Cobalt-catalyzed fischer–tropsch synthesis: chemical nature of the oxide support as a performance descriptor

The effect of the chemical nature of the oxide support on the performance of cobalt Fischer–Tropsch catalysts is investigated. A series of supports is synthesized via monolayer coverage of porous γ-Al2O3 with various oxides representative of a wide range of Lewis acid–base character, as quantified b...

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Principais autores:	Prieto, Gonzalo, Mello, Mariele I. S. de, Concepción, Patricia, Murciano, Raúl, Pergher, Sibele Berenice Castellã, Martı́nez, Agustı́n
Formato:	article
Idioma:	English
Publicado em:	American Chemical Society
Assuntos:	Fischer−Tropsch synthesis Model catalysts Support effects Lewis acidity Structure−performance relationships Turnover frequency CO-FTIR spectroscopy
Endereço do item:	https://repositorio.ufrn.br/jspui/handle/123456789/29636
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spelling	ri-123456789-296362021-02-15T18:36:29Z Cobalt-catalyzed fischer–tropsch synthesis: chemical nature of the oxide support as a performance descriptor Prieto, Gonzalo Mello, Mariele I. S. de Concepción, Patricia Murciano, Raúl Pergher, Sibele Berenice Castellã Martı́nez, Agustı́n Fischer−Tropsch synthesis Model catalysts Support effects Lewis acidity Structure−performance relationships Turnover frequency CO-FTIR spectroscopy The effect of the chemical nature of the oxide support on the performance of cobalt Fischer–Tropsch catalysts is investigated. A series of supports is synthesized via monolayer coverage of porous γ-Al2O3 with various oxides representative of a wide range of Lewis acid–base character, as quantified by UV–vis spectroscopy coupled to alizarin adsorption. Incorporation of cobalt (20 wt %) results in model catalysts with identical porosities and similar Co particle sizes (>10 nm), allowing the study of support effects without overlap from diffusional or particle size factors. Under realistic reaction conditions, the initial TOF scales with the acidity of the oxide support, whereas the cobalt time yield and selectivity to industrially relevant C13+ hydrocarbons show a volcano dependence, with a maximum at an intermediate acid–base character. As inferred from in situ CO-FTIR, “selective” blockage of a few cobalt sites, though crucial for CO hydrogenation, by atoms from basic oxides and “unselective” site blockage via decoration of Co nanoparticles (strong metal–support interaction) with acidic, reducible oxides cause a decrease in reaction rate for supports with pronounced alkaline and acidic character, respectively. The extent of secondary isomerization reactions of α-olefin products, of relevance for chain reinsertion processes and product selectivity, also correlates with the support acidity. For a TiOx/Al2O3 as support, a remarkable C13+ productivity exceeding 0.09 molC gCo–1 h–1 is achieved, owing to the combination of optimal activity and selectivity. These results provide a unifying view of the support effects over a considerably broad study space and delineate a blueprint toward advanced Fischer–Tropsch catalysts. 2020-07-15T02:25:19Z 2020-07-15T02:25:19Z 2015-04-20 article PRIETO, Gonzalo; MELLO, Mariele I. S. de; CONCEPCIÓN, Patricia; MURCIANO, Raúl; PERGHER, Sibele Berenice Castellã; MARTÍNEZ, Agustı́n. Cobalt-Catalyzed Fischer–Tropsch Synthesis: chemical nature of the oxide support as a performance descriptor. Acs Catalysis, [s.l.], v. 5, n. 6, p. 3323-3335, 20 abr. 2015. ISSN 2155-5435 versão online. Disponível em: https://pubs.acs.org/doi/10.1021/acscatal.5b00057. Acesso em 14 jul. 2020. https://doi.org/10.1021/acscatal.5b00057 2155-5435 (online) https://repositorio.ufrn.br/jspui/handle/123456789/29636 10.1021/acscatal.5b00057 en Attribution-NonCommercial-NoDerivs 3.0 Brazil http://creativecommons.org/licenses/by-nc-nd/3.0/br/ application/pdf American Chemical Society
institution	Repositório Institucional
collection	RI - UFRN
language	English
topic	Fischer−Tropsch synthesis Model catalysts Support effects Lewis acidity Structure−performance relationships Turnover frequency CO-FTIR spectroscopy
spellingShingle	Fischer−Tropsch synthesis Model catalysts Support effects Lewis acidity Structure−performance relationships Turnover frequency CO-FTIR spectroscopy Prieto, Gonzalo Mello, Mariele I. S. de Concepción, Patricia Murciano, Raúl Pergher, Sibele Berenice Castellã Martı́nez, Agustı́n Cobalt-catalyzed fischer–tropsch synthesis: chemical nature of the oxide support as a performance descriptor
description	The effect of the chemical nature of the oxide support on the performance of cobalt Fischer–Tropsch catalysts is investigated. A series of supports is synthesized via monolayer coverage of porous γ-Al2O3 with various oxides representative of a wide range of Lewis acid–base character, as quantified by UV–vis spectroscopy coupled to alizarin adsorption. Incorporation of cobalt (20 wt %) results in model catalysts with identical porosities and similar Co particle sizes (>10 nm), allowing the study of support effects without overlap from diffusional or particle size factors. Under realistic reaction conditions, the initial TOF scales with the acidity of the oxide support, whereas the cobalt time yield and selectivity to industrially relevant C13+ hydrocarbons show a volcano dependence, with a maximum at an intermediate acid–base character. As inferred from in situ CO-FTIR, “selective” blockage of a few cobalt sites, though crucial for CO hydrogenation, by atoms from basic oxides and “unselective” site blockage via decoration of Co nanoparticles (strong metal–support interaction) with acidic, reducible oxides cause a decrease in reaction rate for supports with pronounced alkaline and acidic character, respectively. The extent of secondary isomerization reactions of α-olefin products, of relevance for chain reinsertion processes and product selectivity, also correlates with the support acidity. For a TiOx/Al2O3 as support, a remarkable C13+ productivity exceeding 0.09 molC gCo–1 h–1 is achieved, owing to the combination of optimal activity and selectivity. These results provide a unifying view of the support effects over a considerably broad study space and delineate a blueprint toward advanced Fischer–Tropsch catalysts.
format	article
author	Prieto, Gonzalo Mello, Mariele I. S. de Concepción, Patricia Murciano, Raúl Pergher, Sibele Berenice Castellã Martı́nez, Agustı́n
author_facet	Prieto, Gonzalo Mello, Mariele I. S. de Concepción, Patricia Murciano, Raúl Pergher, Sibele Berenice Castellã Martı́nez, Agustı́n
author_sort	Prieto, Gonzalo
title	Cobalt-catalyzed fischer–tropsch synthesis: chemical nature of the oxide support as a performance descriptor
title_short	Cobalt-catalyzed fischer–tropsch synthesis: chemical nature of the oxide support as a performance descriptor
title_full	Cobalt-catalyzed fischer–tropsch synthesis: chemical nature of the oxide support as a performance descriptor
title_fullStr	Cobalt-catalyzed fischer–tropsch synthesis: chemical nature of the oxide support as a performance descriptor
title_full_unstemmed	Cobalt-catalyzed fischer–tropsch synthesis: chemical nature of the oxide support as a performance descriptor
title_sort	cobalt-catalyzed fischer–tropsch synthesis: chemical nature of the oxide support as a performance descriptor
publisher	American Chemical Society
publishDate	2020
url	https://repositorio.ufrn.br/jspui/handle/123456789/29636
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Cobalt-catalyzed fischer–tropsch synthesis: chemical nature of the oxide support as a performance descriptor

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