Methane, catalytic partial oxidation

Horn, R., Williams, K.A., Degenstein, N.J., Bitsch-Larsen, A., Dalle Nogare, D., Tupy, S.A., and Schmidt, L.D. Methane catalytic partial oxidation on autothermal Rh and Pt foam catalysts Oxidation and reforming zones, transport effects, and approach to thermodynamic equilibrium. Journal of Catalysis, 2007, 249 (2), 380. 

Taylor JD, Allendorf MD, McDaniel AH, Rice SF In situ diagnostics and modeling of methane catalytic partial oxidation on Pt in a stagnation-flow reactor, Ind Eng Chem Res 42 6559-6566, 2003. 

Nogare, D., Degenstein, N., Horn, R., et al. (2011). Modeling Spatially Resolved Data of Methane Catalytic Partial Oxidation on Rh Foam Catalyst at Different Inlet Compositions and Flowrates, J. Catal, 277, pp. 134—148. 

The catalytic partial oxidation of methane into CO and H2 according to... 

The catalytic partial oxidation of methane for the production of synthesis gas is an interesting alternative to steam reforming which is currently practiced in industry [1]. Significant research efforts have been exerted worldwide in recent years to develop a viable process based on the partial oxidation route [2-9]. This process would offer many advantages over steam reforming, namely (a) the formation of a suitable H2/CO ratio for use in the Fischer-Tropsch synthesis network, (b) the requirement of less energy input due to its exothermic nature, (c) high activity and selectivity for synthesis gas formation. 

Tonkovich, A. L. Y, Zilka, J. L., Powell, M. R., Gall, C. J., The catalytic partial oxidation of methane in a micro-channel chemical reactor, in Ehrfeld, W, Rinard, I. H., Wegeng, R. S. (Eds.), Process Miniaturization 2nd International Conference on Microreaction Technology, IMRET 2, Topical Conf. Preprints, pp. 45-53, AIChE, New Orleans (1998). 

Voutetakis, S. et al., Catalytic partial oxidation of methane in a spouted bed reactor, in Natural Gas Conversion V, Studies in Surface Science and Catalysis, vol. 119, Parmaliana, A. et al., Eds., Elsevier, Amsterdam, 807 1998. 

The other two main processes for conversion of methane into synthesis gas are partial oxidation and CO2 reforming. In the 1940s, Prettre et al. (3) first reported the formation of synthesis gas by the catalytic partial oxidation of CH4... 

They used a Ni-containing catalyst. In contrast to steam reforming of methane, methane partial oxidation is exothermic. However, the partial oxidation requires pure oxygen, which is produced in expensive air separation units that are responsible for up to 40% of the cost of a synthesis gas plant (2) (in contrast, the steam reforming process does not require pure oxygen). Therefore, the catalytic partial oxidation of methane did not attract much interest for nearly half a century, and steam reforming of methane remained the main commercial process for synthesis gas manufacture. 

Numerous studies have been published on catalyst material directly related to rich catalytic combustion for GTapplications [73]. However, most data are available on the catalytic partial oxidation of methane and light paraffins, which has been widely investigated as a novel route to H2 production for chemical and, mainly, energy-related applications (e.g. fuel cells). Two main types of catalysts have been studied and are reviewed below supported nickel, cobalt and iron catalysts and supported noble metal catalysts. 

Co and Fe catalysts have also been studied for the partial oxidation of methane to synthesis gas. Their potential relies on the fact that Co and Fe have higher melting and vaporizing points than Ni. Lower performances were mostly observed, however, which is probably related to the higher activity of CoO and FC2O3 for the complete oxidation of methane [121, 132, 133]. The recognized order of reactivity for partial oxidation is in fact Ni Co > Fe. However, it was observed that the performance of Co improves when a promoter is added. An extensive study of the catalytic partial oxidation of methane over CO/AI2O3 catalysts with different metals (0.1 wt% of Ni, Pt,... 

Catalytic Activity. The world-wide interest focused in the catalytic partial oxidation of methane to formaldehyde has led to a great variety of conflicting results (9), The main reason of such discrepancies lies in the lack of a generally valid rule for evaluating and comparing the proposed catalytic systems. In effect, this reaction involves a very complex pathway since the desired partial oxidation product, HCHO, exhibits a limited thermal stability at T>4(X)°C and can be oxidized to more easily than CH itself. Hence, a suitable reactor device and appropriate operating conditions result to be of fundamental importance in order to attain reliable data unaffected by experimental artefacts. 

Mayer J, Fichtner M, Wolf D, Schubert K. A microstructured reactor for the catalytic partial oxidation of methane to syngas. Proceedings of the 3rd International Conference on Microreaction Technology. Berlin Springer, 2000 187-196. 

It is fair to state that by and large the most important application of structured reactors is in environmental catalysis. The major applications are in automotive emission reduction. For diesel exhaust gases a complication is that it is overall oxidizing and contains soot. The three-way catalyst does not work under the conditions of the diesel exhaust gas. The cleaning of exhaust gas from stationary sources is also done in structured catalytic reactors. Important areas are reduction of NOv from power plants and the oxidation of volatile organic compounds (VOCs). Structured reactors also suggest themselves in synthesis gas production, for instance, in catalytic partial oxidation (CPO) of methane. 

To check this assumed isothermal behavior, one first has to examine the temperature rise in a single well due to the chemical reaction [38], As test reaction, the catalytic partial oxidation of methane was selected ... 

Geske M, et al. In-situ investigation of gas phase radical chemistry in the catalytic partial oxidation of methane on Pt. Catal Today. 2009 142 61-9. 

Equally important are structural changes on the micrometer and the millimeter length scales, and eventually real reactors on a centimeter or even meter scale. In the first cases, full-field XAS is a well-matched method for in situ monitoring [6, 13, 25], An illustrative example is the catalytic partial oxidation (CPO) of methane to synthesis gas, a relevant reaction in the future s solid-oxide fuel cells. In Figure 4.3.4, it was... 

Figure 4.3.10 Full-field X-ray microscopy on a 5 wt% Rh/Al2C>3 catalyst during catalytic partial oxidation of methane (A) amount of oxidized Rh species (corresponds to XANES species 1 in [D]), (B) reduced Rh species (reduced species 2 in [D]), (C) the distribution of other elements that show a featureless absorption spectrum in the given energy range, and (D) spectra used for X-ray absorption contrast (original image taken by X-ray camera was 3.0 mm x 1.5 mm the reaction gas mixture 6% CH4/3% ()2/I Ie enters from the left) (reproduced with permission from ref. [69], Copyright ACS, 2006).

Kimmerle B, Baiker A, Grunwaldt JD. Oscillatory behaviour of catalytic properties, structure and temperature during the catalytic partial oxidation of methane on Pd/Al203. Phys Chem Chem Phys. 2010 12 2288. 

Basini L, Guarinoni A, Aragno A. Molecular and temperature aspects in catalytic partial oxidation of methane. J Catal. 2000 190 284. 

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