Kinetic study and effect of water on methane oxidation to methanol over copper-exchanged mordenite

2020 ◽  
Vol 10 (2) ◽  
pp. 382-390 ◽  
Author(s):  
Vitaly L. Sushkevich ◽  
Jeroen A. van Bokhoven
Keyword(s):  
Carbon Monoxide ◽  
Water Molecule ◽  
Kinetic Study ◽  
Methane Oxidation ◽  
Active Species ◽  
Effect Of Water ◽  
Primary Products

Kinetic experiments show that both methoxy species and carbon monoxide are primary products. Adsorption of one water molecule reversibly blocks at least two copper atoms in active species.

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>

Effect of Water Vapour on Explosions of Carbon Monoxide

Nature ◽  
1952 ◽  
Vol 170 (4333) ◽  
pp. 838-839 ◽  
Author(s):  
D. E. HOARE ◽  
A. D. WALSH
Keyword(s):  
Carbon Monoxide ◽  
Water Vapour ◽  
Effect Of Water

Complete methane oxidation over Ba modified Pd/Al2O3: The effect of water vapor

2018 ◽  
Vol 231 ◽  
pp. 242-250 ◽  
Author(s):  
Ida Friberg ◽  
Nadezda Sadokhina ◽  
Louise Olsson
Keyword(s):  
Water Vapor ◽  
Methane Oxidation ◽  
Effect Of Water

Strahlenchemie von Alkoholen XVII

1972 ◽  
Vol 27 (1) ◽  
pp. 41-46 ◽  
Author(s):  
C. v. Sonntag
Keyword(s):  
Carbon Monoxide ◽  
Molecular Hydrogen ◽  
Reaction Scheme ◽  
Quantum Yields ◽  
Effect Of Water ◽  
Formed Hydrogen

In the 185 nm photolysis of liquid O2-free isopropanol the following products (quantum yields) are formed: hydrogen (0.75), acetone (0.72), pinacol (0.036), methane (0.046), acetaldehyde (0.04), propane (0.02β), ane (0.0023) and carbon monoxide (0.0015). A detailed reaction scheme is proposed. The major primary processes are the formation of H-atoms by homolytic scission of the O —H-bond (61 — 69%), elimination of molecular hydrogen (21%) and molecular methane (5%). Φ(Η2) is strongly decreased by adding water which does not absorb an appreciable portion of the 185 nm light in the mixtures down to 1 mole/l isopropanol (Φ(Η2) =0.21). In contrast to the strong effect of water there is no effect on Φ(Η2) by diluting isopropanol with n-hexane. From experiments with isopropanol-OD and 2-deutero-isopropanol it is tentatively concluded that H-atoms stemming from the O—H-group of the alcohol are to about 65% the precursors of the hydrogen in these mixtures.

An Operando FTIR Spectroscopic and Kinetic Study of Carbon Monoxide Pressure Influence on Rhodium-Catalyzed Olefin Hydroformylation

2014 ◽  
Vol 20 (37) ◽  
pp. 11921-11931 ◽  
Author(s):  
Christoph Kubis ◽  
Mathias Sawall ◽  
Axel Block ◽  
Klaus Neymeyr ◽  
Ralf Ludwig ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Kinetic Study ◽  
Olefin Hydroformylation
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