Answer to Question #243815 in Chemical Engineering for Vijay

Question

To design a rector of hydrodesulfurization reaction to convert benzothiophene into ethylbenzene with a cobalt-molybdenum catalyst supported on alumina.we have packed bed reactor (adiabatic ) temp-260C and pressure 30bar.please provide solutions for Reactor shape and dimensions

Answer 1

Hydrotreating is a substantial finishing process in large refineries for reducing organic impurities and breaking down the high molecular weight of heavy petroleum feedstock in the presence of a suitable catalyst.The process of hydrotreating aims to raise the quality of petroleum to meet the environmental standards of minimal emission. Catalytic hydrodesulfurization (HDS) of crude oil and petroleum fuels is carried out at high temperatures and hydrogen partial pressures to convert organic sulfur compounds to hydrogen sulfides (H₂S) and hydrocarbons.That, until now, alumina-supported Co or Ni promoted by MoS₂ is still the most widely used hydrotreating catalysts in refineries was found in a previous study related to Co–Mo/Al₂O₃ catalyst in which alumina is not only an inert carrier but also a promoter ion. Since the first development of refining processes of crude oil, alumina is effective as a support for the HDS catalyst, and Ledoux et al.showed that γ-Al₂O₃ is the best among several supports in terms of HDS activity. They reported that the most effective one over η, θ, χ, or amorphous alumina was the γ phase, essentially owing to the impact of its surface orientation and crystallinity on the active phase.

The second factor that becomes important in reactions of substituted benzenes concerns the site at which electrophilic substitution occurs. Since a mono-substituted benzene ring has two equivalent ortho-sites, two equivalent meta-sites and a unique para-site, three possible constitutional isomers may be formed in such a substitution.These reactions involve various steps including hydrogenation and carbon-heteroatom bond cleavage, in which both hydrogen and hydrogen sulfide can play a role. To identify the mechanisms of these reactions, the process of adsorption (and of activation) of H2 and of H 2 S must be well understood.