| Recently, as people’s living standards improve, daily living environment requirements are highly increased. There are many pollutants in people’s living environment, one of which is the pollutants formaldehyde, which exists in interior decoration materials and furniture, it’s harmful to human body. Formaldehyde purification currently on the market mostly is adsorpted with activated carbon, but there are adsorption saturation and other issues for carbon adsorption. With the development of catalytic combustion technology in environmental governance, catalytic combustion becomes one of the most effective methods, with low energy consumption, eliminating effect is good, no secondary pollutions.In this paper, we used Fe/Cr/Al alloy wire as one carrier, the active component is Pt, a series of Pt/Fe/Cr/Al monolithic catalysts was prepared by electroless plating. Catalytic combustion of formaldehyde at room temperature as a probe reaction for catalyst investigation, the catalysts characterized by SEM, XRD, EDS, BET, XPS and other methods, catalytic combustion properties and surface properties of the catalyst was associated and discussed the catalytic mechanism. The main conclusions of this experiment are as follows:The optimal conditions of Platinum plating was conformed by experiment:NH3·H2O:20-40ml/L; NH4C1:5-10g/L; HC1:3-4ml/L; N2H4·H2O:0.2-0.5ml/L; H4PtCl6-6H2O:0.1-1g/L; PH:9-10; reaction temperature:30℃-70℃.The SEM and EDS shows Pt grains uniformly loaded on the Fe/Cr/Al carriers. Studies have shown that Pt/Fe/Cr/Al monolithic catalyst calcined with different temperature (200℃,250℃,300℃,350℃,400℃,450℃,500℃) has a good catalytic performance for the degradation of formaldehyde, when calcined under300℃has the highest catalytic activity. The catalytic activity decreased with the calcination temperature rises, mainly related to the sintering and grow larger of the active species Pt particle. Experiments determined the optimal calcination conditions of Pt/Fe/Cr/Al monolithic catalyst is calcined under300℃for3h, at this time the most active species Pt dispersed on the surface of the carrier, showing spherical particles and the size is the smallest, the catalytic combustion performance of formaldehyde is the highest. From XRD analysis, we can see that the active component of the catalyst is not elemental Pt, but Al-Pt alloy. The specific surface area of the catalysts obtained in the experiment is relatively small, it is possible to consider continue to improve the surface area of carrier. XPS analysis found that the presence of Pt in the form of Pt, PtO and PtO2, showing that the valence of Pt is changed during catalytic process.We simulated the process of the volatilization and stability of formaldehyde at workshop. We found that Pt is good for catalytic combustion of formaldehyde, even if the content is as low as0.1%when the initial concentration of formaldehyde is maintained at about10mg/m3. When the Pt content increased to0.3%, the catalytic activity is the highest and the degradation rate of formaldehyde reached95.6%, the residual formaldehyde concentration as low as0.45mg/m3. When the Pt content continues to increase, the active component appears agglomeration, the catalytic performance decreased, but the degradation rate of formaldehyde is relatively high when Pt content reaches1.0%. The lifetime experiments found that the catalyst can maintain good catalytic performance and also shows stable of the catalyst.We also used the ABS as a carrier for chemical plating Pt, the experiment found that Pt/ABS has a good purification effect of formaldehyde. XRD analysis showed that the active center of the catalyst is Pt simple substance. We found that when the loading amount of Pt is0.2%, the catalyst has the best catalytic performance and the active species Pt uniformly distributed in the surface of the ABS. We found Pt and ABS surface has a good adhesion of the catalyst obtained in the experiment and the catalyst performance is relatively stable. |
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