Cracking reactions, propylene conversion

Cumene Cracking Reactions on Separated Fractions. Cumene cracking reactions were tested on a gravimetric setup the basic flow diagram for the reactor system is shown in Figure 1. The reactor determines both the activity of the catalyst (cracking of cumene to benzene and propylene) and the instantaneous rate at which coke is deposited on the catalyst (polymerization of the propylene). Conversion of the cumene is adjusted to exclude the amount of cumene disproportionation which yields benzene and diisopropyl benzene. 

In addition to the propylene produced for commercial uses, large amounts of the gas are retained by the petroleum industry for conversion to products that are added to gasoline and other petroleum-based products. According to some estimates, between half and three-quarters of all propylene that comes from cracking reactions is retained for this purpose, leaving the remainder for commercial sale. 

On the other hand, for theUS Y-catalyzed alkylation of isobutane with frans-2-butene at high levels of conversion (100%), adding SCCO2 decreased the catalytic longevity and product selectivity. The alkylation of toluene with propylene over siUcon-modifled HZSM-5 zeolite using SCCO2 increased the yield of cymene and reduced the cracking of propylene compared with the reaction under atmospheric pressure (Scheme 41). ... 

The first stage of the process is a hydroformylation (oxo) reaction from which the main product is n-butyraldehyde. The feeds to this reactor are synthesis gas (CO/H2 mixture) and propylene in the molar ratio 2 1, and the recycled products of isobutyraldehyde cracking. The reactor operates at 130°C and 350 bar, using cobalt carbonyl as catalyst in solution. The main reaction products are n- and isobutyraldehyde in the ratio of 4 1, the former being the required product for subsequent conversion to 2-ethylhexanol. In addition, 3 per cent of the propylene feed is converted to propane whilst some does not react. 

As part of the same study selectivity data were provided at 10-100 kPa partial pressures of n-butane at 0-17% conversion over HZSM-5 [90]. With increase in pressure and conversion secondary reactions started to occur. These results are also summarized in Table 13.6. The lowered selectivity to hydrogen, methane and ethane was attributed to increasingly less favorable conditions for monomolecular cracking. The dramatic increase in selectivity to propane which was absent at zero conversion, along with decrease in propylene was considered as signature for bimolecular cracking. More specifically, it was suggested that hydride transfer... 

The materials thus prepared were examined in an acid-catalyzed reaction-the cracking of cumene into benzene and propylene. The conversions of cumene into benzene at 250 °C over the catalysts with 1, 3, 5,10, and 20wt% W for the impregnated concentration are shown in Figure 17.10. The highest activities for 5%-,... 

Desulfurization of petroleum feedstock (FBR), catalytic cracking (MBR or FI BR), hydrodewaxing (FBR), steam reforming of methane or naphtha (FBR), water-gas shift (CO conversion) reaction (FBR-A), ammonia synthesis (FBR-A), methanol from synthesis gas (FBR), oxidation of sulfur dioxide (FBR-A), isomerization of xylenes (FBR-A), catalytic reforming of naphtha (FBR-A), reduction of nitrobenzene to aniline (FBR), butadiene from n-butanes (FBR-A), ethylbenzene by alkylation of benzene (FBR), dehydrogenation of ethylbenzene to styrene (FBR), methyl ethyl ketone from sec-butyl alcohol (by dehydrogenation) (FBR), formaldehyde from methanol (FBR), disproportionation of toluene (FBR-A), dehydration of ethanol (FBR-A), dimethylaniline from aniline and methanol (FBR), vinyl chloride from acetone (FBR), vinyl acetate from acetylene and acetic acid (FBR), phosgene from carbon monoxide (FBR), dichloroethane by oxichlorination of ethylene (FBR), oxidation of ethylene to ethylene oxide (FBR), oxidation of benzene to maleic anhydride (FBR), oxidation of toluene to benzaldehyde (FBR), phthalic anhydride from o-xylene (FBR), furane from butadiene (FBR), acrylonitrile by ammoxidation of propylene (FI BR)... 

At the temperatures ordinarily used these two reactions occur with about equal velocities in the case of propane. Both of the olefins which are formed tend to polymerize and undergo further decomposition at this temperature (700° to 800° C.), the propylene at a much higher rate than the ethylene, with the result that either low yields are obtained or low conversions per pass through the cracking reactor must be accepted. A process which would enable a paraffin hydrocarbon to be converted to an olefin of the same number of carbon atoms by a dehydrogenation reaction would be highly desirable in some cases. 

The gas-oil cracking was carried out in a fixed-bed tubular reactor at atmospheric pressure and 482°C. The yields of the different reaction products, i.e., diesel (300°C), gasoline (210°C), methane, ethane, ethylene, propane, propylene, i-butene, n-butane, butenes and coke, were measured at total conversion levels in the range 30-80% wt/wt. The different conversions were achieved by varying the catalyst oil ratio in the range 0.025-0.40 g.g, but always at 60 seconds the time on stream. The operational procedure is given elsewhere (4). 

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