comparing the performance of heterogeneous pd-supported catalysts: pd/zsm-5, pd/13x and pd/al2o3 for the hydrogenation of benzene in a mixture of normal heptane and benzene

In the presented research, the selective hydrogenation of benzene in a mixture of benzene and normal heptane (5 vol % of benzene) over different kinds of heterogeneous catalysts was investigated. for this purpose, a series of catalysts with various supports such as pd/zsm-5, pd/13x and pd/al2o3 was developed. to prepare pd supported catalysts, the modification of supports was conducted by a specified amount of palladium nitrate in the aqueous solution. experimental catalyst evaluation tests were performed in the catalyst assessment set-up. the characterizations of the physicochemical properties of the prepared catalysts were performed by xrd, nh₃-tpd and bet. it can be found that the conversion of benzene was promoted under the optimized reaction conditions of 200 °c, 1 mpa, h2/hc = 1.3 (molar ratio) and the weight hourly space velocity (whsv) = 25 hr-1. among these catalysts, pd/13x exhibited the maximum conversion of benzene (90 %) and the minimum light-cut production under the optimum conditions. the study on the stability of catalysts shows that, the decline activity of pd/13x catalyst is more than that of the other catalysts (from 90 % to 81 %) in the specified 20 h time on stream, but so far the activity of this catalyst is the highest in comparison with that of other catalysts at the end of the defined time (20 h).