Effect Of Pt-Co/γ-Al₂O₃ Catalyst Coatings And Channel Plate Reactor For Preferential CO Oxidation In Hydrogen-rich Gas Streams

In this paper, we change preparation conditions and composition of the Pt-Co catalyst, in order to improve the active Pt-Co catalyst coating for PROX in H2-rich gas streams. Then the optimized catalys was coated on the channel plate reactor produced via conventional mechanical milling and designed by ourselves, and the performances of coated catalyst was studied by experiments.Experimental results show that the most active catalyst was COAT-1Pt2Co (1 wt.% Pt,2 wt.% Co and Al2O3), which can decrease carbon monoxide concentrations from 1% to a value of less than 10ppm for GHSV values between 40 000～120 000 ml/g/h. And it can keep great performance during continuous operation for 100h at 140℃. From the combination of techniques including TEM, DRIFTS and in situ Laser Raman Spectroscopy, the promotional effect of Co during PROX is confirmed and ascribed to this Pt3Co intermetallic compound and the synergetic effect of Co0 and Cox+.we can found that the Co promoter forms Pt3Co intermetallic compounds and the synergetic of Co and CoOx, which were crucial for PROX.Then, the effect of potassium promoter on the activity of Pt-CO/γ-Al2O3 catalyst coating was investigated by changing the molar rate of K/Pt.When K/Pt=1.5, the performance was best. Not only carbon monoxide conversion was up to 99.9%, but also the ability of resistance to H2O was improved a lot. However, when the addition of potassium increased to K/Pt=3, hydrogen spillover was seized in TPR and there wasn't sufficient oxygen for CO. And then, the addition of potassium reached K/Pt=5, CO outlet concentration increased greatly. That's because Pt atoms are covered by more potassium phase, and in consequence, CO and O2 can hardly be adsorbed on metallic particles, resulting in a very low PROX activity.In addition, we optimized the parameters of the channel plate reactor, and the PROX reaction benefit from it. For the proposed reactor coated with COAT-1Pt2Co,after PROX reaction carbon monoxide concentrations decreased to a value of less than 10 ppm at 120～170℃, and to a value of less than 50 ppm at 180℃for GHSV values of 80 000 ml/g/h.