Rational design of bifunctional catalyst from KF and ZnO combination on alumina for cyclic urea synthesis from CO2 and diamine

• Published in: Applied catalysis. A, General Vol. 598; p. 117550
• Main Authors: Kulal, Nagendra, John, Crowny, Shanbhag, Ganapati V.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 25.05.2020; Elsevier Science SA
• Subjects: 2-Imidazolidinone; Aluminum oxide; Ammonia; Bifunctional catalyst; Carbon dioxide; Catalysts; Chemical synthesis; CO2; Cyclic urea; Diamines; Ethylenediamine; Selectivity; Ureas; Zinc oxide; Ethylenediamine; 2-Imidazolidinone; Bifunctional catalyst; CO2; Cyclic urea
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2020.117550

[Display omitted] •ZnO/KF/Al2O3 as a bifunctional catalyst for carbonylation of diamine with CO2.•Method of tuning ZnO, KF loading and water treatment to remove physisorbed species.•Importance of ZnO-KF combination to generate acid and base sites for this reaction.•Relationship of acidity and basicity of solvent with conversion and selectivity.•ZnO/KF/Al2O3 is a robust and reusable catalyst for 2-imidazolidinone synthesis. This study is mainly focused on the design of stable, active and selective catalyst for direct synthesis of 2-imidazolidinone (cyclic urea) from ethylenediamine and CO2. Based on the rationale for the catalyst properties needed for this reaction, KF, ZnO and Al2O3 combination was selected to design the catalyst. ZnO/KF/Al2O3 catalyst was prepared by stepwise wet-impregnation followed by the removal of physisorbed KF from the surface. High product yield could be achieved by tuning acid-base sites by varying the composition and calcination temperature. The catalysts were characterized by various techniques like XRD, N2-sorption, NH3-TPD, CO2-TPD, TEM, XPS and FT-IR measurements. It is shown that acidic and basic properties of the solvent can influence the activity and product selectivity for this reaction. Under optimized condition; 180 °C, 10 bar and 10 wt.% catalyst in batch mode, 96.3 % conversion and 89.6 % selectivity towards the 2-imidazolidinone were achieved.