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3 results on '"Poon, Po Shan"'

1. K- and Cu-doped CaTiO3-based nanostructured hollow spheres as alternative catalysts to produce fatty acid ethyl esters as potential biodiesel

Author

Lanfredi, Silvania [UNESP], Matos, Juan, Silva, Suzane Rosa da [UNESP], Djurado, Elisabeth, Sadouki, Ahmed S., Chouaih, Abdelkader, Poon, Po Shan, González, Eduardo René Pérez [UNESP], Nobre, Marcos Augusto de Lima [UNESP], and Universidade Estadual Paulista (Unesp)

Subjects
CaTiO3-based catalysts, K- and Cu-doping, FAEE´s synthesis, Ultrasonic spray pyrolysis, Hollow spheres
Abstract

Submitted by Silvania Lanfredi (silvania.lanfredi@unesp.br) on 2021-11-23T12:31:09Z No. of bitstreams: 1 paper uncorrected proof.pdf: 3205049 bytes, checksum: 1b16f52b6136ce7d703c02289d2b15e3 (MD5) Approved for entry into archive by ALESSANDRA KUBA OSHIRO ASSUNÇÃO (alessandra@fct.unesp.br) on 2021-11-23T13:46:36Z (GMT) No. of bitstreams: 1 lanfredi_s_postprint_prud_kand.pdf: 3205049 bytes, checksum: 1b16f52b6136ce7d703c02289d2b15e3 (MD5) Made available in DSpace on 2021-11-23T13:46:36Z (GMT). No. of bitstreams: 1 lanfredi_s_postprint_prud_kand.pdf: 3205049 bytes, checksum: 1b16f52b6136ce7d703c02289d2b15e3 (MD5) Previous issue date: 2020-04-12 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) New functional polycation oxide-type catalysts were synthesized by the ultrasonic spray-pyrolysis method. The catalytic activity in the production of fatty acid ethyl esters (FAEE´s) using soybean oil was studied. Catalysts are conformed by nanostructured hollow spheres of low density with a stoichiometric formula Ca1-KxTiCux/2O3. The influence of the substitutional ratio (x) upon the catalytic activity was verified. The Ca1-xKxTiCux/2O3 sample with x=0.3 showed the highest activity with a yield up to 89 % to produce fatty acid ethyl esters (FAEE´s) after 24h reaction using 15wt.% catalysts, 120°C and 40bars. The enhancement in the activity was ascribed to the substitution of the Ca+2 sites by K+ and Ti+4 by Cu+2 and to the hollow morphology favoring a more effective interaction between the soybean oil and the active basic sites of the catalysts. São Paulo State University (Unesp), School of Technology and Sciences, Presidente Prudente, SP Instituto de Ciencias Químicas Aplicadas, Facultad de Ingeniería, Universidad Autónoma de Chile, 8900000 Santiago, Chile Université Grenoble Alpes, LEPMI, 1130 rue de la Piscine, F-38402 St Martin d'Hères, France CNRS, LEPMI, F-38000 Grenoble, France Laboratory of Technology and Solid Properties (LTPS), Faculty of Sciences and Technology, Abdelhamid Ibn Badis University, Mostaganem, 27000, Algeria Unidad de Desarrollo Tecnológico (UDT), Universidad de Concepción, Barrio Universitario s/n, Concepción, Chile FAPESP: 07/03510-9 FAPESP: 14/11189-0 FAPESP: 19/06623-6 FAPESP: 02/05997-9

Published
2020

3. Enhancing electrochemical capacitor performance of N-doped tannin-derived carbons by hydrothermal treatment in ammonia.

Author

Pinto-Burgos, Oscar, Castro-Gutiérrez, Jimena, Poon, Po Shan, Izquierdo, Maria T., Celzard, Alain, Fierro, Vanessa, and Matos, Juan

Subjects
*SUPERCAPACITORS, *TANNINS, *CARBON-based materials, *DOPING agents (Chemistry), *AMMONIA, *HYDROTHERMAL carbonization
Abstract

This study demonstrates that ammonia concentration when doping carbons using hydrothermal treatment has crucial impact on textural properties. The latter translates into an improvement of the electrochemical performance of carbon materials, when used into electrochemical capacitors, especially at high-rate performance. Nitrogen-doped carbons were synthesized by subjecting tannin to hydrothermal carbonization in ammonia solutions of varying concentrations. After carbonization and CO 2 activation, the as-produced activated carbons (ACs) were tested as electrodes for electrochemical capacitors in symmetric configuration using 1 M H 2 SO 4 as aqueous electrolyte. Interestingly, ammonia concentration during the hydrothermal synthesis step did not significantly affect the final N content (ca. 3 and 4 at. %) nor the nitrogen and oxygen functionalities on the surface. However, the use of ammonia had crucial impact on the textural properties developed by CO 2 activation, and therefore on the electrochemical performance of the ACs. The best-performing N-doped AC showed specific electrode capacitance values, based on carbon material, of 212 F g−1 at 0.5 A g−1 and outstanding capacitance retention of ca. 71 % at 40 A g−1. It also showed high cycling stability, with capacitance retention of ca. 96 % after 30,000 cycles. Furthermore, this AC outperformed similar reported materials, achieving a specific energy of 4.6 W h kg−1 at 12.1 kW kg−1. [Display omitted] • Nitrogen doping through ammonia enhances electrochemical properties. • Ammonia concentration does not significantly affect N content or surface chemistry. • Ammonia concentration affects textural properties, boosted post-CO 2 activation. • N-doped tannin-derived carbons exhibit great performance even at high-power demand.. [ABSTRACT FROM AUTHOR]

Published
2024
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