What substances are sensitive to the precious metal Pt honeycomb catalyst?
Although the Pt honeycomb catalyst has high activity, it is very sensitive to various impurities. Common "toxins" include:
Sulfur compounds (S):
such as SO₂, H₂S, and organic sulfides.
Sulfur will form strongly adsorbed sulfides (such as Pt–S) on the Pt surface, occupying the active sites and causing irreversible or difficult-to-recover poisoning.
Source: coal combustion flue gas, sulfur-containing fuel oil, industrial exhaust gas.
Phosphorus compounds (P):
such as phosphates, organic phosphides.
Phosphorus will deposit on the catalyst surface or react with the carrier, reducing the active surface area and causing gradual loss of activity.
Source: lubricant additives, pesticide exhaust gas, certain chemical processes.
Heavy metals and halogen compounds:
Lead (Pb): comes from leaded gasoline or industrial dust, forming alloys or coatings on the Pt surface, severely deactivating it.
Arsenic (As), mercury (Hg): also tend to adsorb on the active sites and are difficult to remove.
Chlorine (Cl), fluorine (F), and their compounds: such as HCl, HF, organic chlorides, can cause Pt particles to sinter or cause corrosion of the carrier, leading to chemical poisoning and structural damage.
Dust and particulate matter:
Although not chemical poisoning, they can physically block the pores, increase pressure drop, cover the active surface, and prevent gases from fully contacting the Pt active sites.
Source: unfiltered flue gas, workshop dust, road dust.
Acidic gases (except sulfur):
Such as HCl, HF, NO₂ when present in excessive amounts, can react with the carrier or Pt to form unstable or corrosive compounds, accelerating aging.
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