Low-Metal Urea Fluid for SCR Catalyst Protection

The patent extracts and removes harmful metal impurities from the surfactant through purification processes. The surfactant is subjected to treatment that selectively removes metal ions while retaining the functional surfactant molecules, thereby resolving the contradiction between needing surfactant for atomization and avoiding metal contamination that poisons the catalyst.

The patent changes the purity parameter of the surfactant by implementing specific purification steps. The surfactant is purified to reduce metal content below detectable limits or to very low levels, while maintaining its surfactant properties. This parameter change allows the system to benefit from surfactant addition without suffering from metal salt contamination.

The patent introduces a catalyst as an intermediary substance that facilitates the decomposition of urea at lower temperatures. The catalyst provides an alternative reaction pathway with lower activation energy, enabling complete decomposition of urea to ammonia and isocyanic acid even at reduced exhaust temperatures, thereby preventing cyanuric acid formation while maintaining NOx reduction efficiency.

The patent changes the temperature parameter at which urea decomposition occurs by using catalytic assistance. Instead of relying solely on high thermal energy to drive complete decomposition, the catalyst enables the reaction to proceed efficiently at lower temperatures, shifting the operational temperature window to include lower exhaust gas temperatures without forming deposits.