Catalysts For Methanol Decomposition Research Articles

Effect of preparation procedures on the activity of supported palladium/lanthanum methanol decomposition catalysts

A series of palladium catalysts promoted with lanthanum were prepared on a silica support and the activities of these catalysts examined for the decomposition of methanol into CO and H 2. The preparation procedure and the La 2O 3/Pd weight ratio of these Pd/La 2O 3/SiO 2 catalysts (5 wt.% Pd) was found to be important for high catalytic activities. If Pd is deposited after La 2O 3 using a precipitation procedure, the methanol decomposition activity increases up to a La 2O 3/Pd weight ratio of 1.0. The optimized weight ratio for the methods of co-precipitation and co-impregnation were found to be 0.8 and 0.5, respectively. Relatively low activities are obtained if a sequential procedure with La 2O 3 deposition in the final step is applied. The effect of the preparation procedure and La 2O 3/Pd weight ratio on activity of the resulting catalysts can be explained by: (i) the amount of Pd particles in contact with La 2O 3 moieties, positively affecting the activity, and (ii) the extent of coverage of Pd particles by La 2O 3 patches, negatively affecting the activity.

Thermal Performance of the Plate Fin Type Reactor with Anodized Alumina Catalyst for Methanol Decomposition.

The performance of a plate fin type reactor with anodized alumina catalyst for methanol decomposition was prepared and evaluated. The measured temperature difference between heating oil and reaction gas was as small as 3°C and under, and it was smaller than the calculated value using the overall heat transfer coefficient obtained by inert gas and reaction heat. The response of reaction against the change of the gas flow rate and the change of the heating oil temperature were so quick that the gas temperature in the reactor and the gas flow rate of the outlet of the reactor became constant within 1 minute. The excellent thermal performance of the plate fin type reactor with the anodized alumina catalyst was demonstrated.

Development of Methanol Decomposition Catalysts for Production of H2 and CO

Development of Methanol Decomposition Catalysts for Production of H2 and CO

Deactivation and regeneration of Cu/Cr based methanol decomposition catalysts

Multicomponent Cu/Cr containing catalysts have been studied for the decomposition of methanol to CO/H 2. These Cu containing catalysts are quite active for the reaction. However, slow deactivation was observed in the life-time study. The activity of the deactivated catalysts can be completely restored by a treatment in O 2 containing atmosphere followed by reduction in H 2. Characterizations of deactivated and regenerated catalysts indicate that carbonaceous deposit is a cause of catalyst deactivation. Crystallite size of active metallic Cu species does not change during deactivation and after regeneration. The regeneration process decreases the carbonaceous content with no significant change in the Cu dispersion and restores the activity.

Reaction and XRD studies on Cu based methanol decomposition catalysts: Role of constituents and development of high-activity multicomponent catalysts

A series of Cu based catalysts with and without ZnO have been studied for methanol decomposition in the absence of water. CO and H 2 are the major products. A significant amount of methyl formate is produced at low conversions and low reaction temperatures. Cu ZnO based catalysts show high initial activity but quickly deactivate. This may be attributed to the dissolution of Zn into the Cu lattice. Without the component ZnO, other Cu based catalysts show good activity and better stability. Cr increases the stability of the Cu based catalysts but slightly reduces the selectivity to CO. The composition of Cr correlates with the yield of dimethyl ether. Among many other components evaluated, a small amount of Ba, Mn and Si oxides strongly promote the Cu based catalysts in methanol decomposition. Cu, Cr, Si, O and Ba or Mn constitute the components of the highly active multicomponent catalyst. Characterizations of the catalysts combined with the compositional study suggest that metallic Cu is the active species for methanol decomposition. Silica enhances the activity probably by increasing the dispersion of Cu.

Effect of the method of preparation of Ni/SiO2-MgO catalysts on decomposition of methanol.

Since we observed in our previous work that Ni/SiO2-MgO was an efficient catalyst for decomposition of methanol to carbon monoxide and hydrogen, we have here studied the various methods of preparing the catalyst in detail. The following features have been observed. 1) The optimum SiO2 content in SiO2-MgO is about 60mol%; 2) Coprecipitation method is more effective than kneading method for preparation of SiO2-MgO; 3) Sodium silicate and magnesium nitrate are better precursors than ethyl orthosilicate and other magnesium salts; 4) Xerogel of SiO2-MgO is superior to its hydrogel; and 5) Impregnation method is more effective than precipitation, kneading, and tightly homogeneous coprecipitation methods for supporting Ni on SiO2-MgO. Effects of the method of preparation on the catalytic activity and selectivity are discussed in terms of catalyst surface area, acidity, sodium content, the amount of adsorbed hydrogen, and the diameter of Ni particles.

Catalytic activities of supported transition metals for decomposition of methanol to CO and H2.

To search for active and selective catalyst for decomposition of methanol to CO and H2, transition metals such as Co, Ni, Zn, Fe, Cu, Cr, Pt, Pd, Rh, and Ru, supported on active carbon, were prepared. Among them Ni/active carbon was found to be the most promising catalyst from the viewpoint of activity, selectivity, life, and cost. To improve the catalytic behavior of Ni catalysts, Ni was supported on different types of supports, and their catalytic activities were examined. SiO2-MgO was found to be the most suitable support for Ni for the decomposition of methanol to CO and H2. Temperature-programmed reduction studies indicated that NiO on SiO2-MgO was difficult to reduce and suggested that the reason for high activity of Ni/SiO2-MgO was brought about by the interaction of Ni with SiO2-MgO strong enough to maintain a high dispersed state of Ni on the surface.

Coal liquefaction by the hydrogen produced from methanol, 4. effect of catalyst species

Liquefaction of Taiheiyo Japanese coal by hydrogen generated in situ from the decomposition of methanol was examined using various kinds of methanol decomposition and hydrogenation catalysts with conversion compared. CuO containing methanol decomposition catalysts had maximum activity and the maximum yield of oil distilling up to 600°C was nearly 80 wt.% (daf base). Using model compounds the mechanism was examined. This catalyst has high activity in methanol decomposition, and for the splitting of bridge linkages as well as in hydrogenation of aromatic rings. Hydrogenation catalyst also had a significant contribution on the increase of coal conversion, especially in the yield of oil distilling at lower temperatures. Alumina or silica-alumina supports prevent the conversion because they accelerate the synthesis of dimethyl ether from methanol. In such cases the hydrogen amount generated in situ from the decomposition of methanol decreased.

パラジウム触媒のメタノール分解活性におよぼすＴｉＯ２およびＡｌ２Ｏ３の担持効果

The influence of support in using the different sources (commercial ox ides, metal alkoxides, TiCl4, Ti(SO4)2) of metal oxides as supports (TiO2 (anatase), γ-Al2O3) and of the pretreatment of the oxides (evacuation at 773 K) on the activity of Pd catalysts has been studied to find a favorable catalyst for methanol decomposition to H2 and CO. The pretreatment by evacuation gave somewhat high surface area as well as high catalytic activity in comparison with that by no-evacuation. Catalytic activity (conversion to CO) increased as the surface area of these catalysts increased. The specific activity for TiO2-support was higher than that for Al2O3-support (Fig.1). The catalytic activity was found to be proportional to the degree of dispersion of Pd on both TiO2 and Al2O3 supports (Fig.2).