Bimetallic Ru-Ni supported on hierarchical nitrogen doped carbon for efficient catalytic hydrotreatment of fast pyrolysis liquids

Noble metal catalysts, particularly Ru-based, demonstrate exceptional activity during catalytic hydrotreatment of fast pyrolysis liquids (PLs) from lignocellulosic biomass. However, their high cost poses a major barrier to practical applications. Herein, a series of cost-effective bimetallic Ru-Ni catalysts with varying Ru/Ni ratios (5 wt% metal loading, Ru x Ni y /NC) supported on hierarchical nitrogen-doped carbon materials (NC) were facilely prepared by the wet impregnation method. The performance was evaluated for catalytic hydrotreatment of PLs. The results revealed that the introduction of Ni to Ru significantly enhances catalytic performance. Among the tested catalysts, Ru 4 Ni 1 /NC exhibited optimal activity, achieving the product oils with the highest H/C ratio and lowest thermogravimetric (TG) residue. Under mild condition (200 °C, 6 MPa H 2 , 4 h), the catalyst yielded the product oil with an H/C ratio of 1.49 and a TG residue of 10.7 wt%. When subjected to deep hydrotreatment condition (340 °C, 6 MPa H 2 , 4 h), the catalyst generated the product oil with an H/C ratio of 1.32 and a TG residue of 2.9 wt%. To gain insights into the catalytic mechanism, the adsorption behavior of model components in PLs onto the catalyst was investigated through FT-IR. The results revealed that the incorporation of low electronegativity Ni to Ru, induces the electron transfer from Ni to Ru, resulting in electron enrichment at Ru sites and electron deficient at Ni sites, which promotes the adsorption of substrates onto the catalyst, thereby boosting hydrogenation of PLs. These findings highlight the significant potential of bimetallic Ru-Ni/NC for catalytic hydrotreatment of PLs into intermediates that can be co-processed with vacuum gas oil in FCC refinery for biofuel production.