Catalisadores Ni/Al2O3 promovidos com molibdênio para a reação de reforma a vapor de metano

Maluf, S.S.; Assaf, Elisabete Moreira; Assaf, José Mansur

doi:10.1590/s0100-40422003000200007

Cited by 6 publications

(4 citation statements)

References 8 publications

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“…All of the methane oxidations are possible (eqs 4-11) at any temperature. All of the steam reformings (eqs 12 and 13) become possible above 957 K. To make dry reforming possible, CO 2 reforming (eqs 14-18), decreasing the CO 2 quantity as the final product in ATR, must work between 966 and 1419 K. Above 1005 K, the reactions between methane and carbon monoxide (eqs [19][20][21][22] are preferred, provoking the formation of coke, which is why working at higher temperatures is recommended. The partial regeneration of the catalyst through coke elimination (eqs 23-27) is made much easier when performed above 980 K. The CO 2 disproportionalization easily occurs at any temperature (eq 28).…”

Section: ' Materials and Methodsmentioning

confidence: 99%

“…There was no evidence of a γ-alumina transition to δ-alumina. XRD analysis of the catalyst, performed after the calcination step, identified nickel oxide as well as nickel aluminates NiAl 2 O 4 (2θ = 37.08 and 59.78) 22 and NiAl 10 O 16 (2θ = 19.18, 45.58, and 66.88). After reduction step, the analysis also identified the presence of reduced nickel (2θ = 44.58 and 51.88; Figure 2).…”

Section: ' Introductionmentioning

confidence: 99%

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Kinetic-Operational Mechanism to Autothermal Reforming of Methane

Souza¹,

Maciel²,

Cavalcanti-Filho³

et al. 2010

Ind. Eng. Chem. Res.

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A reforming experiment was performed using a nickel catalyst, with the goal of suggesting a mechanism for the autothermal reforming of methane (ATR), under thermally neutral conditions. To bring the process to future scale-up at a fixed-bed reactor, kinetic-operational evaluations were made while taking into account the parameters of the gas phase flow and the temperature. From these evaluations, based on conversions, yields, and selectivities, it was possible to develop a novel approach to a descriptive mathematical model of the process behavior. A thermodynamic evaluation of the ATR was performed to measure the effects of operational conditions (temperature, pressure, and composition of the feed), in relation to the established limit values of the chemical equilibrium.

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Section: ' Materials and Methodsmentioning

confidence: 99%

Section: ' Introductionmentioning

confidence: 99%

Kinetic-Operational Mechanism to Autothermal Reforming of Methane

Souza¹,

Maciel²,

Cavalcanti-Filho³

et al. 2010

Ind. Eng. Chem. Res.

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show abstract

“…): γ-Al 2 O 3 (2θ 19.4 • , 31.9 • , 37.6 • , 39.5 • , 45.9 • , 60.9 • , 67.0 • ), Ni (2θ 44.4 • , 51.7 • , 76.3 • , 92.9 • , 98.6 • ), NiO (2θ 37.2 • , 62.9 • , 43.30 • , 62.9 • , 75.4 • , 79.4 • , 95.0 • ), the spinel NiAl 2 O 4 (2θ 19.1 • , 31.4 • , 45.0 • , 59.7 • )[24,25], by the textural characteristics (BET-N 2 ), specific surface area, Sp γ-Al2O3 = 174 m 2 g −1 and Sp Ni/γ-Al2O3 = 165 m 2 g −1 ), and pore volume, Vp γ-Al2O3 = 0.71 cm 3 g −1 e Vp Ni/γ-Al2O3 = 0.65 cm 3 g −1 .…”

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confidence: 99%

Performance of Alternative Methane Reforms Based on Experimental Kinetic Evaluation and Simulation in a Fixed Bed Reactor

et al. 2021

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A comparative evaluation of alternative methane reforming processes as an option to steam reforming was performed by carrying out simulations of operations in a fixed bed reactor with a Ni (4.8 wt.%/γ-Al2O3) catalyst at 1023 K under 1.0 bar. Methane reforms, including processing with carbon dioxide (DRM, CH4/CO2), autothermal reform (ATRM, CH4/H2O/O2), and combined reform (CRM, CH4/CO2/H2O/O2) had their operations predicted based on experimental data developed to represent their kinetic behavior, formalized with mechanisms and parametric quantifications. The performance of fixed bed reactor operations for methane conversions occurred with different reaction rates in the three alternative processes, and comparatively the orders of magnitude were 102, 10−1, and 10−4 in CRM, ATRM, and DRM, respectively. According to each process, the methane conversions were oriented towards the predominant productions of hydrogen or carbon monoxide, indicating the kinetic selectivities of H2, 86.1% and CO, 59.2% in CRM and DRM, respectively. Considering the possibility of catalyst deactivation by carbon deposition, its predicted yields are low due to the slow stages of its production and due to its simultaneous consumption through interactions with O2, CO2, and H2O, reflecting favorably in additional productions of H2 and CO.

