scholarly journals Mechanistic Insights for Dry Reforming of Methane on Cu/Ni Bimetallic Catalysts: DFT-Assisted Microkinetic Analysis for Coke Resistance

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1043
Author(s):  
Ahmed Omran ◽  
Sun Hee Yoon ◽  
Murtaza Khan ◽  
Minhaj Ghouri ◽  
Anjaneyulu Chatla ◽  
...  
Keyword(s):  
Energy Barrier ◽  
Density Functional ◽  
Carbon Deposition ◽  
Bimetallic Catalyst ◽  
Dry Reforming ◽  
Coke Deposition ◽  
Dry Reforming Of Methane ◽  
Catalyst Stability ◽  
Effect Of Temperature ◽  
Elimination Mechanism

Density functional theory (DFT) calculations have been utilized to evaluate the complete reaction mechanism of methane dry reforming (DRM) over Ni2Cu (111) bimetallic catalyst. The detailed catalytic cycle on Ni2Cu (111) catalyst demonstrated superior coke resistance compared to pure Ni (111) and Ni2Fe (111) reported in the literature. Doping Cu in the Ni–Ni network enhanced the competitive CH oxidation by both atomic O and OH species with the latter having only 0.02 eV higher than the 1.06 eV energy barrier required for CH oxidation by atomic O. Among the C/CH oxidation pathways, C* + O* → CO (g) was the most favorable with an energy barrier of 0.72 eV. This was almost half of the energy barrier required for the rate-limiting step of CH decomposition (1.40 eV) and indicated enhanced coke deposition removal. Finally, we investigated the effect of temperature (800~1000 K) on the carbon deposition and elimination mechanism over Ni2Cu (111) catalyst. Under those realistic DRM conditions, the calculations showed a periodic cycle of simultaneous carbon deposition and elimination resulting in improved catalyst stability.

scholarly journals Catalytic Performance of Metal Oxides Promoted Nickel Catalysts Supported on Mesoporous γ-Alumina in Dry Reforming of Methane

Processes ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 522
Author(s):  
Anis H. Fakeeha ◽  
Abdulaziz A. Bagabas ◽  
Mahmud S. Lanre ◽  
Ahmed I. Osman ◽  
Samsudeen O. Kasim ◽  
...  
Keyword(s):  
Metal Oxides ◽  
Nickel Catalysts ◽  
Catalytic Performance ◽  
Dry Reforming ◽  
Coke Deposition ◽  
Dry Reforming Of Methane ◽  
Catalyst Stability ◽  
Incipient Wetness Impregnation ◽  
Impregnation Method ◽  
Ni Catalysts

Dry reforming of CH4 was conducted over promoted Ni catalysts, supported on mesoporous gamma-alumina. The Ni catalysts were promoted by various metal oxides (CuO, ZnO, Ga2O3, or Gd2O3) and were synthesized by the incipient wetness impregnation method. The influence of the promoters on the catalyst stability, coke deposition, and H2/CO mole ratio was investigated. Stability tests were carried out for 460 min. The H2 yield was 87% over 5Ni+1Gd/Al, while the CH4 and CO2 conversions were found to decrease in the following order: 5Ni+1Gd/Al > 5Ni+1Ga/Al > 5Ni+1Zn/Al > 5Ni/Al > 5Ni+1Cu/Al. The high catalytic performance of 5Ni+1Gd/Al, 5Ni+1Ga/Al, and 5Ni+1Zn/Al was found to be closely related to their contents of NiO species, which interacted moderately and strongly with the support, whereas free NiO in 5Ni+1Cu/Al made it catalytically inactive, even than 5Ni/Al. The 5Ni+1Gd/Al catalyst showed the highest CH4 conversion of 83% with H2/CO mole ratio of ~1.0.

scholarly journals Experimental and computational investigation on underlying factors promoting high coke resistance in NiCo bimetallic catalysts during dry reforming of methane

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tinnakorn Saelee ◽  
Mongkol Lerdpongsiripaisarn ◽  
Meena Rittiruam ◽  
Siriwimol Somdee ◽  
Anchittha Liu ◽  
...  
Keyword(s):  
Density Functional ◽  
High Stability ◽  
Bimetallic Catalyst ◽  
Diffusion Rate ◽  
High Surface ◽  
Dry Reforming ◽  
Dry Reforming Of Methane ◽  
Computational Techniques ◽  
Comparable Amount ◽  
Monometallic Catalysts

