Studies of potassium-promoted nickel catalysts for methane steam reforming: Effect of surface potassium location

2014 ◽  
Vol 300 ◽  
pp. 191-200 ◽  
Author(s):  
Tadeusz Borowiecki ◽  
Andrzej Denis ◽  
Michał Rawski ◽  
Andrzej Gołębiowski ◽  
Kazimierz Stołecki ◽  
...  
Keyword(s):  
Steam Reforming ◽  
Nickel Catalysts ◽  
Methane Steam Reforming ◽  
Methane Steam ◽  
Effect Of Surface

Nickel catalysts based on porous nickel for methane steam reforming

2008 ◽  
Vol 49 (3) ◽  
pp. 428-434 ◽  
Author(s):  
Z. A. Sabirova ◽  
M. M. Danilova ◽  
V. I. Zaikovskii ◽  
N. A. Kuzin ◽  
V. A. Kirillov ◽  
...  
Keyword(s):  
Steam Reforming ◽  
Nickel Catalysts ◽  
Methane Steam Reforming ◽  
Porous Nickel ◽  
Methane Steam

scholarly journals Methane steam reforming at low temperature over Ni-MgO-Al2O3 catalysts: activity and resistance to coking

2018 ◽  
Vol 72 (2) ◽  
pp. 1
Author(s):  
Monika Pańczyk ◽  
Andrzej Denis ◽  
Kazimierz Stołecki ◽  
Tadeusz Krzysztof Borowiecki
Keyword(s):  
Steam Reforming ◽  
Specific Activity ◽  
Catalyst Activity ◽  
Coke Formation ◽  
Nickel Catalysts ◽  
Precipitation Method ◽  
Methane Steam Reforming ◽  
Deep Minimum ◽  
Methane Steam ◽  
Co Precipitation

<p>The role of MgO as a factor improving the resistance to coking of the alumina supported nickel catalysts in the steam reforming of hydrocarbons is discussed.    A series of catalysts containing variable amounts of MgO, NiO and a constant amount of Al<sub>2</sub>O<sub>3</sub> was prepared by the co-precipitation method. It was found that the specific activity of the catalysts exhibits a broad but not deep minimum for the MgO contents from 8.5 to 27.3 wt.%. At the same time these catalysts reveal a high resistance to coking either in the reaction with methane or with <em>n</em>-butane. The most promising composition, in terms of the activity and simultaneous resistance to the coke formation, was found to be 27.3 wt.% of MgO and 39.0 wt.% of NiO. The analysis of various factors controlling the activity and resistance to coking leads to the conclusion that MgO reduces the catalysts acidity what, in consequence, reduces the rate of coke formation during the reforming reactions. Furthermore, The resistance to coking correlates well with the mean size of nickel crystallites, the same is observed for the specific catalyst activity.</p><p> </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>

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