HDS—See Hydrodesulfurization

M0S2 and WS2 modified with Ni and Co have major uses in the hydrotreating of various refinery streams. The composition chosen is a function of the feed and of the specific treatment needed hydrodesulfurization (HDS see Chapter 3.2.4), hydrodenitrogenation, demetallization, and reduction of unsaturation. 

Can you think of reasons why substituted dibenzothiophenes are more difficult to desulfurize than thiophene or simple thiols (see Fig. 9.2) Depending on the choice of catalyst, hydrodesulfurization can be accompanied by hydrogenation to various extents. In which of the product streams in the refinery would you choose hydrogenative HDS and in which would you not ... 

Gulf HDS A process for hydrorefining and hydrocracking petroleum residues in order to make fuels and feeds for catalytic cracking. Developed by the Gulf Research Development Company. See also hydrodesulfurization. 

Hydrodesulfurization (HDS) is an important process in petrochemical refinery as it allows deaeasing the sulfur content in diesel fuel. Compounds such as alkylated dibenzothiophene (DBT) raise some problems in HDS. The alkyl groups, especially when located in the 4 and 6 positions of the ring (see Figure 18) make alkylated DBT resistant to classical HDS catalysts because of the methyl groups that prevent the thiophenic sulfur atom to be in contact with the active site of the catalyst. 

If the PMcj and dppe (diphenylphosphino ethane) PtLj analogues are used, complete hydrodesulfurization of DBT and 4-MeDBT to biphenyl and 3-Me-biphenyl, respectively, takes place under 20 atm H, at 100 °C interestingly, the presence of acid-washed alumina promoted the HDS reaction (see e.g. Eq. 4.9). Neither the fate of the sulfur nor the HDS mechanism is clear in this case [42, 43]. 

The removal of sulfur from petroleum is commonly achieved by hydrogenation on heterogeneous catalysts (in a hydrodesulfurization, or HDS, process) but a few homogeneously catalyzed reactions are also known [61,62]. Eor biphasic processes, see Section 2.4.2.2. 

Studies of nucleophilic attack on the 7r-bound benzo[b]thiophene (BT) complexes [CpRu(BT)] and [Cp Ir(BT)] have been undertaken as potential models for the reactions of BT on hydrodesulfurization (HDS) catalysts. In these complexes, the BT coordinates to the metal via the benzene rather than the thiophene ring. A range of nucleophiles, including hydrides and sulfides which are proposed to be present on HDS catalyst surfaces, add to the benzene ring to give primarily C-7 adducts see Eq. (24). However, products that might be precursors to, or are similar to, proposed intermediates in the HDS of BT, such as... 

The reaction of thiophenes and other related sulfur heterocycles with low-valent metal fragments has importance in relation to the catalytic hydrodesulfurization (HDS) process (see Section 8.02.4.1). Oxidative addition of halogenated thiophenes can involve C-S bond cleavage (Equation (40)) or oxidative addition of the G-X bond... 

Such a selective hydrodesulfurization must clarify the active sites of CoMo and NiMo sulfides supported on alumina for hydrodesulfurization and hydrogenation. CoMo is certainly more selective for hydrodesulfurization with limited hydrogenation activity than NiMo. Hence, cobalt is applied for the present purpose. Coordinatively unsaturated Co sulfide on M0S2 is often postulated as the active site for both reactions (see Fig.7). The metal with unsaturated valence is proposed as the hydrogenative site in cooperation with a Mo-S-H group while the metal with the unsaturated valences must be the hydrodesulfiiiization site. H2S concentration in HDS can be reduced to enhance the hydrodesulfiiiization selectivity. 

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