Black sand as source of catalysts that selectively isomerize α‑ and β‑pinene epoxides

Black sand (TBS), that is a mining waste, was treated by several procedures for obtaining materials that were tested as catalysts for isomerization of α- and β-pinene epoxides. The materials were obtained by milling (IC), heat treatment (CTT_800) and hydrothermal reaction with H2SO4 (CAT_400). Characterization analysis included NH3-TPD, XRD, Raman, FTIR-pyridine, XPS, and SEM–EDX. The presence of hematite, ilmenite and rutile was identifed by XRD and Raman analysis. FTIR-Py analysis showed only the presence of Lewis sites for CTT_800 and CAT_400, sites that favor aldehyde formation from monoterpene epoxide isomerization. The measured acid content was 364, 316, 214, and 167 µmolNH3/g for CAT_400, CTT_800, IC, and TBS, respectively; the increase of acidity was related with a higher content of hematite and rutile phases after treatment of the mining waste. Fe, Ti, and O were identifed as the main elements of the solids; no S was detected neither by FTIR, nor by XPS analysis. Over CAT_400 catalyst, α-pinene conversion and campholenic aldehyde selectivity were 96% and 64%, respectively. In the case of β-pinene epoxide isomerization, substrate conversion was 98% and myrtanal selectivity was 92%. For reusing tests, several catalyst treatments were evaluated. After fve reuses of CAT_400 for α- and β-pinene epoxide isomerization, selectivity did not change but conversion decreased, which was related to the decrease of strong acid sites and hematite and/or rutile content variation; a good procedure for catalyst activation is the treatment at 300 °C.

• Autores: Villa Holguín, Aída Luz; Valencia Cardona, Luis Fernando
• Tipo de recurso: Article of investigation
• Fecha de publicación: 2025
• Institución: Universidad de Antioquia
• Repositorio: Repositorio UdeA
• Idioma: eng
• OAI Identifier: oai:bibliotecadigital.udea.edu.co:10495/47003
• Acceso en línea: https://hdl.handle.net/10495/47003
• Palabra clave: Arena negra; Black sand; Isomerasas; Isomerases; Compuestos Epoxi; Epoxy Compounds; Catalizadores; Catalysts; Catálisis; Catalysis; Pineno; Pinene; Zeolitas; Zeolites; http://id.loc.gov/authorities/subjects/sh85014615; https://id.nlm.nih.gov/mesh/D007535; https://id.nlm.nih.gov/mesh/D004852
• Rights: openAccess
• License: http://creativecommons.org/licenses/by/4.0/