Propane selectivity

The role of adsorbed oxygen species in the mechanism of alkane transformation, on the contrary, is more questionable. The effect induced by the substitution of O2 with N2O and IR indications are in agreement with this interpretation, but, on the other hand, activated electrophilic oxygen species form on reduced sites, preferably in tetrahedral coordination (79). The partial reduction of tetrahedral V =0 with formation of tetrahedral v after propane oxidative dehydrogenation can be observed using UV-Visible diffuse reflectance, ESR and V-NMR spectroscopies. It is thus not possible to assign unequivocally the active species in propane selective activation to a tetrahedral V =0 species or to or V -0-0 species formed in the... 

Products obtained by propane-selective oxidation have been analyzed by gas sensor systems [19, 26]. Usually, several or multiple kinds of compounds are produced during the selective oxidation of propane. The formation of CO, C02, aldehydes such as acrolein, and ketone were observed over iron-silica catalysts [28, 29]. During the initial stage of catalyst investigation, the conversion of propane and the selectivity toward useful oxygenate products as chemical resources are of interest. Semiconductor-type gas sensors selective toward the oxygenate were employed to estimate the yield of oxygenate products, with a combination of the potentiometric CO sensor and the ND-IR C02 sensor [30]. 

The problem with use of polymeric membranes in this application is plasticization, leading to much lower selectivities with gas mixtures than the simple ratio of pure-gas permeabilities would suggest. For this type of separation, a Robeson plot based on the ratio of pure-gas permeabilities has no predictive value. Although membranes with pure-gas propylene/propane selectivities of 20 or more have been reported [43, 44], only a handful of membranes have been able to achieve selectivities of 5 to 10 under realistic operating conditions, and these membranes have low permeances of 10 gpu or less for the fast component (propylene). This may be one of the few gas-separation applications where ceramic or carbon membranes have an industrial future. 

Hydrogenolysis of alkanes and related reactions on these catalysts have been studied by a number of groups [18, 19, 21-23], Kinetic parameters for ethane, propane, and n-butane on both catalysts are summarized in Table 3. With propane, selectivities to ethane on... 

Trunschke A. Propane selective oxidation to acrylic acid. In Hess C, Schlogl R, editors. Nanostructured catalysts Selective oxidation reactions. Cambridge RSC Nanoscience Nanotechnology 2011. p. 56-95. 

Lin MM. Complex metal-oxide catalysts for selective oxidation of propane and derivatives. I. Catalysts preparation and application in propane selective oxidation to acrylic acid. Applied Catalysis, A General. 2003 250(2) 305-318. 

Turning now to the reaction side, it is generally accepted that the rate-hmiting step of propane selective (amm)oxidation is activation of the first C—H bond. Vanadium 5-i- was proposed by several authors as being responsible for this elementary step [148, 204-206], However, XPS does not seem to support this proposal, since vanadium was observed in its formal 4+ oxidation state on the surface of Ml (Tables 6.4 and 6.5). The deficiency of the surface in vanadium and the minority of its fraction (if any) relative to V" cast serious doubts that vanadium... 

Propane Selective Oxidation to Propene and Oxygenates on Metal Oxides. In Metal Oxides, Chemistry and Applications (ed. J.LG. Eierro), CRC Press, Boca Raton, p. 414. 

Olefin selectivities also decrease with increasing bed residence time and chain size on Ru catalysts (4,14). For example, propylene selectivity decreases with increasing bed residence time without a corresponding increase in propane selectivity, leading to a net decrease in the fraction of the converted CO that appears as C3 molecules (Fig. 7b). Readsorbed olefins initiate chains that continue to grow and ultimately desorb as larger olefins or paraffins, ( alitative trends are similar on all supports and on both Ru and Co catalysts. The selectivity details depend on the support physical structure, on the density of exposed surface metal atoms, and on the intrinsic readsorption properties (j8r) of Co and Ru surfaces. 

Figure 11. Influence of water and temperature on the homogeneous oxidative dehydrogenation of propane selectivity to propene. Conditions as in fig. 10 [98].

Allene H. Propylene Propane Selective hydrogenation to olefin... 

Zeolite Conversion rKlc%l Selectivity [glc %] 2-Methyl-propanal Selectivity [glc %] 2-Methyl-butanal... 

Partial oxidation of propane (Coating characterization) Partial oxidation of propane Selective catalytic reduction of NOx (Coating characterization) Water gas shift Methane steam reforming Methanol steam reforming Schwarz et al. [178] Roumanie et al. [179] Pennemann et al. [183] Ercoli et al. [184] Stefanescu et al. [181] Germani et al. [177] Tonkovich et al. [182] Yu et al. [185]... 

Little work has been reported on the use of bimetallic catalysts.Addition of copper to nickel as powder lowered the overall rate, without major change to the propane selectivity. Activation energies varied irrationally between 40 and 93 kJmol- ... 

Figure 9-12. Propylene permeance and propylene/propane selectivity with increasing carrier concentration [12]. AgBF4-POZ, AgBF4-PVP and O propane.

Xu J, Mojet BL, van Ommen JG, Lefferts L (2005) Formation of M2-F(02)(C3H8) species in alkaline-earth-exchanged Y zeolite during propane selective oxidation. J Phys Chem B... 

Table 21.3 Experimental versus simulation results for propene/propane selectivity as a function of temperature.

Ueda W, Vitry D, Katou T (2004) Stmctural organization of catalytic functions in Mo-based oxides for propane selective oxidation. Catal Today 96 (4) 235-240 Farges F, Brown GE, Rehr JJ (1997) Ti K-edge XANES studies of Ti coordination and disorder in oxide compounds Comparison between theory and experiment Phys Rev B 56 (4) 1809-1819... 

Extensive efforts have been undertaken for propane selective oxidation and ammox-idation to acrylic acid and acrylonitrile, respectively. In fact, as can be seen in Fig. 24.1, and according to the literature of patents, the major interest in alkane heterogeneous catalysis over the last few years has covered the selective oxidation of propane. 

With respect to the catalytic reactions, there are well-established industrial reactions (as occurs in the case of n-butane to maleic anhydride), reactions in the preindustrial stage (such as the transformation of propane to acrylonitrile), very promising reactions (such as ethane oxidative dehydrogenation to ethylene), and potential reactions whose economical viability will depend on the prices of crude and natural gas in the future (such as propane selective oxidation to acrylic acid or methane transformation). 

Vitry, D., Morikawa, Y, Dubois, J., et al. (2003). Propane Selective Oxidation over Monophasic Mo-V-Te-O Catalysts Prepared by Hydrothermal Synthesis, Top. Catal., 23, pp. 47-53. KendeU, S., Alston, A. and Brown, T. (2009). Kinetic Simulation of Methacrolein and Lactone Production from the Catalytic Oxidation of Isohutane over Lanthanide Phosphomolybdates, Chemical Product and Process Modeling, 4, pp. No pp given. 

Li, W., Oshihara, K. and Ueda, W. (1999). Catalytic Performance for Propane Selective Oxidation and Surface Properties of 12-Molybdophosphoric Acid Treated with Pyridine, Appl. Catal. A. Gen., 182, pp. 357—363. 

Vitry, D., Dubois, J. and Ueda, W. (2004). Strategy in Achieving Propane Selective Oxidation over Multi-Functional Mo-Based Oxide Catalysts, J. Mol. Catal. A Chem., 220, pp. 67-76. 

Propane Selective Oxidation to Propene and Oxygenates on Metal Oxides 415... 

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