Stefano Amarilli

Alkylation of benzene catalysed by supported heteropolyacids

A new kind of solid acid based on heteropolyacids has been proved to be a useful catalyst in alkylation of benzene with propylene to obtain cumene. The new catalysts are based on a heteropolyacid supported on zirconia treated with very low contents of sulphate anions. Two different heteropolyacids have been studied, both with Keggin structure, (H 3 PMo 12 O 40 , H 3 PW 12 O 40 ), and both produced active catalysts. The zirconia was used either pure or doped with few percent of iron oxide. The catalysts have been characterised through XRD, 31 P NMR and HREM. These catalysts are very active in alkylation reaction even at mild temperature. Their two outstanding features are the low n-propylbenzene production and the possibility to regenerate it at moderate temperature (350°C). The best catalyst is based on H 3 PW 12 O 40 supported on zirconia doped with iron and treated with sulphate ions.

Ethylation of ethylbenzene over some aluminosilicates with molecular sieve structure

Abstract A β-zeolite, a ZSM-5 and an XRD-amorphous alumino silicate were prepared by the usual hydrother- mal technique in the presence of templating agents. The solids so obtained were characterised by various techniques and tested as catalysts for the title reaction, under typical industrial reaction conditions (T=180 to 260°C, P=35 bar, ethylbenzene WHSV =5 h -1 ). For none of the three catalysts was the structure and the pore size of the solid shown to play a significant role in directing the selectivity towards a particular diethylbenzene isomer. A major role appeared to be played by the concentration of Brensted acid surface sites and by reaction temperature, the distribution of diethylbenzene isomers being gov- erned by either kinetic or thermodynamic factors, rather than by shape-selective restraints.