Process-intensified Methane-Assisted Catalytic Partial Upgrading of SAGD Bitumen: Coupling Methane Pre-Activation and Off-Gas Recycle for Improved Product Quality and Catalyst Stability

Steam-assisted gravity drainage bitumen requires extensive diluent addition or severe hydrotreating because of its high viscosity, density, acidity, sulfur content, and asphaltene-rich composition. Here, an experimentally validated process-intensified methane-assisted catalytic partial-upgrading strategy coupling methane pre-activation with off-gas recycle over Ce–Co–Ag–Ga–Mo/ZSM-5 was benchmarked against once-through methane operation using the same SAGD bitumen feed and catalyst. Recycling H₂- and C₂–C₄-containing off-gas generated an internally enriched gas phase associated with enhanced methane utilization and hydrogen-transfer chemistry without external H₂. Methane conversion increased from 1.1% to 9.5% while maintaining a 94.3 wt% liquid yield. Relative to the once-through product, viscosity decreased from 520 to 180 cP, density from 0.982 to 0.958 g mL−1, total acid number from 0.55 to 0.12 mg KOH g−1, sulfur from 2.4 to 1.5 wt%, and asphaltenes from 7.4 to 3.8 wt%. Simulated distillation showed that recovery below 400 °C increased from 48% to 63%. Post-reaction BET, TGA, Raman, XRD, NH3-TPD, pyridine-FTIR, and TEM characterizations indicated distinct deactivation pathways: once-through operation produced graphitic coke shells, pore blockage, and active-site agglomeration, whereas the intensified configuration preserved framework accessibility and formed thinner, disordered carbon. The strategy improves bitumen quality, methane utilization, and catalyst durability without external H₂.