HDO and HDM Reactions

Recently, the C - N bond was proposed to be associated with H2S in the formation of C - SH and NH3. The C - SH bond is easily eliminated under hydrotreating conditions. Prins et al. reported that 2-methylcyclo-hexylamine (MCHA) is hydrodenitrogenated through three ways (a) direct elimination of ammonia, (b) nucleophilic removal of the NH2 group by H2S followed by removal of the -SH group, and (c) direct 

The involvement of aromatic C - N , especially derivatives from carbazoles, is not definite yet. Such a mechanism would be desired to reduce hydrogen consumption. HDO is not an important reaction for petroleum products, but it is very important in stabilizing coal-derived liquids. HDO of dibenzofuran is very slow. An acidic support is helpful for the HDO of dibenzofuran species. 

HDM is a key for the hydrotreatment of heavy oil because it removes asphaltenes and affects the capacity of downstream catalysts to hold eliminated metal sulfides.Liberation of asphaltene aggregation as well as the pore-mouth size and pore volume are important criteria for the design of catalysts to enhance HDM of heavy feeds. 

Aromatic species are also inhibitors for HDS of refiactory sulfur species as described above, because refiactory sulfur species are desulfiized through the hydrogenation route. Aromatic species can be highly concentrated and can inhibit the last stages of HDS. Overcoming this difficulty is not easy. 

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Catalytic and thermal kinetic expressions (Equations 10.27 and 10.28) were analyzed under the following assumptions the reaction rate follows a power-law approach the stoichiometric coefficient of hydrogen for the whole set of catalytic reaction is 3 a heavier cut could only be converted into lighter cuts reaction orders are the same for all reactions and HDO, HDS, HDN, HDM reactions are... 

Enthalpies for the reactions (AHr) can be grouped into three categories. For HDS, HDN, HDO, HDM, and aromatics saturation, AHr are about -2.5 to -3.0 kJ per standard cubic meter of consumed H2. For reactions that break carbon-to-carbon bonds, AHr are about -1.3 to -1.7 kJ per m of consumed H2. And for saturation of olefins, AHr are about -5.5 kJ per m of consumed H2. Isomerization reactions produce a small amount of heat, but this can be neglected. 

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