Effect on the rate of pressure carbon deposition in the reforming system
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In all books on reforming theory, it is stated that the lower the system pressure, the faster the catalyst will coking and accumulate carbon deposits. My understanding is that when the system pressure is low, the hydrogen partial pressure decreases, which slows down the saturation of the cracked dienes and polycyclic aromatics; as a result, the proportion of condensation reactions increases, leading to faster carbon deposition. Polymerization reactions are generally reactions that result in a decrease in volume. From a purely kinetic perspective, shouldn’t lower pressure cause the reaction to proceed in the opposite direction, thereby reducing the rate of coking and condensation?
The saturation rate of the cracked dienes and polycyclic aromatics decreases, while the corresponding condensation ratio increases, leading to accelerated carbon deposition
The lower the pressure, the more favorable the dehydrogenation reaction is; the carbon-hydrogen bonds break apart, and after hydrogen is removed, only carbon remains
Well, in the end, it’s still the saturation effect of hydrogen partial pressure on the precursors of carbon deposits; this shifts the equilibrium of the saturation reaction to the left, resulting in an increase in the amount of precursors such as dienes and polycyclic aromatic hydrocarbons, which in turn leads to an increase in carbon deposit formation~~
The impact of the dehydrogenation reaction should be relatively minor, after all, dehydrogenation is the purpose of reforming. I think, in the end, it’s still the hydrogen partial pressure that causes saturation of the precursors to carbon deposits; this shifts the equilibrium of the saturation reaction to the left, resulting in an increase in the amount of precursors such as dienes and polycyclic aromatic hydrocarbons, which in turn leads to an increase in carbon deposit formation~~