An investigation of the surface intermediates of H2-SCR of NOx over Pt/H-FER

Catalytic performance of platinum supported on H-ferrierite (H-FER) in selective catalytic reduction of NO and NO2 by hydrogen (H2-SCR) was investigated. 87.9% of the NOx was reduced with 56% of selectivity to N2 when a gas mixture of 910 ppm NO, 90 ppm NO2, 5000 ppm H2, 10% O2 in N2 passed through a 0.5 wt.%Pt/H-FER catalyst at 110 °C and gas hourly space velocity (GHSV) of 36,000 h−1. It was found that the NOx reduction sharply decreased at higher reaction temperature, accompanied by large amount of NO2 formation. The NOx conversion was also drastically decreased by increasing the concentration of NO2 while holding the total concentration of NO + NO2 in the feed gas mixture. Based on in situ Fourier transform infrared spectroscopy investigation, it was proposed that NO2 and nitrate species were not essential intermediates of H2-SCR over the catalyst, while NOδ+ species on Pt was a possible species for efficient elimination of NO.

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► High NOx elimination level was reached in H2-SCR at 110 °C over 0.5%Pt/H-FER.
► The reaction route over the catalyst was investigated.
► NO2 and nitrate species were demonstrated not to be intermediates of the reaction.
► NO2 was firstly reduced to NO when it engaged in the reaction over the catalyst.