US Patent 7772448 Alkylaromatics production

A process is described for producing an alkylaromatic compound in a multistage reaction system comprising at least first and second series-connected alkylation reaction zones each containing an alkylation catalyst. A first feed comprising an alkylatable aromatic compound and a second feed comprising an alkene and one or more alkanes are introduced into said first alkylation reaction zone. The operating conditions, e.g. temperature and pressure, of the first alkylation reaction zone are controlled effective to cause the alkylatable aromatic compound to be partly in the vapor phase and partly in the liquid phase, and the ratio of the volume of liquid to the volume of vapor of the feed in each zone to be from about 0.1 to about 10. The aromatic compound and the alkene of the feed are reacted in the presence of the alkylation catalyst to form an effluent comprising the alkylaromatic compound, unreacted alkylatable aromatic compound, any unreacted alkene and the alkane. The effluent is withdrawn from the first alkylation reaction zone and then supplied to the second alkylation reaction zone without removal of the alkane.