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The role of alkali dopants on the oil methanolysis behavior of lime catalyst: activity & stability

2022-03-12Journal article Restricted access
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dc.contributor.authorSoares Dias, A. P.
dc.contributor.authorPuna, Jaime
dc.contributor.authorGomes, João
dc.contributor.authorRamos, Marta
dc.contributor.authorRijo, Bruna
dc.contributor.authorBordado, João
dc.date.accessioned2022-03-17T08:57:23Z
dc.date.available2022-03-17T08:57:23Z
dc.date.issued2022-03-12
dc.description.abstractHeterogeneous basic catalysts, namely calcium oxide, are referred to as promising catalysts for biodiesel (FAME, fatty acid methyl esters) production since they can be easily separated from the reaction medium allowing them to operate in a continuous mode. Despite the relatively high catalytic activity of calcium catalysts, they present slower alcoholysis rates than homogeneous conventional catalysts (sodium or potassium methanoate). In order to improve the catalytic activity, CaO-based catalysts, modified with alkali elements (Li, Cs, Sr, and Mg) were prepared. Dopant element contents of 10% and 30%, as weight basis (5–50% molar), were introduced by wet impregnation using aqueous solutions of nitrate salts. The effect of calcination temperature (575°C and 800°C) on both activity and stability was studied. All the prepared catalysts, raw and alkali modified, showed pKa<15.0 when characterized by Hammett indicators in methanolic solution. Such basicity is characteristic of Ca hydroxide, thus indicating that the catalysts surfaces were covered with Ca-OH species. FAME yield, in soybean oil methanolysis, higher than 96% was obtained for the first batch reaction for all the tested catalysts showing that alkali dopants have an almost nihil effect on the catalysts performances. The deactivation tests performed with catalysts without intermediate reactivation showed that calcination temperature plays a major role in stability as it enhances the formation of calcium diglyceroxide. The presence of Ca hydroxide in fresh catalysts appears to be responsible for fast deactivation. The dopant elements prompt the catalysts deactivation. Catalysts calcined at higher temperatures showed slower deactivation, which can be due to the formation of larger particles, thus reducing the contact with the formed glycerin. Alkali dopants enhanced the CaO sintering for the highest calcination temperature. Calcium diglyceroxide formed during the reaction is responsible for deactivating the catalyst, due to leaching, and such effect is prompted by alkali dopants.pt_PT
dc.description.versioninfo:eu-repo/semantics/publishedVersionpt_PT
dc.identifier.citationDIAS, Ana Paula Soares – The role of alkali dopants on the oil methanolysis behavior of lime catalyst: activity & stability. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects. ISSN 1556-7036. Vol. 44, N.º 1 (2022), pp. 748-757.pt_PT
dc.identifier.doi10.1080/15567036.2022.2050853pt_PT
dc.identifier.issn1556-7036
dc.identifier.urihttp://hdl.handle.net/10400.21/14489
dc.language.isoengpt_PT
dc.peerreviewedyespt_PT
dc.publisherTaylor & Francispt_PT
dc.relation.publisherversionhttps://www.tandfonline.com/doi/epub/10.1080/15567036.2022.2050853?needAccess=truept_PT
dc.subjectBiodieselpt_PT
dc.subjectCalcium catalystspt_PT
dc.subjectAlkali dopantspt_PT
dc.subjectCalcium diglyceroxidept_PT
dc.subjectCa leachingpt_PT
dc.subjectDeactivationpt_PT
dc.titleThe role of alkali dopants on the oil methanolysis behavior of lime catalyst: activity & stabilitypt_PT
dc.typejournal article
dspace.entity.typePublication
oaire.citation.endPage757pt_PT
oaire.citation.issue1pt_PT
oaire.citation.startPage748pt_PT
oaire.citation.titleEnergy Sources, Part A: Recovery, Utilization, and Environmental Effectspt_PT
oaire.citation.volume44pt_PT
person.familyNameVieira Soares Pereira Dias
person.familyNamePuna
person.familyNameGomes
person.familyNameRamos
person.familyNameRijo
person.familyNameBordado
person.givenNameAna Paula
person.givenNameJaime
person.givenNameJoão
person.givenNameMarta
person.givenNameBruna
person.givenNameJoão
person.identifier790253
person.identifier60203
person.identifier.ciencia-id7711-D804-97B8
person.identifier.ciencia-idEE14-5CB2-AF04
person.identifier.ciencia-id0212-E6D6-566C
person.identifier.ciencia-idF813-1438-B3B9
person.identifier.ciencia-idF212-6F13-4A64
person.identifier.ciencia-id5A1C-D29F-324A
person.identifier.orcid0000-0002-4585-470X
person.identifier.orcid0000-0002-2763-3655
person.identifier.orcid0000-0003-2579-6669
person.identifier.orcid0000-0003-4967-4850
person.identifier.orcid0000-0001-6720-6132
person.identifier.orcid0000-0002-9832-6433
person.identifier.ridA-6442-2011
person.identifier.ridM-1952-2014
person.identifier.scopus-author-id24402152700
person.identifier.scopus-author-id56113031900
person.identifier.scopus-author-id6603731772
rcaap.rightsclosedAccesspt_PT
rcaap.typearticlept_PT
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