scholarly journals Differences in the Nature of Active Sites for Methane Dry Reforming and Methane Steam Reforming over Nickel Aluminate Catalysts

ACS Catalysis ◽  
2016 ◽  
Vol 6 (9) ◽  
pp. 5873-5886 ◽  
Author(s):  
Jessica L. Rogers ◽  
Michael C. Mangarella ◽  
Andrew D. D’Amico ◽  
James R. Gallagher ◽  
Michael R. Dutzer ◽  
...  
Keyword(s):  
Steam Reforming ◽  
Active Sites ◽  
Dry Reforming ◽  
Methane Steam Reforming ◽  
Nickel Aluminate ◽  
Methane Dry Reforming ◽  
Methane Steam

Effect of Catalytic Distribution on the Performance of Microreactor for Hydrogen Production through Methane Steam Reforming

2010 ◽  
Vol 156-157 ◽  
pp. 873-876 ◽  
Author(s):  
Feng Wang ◽  
Zi Long An ◽  
Bo Qi ◽  
Jing Zhou
Keyword(s):  
Steam Reforming ◽  
Active Sites ◽  
Flow Direction ◽  
Space Velocity ◽  
H2 Production ◽  
Methane Steam Reforming ◽  
Reactor Performance ◽  
Methane Steam ◽  
Site Density ◽  
Availability Ratio

The effect of catalyst coating distributing on the reactor performance for methane steam reforming(MSR) was numerically investigated. In calculation, the amount catalyst loaded on the microreactor wall was fixed but the catalyst active site density was distributed according to arithmetic progression along the flow direction. Results show that it is possible to get the higher conversion of CH4 and output of H2 due to the higher availability ratio of catalyst surface active sites at this distribution. And this distribution effect is more remarkable at higher space velocity or lower reaction temperature, however, there exists an optimal distribution which can reach the highest CH4 conversion and H2 production at 900K.

Syngas production from methane steam reforming and dry reforming reactions over sintering-resistant Ni@SiO2 catalyst

2019 ◽  
Vol 46 (3) ◽  
pp. 1735-1748 ◽  
Author(s):  
Bolin Han ◽  
Fagen Wang ◽  
Linjia Zhang ◽  
Yan Wang ◽  
Weiqiang Fan ◽  
...  
Keyword(s):  
Steam Reforming ◽  
Dry Reforming ◽  
Methane Steam Reforming ◽  
Syngas Production ◽  
Methane Steam ◽  
Reforming Reactions

scholarly journals Reaction Pathway for Coke-Free Methane Steam Reforming on a Ni/CeO2 Catalyst: Active Sites and the Role of Metal–Support Interactions

ACS Catalysis ◽  
2021 ◽  
pp. 8327-8337
Author(s):  
Agustín Salcedo ◽  
Pablo G. Lustemberg ◽  
Ning Rui ◽  
Robert M. Palomino ◽  
Zongyuan Liu ◽  
...  
Keyword(s):  
Steam Reforming ◽  
Active Sites ◽  
Reaction Pathway ◽  
Methane Steam Reforming ◽  
Methane Steam ◽  
Metal Support ◽  
Metal Support Interactions

scholarly journals Reaction Pathway for Coke-Free Methane Steam Reforming on a Ni/CeO2 Catalyst: Active Sites and Role of Metal-Support Interactions

2021 ◽  
Author(s):  
Agustin Salcedo ◽  
Pablo Lustemberg ◽  
Ning Rui ◽  
Robert M. Palomino ◽  
Zongyuan Liu ◽  
...  
Keyword(s):  
High Activity ◽  
Steam Reforming ◽  
Active Sites ◽  
Density Functional ◽  
Ambient Pressure ◽  
Carbon Accumulation ◽  
Methane Steam Reforming ◽  
Severe Problem ◽  
Methane Steam ◽  
Water Activation

