Laboratory study finds confined FER zeolite enables selective olefin carbonylation

A laboratory study reports that spatial confinement in FER zeolite, combined with a high carbon monoxide-to-olefin ratio, can produce primary and secondary carboxylic acids as the main products of olefin carbonylation. At a carbon monoxide-to-olefin ratio of 360, ethylene was converted to propanoic acid with 80% selectivity over 100 hours, while propylene was converted to isobutyric acid with 95% selectivity over 750 hours. The findings suggest that changing the reaction environment inside a porous catalyst can overcome a previously reported restriction in Brønsted-acidic zeolite-catalysed olefin carbonylation.

Carbonylation is used to produce aldehydes, carboxylic acids and esters. It is usually catalysed by homogeneous metal complexes containing ligands and iodide promoters, while Koch reported that protons in mineral acids can also catalyse the reaction. Previous studies showed that Brønsted-acidic zeolites can act as heterogeneous, Koch-type catalysts for the carbonylation of alcohols and olefins.

For olefins, however, the products were limited to tertiary carboxylic acids. The new study indicates that targeted spatial confinement and a high carbon monoxide-to-olefin ratio can shift the outcome toward primary and secondary carboxylic acids without introducing the conventional metal-complex catalyst system. Under a carbon monoxide-to-olefin ratio of 360, propanoic acid and isobutyric acid became the main products for ethylene and propylene carbonylation, respectively.

The trend was not equally strong at lower ratios: propylene carbonylation selectivity declined to 61% when the ratio was 24, and ethylene carbonylation selectivity fell to 57% when the ratio was 90. These comparisons support the conclusion that the high carbon monoxide-to-olefin ratio was important for the high selectivities reported under the study conditions. The available research summary does not provide the full operating range, catalyst quantities, olefin conversions or complete product distributions.

Experiments combined with theoretical calculations identified distinct sites for the two olefins. The researchers assigned T2–O5 sites in the eight-membered-ring cavities of FER zeolite as the primary active sites for ethylene carbonylation. For propylene carbonylation, they assigned T3–O1 sites in the ten-membered rings as the primary active sites.

These assignments provide a molecular explanation for why the two olefins behaved differently in the confined catalyst. They are interpretations supported by experimental evidence and calculations, rather than direct observations of every elementary step in the reaction network. The results nevertheless connect site location and spatial confinement with the ability to steer olefin carbonylation toward different classes of carboxylic acids.

Long-duration experiments showed that the reported selectivities were sustained under the tested conditions: ethylene carbonylation maintained 80% selectivity to propanoic acid over 100 hours, and propylene carbonylation maintained 95% selectivity to isobutyric acid over 750 hours. The study therefore presents a proof-of-concept for a heterogeneous olefin-carbonylation process in which confinement and reactant ratio act together to control product formation. Its evidence comes from laboratory catalyst experiments, and the available summary does not establish industrial productivity, commercial viability, catalyst regeneration or performance beyond the reported conditions.

Within those limits, the work identifies specific prerequisites for developing new zeolite-based carbonylation processes and offers a route toward producing primary and secondary carboxylic acids that were not obtained as principal products in earlier Koch-type zeolite systems.

Subject of Research: Selective olefin carbonylation using spatial confinement in FER zeolite

Article Title: Zeolite-catalysed olefin carbonylation based on tuning spatial confinement

Article References: Qi, L., Sheng, Y., Zhang, W., Ni, Y., He, L., Li, B., Wang, A., Zhu, W., Bell, A. T., & Liu, Z. (2026). Zeolite-catalysed olefin carbonylation based on tuning spatial confinement. Nature. https://doi.org/10.1038/s41586-026-11183-2

Image Credits: AI Generated

DOI: 10.1038/s41586-026-11183-2

Keywords: zeolite catalysis, olefin carbonylation, spatial confinement, FER zeolite, carbon monoxide, carboxylic acids, ethylene, propylene, Brønsted acidity, active sites, Zeolite-catalysed, olefin