Abstract: Process for the production of at least one compound that is selected from among monoalkyl aromatic compounds, dialkyl aromatic compounds and trialkyl aromatic compounds by alkylation or transalkylation of an aromatic compound by at least one alkylating agent that is selected from among the olefins, whereby the process is characterized in that it is carried out in one or two stages, involving two reaction zones in series, whereby one of these two zones can be switched off so as to be able, depending on whether or not one of the zones is switched off, to meet the demand either of the three types of mono, di- and trialkyl aromatic compounds, or two of these types or a single one of the types of mono- or di- or trialkyl aromatic compounds.

Abstract: The invention concerns a process and catalyst for the production of cyclohexane by hydrogenation of benzene, comprising at least the two following steps: a) gradually introducing the feed of benzene for hydrogenation and a hydrogen-rich gas into a reaction zone containing a cyclohexane-rich liquid and a nickel-based catalyst in colloidal suspension and recovering a gaseous phase containing cyclohexane, hydrogen and benzene; b) introducing the gaseous phase into a reactor operating under hydrogenation conditions and containing at least one fixed bed of a solid nickel-based hydrogenation catalyst, wherein the nickel-based catalyst used in step a) is a product which results from the reduction, by at least one trialkylaluminium compound, of a solution of at least one nickel carboxylate and at least one sodium carboxylate in solution, the Ni:Na molar ratio being between 2:1 and 1000:1 in a hydrocarbon or a hydrocarbon mixture.

Abstract: Process for extracting dyestuffs and particularly a blue pigment, called phycocyanine, from cyanophyceae algae, particularly of the Spirulina species, comprising contacting said algae with a first aqueous phase containing calcium ions, separating therefrom the mass of algae and contacting it with a second aqueous phase of alkaline character, separating the algae therefrom and extracting phycocyanine from said second aqueous phase by subjecting the same to an ultrafiltration step for concentrating the solution and then to a drying step.