<p>Methane steam reforming (MSR) plays a key role in the production of syngas and hydrogen from natural gas. The increasing interest in the use of hydrogen for fuel cell applications demands the development of catalysts with high activity at reduced operating temperatures. Ni-based catalysts are promising systems because of their high activity and low cost, but coke formation generally poses a severe problem. Studies of ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) indicate that CH<sub>4</sub>/H<sub>2</sub>O gas mixtures react with Ni/CeO<sub>2</sub>(111) surfaces to form OH, CH<i><sub>x</sub></i> and CH<i><sub>x</sub></i>O at 300 K. All these species are easy to form and desorb at temperatures below 700 K when the rate of the MSR process accelerates. Density functional theory (DFT) modeling of the reaction over ceria-supported small Ni nanoparticles predicts relatively low activation barriers between 0.3–0.7 eV for the complete dehydrogenation of methane to carbon and the barrierless activation of water at interfacial Ni sites. Hydroxyls resulting from water activation allow CO formation via a COH intermediate with a barrier of about 0.9 eV, which is much lower than that through a pathway involving lattice oxygen from ceria. Neither methane nor water activation are rate-determining steps, and the OH-assisted CO formation through the COH intermediate constitutes a low-barrier pathway that prevents carbon accumulation. The interaction between Ni and the ceria support and the low metal loading are crucial for the reaction to proceed in a coke-free and efficient way. These results could pave the way for further advances in the design of stable and highly active Ni-based catalysts for hydrogen production.</p>

scholarly journals Reaction Pathway for Coke-Free Methane Steam Reforming on a Ni/CeO2 Catalyst: Active Sites and Role of Metal-Support Interactions

2021 ◽  
Author(s):  
Agustin Salcedo ◽  
Pablo Lustemberg ◽  
Ning Rui ◽  
Robert M. Palomino ◽  
Zongyuan Liu ◽  
...  
Keyword(s):  
High Activity ◽  
Steam Reforming ◽  
Active Sites ◽  
Density Functional ◽  
Ambient Pressure ◽  
Carbon Accumulation ◽  
Methane Steam Reforming ◽  
Severe Problem ◽  
Methane Steam ◽  
Water Activation

<p>Methane steam reforming (MSR) plays a key role in the production of syngas and hydrogen from natural gas. The increasing interest in the use of hydrogen for fuel cell applications demands the development of catalysts with high activity at reduced operating temperatures. Ni-based catalysts are promising systems because of their high activity and low cost, but coke formation generally poses a severe problem. Studies of ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) indicate that CH<sub>4</sub>/H<sub>2</sub>O gas mixtures react with Ni/CeO<sub>2</sub>(111) surfaces to form OH, CH<i><sub>x</sub></i> and CH<i><sub>x</sub></i>O at 300 K. All these species are easy to form and desorb at temperatures below 700 K when the rate of the MSR process accelerates. Density functional theory (DFT) modeling of the reaction over ceria-supported small Ni nanoparticles predicts relatively low activation barriers between 0.3–0.7 eV for the complete dehydrogenation of methane to carbon and the barrierless activation of water at interfacial Ni sites. Hydroxyls resulting from water activation allow CO formation via a COH intermediate with a barrier of about 0.9 eV, which is much lower than that through a pathway involving lattice oxygen from ceria. Neither methane nor water activation are rate-determining steps, and the OH-assisted CO formation through the COH intermediate constitutes a low-barrier pathway that prevents carbon accumulation. The interaction between Ni and the ceria support and the low metal loading are crucial for the reaction to proceed in a coke-free and efficient way. These results could pave the way for further advances in the design of stable and highly active Ni-based catalysts for hydrogen production.</p>

Ultra-Low Amounts of Palladium (0.005-0.05 Wt% Pd) Supported on Titania: Remarkable Low-Temperature Activity for NO Reduction with CO and Structure-Function Property Relationships in Methane Oxidation

2020 ◽  
Author(s):  
Konstantin Khivantsev ◽  
Libor Kovarik ◽  
Nicholas R. Jaegers ◽  
János Szanyi ◽  
Yong Wang
Keyword(s):  
Nitric Oxide ◽  
Carbon Monoxide ◽  
Methane Oxidation ◽  
Steam Reforming ◽  
Methane Steam Reforming ◽  
Oxide Reduction ◽  
Water Steam ◽  
Methane Steam ◽  
Anatase Titania ◽  
Nitric Oxide Reduction

