Catalytic pyrolysis of waste tire over Rh, Ni and Co supported on KL zeolite and their bimetallic catalysts

Abstract

Taking advantages of bifunctional catalysts, the catalytic pyrolysis of waste tire has been investigated aiming to improve the quality and quantity of products. The combination of basic property in KL zeolite with the ring-opening and hydrogenation properties of rhodium was investigated for its influence. Furthermore, two non-noble metals, Ni and Co, supported on KL zeolite and the effect of bimetallic NiRh and CoRh catalysts with varying the metal ratio were investigated in this process as alternative choices in the view of cost reduction and metal availability. The amount of Rh was fixed at 1% wt whereas the amount of Ni and Co were varied from 1 tp 20%wt. It was clear from the results that the presence of KL containing Rh resulted in an increase in the gas yield at the expense of liquid yield with a high concentration of mono-aromatics. Meanwhile, 1% Co loading produced the highest gas yield among all monometallic catalysts. Moreover, the addition of greater amount of Co content from 5% to 20% provided a significantly higher amount of mono-aromatics in the liquid fraction, and gave a comparable concentration of single-ring aromatics with that obtained from 1%Rh/KL. For the case of Ni catalysts, increasing Ni loading resulted in an increment of gas yield with a significant high amount of mono-aromatics content, and using 20%Ni/KL can also be comparable with using 1%RH/KL. Furthermore, the combination of Rh and Co as bimetallic catalysts caused a significantly increasing concentration of saturated hydrocarbons in the liquid fraction. Especially, the small amount of 0.05%Rh modified with 0.95%Co exhibited the maximum concentration of saturated hydrocarbons. Meanwhile, the highest content of single-ring aromatics was found in the use of 0.25% Rh modified with 0.75% Ni among all bimetallic catalysts.