Glycerol, the thick syrup left behind in large volumes whenever biodiesel is produced, has long been a disposal problem for the fuel industry. A new study in Catalysis Letters reports a CeO2-Cu composite catalyst that converts this by-product into lactic acid with striking efficiency, achieving complete glycerol conversion and 90.34% lactic acid selectivity at 190 °C after six hours of reaction. The work, led by Jili Zhang, Hongju Ren, Shuangming Li, Yiwen Wang, Feng Chen, Shuang Ren and Sansan Yu, addresses two persistent weaknesses of earlier catalysts: poor selectivity toward lactic acid and severe aggregation of the active metal components during use.
The researchers prepared their catalysts by a hydrothermal co-precipitation method, mixing cerium and copper precursors and systematically varying the cerium molar fraction. According to the abstract, this preparation route promoted the formation of spherical structures, while the pore architecture of the resulting materials could be tuned simply by adjusting the Ce:Cu ratio. Among the compositions tested, a catalyst containing a Ce:Cu molar ratio of 5:95 stood out. It developed a well-defined porous structure and delivered the best catalytic performance for the oxidation of glycerol to lactic acid under the reported conditions.
Structural characterization using X-ray diffraction, transmission electron microscopy and complementary techniques showed that the small cerium addition did more than modify porosity. The introduction of Ce led to the formation of CeO2-Cu interfaces, and the authors propose that these interfacial structures help stabilize the copper species through interfacial interactions while also promoting the formation of oxygen vacancies.
The stability results are among the most notable numbers in the report. After five consecutive reaction cycles, the average copper particle size increased only slightly, from 69.8 nm to 72.3 nm. The authors attribute this robustness to the interfacial interactions that hold the copper particles in place across successive batches.
The reaction chemistry itself is a demanding one. The 190 °C reaction temperature and six-hour residence time define the operating window under which this performance was measured.
The practical context adds weight to the result. Biodiesel production generates glycerol as its major by-product, and growing demand for value-added utilization of this stream has made catalytic oxidation to lactic acid an attractive target.
The study also illustrates how modest compositional changes can reshape catalyst behavior. By varying only the cerium molar ratio within the CeO2-Cu family, the team could regulate pore structure and, in turn, catalytic performance, identifying the 5:95 composition as the optimum.
As with any laboratory-scale catalytic study, the reported figures apply to the specific conditions tested, and the mechanistic interpretation of the CeO2-Cu interfaces is presented as a proposal supported by structural evidence rather than a definitive reaction mechanism. Nevertheless, the combination of full glycerol conversion, 90.34% lactic acid selectivity and near-constant copper particle size over five cycles marks this CeO2-Cu composite as a promising candidate in the ongoing effort to convert biodiesel’s most abundant by-product into a chemical of real industrial value.
Subject of Research: Catalytic oxidation of biodiesel-derived glycerol to lactic acid using CeO2-Cu interfacial composite catalysts
Article Title: CeO2-Cu Interfacial Synergy for Highly Efficient and Selective Conversion of Glycerol to Lactic Acid
Article References: Zhang, J., Ren, H., Li, S., Wang, Y., Chen, F., Ren, S., & Yu, S. (2026). CeO2-Cu Interfacial Synergy for Highly Efficient and Selective Conversion of Glycerol to Lactic Acid. Catalysis Letters, 156(11), Article 314. https://doi.org/10.1007/s10562-026-05563-6
Image Credits: AI Generated
DOI: 10.1007/s10562-026-05563-6
Keywords: glycerol, lactic acid, CeO2-Cu catalyst, biodiesel by-product, catalytic oxidation, oxygen vacancies, copper stabilization, hydrothermal co-precipitation, catalyst stability, interfacial synergy, porous structure, value-added utilization
News Source: Bethany Barker. (November 6, 2026). Ceria-Copper Catalyst Turns Biodiesel Waste Glycerol into Lactic Acid with 90% Selectivity. Scienmag.
