Hydrogenation of Carbamates, Ureas, and Polyurethanes Using Heterogeneous Catalysts
Benjamin Sole1, Julian S Kolb1, Raymundo Marcial-Hernandez1
1EaStCHEM, School of Chemistry, University of St. Andrews, North Haugh, St. Andrews KY16 9ST, U.K.
ACS Sustainable Chemistry & Engineering
|October 24, 2025
Summary
This study demonstrates the effective hydrogenation of carbamates and ureas into valuable chemicals using heterogeneous catalysts. Polyurethanes were successfully depolymerized into diamines and polyols, with catalyst recycling shown over ten cycles.
Area of Science:
- Green Chemistry
- Catalysis
- Polymer Science
Background:
- Carbamates, ureas, and polyurethanes are important industrial chemicals.
- Efficient and sustainable methods for their transformation are needed.
- Hydrogenation and depolymerization offer pathways to valuable chemical building blocks.
Purpose of the Study:
- To investigate the heterogeneous catalytic hydrogenation of carbamates and ureas.
- To explore the hydrogenative depolymerization of polyurethanes.
- To assess the reusability of the employed catalysts.
Main Methods:
- Utilized heterogeneous catalysts for chemical transformations.
- Performed selective hydrogenation reactions under specific catalytic conditions.
- Conducted hydrogenative depolymerization of polyurethane materials.
Main Results:
- Achieved selective hydrogenation of carbamates to formamides and alcohols.
- Converted urea derivatives to amines.
- Successfully depolymerized polyurethanes into diamines and polyols.
- Demonstrated catalyst recyclability for ten cycles in polyurethane depolymerization.
Conclusions:
- Heterogeneous catalysis provides an efficient route for carbamate and urea hydrogenation.
- Hydrogenative depolymerization is a viable method for polyurethane recycling.
- The developed catalytic system exhibits excellent stability and reusability.
Related Concept Videos
02:50Catalysis
30.1K
The presence of a catalyst affects the rate of a chemical reaction. A catalyst is a substance that can increase the reaction rate without being consumed during the process. A basic comprehension of a catalysts’ role during chemical reactions can be understood from the concept of reaction mechanisms and energy diagrams.
30.1K
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
3.8K
Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
3.8K
02:13Reduction of Alkenes: Catalytic Hydrogenation
13.9K
Alkenes undergo reduction by the addition of molecular hydrogen to give alkanes. Because the process generally occurs in the presence of a transition-metal catalyst, the reaction is called catalytic hydrogenation.
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...
13.9K
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
8.9K
Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
8.9K
02:34Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
9.5K
The rate of acid-catalyzed hydration of alkenes depends on the alkene's structure, as the presence of alkyl substituents at the double bond can significantly influence the rate.
9.5K
01:28Reduction of Benzene to Cyclohexane: Catalytic Hydrogenation
5.7K
Unlike the easy catalytic hydrogenation of an alkene double bond, hydrogenation of a benzene double bond under similar reaction conditions does not take place easily. For example, in the reduction of stilbene, the benzene ring remains unaffected while the alkene bond gets reduced. Hydrogenation of an alkene double bond is exothermic and a favorable process. In contrast, to hydrogenate the first unsaturated bond of benzene, an energy input is needed; that is, the process is endothermic. This is...
5.7K