Molybdena reforming catalysts

The composition of a reforming catalyst is dictated by the composition of the feedstock and the desired reformate. The catalysts used are principally molybdena-alumina, chromia-alumina, or platinum on a silica-alumina or alumina base. The nonplatinum catalysts are widely used in regenerative process for feeds containing, for example, sulfur, which poisons platinum catalysts, although pretreatment processes (e.g., hydrodesulfurization) may permit platinum catalysts to be employed. 

During the Second World War methylcyclohexane was transformed into toluene over molybdena/alumina catalysts. An attempt was made to use the same process for the catalytic reforming of naphtha in order to increase the octane number by carrying out isomerisation, cyclisation and dehydrogenation of... 

PHD A petroleum reforming process operated in Germany from 1940. The catalyst was molybdena on alumina. 

Hydroforming. The first commercial catalytic reforming plant was built around 1940. The process used a molybdena-on-alumina catalyst at about 475-550°C under 10-20 atm pressure, a large part of which was due to hydrogen.95 The process was termed hydroforming, which refers to reforming in the presence of hydrogen. 

Catalytic reforming has become the most important process for the preparation of aromatics. The two major transformations that lead to aromatics are dehydrogenation of cyclohexanes and dehydrocyclization of alkanes. Additionally, isomerization of other cycloalkanes followed by dehydrogenation (dehydroisomerization) also contributes to aromatic formation. The catalysts that are able to perform these reactions are metal oxides (molybdena, chromia, alumina), noble metals, and zeolites. 

Catalysts other than platinum catalysts have been considered for reforming. Included among these are certain metal oxides, e.g., chromia and molybdena. However, these catalysts are much less active than platinum and also less selective toward the reactions of most interest in reforming, at least under the conditions usually employed in commercial... 

By temperature compensations, such results can be sustained for periods of a few hundred hours. However, a slow continuing deactivation occurs, and eventually the catalyst must be regenerated by combustion of the deposited coke. After regeneration, reasonable dehydrogenation results are again obtained after a rapid initial deactivation of the catalyst. Steam was found to be a particularly useful diluent with this type of catalyst. In contrast to this, the best results with molybdena-alumina for catalytic reforming are obtained over fresh catalyst and when steps such as dilution with hydrogen are employed to repress the initial rapid deactivation. 

Catalyst pellets, x 3 in., with molybdena content from 6 to 15 % were used to reform a heavy virgin mixed naphtha with a research clear octane number of 39, a 240-430° F boiling range (ASTM), and a sulfur content near 0.1%. Pilot-plant studies were made at 488 to 530° and 250 psi. The feed rate was 1.0 volume of oil per volume of catalyst per hour and the hydrogen addition rate, 2500 SCF/Bbl. Activity and yield studies were made with the cogelled catalysts whereas activity determinations only were made on the impregnated catalysts. 

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