Hydroisomerization of n-Heptane in a Fixed-Bed Reactor Using a Synthesized Bimetallic Type-HY Zeolite Catalyst

Abstract

The synthesis of NaY-zeolite was performed hydrothermally. The preparation ofthe bifunctional catalysts was achieved by loading NH4Y-zeolite with a cheap Zrmetal, as a second loading metal, with tiny amounts of Pt to compose a Pt-Zr/Yzeolitecatalyst. Different characterization methods (i.e., XRD, SEM, EDX, BET,and AFM) were used to investigate the catalyst properties. The catalyticperformance was studied by performing the hydroisomerization of n-heptane in agas phase at a temperature of 275°C and atmospheric pressure in a fixed-bedreactor. The GC-FID results of the products confirmed the positive role of Zr inenhancing the catalytic features, as reflected by the increase in the isomerizedproducts and the decrease in the unwanted by-products. Incorporating 1.0wt%Zrwith 1.0wt% of Pt significantly improved the activity and selectivity and increasedthe yield of branched alkanes. This was achieved because the addition of zirconiumprovided an extraordinary Lewis acidity to the zeolite-framework structure andsimultaneously took advantage of the electronic and catalytic properties of Zr andPt metals to enhance its novel catalytic features. This reduced the amount of Ptmetal and halved the cost of the catalyst. In addition, the bimetallic catalyst (HYzeoliteloaded with 1wt%Pt & 1wt%Zr) achieved values of 74.2, 78.8, and58.5mol% for conversion, selectivity, and yield, respectively. The conversion wasimproved to a level close to 2wt% Pt/HY-zeolite catalyst, while selectivity was notsignificantly decreased from that of 2wt% Zr/HY-zeolite catalyst, reaching a yieldlevel of isomers close to that of 2wt% Pt/HY-zeolite catalysts