Propane catalytic combustion

Kaisare NS, Deshmukh SR, Vlachos DG (2008) Stability and performance of catalytic microreactors simulations of propane catalytic combustion on Pt. ChemEng Sci 63 1098-1116... 

Early studies in this field [35, 36] indicated that a high surface-to-volume ratio, which represents a hurdle for gas-phase combustion, is instead an advantage for catalytic combustion. In fact the small scale enhances considerably the rate of gas-solid mass transfer, which favors the kinetics of the combustion process and compensates for the short residence time. Also, as is well established for large-scale systems, the presence of a catalytic phase allows for stable combustion at significantly lower temperature than traditional homogeneous burners [55, 56]. This makes the design and operation of microcombustors more fiexible. Several recent studies have explored the potential of catalytic microcombustors using H2 [37, 38, 50], methane [37], propane [52,53,57] and mixtures of H2 with propane [57], butane [38,47,52] and dimethyl ether [52]. 

Two reaction mechanisms for partial propane oxidation exist in the literature. One of them proposes that the reaction starts with catalytic combustion followed by reactions of a lower rate, namely steam reforming, C02 reforming and water-gas shift [54], Aartun et al. [55] investigated both reactions. The other mechanism proposes that the partial oxidation reaction occurs directly at very short residence times [56], which are easier to achieve in the micro channels. 

Catalytic combustion of hydrocarbons on ceria has been studied for a long time. Both paraffins and unsaturated hydrocarbons are totally oxidised on ceria between 300°C and 500 C. Previous results of Morooka and co-workers have clearly evidence the catalytic properties of ceria compared to other oxides in total oxidation of acetylene, ethylene, propene, isobutene and propane [39]. They noted... 

Most of the work on catalytic combustion applications has dealt with the use of natural gas, since this is a clean gaseous fuel with low nitrogen content. However, a number of other hydrocarbon fuels have been investigated as well [99-101], such as propane, gasoline, diesel fuel, and kerosenes. 

Saracco G., Veldsink J.W., Versteeg G.F. and van Swaaij W.P.M., Catalytic combustion of propane in a membrane reactor with separate feed of reactants. I. Operation in absence of trans-membrane pressure gradients, Chem. Eng. Sci., 56 2005 (1995). 

Fig. 6.26. Temperature for 50% conversion in the catalytic combustion of hydrocarbons lwt% Pd/AbOs and Pt/ApOs were prepared by IMP. 1 19 Au/support catalysts were prepared by CP and calcined in air at 673 K. (I) 1 wt% Pd/Al203 (II) lwt% Pt/ApOa (III) 10wt% Au/Fe203 (IV) 10wt% Au/ZnFe204 (V) 10wt% Au/NiFe204 (VI) 10 wt% AU/C03O4. (A) Methane (B) propene (C) trimethy-lamine (D) propane. The concentrations of reactant gases in air was CH4 0.25 vol% CaHs and CsHe 0.1 vol% (CH3)3N 0.05 vol% balanced with air to 1 atm SV 2 X 10" ml g th (based on [535])...

Metal oxide catalysts are extensively employed in the chemical, petroleum and pollution control industries as oxidation catalysts (e.g., oxidation of methanol to formaldehyde, oxidation of o-xylene to phthalic anhydride, ammoxidation of propylene/propane to acrylonitrile, selective oxidation of HjS to elemental sulfur (SuperClaus) or SO2/SO3, selective catalytic reduction (SCR) of NO, with NHj, catalytic combustion of VOCs, etc.)- A special class of metal oxide catalysts consists of supported metal oxide catalysts, where an active phase (e.g., vanadium oxide) is deposited on a high surface area oxide support (e.g., alumina, titania, ziiconia, niobia, ceria, etc.). Supported metal oxide catalysts provide several advantages over bulk mixed metal oxide catalysts for fundamental studies since (1) the number of surface active sites can be controlled because the active metal oxide is 100% dispersed on the oxide support below monolayer coverage,... 

Guam G., Zapf, R., Kolb, G., Men, Y, Hessel, V, Lowe, H., Ye, J. and Zentel, R. (2007) Low temperatue catalytic combustion of propane over MoOj-promoted Pt/Al20j catalyst with inverse opal microstructure in microchannel reactor. Chem. Commun., 3, 260-262. 

On occasion, a reaction takes place in more than one phase of a multiphase reactor. An example is the so-called catalytic combustion. If the temperature is high enough, a hydrocarbon fuel such as propane can be oxidized catalyticaUy, on the surface of a heterogeneous catalyst, at the same time that a homogeneous oxidation reaction takes place in the gas phase. This situation calls for two separate definitions of the reaction rate, one for the gas phase and the other for the heterogeneous catalyst. 

Deutschmann O, Maier LI, Riedel U, Stroemman AH, Dibble RW (2000) Hydrogen assisted catalytic combustion of methane on platinum. Catai Today 59 141-150 Aghalayam P, Park YK, Fernandes N, Papavassiliou V, Mhadeshwar AB, Vlachos DG (2003) A Cl mechanism for methane oxidation on platinum. J Catai 213 23-38 Garetto TF, Rincon E, Apesteguia CR (2004) Deep oxidation of propane on Pt-supported catalysts drastic turnover rate enhancement using zeolite supports. Appl Catai B Environ 48 167-174... 

Bruno C, Walsh PM, Santavicca DA, Sinha N, Yaw Y, Bracco FV (1983) Catalytic combustion of propane/air mixtures on platinum. Combust Sci Technol 31 43-74... 

The lack of a detailed surface reaction mechanism for propane/air combustion on platinum necessitated the use of a global-step reaction model in this work. Secondary hetero-Zhomogeneous chemistry interactions are not taken into account this way (such as the homogeneous conversion of C3Hg to CO and the subsequent conversion of the latter to CO2 on the catalytic surface) a closer-to-reahty description of the in-channel combustion processes in catalytic microreactors is thus not possible. While the impact of such a simplification in cases where total oxidation of the fuel is required is minimal, this does not hold true in catalytic partial oxidation applications. Therein, a detailed surface chemistry description would be necessary. 

Experimental and numerical investigation of lean hetero-/ homogeneous propane/air combustion on platinum and numerical studies of hydrocarbon-fueled catalytic microreactors for portable power generation Aristotle University of Thessaloniki, Greece Research Assistant... 

This chapter reports about an investigation on the catalytic gas-phase armnoxidation of u-hexane aimed at the production of 1,6-Ce dinitriles, precursors for the synthesis of hexamethylenediamine. Catalysts tested were those also active and selective in the ammoxidation of propane to aciylonitrile mtile-type V/Sb and SnA /Nb/Sb mixed oxides. Several A-containing compounds formed however, the selectivity to cyano-containing aliphatic linear Ce compounds was low, due to the relevant contribution of side reactions such as combustion, cracking and formation of heavy compounds. 

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