Banca de DEFESA: IANA GABRIELA COSTA PEREIRA
Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.STUDENT : IANA GABRIELA COSTA PEREIRA
DATE: 26/04/2024
TIME: 15:00
LOCAL: SALA DE SEMINÁRIOS DO IQ
TITLE:
SYNTHESIS AND CHARACTERIZATION OF Ni/La2O3 CATALYSTS MODIFIED WITH CERIUM OR IRON APPLIED IN THE DRY REFORMING OF METHANE IN THE PRESENCE OF OXYGEN
KEY WORDS:
Syngas, Nickel, Cerium,Iron,Lanthanum,Methane reform.
PAGES: 105
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Inorgânica
SPECIALTY: Físico Química Inorgânica
SUMMARY:
The worsening of environmental problems associated with the decrease in fossil fuel reserves has brought into vogue the need to use less polluting and renewable sources. In this scenario, hydrogen emerges as a promising alternative and natural gas is one of its possible raw material sources. Methane, the main constituent of natural gas, can react with other substances and form synthesis gas (CO+H2), through catalyzed methane reforming reactions. This work is aimed at the synthesis of nickel-based catalysts and
lanthanum, NLA, NCL and NFL, with respectively 24%, 17% and 12% of nickel in their composition, synthesized by the wet impregnation method for application in the methane reforming reaction in the presence of oxygen, with the aim of to evaluate the influence of cerium and iron on catalytic performance. The materials were characterized by X-ray diffraction techniques of calcined, reduced and post-catalytic test samples, thermogravimetric analysis (TG-O2), reduction with hydrogen at programmed temperature (TPR), determination of surface area by the BET method, surface reaction to temperature-programmed (TPSR), temperature programmed oxidation (TPO) after TPSR, were tested in the reaction through a 20-hour catalytic test and TPO was carried out after the catalytic test. It was verified that the insertion of iron and cerium contents in the structure enabled the formation of phases segregated from their respective oxides and variation in the reductive behaviour of the samples. The perovskite phase was identified in all samples under study after the calcination process of the precursors. The sample with cerium content in its composition (Ni/CexOy/La2O3) showed conversion and selectivity close to the sample without its presence, which may be related to the participation of cerium oxides in the formation mechanism of metallic nickel species. The Ni/CexOy/La2O3 catalyst presented medium-size values
of smaller crystals, which may have promoted the highest conversion values of CH4 and CO2. We found that the Ni-Fe/La2O3 sample presented higher values of average crystal size, which may be related to the interaction of nickel and iron species, which reduces the availability of active sites and consequently
reflects on conversion and selectivity values. The amount of coke formed was similar for the catalysts under study, and there was no evidence of deactivation of the catalysts during the 20-hour reaction, an effect which can be attributed to the presence of species based on lanthanum and cerium, which can act in the coking process. Carbon removal. The Ni/CexOy/La2O3 catalyst presented catalytic performance close to the sample with only nickel and a higher content of this element, which indicates that the insertion of cerium and the presence of its oxides contributed to the performance of this catalyst in the dry reforming of methane. In the presence of oxygen. Comparing the replacement with cerium and iron, it is clear that the presence of cerium generated a positive balance in terms of activity, selectivity and resistance to carbon deposition, while the replacement with iron brought losses in catalytic performance. The combination of the wet impregnation methodology, the presence of the perovskite phase and the participation of oxides that act as carbon scavengers allowed the formation of catalysts with good activity and catalytic stability, with emphasis on the Ni/CexOy/La2O3 sample.
COMMITTEE MEMBERS:
Presidente - 1100392 - SORAIA TEIXEIRA BRANDAO
Interna - 2494172 - LILIAN MARIA TOSTA SIMPLICIO RODRIGUES
Interno - 1673526 - MARCOS MALTA DOS SANTOS
Externo ao Programa - 1104702 - MAURICIO BRANDAO DOS SANTOS - UFBAExterno à Instituição - ROBERT NEWTON DA SILVA HENRIQUES MAGALHÃES - IFBA