Catalytic partial oxidation of methane

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

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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. 

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. 

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. 

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. 

Hannemann S, Grunwaldt J-D, Gunther D, Krumeich F, Lienemann P, Baiker A. Combination of flame synthesis and high throughput experimentation preparation of alumina supported noble metal particles and their application in the catalytic partial oxidation of methane. Appl Catal A. 2007 316 226. 

Basile, F., Basini, L., Damore, M., Fornasari, G., Guarinoni, A., Matteuzzi, D., DelPiero, G, Trifiro, F. and Vaccari, A. (1998). Ni/Mg/Al anionic clay derived catalysts for the catalytic partial oxidation of methane - residence time dependence of the reactivity features. J. Catal. 173, 247. 

At relatively low temperatures (< 800 °C), over most catalysts investigated, the catalytic partial oxidation of methane to synthesis gas is thought to follow the so-called indirect scheme, according to which initially methane is combusted until all... 

Lyubovsky, M., Roychoudhury, S., and LaPierre, R. Catalytic partial oxidation of methane to syngas at elevated pressures. Catalysis Letters, 2005, 99, 113. 

Horn, R., Williams, K. A., Degenstein, N.J., and Schmidt, L.D. Syngas by catalytic partial oxidation of methane on rhodium Mechanistic conclusions from spatially resolved measurements and numerical simulations. Journal of Catalysis, 2006, 242, 92. 

Burke, N. and David, T. Coke formation during high pressure catalytic partial oxidation of methane to syngas. Reaction Kinetics and Catalysis Letters, 2005, 84, 137. 

Zhu, T. and Flytzani-Stephanopoulos, M. Catalytic partial oxidation of methane to synthesis gas over Ni-Ce02. Applied Catalysis. A, General, 2001, 208, 403. 

Rabe, S., Truong, T.-B., and Vogel, F. Low temperature catalytic partial oxidation of methane for gas-to-liquids applications. Applied Catalysis. A, General, 2005, 292, 177. 

Bizzi, M., Basini, L., Saracco, G., and Specchia, V. Short contact time catalytic partial oxidation of methane Analysis of transport phenomena effects. Chemical Engineering Journal, 2002, 90, 97. 

In the catalytic partial oxidation of methane to produce syngas the use of permselective dense perovskite membranes avoids (or minimizes) the need of air separation, the most costly step in the process. Although both these O2- and H2-permeoselective membranes (based on perovskites or thin supported Pd-based dense films, respectively) have still to be further developed for commercial applications the outlook appears quite interesting for intensifying various large chemical processes. 

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