<p>Atomically dispersed Pd +2 cations with ultra-dilute loading of palladium (0.005-0.05 wt%) were anchored on anatase titania and characterized with FTIR, microscopy and catalytic tests. CO infrared adsorption produces a sharp, narrow mono-carbonyl Pd(II)-CO band at ~2,130 cm<sup>-1</sup> indicating formation of highly uniform and stable Pd+2 ions on anatase titania. The 0.05 wt% Pd/TiO<sub>2</sub> sample was evaluated for methane combustion under dry and wet (industrially relevant) conditions in the presence and absence of carbon monoxide. Notably, we find the isolated palladium atoms respond dynamically upon oxygen concentration modulation (switching-on and switching off). When oxygen is removed from the wet methane stream, palladium ions are reduced to metallic state by methane and catalyze methane steam reforming instead of complete methane oxidation. Re-admission of oxygen restores Pd<sup>+2</sup> cations and switches off methane steam reforming activity. Moreover, 0.05 wt% Pd/TiO<sub>2</sub> is a competent CO oxidation catalyst in the presence of water steam with 90% CO conversion and TOF ~ 4,000 hr<sup>-1</sup> at 260 ⁰C. </p><p>More importantly, we find that diluting 0.05 wt% Pd/titania sample with titania to ultra-low 0.005 wt% palladium loading produces a remarkably active material for nitric oxide reduction with carbon monoxide under industrially relevant conditions with >90% conversion of nitric oxide at 180 ⁰C (~460 ppm NO and 150 L/g*hr flow rate in the presence of >2% water steam) and TOF ~6,000 hr<sup>-1</sup>. Pd thus outperforms state-of-the-art rhodium containing catalysts with (15-20 times higher rhodium loading; rhodium is ~ 3 times more expensive than palladium). Furthermore, palladium catalysts are more selective towards nitrogen and produce significantly less ammonia relative to the more traditional rhodium catalysts due to lower Pd amount nd lower water-gas-shift activity. Our study is the first example of utilizing ultra-low (0.05 wt% and less) noble metal (Pd) amounts to produce heterogeneous catalysts with extraordinary activity for nitric oxide reduction. This opens up a pathway to study other Pd, Pt and Rh containing materials with ultra-low loadings of expensive noble metals dispersed on titania or titania-coated oxides for industrially relevant nitric oxide abatement.</p>

scholarly journals DFT Benchmark Studies on Representative Species and Poisons of Methane Steam Reforming on Ni(111)

2021 ◽  
Author(s):  
Sai Sharath Yadavalli ◽  
Glenn Jones ◽  
Michail Stamatakis
Keyword(s):  
Steam Reforming ◽  
Graphitic Carbon ◽  
Methane Steam Reforming ◽  
Ni Catalysts ◽  
Methane Steam ◽  
Representative Species ◽  
Industrial Operations ◽  
Major Impediment ◽  
Carbon Based

Ni catalysts used in Methane Steam Reforming (MSR) are highly susceptible to poisoning by carbon-based species, which poses a major impediment to the productivity of industrial operations. These graphitic carbon-like...

scholarly journals Retraction: Computational fluid dynamics modeling of the millisecond methane steam reforming in microchannel reactors for hydrogen production

RSC Advances ◽  
2021 ◽  
Vol 11 (21) ◽  
pp. 12531-12531
Author(s):  
Junjie Chen ◽  
Xuhui Gao ◽  
Longfei Yan ◽  
Deguang Xu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Hydrogen Production ◽  
Steam Reforming ◽  
Methane Steam Reforming ◽  
Dynamics Modeling ◽  
Computational Fluid Dynamics Modeling ◽  
Microchannel Reactors ◽  
Methane Steam

Retraction of ‘Computational fluid dynamics modeling of the millisecond methane steam reforming in microchannel reactors for hydrogen production’ by Junjie Chen et al., RSC Adv., 2018, 8, 25183–25200, DOI: 10.1039/C8RA04440F.

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