High-value utilization of agricultural waste: A study on the catalytic performance and deactivation characteristics of iron-nickel supported biochar-based catalysts in the catalytic cracking of toluene

This study synthesized monometallic and bimetallic Fe-Ni catalysts using rice husk as the raw material, and investigated the catalytic performance of the catalysts on tar model compounds as well as their deactivation characteristics. The results showed that after 20 min of reaction, the Fe-Ni catalyst achieved the highest efficiency of 54.01 %, the largest micropore area of 9.95 m2/g, and the lowest carbon deposition rate of 3.15 %. After 80 min of reaction, the efficiency of the bimetallic Fe-Ni catalyst decreased to 33.41 %, with mild pore carbon deposition and a carbon deposition rate of 12.35 %. In contrast, the efficiency of the monometallic Ni catalyst decreased to 17.23 %, with severe pore blockage and a higher carbon deposition rate of 16.17 %. The deposited carbon was primarily inert carbon (Cγ), with the highest content observed in the monometallic Ni catalyst. During the reaction, toluene and carbon deposition competed for the oxygen source, and the O/C ratio of the bimetallic Fe-Ni catalyst showed the largest decrease of 0.13, while also exhibiting higher C-O and C=O contents. Due to strong metal interactions between Fe and Ni, an Fe0.64Ni0.36 alloy was formed, which provided an oxygen source for the reaction and enhanced the catalyst's resistance to carbon deposition.