AbstractGlobal warming remains one of the greatest challenges. One of the most prominent solutions is to close the carbon cycle by utilizing the greenhouse gas: CO2, and CH4, as a feedstock via the dry reforming of methane (DRM). This work provided an insight into how the NiCo bimetallic catalyst can perform with high stability against coking during DRM compared to the Ni and Co monometallic catalysts, in which the experimental and computational techniques based on density functional theory were performed. It was found that the high stability against coking found on the NiCo surface can be summarized into two key factors: (1) the role of Co weakening the bond between a Ni active site and coke (2) significantly high surface coke diffusion rate on NiCo. Moreover, the calculation of the surface fraction weighted rate of coke diffusion which modeled the real NiCo particle into four regions: Ni-dominant, Co-dominant, NiCo-dominant, and the mixed region consisting a comparable amount of the former there regions, have shown that the synthesis of a NiCo particle should be dominated with NiCo region while keeping the Ni-dominant, and Co-dominant regions to be as low as possible to facilitate coke diffusion and removal. Thus, to effectively utilize the coke-resistant property of NiCo catalyst for DRM, one should together combine its high coke diffusion rate with coke removal mechanisms such as oxidation or hydrogenation, especially at the final diffusion site, to ensure that there will not be enough coke at the final site that will cause back-diffusion.

scholarly journals Performance Analysis of TiO2-Modified Co/MgAl2O4 Catalyst for Dry Reforming of Methane in a Fixed Bed Reactor for Syngas (H2, CO) Production

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3347
Author(s):  
Arslan Mazhar ◽  
Asif Hussain Khoja ◽  
Abul Kalam Azad ◽  
Faisal Mushtaq ◽  
Salman Raza Naqvi ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Fixed Bed ◽  
Catalytic Performance ◽  
Dry Reforming ◽  
Fixed Bed Reactor ◽  
Dry Reforming Of Methane ◽  
Catalyst Stability ◽  
Feed Ratio ◽  
Catalyst Loading ◽  
Impregnation Method

Co/TiO2–MgAl2O4 was investigated in a fixed bed reactor for the dry reforming of methane (DRM) process. Co/TiO2–MgAl2O4 was prepared by modified co-precipitation, followed by the hydrothermal method. The active metal Co was loaded via the wetness impregnation method. The prepared catalyst was characterized by XRD, SEM, TGA, and FTIR. The performance of Co/TiO2–MgAl2O4 for the DRM process was investigated in a reactor with a temperature of 750 °C, a feed ratio (CO2/CH4) of 1, a catalyst loading of 0.5 g, and a feed flow rate of 20 mL min−1. The effect of support interaction with metal and the composite were studied for catalytic activity, the composite showing significantly improved results. Moreover, among the tested Co loadings, 5 wt% Co over the TiO2–MgAl2O4 composite shows the best catalytic performance. The 5%Co/TiO2–MgAl2O4 improved the CH4 and CO2 conversion by up to 70% and 80%, respectively, while the selectivity of H2 and CO improved to 43% and 46.5%, respectively. The achieved H2/CO ratio of 0.9 was due to the excess amount of CO produced because of the higher conversion rate of CO2 and the surface carbon reaction with oxygen species. Furthermore, in a time on stream (TOS) test, the catalyst exhibited 75 h of stability with significant catalytic activity. Catalyst potential lies in catalyst stability and performance results, thus encouraging the further investigation and use of the catalyst for the long-run DRM process.

Co–Ni alloy supported on CeO2 as a bimetallic catalyst for dry reforming of methane

2020 ◽  
Vol 45 (11) ◽  
pp. 6538-6548 ◽  
Author(s):  
Yusan Turap ◽  
Iwei Wang ◽  
Tiantian Fu ◽  
Yongming Wu ◽  
Yidi Wang ◽  
...  
Keyword(s):  
Bimetallic Catalyst ◽  
Dry Reforming ◽  
Dry Reforming Of Methane ◽  
Ni Alloy

scholarly journals Effect of La2O3 as a Promoter on the Pt,Pd,Ni/MgO Catalyst in Dry Reforming of Methane Reaction

