Hydrodesulphurization

Residues (petroleum), heavy coker and light vacuum Residues (petroleum), catalytic reformer fractionator Residues (petroleum), hydrodesulphurized atmospheric tower Residues (petroleum), topping plant, low sulphur Residues (petroleum), heavy coker gas oil and vacuum gas oil Residues (petroleum), thermal cracked... 

Molybdenum compounds Hydrodesulphurization and hydrotreating of petroleum Oxidation of methanol to formaldehdye Epoxidation of olefins Decomposition of alkali metal nitrides Irritation of eyes and respiratory tract Pneumoconiosis... 

Clarified oils (petroleum), hydrodesulphurized catalytic cracked... 

Distillates (petroleum), hydrodesulphurized intermediate catalytic cracked Distillates (petroleum), hydrodesulphurized heavy catalytic cracked... 

Gas oils (petroleum), thermal cracked, hydrodesulphurized Gas oils (petroleum), heavy atmospheric... 

Partially Crystalline Transition Metal Sulphide Catalysts. Chiannelli and coworkers (6, 7, 8) have shown how, by precipitation of metal thio-molybdates from solution and subsequent mild heat-treatment many selective and active hydrodesulphurization catalysts may be produced. We have shown (18) recently that molybdenum sulphide formed in this way is both structurally and compositionally heterogeneous. XRES, which yields directly the variation in Mo/S ratio shows up the compositional nonuniformity of typical preparations and HREM images coupled to SAED (see Figure 2) exhibit considerable spatial variation, there being amorphous regions at one extreme and highly crystalline (18, 19) MoS at the other. 

Correlations between catalytic activity and a variety of bulk properties of semiconductors have been reported (i) the average band gap of III-V and II-VI semiconductors and activity towards hydrogenation of isopropanol (ii) enthalpy of oxides and their activity towards oxidation of propylene and (iii) number of d-electrons (and crystal field stabilization energy) or 3rf-metal oxides and their activity towards N2O decomposition. The last correlation, due to Dowden (1972), is important since it provides a connection between heterogeneous catalysis and coordination chemistry of transition-metal compounds. A correlation between the catalytic activity of transition-metal sulphides towards hydrodesulphurization of aromatic compounds and the position of the transition metal in the periodic table has been made by Whittingham ... 

Figure 8.19 Catalytic activity of transition-metal sulphides for hydrodesulphurization of dibenzothiophene. (After Whittingham Chianelli,...

The objective of the present work is to classify the catalytic performances of unsupported transition metal sulphides (TMS) for these different reactions dehydrogenation of a sulphur containing molecule without sulphur elimination, hydrodesulphurization and hydrogenation. 

The catalysts were tested in the dehydrogenation of tetrahydrothiophene (DHN of THT), the hydrodesulphurization of thiophene (HDS of thiophene) and the hydrogenation of biphenyl (HN of BP). The reactions were carried out in the vapor phase using dynamic flow microreactors equipped with an automatic online analysis. Reaction conditions are given in Table 1. 

Mitchell, P. C. H., The Chemistry of Some Hydrodesulphurization Catalysts Containing Molybdenum. Climax Molybdenum Co., London, 1967. 

Sites at the surface of non-metallic catalysts have also been investigated. The adsorption of H2 by Co304 has been studied by diffraction and has been referred to earlier.12 The adsorption of H2 by Mo and W sulphides however, has been the subject of a number of inelastic scattering investigations which have gone a long way to clarify the sites at which adsorption occurs, and probably the sites from which H2 is transferred in hydrodesulphurization reactions. 

The best way to remove sulphur compounds is to convert the organic sulphur species to H2S over a hydrodesulphurization catalyst. The next step is sulphur removal with an absorbent. The same catalyst can usually convert any organo-chloride species to give HC1 and also act as an absorbent for most problematic metal species. A second absorbent is used for chloride removal70. 

Since a somewhat higher active phase loading can be achieved in the ammoniacal as against the phosphoric acid route, one may wonder why P-containing catalysts are still in use. Well, here we have to drawn a distinction between hydrodesulphurization (HDS) and hydrodenitrogenation (HDN). In the former... 

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