Synthesis of bio-based diethyl pentane-1,5-diyldicarbamate via the carbonylation of pentanediamine with CO2 over a zirconium-doped CeO2 catalyst.

• The bio-based carbamate was directly synthesized from CO 2 and pentanediamine (PDA). • The performance of the CeO 2 catalyst was influenced by doping a small amount of Zr. • The diethyl carbonate intermediate is generated from the reaction of CO 2 and ethanol, and subsequently transformed into PDC. • The Zr 0.05 Ce catalyst showed good catalytic activity in the carbonylation between PDA and CO 2. Diethyl pentane-1,5-diyldicarbamate (PDC), a bio-based intermediate used for isocyanate and polyurethanes, was synthesized by the direct carbonylation of CO 2 and pentanediamine (PDA) with 2-cyanopyridine (2-CP) over Zr-doped CeO 2. In this study, Zr-doped CeO 2 catalysts with different contents of Zr are successfully synthesized to produce PDC from PDA, CO 2 , and ethanol. Among them, Zr 0.05 Ce exhibits enhanced reaction activity and the productivity reached 6.0 mmol·g−1·h−1. Characterizations based on X-ray photoelectron spectroscopy, Raman, and CO 2 /NH 3 -temperature-programmed desorption prove that the doping of Zr atoms into CeO 2 regulates the acid–base sites and promotes oxygen vacancy formation, which is primarily responsible for the formation of monoethyl carbonate, an intermediate for diethyl carbonate (DEC). In-situ diffuse reflectance Fourier-transform spectrometry and Fourier-transform infrared spectroscopy reveal that PDA reacts with 2-CP to form N, N'-(pentane-1,5-diyl)dipicolinamide, which are transformed into PDC. Finally, the catalytic activity could be regenerated after calcination. This study presents a green route for producing bio-based carbamate by constructing C-N bond using CO 2 as a carbonyl source, which can replace carbamates derived from petrochemical resources in the future. [Display omitted] [ABSTRACT FROM AUTHOR]