Catalysts ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 750 ◽  
Author(s):  
Ali M. A. Al-Najar ◽  
Faris A. J. Al-Doghachi ◽  
Ali A. A. Al-Riyahee ◽  
Yun Hin Taufiq-Yap
Keyword(s):  
Carbon Deposition ◽  
Dry Reforming ◽  
Dry Reforming Of Methane ◽  
Precipitation Method ◽  
Gravimetric Analysis ◽  
Bet Method ◽  
Spent Catalysts ◽  
Ft Ir ◽  
Co Precipitation ◽  
Surfactant Assisted

Pt,Pd,Ni/MgO, Pt,Pd,Ni/Mg0.97La3+0.03O, Pt,Pd,Ni/Mg0.93La3+0.07O, and Pt,Pd,Ni/Mg0.85La3+0.15O (1% of each of the Ni, Pd, and Pt) catalysts were prepared by a surfactant-assisted co-precipitation method. Samples were characterized by the XRD, XPS, XRF, FT-IR, H2-TPR, TEM, the Brunauer–Emmett–Teller (BET) method, and TGA and were tested for the dry reforming of methane (DRM). TEM and thermal gravimetric analysis (TGA) methods were used to analyze the carbon deposition on spent catalysts after 200 h at 900 °C. At a temperature of 900 °C and a 1:1 CH4:CO2 ratio, the tri-metallic Pt,Pd,Ni/Mg0.85La3+0.15O catalyst with a lanthanum promoter showed a higher conversion of CH4 (85.01%) and CO2 (98.97%) compared to the Ni,Pd,Pt/MgO catalysts in the whole temperature range. The selectivity of H2/CO decreased in the following order: Pt,Pd,Ni/Mg0.85La3+0.15O > Pt,Pd,Ni/Mg0.93La3+0.07O > Pt,Pd,Ni/Mg0.97La3+0.03O > Ni,Pd,Pt/MgO. The results indicated that among the catalysts, the Pt,Pd,Ni/Mg0.85La23+0.15O catalyst exhibited the highest activity, making it the most suitable for the dry reforming of methane reaction.

scholarly journals One-Step Synthesis of Highly Dispersed and Stable Ni Nanoparticles Confined by CeO2 on SiO2 for Dry Reforming of Methane

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5956
Author(s):  
Chengyang Zhang ◽  
Renkun Zhang ◽  
Hui Liu ◽  
Qinhong Wei ◽  
Dandan Gong ◽  
...  
Keyword(s):  
Carbon Deposition ◽  
Combustion Method ◽  
Dry Reforming ◽  
Dry Reforming Of Methane ◽  
Solution Combustion ◽  
Spatial Confinement ◽  
Oxide Interfaces ◽  
Highly Dispersed ◽  
One Step ◽  
The One

Sintering and carbon deposition are the two main ways to deactivate Ni-based catalysts during methane reforming. Herein, a stable Ni-CeO2/SiO2(CSC) catalyst was prepared by a one-step colloidal solution combustion method (CSC) and used for dry reforming of methane. In the catalyst, the small Ni particles were confined by CeO2 particles and highly dispersed on the surface of SiO2, forming a spatial confinement structure with a rich Ni-CeO2 interface in the catalyst. The Ni-CeO2/SiO2(CSC) catalyst prepared by the one-step CSC method exhibited superior activity at 700 °C during dry reforming of methane, and the performance of the catalyst was stable after 20 h of reaction with only a small amount of carbon deposition present (1.8%). Due to the spatial confinement effect, Ni was stable and less than 5 nm during reaction. The small Ni particle size and rich Ni-CeO2 interface reduced the rate of carbon deposition. This colloidal combustion method could be applied to prepare stable metal-based catalysts with rich metal–oxide interfaces for high-temperature reactions.

scholarly journals Factors affecting the long-term stability of mesoporous nickel-based catalysts in combined steam and dry reforming of methane

2016 ◽  
Vol 6 (12) ◽  
pp. 4616-4631 ◽  
Author(s):  
K. Jabbour ◽  
N. El Hassan ◽  
A. Davidson ◽  
S. Casale ◽  
P. Massiani
Keyword(s):  
Dry Reforming ◽  
Coke Deposition ◽  
Dry Reforming Of Methane ◽  
One Pot ◽  
Factors Affecting ◽  
Term Stability ◽  
Long Term Stability ◽  
Highly Efficient ◽  
One Pot Synthesis

Direct “one-pot” synthesis is highly efficient to obtain performing mesoporous Ni–Al2O3catalysts able to resist deactivation by sintering and coke deposition during CH4reforming by CO2and H2O to produce “metgas”.

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