterification) typically require the use of a strong acid catalyst in order to make them viable for commercial use. Often times sulfuric acid or a metallic lewis acid catalyst like organostannanes (tin) are used to improve reaction rates and conditions and make esterification commercially viable. These traditional catalysts, however, are toxic, have long lasting environmental impacts, and produce unwanted by products such as olefins.
Tyzor® - Non-Toxic Catalysts
Tyzor® Organic Titanates are useful, non-toxic, organometallic catalysts for esterification and transesterification reactions that provide faster reaction rates and higher yield than traditional catalysts like sulfuric acid and organostannanes. This makes Tyzor® and excellent choice for ester manufacturers that are looking to improve efficiency while reducing the hazards and environmental impact associated with esterification reactions. To highlight the usefulness of Tyzor® Organic Titanates as an esterification catalyst, Tyzor® TPT and Tyzor® TE were compared to sulfuric acid in the direct esterification of adipic acid to bis-2-ethylhexyl adipate. The percent conversion over time is shown in the table and graph below.
You can see in the data above that Tyzor® TPT is a highly reactive esterification catalyst and reaches 100% conversion more quickly than sulfuric acid. Although it is the most active Tyzor® grade, Tyzor® TPT may not always be the most economical because it is highly sensitive to water, alcohols, and acids. In certain cases a titanium chelate like Tyzor® TE is more stable and can provide a more practical source of titanium for catalysis.
How to Use Tyzor® Catalysts
Tyzor® Titanate catalysts are soluble and can be added to the reaction mixture at any point in the process. In alcohol - carboxylic acid esterifications like the one mentioned above it is recommended to add Tyzor® at temperature above 150°C and run the reaction at a temperature between 180°C and 220°C to achieve the most efficient conversion. It is also particularly important that water produced from the reaction be removed as rapidly as possible to avoid deactivating the moisture sensitive Tyzor® catalyst. In most cases a polymerization inhibitor and nitrogen blanket are useful if a sensitive ester is being prepared. Usage rates can vary based on the reaction but typically 0.1-0.5 wt% of Tyzor® based on the weight of total product expected from the reaction is sufficient.
Removal of Catalyst
In some cases it may be necessary to remove the Tyzor® catalyst from the end product. While Tyzor® is generally soluble in product esters, it can easily be removed by conversion to it's insoluble hydrolysis product. Agitation with a small amount of water and then steam stripping is usually sufficient for hydrolysis of Tyzor® catalysts. The resulting titanium oxides are insoluble solids and can be removed by filtration.
Tyzor® Organic Titanates are safe and efficient catalysts for the production of high purity esters and are superior to most other catalysts for the following reasons:
They are non-toxic
They can be removed from end product
Catalyst residue upon removal is non-toxic
Higher conversion rates in lower cycle times
Higher yield on acids and alcohols
Lower byproduct formation
Lower color formation
Lower odor formation
Selection of the Tyzor® catalyst for your esterification reaction is critical for maximizing efficient production. Contact us today to discuss your reaction with one of our product experts and find the grade of Tyzor® that is best suited for your application.