The reactions of the CO and CO
2
methanation in the excess of hydrogen were studied over Ni/CeO
2
and Ni(Cl)/CeO
2
catalysts prepared from nitrate and chloride precursors, respectively. Macrokinetic ...parameters of the CO and CO
2
methanation over Ni/CeO
2
and Ni(Cl)/CeO
2
catalysts were determined. The nature of surface species during the CO and CO
2
methanation over Ni/CeO
2
and Ni(Cl)/CeO
2
catalysts was studied by the Fourier transform infrared spectroscopy in situ technique. It was shown that the CO methanation proceeds similar ways over both Ni/CeO
2
and Ni(Cl)/CeO
2
catalysts via CO and H
2
chemisorption on the surface of Ni particles. The CO
2
methanation over Ni/CeO
2
catalyst proceeds via the CO
2
adsorption on the ceria surface and stepwise hydrogenation to methane through hydrocarbonate and formate intermediates by the hydrogen spilled over from Ni particles. With the Ni(Cl)/CeO
2
catalyst, this reaction pathway is locked due to the ceria surface blockage by chlorine, to inhibit the CO
2
methanation and therefore provide a high efficiency of Ni(Cl)/CeO
2
catalyst in preferential CO methanation in the presence of CO
2
.
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•CuO-CeO2/γ-Al2O3 catalyst for dimethyl ether partial oxidation was studied.•The catalyst is high active and stable in hydrogen-rich gas production.•The catalyst contains CuCeOx mixed ...oxide and copper nanoparticles on its surface.
Low temperature dimethyl ether partial oxidation (DME PO) to hydrogen-rich gas was studied over Cu-Ce-Ox/γ-Al2O3 catalyst. The catalyst demonstrated stable operation under atmospheric pressure, T = 350 °C and gas hourly space velocity (GHSV = 20000 h−1) using reaction mixture (vol. %) CH3OCH3:O2:N2 = 16.7:16.7:66.6 (that corresponds to molar ratio DME:air = 1:5). X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray analysis techniques were used for catalyst characterization. It was shown that the surface of the CuCeOx/γ-Al2O3 catalyst held copper-containing species of two types, namely, compact agglomerates of the CuO-CeO2 mixed oxides (up to ~100 nm in size) and copper nanoparticles (<5 nm).
Catalytic partial oxidation (PO) of dimethoxymethane (DMM) to syngas was investigated in a fixed-bed continuous flow reactor under ambient pressure and at 250–500 °C over Pt-, Rh- and Ru-supported on ...Ce
0.75
Zr
0.25
O
2–δ
catalysts. The Pt catalyst was found to be the most active and selective. It provided complete conversion of DMM to gas mixture containing ˃ 60 vol% of H
2
and CO at 400 °C, GHSV = 10,000 h
−1
using a reaction mixture: DMM:O
2
:N
2
= 28.6:14.3:57.1 (vol%).
—We develop the notion that, near the glass transition temperature, amorphous substances undergo reversible configurational structural changes accompanied by local expansion and compression (atom ...delocalization). They are similar in nature to configurational changes in the structure of glasses in the case of reversible frozen deformation and its thermally stimulated relaxation.
—
A modification to a previously proposed glass transition criterion is analyzed and substantiated in terms of the delocalized atom model. The atom delocalization energy in sodium germanate, alkali ...silicate, and sodium borate glasses is shown to be a linear function of their glass transition temperature.
—
The basic concepts of the delocalized-atom model have been shown to be applicable to low-melting-point sulfophosphate glasses and parameters of the model have been calculated. The parameters have ...been used to gain insight into the “atom delocalization” process in the glasses and assess their properties (viscosity, microhardness, glass transition temperature, and internal pressure). The results demonstrate that there is a linear correlation between the atom delocalization energy and glass transition temperature. The melt–glass transition is accompanied by the freezing of the atom delocalization process.
A thermodynamic analysis of the conversion of dimethoxymethane by steam reforming and partial oxidation into a hydrogen-rich gas for fuel cell feeding has been carried out. Calculations were carried ...out at a pressure of 1 atm, temperatures of 100–1000°C, and the molar ratios O
2
/DMM = 0.5–3.5 and H
2
O/DMM = 1–5. The effects of temperature and reaction mixture composition on the equilibrium reaction product distribution and carbon (graphite) formation boundaries have been studied. The calculated data are compared with the known experimental results.
Methanol, dimethyl ether and bioethanol steam reforming to hydrogen-rich gas were studied over CuO/CeO2 and CuO–CeO2/γ-Al2O3 catalysts. Both catalysts were found to provide complete conversion of ...methanol to hydrogen-rich gas at 300–350 °C. Complete conversion of dimethyl ether to hydrogen-rich gas occurred over CuO–CeO2/γ-Al2O3 at 350–370 °C. Complete conversion of ethanol to hydrogen-rich gas occurred over CuO/CeO2 at 350 °C. In both cases, the CO content in the obtained gas mixture was low (<2 vol.%). This hydrogen-rich gas can be used directly for fuelling high-temperature PEM FC. For fuelling low-temperature PEM FC, it is needed only to clean up the hydrogen-rich gas from CO to the level of 10 ppm. CuO/CeO2 catalyst can be used for this purpose as well. Since no individual WGS stage, that is necessary in most other hydrogen production processes, is involved here, the miniaturization of the multifuel processor for hydrogen production by methanol, ethanol or DME SR is quite feasible.
► Copper-ceria containing catalysts are active in steam reforming of methanol, ethanol and dimethyl ether. ► The catalysts provide production of H2-rich gas containing less than 2 vol.% CO. ► It can be used directly for fuelling high-temperature PEM FC. ► Creation of multifuel processor for hydrogen production is quite feasible.
It is found that in the Leont’ev and Belomestnykh–Tesleva formulas for the Grüneisen parameter, the righthand sides of the equalities depend on the anharmonicity through the dependence of the ratio ...of the squared acoustic wave velocities
v
L
2
/
v
S
2
on the Grüneisen parameter γ. The theoretical dependence of
v
L
2
/
v
S
2
on γ in general agrees with experimental data both for crystals and glassy solids. The quantity
v
L
2
/
v
S
2
turns out to be a single-valued function of the ratio of the tangential and normal stiffness of the interatomic bond.
The properties of supported Pt-containing granular (Pt/Ce
0.75
Zr
0.25
O
2 – δ
) and structured catalysts (Pt/Ce
0.75
Zr
0.25
O
2 – δ
/η-Al
2
O
3
/FeCrAl) in methanol decomposition to synthesis gas ...for feeding solid oxide fuel cells have been studied. It has been shown that the use of a structured catalyst for the methanol decomposition reaction is promising. It has been found that the addition of a small amount of oxygen to the feed mixture hinders the formation of carbon and thereby increases the on-stream stability of the catalyst. At atmospheric pressure, a temperature of ≈400°C, a reaction mixture feed space velocity of 5.6 L/(g
cat
h), and a CH
3
OH : air volume ratio of 1, the proposed 0.15 wt % Pt/8 wt % Ce
0.75
Zr
0.25
O
2 – δ
/6 wt % η-Al
2
O
3
/FeCrAl structured catalyst can provide a complete methanol conversion to synthesis gas with a total content of H
2
and CO of ≈64 vol % and a productivity with respect to synthesis gas of ≈6.7 L(H
2
+ CO)/(g
cat
h).
