Effect on propylene conversion

Effect of Temperature on Propylene Conversion at Atmospheric Pressure... 

Fig. 12. Secondary reactions of primary synthesis products at low CO concentrations (Co/SiO, 2700 kPa, H2/CO = 3.0, 6.2 wt% Co, 4.8% dispersion), (a) Bed residence time effects on CO conversion and C5+ selectivity (b) CO depletion effects on propylene and propane carbon selectivity.

Using the experimental results of the pyrolysis of propane-propylene mixtures under the conditions of temperatures near 900 C, atmospheric pressure and hydrogen dilution, the relation between the decomposition rate constant of propane or propylene and the ratio of both reactants was obtained. It was found from the results that propylene had an inhibition effect on propane decomposition, and conversely, propane had an acceleration effect on propylene decomposition. 

Figure 31 shows the model analysis of the effects of radial gas dispersion coefficient on radial profiles of propylene concentration. The radial mass transfer has a significant effect on the conversion and yield. When the radial Peclet number decreases from 1400 to 200, the conversion of propylene increases by over 10%, and the yield of acrylonitrile increases by about 7%. Since the reaction is first order with respect to propylene, risers are operated under dilute conditions at Pe = 200, so the radial concentration distribution of propylene is uniform and radial mass transfer is not... 

The frictional pressure has increased. Perhaps the flowrate from the tank has increased, causing an increase in frictional losses. The flowrate monitors and the settings on the control valve after the pump should be checked. This scenario would have additional consequences, because an increased propylene flowrate would have an effect on reactor conversion and possibly on product production rate and purity. Therefore, the flowrate and purity of the reactor effluent should also be checked. 

However, (Ph3P)2Rh(CO)Cl on alumina or activated carbon were effective hydroformylation catalysts under more severe conditions 108). At 148°C and a pressure of 49 atm (CO 37.5 mol%, H2 37.5, propylene 25), good activity was found. The propylene conversion was 30% at a contact time of 0.92 cm3 of reactor void space/cm3 of feed per minute. Isomer ratios of 1.3 to 1.9 1 n iso were realized. By-product formation was low, with <1% conversion to alcohols plus alkanes and 2.2% high-boiling materials. This system was stable for a 300 hour operating time, with no detectable loss of activity or selectivity. 

In the chapter on olefms plants, in the section on propylene, a route to making propylene involved butene-2. In this process, called metathesis, ethylene and butene-1 are passed over a catalyst, and the atoms do a musical chair routine. When the music stops, the result is propylene. The conversion of ethylene to propylene is an attraction when the growth rate of ethylene demand is not keeping up with propylene. Then the olefins plants produce an unbalanced product slate, and producers wish they had an on-purpose propylene scheme instead of just a coproduct process. The ethylene/butene-2 metathesis process is attractive as long as the supply of butylenes holds out. Refineries are big consumers of these olefins in their alkylation plants, and so metathesis process has, in effect, to buy butylene stream away from the gasoline blending pool. 

Figure 34. Effect of temperature on NO conversion to N2 ( ), NO conversion to NO2 ( ) and propylene conversion (A) over Cu-Al-MCM-41-10-61 catalyst (reaction conditions GHSV = 100,000 h, ...

The organoactinide surface complexes exhibited catalytic activities comparable to Pt supported on sihca [at 100% propylene conversion at —63°C, >0.47s (U) and >0.40 s (Th)], despite there being only a few active sites (circa 4% for Th, as determined by CO poisoning experiments and NMR spectroscopy) [92]. Cationic organoactinide surface complexes [Cp An(CH3 ) ] were proposed as catalytic sites. This hypothesis could be corroborated by the use of alkoxo/hydrido instead of alkyl/hydrido surface ligands, which led to a marked decrease of the catalytic activity, owing to the oxophilic nature of the early actinides [203, 204]. Thermal activation of the immobihzed complexes, support effects, different metal/ligand environments and different olefins were also studied. The initial rate of propylene conversion was increased two-fold when the activation temperature of the surface complexes under H2 was raised from 0 to 150°C (for Th 0.58 0.92 s" ). 

Figs. 3 and 4 show the effect of space-time (W/Fc3Hs) on propane conversion and propylene selectivity over the tested set of catalysts. The selectivity of propylene decreases when propane conversion increases due to the consecutive transformation of the propylene formed to COx products. 

The effect of the residence time on the IBA conversion and products selectivity at the temperature of 235C is drawn in Figure 1, for the Ko sample (ammoniacal salt) calcined at 320C. The proportionality between conversion and residence time allows to exclude diffusion as the rate-determining step. Moreover, it is shown that the selectivities to the various products were substantially independent on the conversion. This is in favour of a reaction network constituted of parallel reactions (probably sharing a common reaction intermediate, obtained by IBA activation) for the formation of methacryhc add, acetone plus CO2, propylene plus CO, and carbon oxides from combustion (1,4,7). 

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