Sodium promotion

Methyl-l-Pen ten e. This olefin is produced commercially by dimeriza tion of propylene in the presence of potassium-based catalysts at 150—160°C and - 10 MPa. Commercial processes utilize several catalysts, such as sodium-promoted potassium carbonate and sodium- and alurninum-promoted potassium hydroxide (12—14) in a fixed-bed reactor. The reaction produces a mixture of C olefins containing 80—85% of 4-methyl- 1-pentene. 

Figure 8.66. Dependence of the catalytic rates and turnover frequencies of N20 formation of the sodium promoted Rh/YSZ catalyst (squares, continuous lines) on the reaction temperature and on the catalyst potential and comparison with the sodium free catalyst (circles, dashed lines).69 Reprinted with permission from Elsevier Science.

Figure 2 depicts the dependence of N2 rate on Pco at fixed Pno= 0.52 k Pa for three different values of the catalyst potential. Vwr=+KXX) mV corresponds to the clean Pt surface (unpromoted rate) and Vwr=- 200 mV corresponds to a sodium promoted surface. Both CO2 and N2 rates exhibit Langmuir-Hinshelwood behaviour and as can be seen from Figure 2 for N2 rate, increased levels of Na result in a systematic increase in the CO partial pressure (P co) necessary for inhibition. The N2O rate also exhibits Langmuir-Hinshelwood kinetics, but the effect of increased Na is somewhat different in particular, high levels of Na tend to suppress the N2O rate and there is no systematic shift in P co-... 

Pigos, J.M., Brooks, C.J., Jacobs, G., and Davis, B.H. 2006. Evidence of enhanced LTS water-gas shift rate with sodium promoted Pt-Zr02-based catalyst discovered by combinatorial methods. Paper presented at the AICHE Annual Meeting, San Fransisco, November 12-17. 

Laboratory studies have indicated an increasing number of further processes for which iron oxides may be used as catalysts. A sodium promoted iron oxide on a support of Si02 catalyses the gas phase oxidation (377-427 °C) by nitrous oxide, of pro-pene to propene oxide (Duma and Honicke, 2000). Ferrihydrite or akaganeite can be used to catalyse the reduction (at 55-75 °C) by hydrazine, of aromatic nitro compounds to aromatic amines (which are the starting materials for a huge range of chemicals) these Fe oxides have the potential to provide a safe and economical pathway to the production of these important organics (Lauwiner et al., 1998). 

To determine the effect of alkali-metal promotion on the surface morphology, the catalysts were investigated by IR spectroscopy.9 DRIFT spectra revealed two intense reflectance bands at 760-680 cm-1 and 650-570 cm-1 for the sodium promoted sample. Moreover, an absorption band at 535 cm, which has previously been assigned to PdC>3,28 was observable in the DRIFT spectra of oxidized Na-PdO/Sn02. 

N. Macleod, J. Isaac, and R. M. Lambert, Sodium promotion of Pd/y-Al203 catalysts operated under simulated three-way conditions, J. Catal. 198, 128-135 (2001). 

B. Mirkelamoglu and G. Karakas, CO oxidation over palladium- and sodium-promoted tin dioxide, catalyst characterization and temperature-programmed studies, Appl. Catal. A 281, 275-284 (2005). 

Figure 5 Reaction mechanism for the oxidative coupling of methane on sodium-promoted praseodymium oxide. ...

Other steps used in the model assume that the heterogeneous conversion of methane is limited to the gas-phase availability of oxygen, O2 adsorption is fast relative to the rate of methane conversion, and heat and mass transports are fast relative to the reaction rates. Calculations for the above model were conducted for a batch reactor using some kinetic parameters available for the oxidative coupling of methane over sodium-promoted CaO. The results of the computer simulation performed for methane dimerization at 800 °C can be found in Figure 7. It is seen that the major products of the reaction are ethane, ethylene, and CO. The formation of methanol and formaldehyde decreases as the contact time increases. 

With the series of promoted platinum catalysts it was seen that those promoted by compounds containing non-transition elements (Sn and Ge) appeared to be promising, the selectivities to furfuryl alcohol were 40.0% and 16.8%, respectively. Promoters like V and Ti compounds did not enhance the selectivity above that of pure platinum and the sodium promoter even caused a lowering of the selectivity to furfuryl alcohol (Figure 2 and Table 2). The values plotted in Figure 2 for the promoted platinum catalysts were obtained in the non-isothermic way. In the non-isothermic experiments the temperature was stepwisely varied in the range of 170° to 210°C. 

Hawthorne, A.J. Markwell, P, J. (2004) Dietary sodium promotes increased water intake and urine volume in cats. J. Nutr. 134, 2128S-2129S. 

Lin, C., Wang, J., and Lunsford, J.H. Oxidative dimerization of methane over sodium promoted calcium oxide. J. Catal 1988, 111, 302-316. 

In patients with xmresectable cholangjocardnoma, PDT with porfimer sodium promotes biliary drainage and may improve survival and quality of life. In order to prospectively evaluate the safety and efficacy of PDT in eligible patients with locally advanced biliary tract carcinoma and unresectable, histologically confirmed disease, a Kamof-sky performance status of >30% and life expectancy >12 weeks, patients were given 2mg/kg intravenous porfimer sodium, followed by endobiliary laser activation and stent replacement 48h later. 

Gaffney, A.M., Jones, C.A., Leonard, J.J., and Sofranko, J.A. (1988) Oxidative Coupling of Methane Over Sodium Promoted Praseodymium Oxide , J. of Catal. 114,422-32. 

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