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“…Diversos catalisadores têm sido utilizados para a reforma a vapor de hidrocarbonetos, alcoóis e ácidos carboxílicos, e entre eles destacam-se os materiais a base de níquel (Ni) (BUFFONI et al, 2009;RIOCHE et al, 2005), devido principalmente a sua viabilidade econômica comparado com os metais nobres, bem como sua comprovada eficiência catalítica em processos de reforma (SEHESTED, 2006). Entretanto, um dos maiores desafios na utilização desses materiais está relacionado a sua rápida desativação, resultante da deposição de resíduos carbonáceos em sua superfície e a sinterização da fase ativa, a qual pode levar a aglomeração das partículas de Ni afetando de maneira significativa a atividade catalítica (MALUF et al, 2003). É importante ressaltar que os principais fatores que levam a deposição de coque são a estrutura superficial e a acidez dos catalisadores (HU; RUCKENSTEIN, 2002).…”

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Catalisadores de Ni promovidos com Mg e Nb para reforma a vapor do ácido acético como molécula modelo do bio-óleo

Nogueira¹

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The development of technologies for generating hydrogen in Brazil has become an important factor because it is a source of clean fuel which can be obtained from different renewable raw materials. Among these technologies, the steam reforming of bio-oil from the pyrolysis of biomass can be highlighted. The bio-oil is a complex mixture of different oxygenated organic compounds such as aldehydes, carboxylic acids, ketones, carbohydrates and alcohols with acetic acid being one of the major compounds (~12-15%), which may be used as a model molecule of bio-oil steam reforming reactions. However, the steam reforming of acetic acid presents some difficulties, such as coke formation on the surface of the catalysts, which may result in its deactivation. Thus, this work aimed to develop catalysts based on nickel (Ni) promoted with magnesium (Mg) and niobia (Nb) supported on alumina (γ-Al 2 O 3), for application in steam reforming of acetic acid in order to minimize the formation of carbonaceous residues, as well as increase the activity and selectivity for hydrogen. For this purpose, initially three catalysts were synthesized with different Ni content, (10, 15 and 20%), and the catalyst with 15% Ni mass showed the best activity and selectivity for the steam reforming of acid acetic acid. From the best Ni loading, was added four different concentrations of Mg and Nb, 1%; 2.5%; 5% and 10% by weight. Among the catalysts promoted with Mg, the catalyst with 5% Mg (15% Ni5% Mg/Al) at a temperature of 600 °C, showed a 96% conversion of acetic acid, with selectivity to hydrogen of around 65 %. In addition, this catalyst showed lower rate of coke formation and lower Ni particle size compared to the non-promoted catalyst (15% Ni/Al), showing that the addition of Mg can prevent sintering of Ni particles. Among the catalysts promoted with Nb, the catalyst 15% Ni 2, 5% Nb/Al showed higher selectivity to hydrogen (~73%) at 600 o C compared to the others. Despite having a larger particle size, the addition of Nb increased the capacity of decomposition of methane from of the decomposition reaction and methanation of acetic acid favoring the production of hydrogen and promoted the formation of nanostructures. Thus, the addition of catalytic promoters can contribute to the increase in hydrogen production, either by a reduction in carbonaceous deposits or the modification of structures formed on the surface of the materials.

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Catalisadores Ni/Al2O3 promovidos com molibdênio para a reação de reforma a vapor de metano

Cited by 6 publications

References 8 publications

Kinetic-Operational Mechanism to Autothermal Reforming of Methane

Kinetic-Operational Mechanism to Autothermal Reforming of Methane

Performance of Alternative Methane Reforms Based on Experimental Kinetic Evaluation and Simulation in a Fixed Bed Reactor

Catalisadores de Ni promovidos com Mg e Nb para reforma a vapor do ácido acético como molécula modelo do bio-óleo

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