Mg-promotion of Ni natural clay-supported catalysts for dry reforming of methane

Liu, Hong; Costa, Patrick Da; Taief, Haithem Bel Hadj; Benzina, Mourad; Gálvez, María Elena

doi:10.1039/c8ra02615g

Cited by 37 publications

(20 citation statements)

References 41 publications

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“…In the scenario of a TPR profile, the results of all catalysts presented a main area of interest in which several H 2 -consumption peaks can be observed in the temperature range of 500 to 700 °C. It means that the H 2 reduction of finely dispersed NiO x and/or Ni-species is in tight interaction with the catalyst support . The H 2 consumption of the produced 100CF-10NAM/PU catalyst with 5 °C/min of heating rate was obviously predominant compared to the rest of the catalysts (Figure ).…”

Section: Resultsmentioning

confidence: 71%

Fabrication of a Ceramic Foam Catalyst Using Polymer Foam Scrap via the Replica Technique for Dry Reforming

2022

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Megapores with spherical-like cells connected through windows and high porosities make up catalyst supports in the form of ceramic foams. These characteristics provide significant benefits for catalytic processes that are limited by mass or heat transport. This study focuses on the manufacture of ceramic foam using a polymeric sponge replica process and polymer foams as a template for catalyst supports, which are industrial waste from the packaging sector. To make ceramic foam catalysts, they were dipped in a catalyst solution, followed by a breakdown stage and a sintering process. Experiments focused on determinants that affect the desired characteristics of ceramic foams, such as the types of polymer foams that affect foam morphology, the rheology of catalyst solution that affects catalyst dispersion, and the polymer decomposition rate that affects catalytic performance during dry reforming of the methane process. The cell architectures of polyurethane and polyvinyl alcohol foams are attractive for catalyst support preparation because they have 98−99% porosity and typical cell sizes of 200 and 50 μm, respectively. The polyurethane performance was superior to the performance of polyvinyl alcohol in terms of higher porosity and better catalytic-solution absorption offering high catalyst active areas. The catalyst prepared from concentrated 10 wt % Ni/Al 2 O 3 −MgO (10NAM) slurry had the highest surface area (59.18 m 2 /g) and the highest metal oxide dispersion (5.65%). These results are relevant to the flow behavior of catalyst slurry which plays a key role in coating the catalyst gel on the polymer template. The thermal decomposition rate used to remove the polymer template from the catalyst structure is proportional to the ceramic foam structure (catalyst support structure). The slow decomposition rate bent and fractured foam-cell struts more than the faster rate. On the other hand, achieving good catalyst dispersion on catalyst supports necessitated a high sintering rate. When sintering was adjusted at a high sintering rate, the metal− particle dispersion was relatively high, around 7.44%, and the surface area of ceramic foam catalysts was 64.61 m 2 /g. Finally, the catalytic behavior toward hydrogen production through the dry reforming of methane using a fixed-bed reactor was evaluated under certain operating conditions.

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Section: Resultsmentioning

confidence: 71%

Fabrication of a Ceramic Foam Catalyst Using Polymer Foam Scrap via the Replica Technique for Dry Reforming

2022

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“…[50] However, the relatively short time for the ammonium vapour treatment of this method (the 10Ni (12T)/MA catalyst) can cause too strong adsorption of CO 2 during the CRM process because of the large number of the strong basic sites. [54] CRM tests over the 10Ni(xT)/MA catalysts at 620 C for 6 hours under ambient pressure were conducted to find the suitable 10Ni(xT)/MA catalyst for the CRM process. The catalytic performance was determined based on CH 4 and CO 2 conversions as well as the generated H 2 /CO ratio (Figure 7A-C).…”

Section: Resultsmentioning

confidence: 99%

“…It indicated that the strong basic sites result in far too tight adsorption of CO 2 and thus its limited reaction with CH 4 . [54] Therefore, the catalyst should be treated in the ammonium vapour until the Ni nanosheets are formed to avoid a large number of strong basic sites. Furthermore, all 10Ni(xT)/MA catalysts produced a H 2 /CO ratio of approximately 0.9, which was ascribed to a less reverse water gas shift due to the basicity of the 10Ni(xT)/MA catalysts.…”

