126500 20241125101131.0 doi 10.1016/j.cej.2022.140723 sideral 132455 ART-2023-132455 eng Mercadal, Juan J. Improved O2-assisted styrene synthesis by double-function purification of SWCNT catalyst 2023 Access copy available to the general public Unrestricted The catalytic performance of SWCNT was notably improved in the oxidative dehydrogenation of ethylbenzene (EB) to styrene (ST) upon a double-function purification in one step of the raw SWCNT. This consists of lowering the MeOx concentration and generating surface C=O groups after processing it in nitric acid at controlled conditions, while preserving the structure. The textural improvement was ascribed to the cutting of the tubes/bundles by oxidation and to MeOx removal itself (dilution effect). Both EB conversion and ST selectivity increased with a parallel lowering of the undesired COx selectivity. The conversion was interpreted by the enhancement of the intrinsic properties (i.e., more surface ketonic groups) but also to the higher load of SWCNT in the bed upon purification; both factors contribute to a higher number of active sites (C=O) in the bed for styrene formation. The most purified catalyst underperformed in conversion once the purification altered the SWCNT structure notably. Thus, preserving the structure is an important condition to achieve high conversion and yield. The better selectivity was explained in two ways; more styrene-forming sites (C=O) or less COx-forming sites (uncoated MeOx) in the bed, or both. The styrene yield per catalyst volume was improved by an average of ca. 240 % in comparison to the non-purified SWCNT. Deactivation is critical in maximizing the purification effect on the intrinsic and volumetric yields. In practical terms, the purification method proved to enhance the reaction; the selectivity towards the unwanted COx was significantly lowered with a gain towards styrene, achieving comparable selectivity values as in the conventional process, but operated at much lower temperature. info:eu-repo/grantAgreement/ES/DGA/E13-20R info:eu-repo/grantAgreement/ES/DGA/T03-20R info:eu-repo/grantAgreement/EC/H2020/823717/EU/Enabling Science and Technology through European Electron Microscopy/ESTEEM3 This project has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No H2020 823717-ESTEEM3 info:eu-repo/grantAgreement/ES/MICINN/RYC-2018-024561-I info:eu-repo/semantics/openAccess All rights reserved http://www.europeana.eu/rights/rr-f/ 13.4 2023 ENGINEERING, ENVIRONMENTAL 3 / 81 = 0.037 2023 Q1 T1 ENGINEERING, CHEMICAL 7 / 170 = 0.041 2023 Q1 T1 2.852 2023 Environmental Chemistry 2023 Q1 Industrial and Manufacturing Engineering 2023 Q1 Chemistry (miscellaneous) 2023 Q1 Chemical Engineering (miscellaneous) 2023 Q1 21.7 2023 info:eu-repo/semantics/article info:eu-repo/semantics/acceptedVersion Mayoral, Alvaro Universidad de Zaragoza (orcid)0000-0002-5229-2717 Fierro, José Luis G. García-Bordejé, Enrique (orcid)0000-0001-8158-1270 Melián-Cabrera, Ignacio 2003 395 Universidad de Zaragoza Dpto. Física Materia Condensa. Área Física Materia Condensada 455 (2023), 140723 [13 pp.] Chem. eng. j. Chemical Engineering Journal 1385-8947 1526998 http://zaguan.unizar.es/record/126500/files/texto_completo.pdf Postprint 2877777 http://zaguan.unizar.es/record/126500/files/texto_completo.jpg?subformat=icon icon Postprint oai:zaguan.unizar.es:126500 articulos driver 2024-11-22-11:58:57 ARTICLE