Selective Hydrogenation of Pyrolysis Gasoline

Steam cracking, of course, is designed to produce unsaturated hydrocarbons so pyrolysis gasoline contains dienes which must be removed by selective hydrogenation. 

There are two ways in which raw pyrolysis gasoline can be treated to provide a useful product  

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It follows that regeneration may consist of either (i) removal of IS sometimes poisons, most often inhibitors or fouling agents, e.g., coke (hydrogenation catalysts, e.g., selective hydrogenation of pyrolysis gasoline) or (ii) redispersion of the active species (platinum catalysts) or (iii) both (hydrodesulfurization or catalytic reforming catalysts). 

The selective hydrogenation of pyrolysis gasoline is a conventional process vapor under high-pressure reaction conditions and temperatures around 100 °C. The process aims to hydrogenate the unsamrated chains of a load containing compounds such as styrene, olefins and diolefins, and other aromatic compounds. 

The results of activity (styrene conversion) at 120°C in the hydrogenation of pyrolysis gasoline are shown in Figure 19.8 for selected samples. 

Neste Oy, Engineering Olefins FCCU light gasoline, EC pyrolysis gasoline Selective hydrogenation of C5, C6 and C7 diolefins to olefins 1 1995... 

H.A. Smits, Selective hydrogenation of model compounds for pyrolysis gasoline over a monolithic palladium catalyst, SPE thesis. Delft University of Technology, Delft, The Netherlands, 1994. 

Selective catalytic hydrogenation of dienes and polyenes to monoenes over nickel sulphide supported on alumina or silica finds application in the partial hydrogenation of soybean oil and isoprene in the presence of methylbutenes. A sulphided C0-W/AI2O3 catalyst has been proposed for the selective hydrogenation of dienes in pyrolysis gasoline. 

Figure 2. Flow schematic of three-stage pyrolysis gasoline/gas oil hydrotreater for selective hydrogenation of gasoline...

Nickel oxide supported on y-alumina is also active and selective with typical pyrolysis gasolines. It can be reactivated very easily at intervals of two to nine months by heating in hydrogen or regenerated by conventional burning of deposits in air when necessary. Replacement is required after about two years. 

Application Increase the value of steam cracker pyrolysis gasoline (py-gas) using conversion, distillation and selective hydrogenation processes. Pygas, the C5-C9 fraction issuing from steam crackers, is a potential source of products such as dicyclopentadiene (DCPD), isoprene, cyclopentane, benzene, toluene and xylenes. 

This study aims to evaluate samples of commercial catalysts based on palladium or nickel, selected by the Petrochemical Company (COPESUL), comparing them for activity and selectivity for use in industrial drive pyrolysis gasoline hydrogenation. 

Many other catalytic fluidized-bed processes have been tested at various scales. These include catalytic low-temperature oxidation, catalytic gasification and pyrolysis of biomass and waste plastic, production of carbon nanotubes, dry reforming of methane, hydrogenation and dehydrogenation of hydrocarbons, methanol-to-gasoline (MTC) process, synthesis of dimethyl ether (DME), and selective catalytic reduction of nitrogen... 

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