Section: Resultsmentioning

confidence: 99%

CO₂ reforming of methane over the growth of hierarchical Ni nanosheets/Al₂O₃‐MgO synthesized via the ammonia vapour diffusion impregnation

et al. 2021

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A novel ammonia vapour diffusion-assisted impregnation technique was developed to synthesize the Al 2 O 3 -MgO-supported hierarchical Ni nanosheets. The resulting catalysts with different times for ammonia vapour treatments (at 12, 18, and 20 hours) were prepared to investigate the growth of Ni nanosheets on the catalyst surface. All catalysts were tested for CO 2 reforming of methane and a comprehensive characterization study was conducted by XRD, N 2 adsorption-desorption, H 2 -TPD, H 2 -TPR, CO 2 -TPD, and TGA. The Ni nanosheets were obtained using the ammonia vapour treatment for 20 hours, improving the selectivity toward H 2 generation without a lower CH 4 conversion. When compared to the reference catalyst prepared by a conventional impregnation method, the H 2 /CO ratio for CO 2 reforming of the methane process was enhanced by 0.35. Additionally, the carbon deposition was reduced by half using hierarchical Ni nanosheets for the CO 2 reforming of methane at 620 C for 20 hours. The mechanism of this improvement was achieved by the increase in medium basicity associated with a strong metal-support interaction that promotes the CO 2 activation-dissociation pathways, preventing carbon formation and inhibiting the reverse water gas shift.

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“…Doping a promoter element is a common way to modify the Ni catalysts to improve the carbon resistance. − It was found that the dopant of noble metals like Pt or Rh could alleviate the carbon deposition and decrease the deactivation rate, but cannot prevent the deactivation completely. − Alkali metal dopants like K could decrease the carbon deposition, whereas alkaline earth metal dopants like Mg would increase the deposition of carbon over Ni catalysts . As for other transition metals or the main-group metals, − most of them show improved carbon resistance, , but some of them show no improvement in carbon resistance or activity.…”

Section: Introductionmentioning

confidence: 99%

“…17−21 Alkali metal dopants like K could decrease the carbon deposition, 22 whereas alkaline earth metal dopants like Mg would increase the deposition of carbon over Ni catalysts. 23 As for other transition metals or the main-group metals, 24−26 most of them show improved carbon resistance, 24,25 but some of them show no improvement in carbon resistance or activity. For example, Zhu and co-workers found that the activity of the Ni/Al 2 O 3 catalyst was not improved upon the doping of Mg, and the carbon deposition even became more severe than that on the unmodified Ni/Al 2 O 3 catalyst.…”

Section: Introductionmentioning

confidence: 99%

Descriptor Design in the Computational Screening of Ni-Based Catalysts with Balanced Activity and Stability for Dry Reforming of Methane Reaction

2020

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Dry reforming of methane (DRM) is an important reaction in the actual environmental and energy crisis context. It enables the production of syngas from CO 2 and CH 4 reforming. While Ni catalyst presents a high activity regarding this process, it often suffers from deactivation. It was found that the Sn-doped Ni catalyst can avoid carbon deposition, but a decrease in DRM reactivity was also observed. In this work, we used density functional theory calculations in combination with microkinetic modeling first to understand how Sn doping affects the resistance to carbon deposition and the surface catalytic activities of Ni. Based on the understandings, we found that an ideal dopant should give rise to a proper adsorption energy of carbon such that (i) the C* formation process, e.g., CH 4 dissociation, is rate-controlling to improve the carbon resistance and (ii) relatively low dissociation barriers of CH 4 and CO 2 can be achieved to maintain a good activity. Therefore, the adsorption energy of carbon and the dissociation barriers of CH 4 and CO 2 can be utilized as descriptors for the stability and activity of Ni-based catalysts. Subsequently, we screened several metal dopants and found that the descriptors designed are capable of providing a consistent activity and stability trend with experiments reported in the literature. Therefore, our work could provide relevant guidelines to rationally design efficient catalysts for the DRM reaction.

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Mg-promotion of Ni natural clay-supported catalysts for dry reforming of methane

Cited by 37 publications

References 41 publications

Fabrication of a Ceramic Foam Catalyst Using Polymer Foam Scrap via the Replica Technique for Dry Reforming

Fabrication of a Ceramic Foam Catalyst Using Polymer Foam Scrap via the Replica Technique for Dry Reforming

CO₂ reforming of methane over the growth of hierarchical Ni nanosheets/Al₂O₃‐MgO synthesized via the ammonia vapour diffusion impregnation

Descriptor Design in the Computational Screening of Ni-Based Catalysts with Balanced Activity and Stability for Dry Reforming of Methane Reaction

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Mg-promotion of Ni natural clay-supported catalysts for dry reforming of methane

Cited by 37 publications

References 41 publications

Fabrication of a Ceramic Foam Catalyst Using Polymer Foam Scrap via the Replica Technique for Dry Reforming

Fabrication of a Ceramic Foam Catalyst Using Polymer Foam Scrap via the Replica Technique for Dry Reforming

CO2 reforming of methane over the growth of hierarchical Ni nanosheets/Al2O3‐MgO synthesized via the ammonia vapour diffusion impregnation

Descriptor Design in the Computational Screening of Ni-Based Catalysts with Balanced Activity and Stability for Dry Reforming of Methane Reaction

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CO₂ reforming of methane over the growth of hierarchical Ni nanosheets/Al₂O₃‐MgO synthesized via the ammonia vapour diffusion impregnation