An experimental and first principles DFT investigation on the effect of Cu addition to Ni/Al2O3 catalyst for the dry reforming of methane

Chatla, Anjaneyulu; Ghouri, Minhaj; Hassan, Omar Wissam El; Mohamed, Nosaiba; Prakash, Anuj; Elbashir, Nimir O.

doi:10.1016/j.apcata.2020.117699

Cited by 72 publications

(47 citation statements)

References 69 publications

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“…As a descriptor of coke resistance, the adsorption energy of the C atom indicates that the more strongly the carbon is adsorbed on a specific surface, the lower the coke resistance. The C atom preferentially adsorbed to HCP site with an E ads of −7.04 eV and is less than the E ads of −7.50 eV in a monometallic Ni catalyst [27,29,30]. This means that the Cu dopant on Ni (111) reduces coke deposition, and, as a result, it can increase the coke resistance of the catalyst surface.…”

Section: Ch 4 + Comentioning

confidence: 99%

“…The Cu/Ni (111) surface alloy was then constructed by replacing three nickel atoms in the topmost layer of Ni (111) by copper atoms (i.e., at the dopant coverage of 1/3 ML). The ratio (1/3 ML) was chosen from the experimental results [27] as having better carbon gasification and suitable activation energies for the CH4 dehydrogenations, compared to high Cu loading (1.0 ML) and low Cu loading (1/9ML). The slab model surface is shown in Figure 1.…”

Section: Computational Detailsmentioning

confidence: 99%

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

et al. 2020

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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.

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Section: Ch 4 + Comentioning

confidence: 99%

Section: Computational Detailsmentioning

confidence: 99%

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

et al. 2020

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“…The addition of an appropriate amount of Cu increases the energy barrier for CH* cracking and makes C* more easily oxidized. And the result was confirmed by experiments 38,39 . However, the accumulation of carbon is rarely considered and the detailed mechanism of Rh‐doped Ni‐based catalyst is lacking.…”

Section: Introductionmentioning

confidence: 74%

Comparative density functional theory study of carbon formation and removal mechanism on Rh modified Ni‐based catalyst in theCH₄/CO₂reforming

et al. 2021

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Summary Rh catalyst shows promising performance for coke resistance in the CH4/CO2 reforming reaction. In this study, a single atom Rh was added to the surface of Ni(111) by doping and adsorbing ways, and the performance of these surfaces was compared with the pure Ni(111) through density functional theory (DFT) calculation. The reactions related to the carbon formation were studied to obtain the favored adsorption site and dominant reaction paths on three surfaces. A good linear relationship between the charge difference and the reaction barrier was proposed. On the Ni(111) surface, the highest energy barrier of CH* oxidation and decomposition is 1.24 and 1.30 eV, respectively, thus these two reaction paths are dominant. The most favorable pathway for the Rh/Ni(111) is CH* + O* → CHO* → CO* + H*, with the highest energy barrier of 1.34 eV. However, C* is more likely to be converted into C‐C (C2) than oxidized on all three catalyst surfaces. As a result, Rh/Ni(111) surface shows better catalytic activity thermodynamically and more superior carbon deposition resistance. In general, compared with pure Ni catalyst, the modification of Rh could manipulate the reaction path of CH* consumption, which could inhibit the direct decomposition of CH*, and finally suppress the carbon deposition.

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“…where k s is the thermal conductivity of the catalyst bed and k f is the thermal conductivity of the fluid mixture. Equation (12) was solved along with boundary conditions corresponding to (i) radial symmetry, (ii) external cooling (heat transfer between the reactor and a constant temperature cooling medium), (iii) inlet temperature and (iv) open outflow:…”

Section: Heat Transport Expressionsmentioning

confidence: 99%

“…FT synthesis is a highly exothermic reaction (the total heat released per mole of CO consumed is from 140 kJ/mol to 160 kJ/mol), and therefore, efficient heat removal is one of the main considerations while designing commercial-scale FT reactors [7,8]. Uncontrollable temperature gradients lead to the formation of local hotspots, and in some cases, unstable temperature runaways, which promote methane formation, lower the selectivity of the desired hydrocarbon products and lead to fast catalyst deactivation [2,6,[9][10][11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Thermal Assessment of a Micro Fibrous Fischer Tropsch Fixed Bed Reactor Using Computational Fluid Dynamics

et al. 2020

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A two-dimensional (2D) Computational Fluid Dynamics (CFD) scale-up model of the Fischer Tropsch reactor was developed to thermally compare the Microfibrous-Entrapped-Cobalt-Catalyst (MFECC) and the conventional Packed Bed Reactor (PBR). The model implements an advanced predictive detailed kinetic model to study the effect of a thermal runaway on C5+ hydrocarbon product selectivity. Results demonstrate the superior capability of the MFECC bed in mitigating hotspot formation due to its ultra-high thermal conductivity. Furthermore, a process intensification study for radial scale-up of the reactor bed from 15 mm internal diameter (ID) to 102 mm ID demonstrated that large tube diameters in PBR lead to temperature runaway >200 K corresponding to >90% CO conversion at 100% methane selectivity, which is highly undesirable. While the MFECC bed hotspot temperature corresponded to <10 K at >30% CO conversion, attributing to significantly high thermal conductivity of the MFECC bed. Moreover, a noticeable improvement in C5+ hydrocarbon selectivity >70% was observed in the MFECC bed in contrast to a significantly low number for the PBR (<5%).

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An experimental and first principles DFT investigation on the effect of Cu addition to Ni/Al2O3 catalyst for the dry reforming of methane

Cited by 72 publications

References 69 publications

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

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

Comparative density functional theory study of carbon formation and removal mechanism on Rh modified Ni‐based catalyst in theCH₄/CO₂reforming

Thermal Assessment of a Micro Fibrous Fischer Tropsch Fixed Bed Reactor Using Computational Fluid Dynamics

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An experimental and first principles DFT investigation on the effect of Cu addition to Ni/Al2O3 catalyst for the dry reforming of methane

Cited by 72 publications

References 69 publications

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

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

Comparative density functional theory study of carbon formation and removal mechanism on Rh modified Ni‐based catalyst in theCH4/CO2reforming

Thermal Assessment of a Micro Fibrous Fischer Tropsch Fixed Bed Reactor Using Computational Fluid Dynamics

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Comparative density functional theory study of carbon formation and removal mechanism on Rh modified Ni‐based catalyst in theCH₄/CO₂reforming