Chemical recycling of Nylon 6,6 via ammonia depolymerization was studied with catalyst selection and condition optimization. Ammonia provides stable reaction conditions but lower reactivity than HCl-based systems, requiring activation of the amide bond. Lewis acids were used to reduce carbonyl electron density, and hydrogen-bonding solvents (ethylene glycol, glycerol, PEG 600) were evaluated to weaken amide linkages. With La(OTf)3 at 200 °C under 3 bar NH3 for 24 h, higher hydrogen-bonding functionality decreased the residual polymer fraction to 27.4 wt%, but high-boiling solvents limited separation. Ethylene glycol was selected for processability, and catalyst strength was tuned using La(OTf)3(bpy), La(OTf)3, and In(OTf)3. Stronger Lewis acidity improved depolymerization; In(OTf)3 was optimal. At 0.1 mol% In(OTf)3 and 72 h, residual polymer decreased to 5.2 wt%. DSC and Flory–Fox analysis confirmed reduced molecular weight of precipitated polymer.