Preparation of graphene supported Ni–Fe bimetallic nanocatalyst and its catalytic upgrading and viscosity reduction performance for heavy oil

Graphene supported single metal catalyst can improve the dispersion of active components and enhance the viscosity reduction effect of heavy oil. However, there is little research on graphene-supported bimetallic catalysts in the field of heavy oil upgrading and viscosity reduction. In this paper, super heavy oil of Liaohe Oilfield was taken as the research object. Graphene was selected as the carrier material, and nickel and iron chlorides were used as precursors. Graphene-supported nickel-iron bimetallic nanocatalysts were prepared by solvothermal method, and their synthesis feasibility was proved by microscopic characterization. Then the prepared catalyst was used in the evaluation experiment of catalytic upgrading and viscosity reduction performance of Liaohe heavy oil. By analyzing the parameters of oil samples before and after catalytic upgrading and viscosity reduction, the catalytic upgrading and viscosity reduction effect was evaluated and the viscosity reduction mechanism was revealed. The results showed that the viscosity reduction rate of heavy oil with graphene supported Ni–Fe bimetallic catalyst was 42.38%. With the aid of decalin, the viscosity reduction rate of heavy oil could reach 71.43%. At this time, the content of heavy components, the average molecular weight of heavy components and the aromaticity fA of oil samples decreased after catalytic upgrading and viscosity reduction, while the aromatic condensation degree HAU/CA and the branched chain index BI increased, and the modification effect was significant. Among them, the average molecular weight of asphaltene decreased from 2266 to 1444, with the most obvious decrease. The decrease of heteroatom content in asphaltene led to a significant decrease in intermolecular force and hydrogen bonding, which was the main reason for the catalytic upgrading and viscosity reduction of heavy oil by graphene supported Ni–Fe bimetallic catalyst.