Introduction Alkylation reactions are significant in industry as many important commercial alkyl aromatics are produced worldwide. Among these alkylation reactions is the alkylation of benzene with propylene, which produces cumene, a petrochemical commodity produced in large quantities for use in the manufacture of phenol and acetone [1, 2]. Conventionally, cumene is manufactured using AlCl 3 or ... [Show full abstract] phosphoric acid catalysts. However, corrosion and environmental problems arising from these conventional catalysts have impelled the use of solid acids such as zeolite-based catalysts [3, 4]. Several medium to large pore zeolites are highly effective catalysts for the reaction of alkylation of benzene to produce cumene, but suffer from rapid deactivation of the zeolite catalysts [5, 6]. In the present work, the activity of several modified H + -beta zeolites was studied in a batch reactor and the life span of the catalyst was tested in a fixed-bed reactor. Results and Discussion Benzene alkylation reactions were tested in a batch reactor at 175°-250°C, with 7:1 benzene:propylene molar ratio, using modified H + -beta catalysts. Baseline H + -beta catalysts (Si/Al 2 =25) were loaded with 1 wt.% of either Pt, La, Ga, or Ce. Platinum–impregnated beta zeolite was prepared by mixing beta zeolite with a solution of hexachloroplatinic acid. The other catalysts were prepared by ion exchange of the beta zeolite with aqueous solutions of lanthanum chloride, gallium nitrate and cerium chloride, respectively. In addition, carbonized samples were prepared by exposing (at temperature) the beta zeolite to a gaseous mixture of hydrocarbons. The catalytic activity of the modified catalysts was tested and compared with that of the unmodified H + -beta zeolite. Our early results in the batch reactor indicated that catalysts modified with Pt, Ga, and n-pentane were the most promising. These samples showed high selectivity on par with the unmodified baseline sample. The lifespan of these three catalysts in the cumene reaction was tested over extended periods of time (8 h continuous operation) using a stainless steel fixed-bed reactor at 225°C, with 7:1 benzene:propylene molar ratio and WHSV propylene = 1.6/h.