A γ-AlOOH/γ-Al₂O₃ washcoat overlayer, applied to a PdO(Pt/CeO₂)/γ-AlOOH/γ-Al₂O₃ on cordierite (2MgO·2Al₂O₃·5SiO₂) mini-monolith catalyst (400 cells per square inch, 1 cm diameter × 2.5 cm length), is shown to reduce the impact of H₂O and SO₂ on the catalyst activity and stability during CH₄ oxidation at low temperatures (<500 °C). The washcoat overlayer covered the Pd (and Ce and Pt when present) and decreased the catalyst CH₄ oxidation activity in a dry feed gas (0.07 vol % CH₄, 8.5 vol % O₂, 0.06 vol % CO, 8 vol % CO₂) at a gas hourly space velocity (GHSV) of 36 000 h^–1. However, when H₂O (2, 5, and 10 vol %) and SO₂ (2 and 5 ppm) were added to the feed gas, the loss in catalyst activity was reduced and the catalyst stability was improved. The overlayer provided additional sites for both SO_x and H₂O adsorption, thereby reducing their adsorption on the active phase of the catalysts, and consequently, the catalysts maintained higher activity in the presence of both SO₂ and H₂O over periods of up to 200 h.

中文翻译：

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修补基面涂层，用于改善在H ₂ O和SO ₂存在下运行的天然气汽车整体催化剂的活性和稳定性

甲γ-AlOOH的/γ-Al系₂ ö ₃修补基面涂层的覆盖层，施加到的PdO（PT /的CeO ₂）/γ-AlOOH的/γ-Al系₂ ö ₃上堇青石（2MgO·2AL ₂ ö ₃ ·5SiO ₂）微型整体式催化剂（每平方英寸400个单元，直径1厘米×长度2.5厘米）可减少H ₂ O和SO ₂对低温（<500°C）CH ₄氧化过程中催化剂活性和稳定性的影响。覆盖层所覆盖的钯（和Ce和Pt当存在时）和降低的催化剂CH修补基面涂层₄的干进料气中的氧化活性（0.07％（体积）CH ₄，8.5体积％氧气₂，在36000 h ^–1的气体时空速（GHSV）下为0.06 vol％CO，8 vol％CO ₂）。然而，当将H ₂ O（2、5和10体积％）和SO ₂（2和5ppm）添加到进料气中时，催化剂活性的损失减少并且催化剂稳定性提高。覆盖层为SO _x和H ₂ O的吸附提供了额外的位置，从而减少了它们在催化剂的活性相上的吸附，因此，在SO ₂和H ₂ O的存在下，催化剂在较高的吸附时间内保持较高的活性。到200小时