Atmospheric-pressure Cold Plasma For Preparation Of Supported Au,Pd Catalysts

Supported Au, Pd catalytic materials can effectively remove significant air pollutant CO. Cold plasma technique,which can treat the catalytic materials by decomposition,reduction, regeneration and modification at low temperature,is an effective method for preparing supported metal catalytic materials. Supported metal catalytic materials prepared by cold plasma have small size and high dispersion of metal nanoparticles and exhibit strong interaction between metal and supports. However, it is often operated under low pressure, and can not be scaled up easily. Recently, dielectric barrier discharge(DBD) is found to be an effective method for generating atmospheric-pressure cold plasma, which is often operated with simple devices and can be scaled up easily, and recently has been used for preparing supported metal catalytic materials.In this study, supported Au, Pd catalytic materials were prepared by DBD cold plasma at atmospheric pressure. Au precursor was supported on Ti O2 using precipitation deposition with chloroauric acid as Au source. Au catalytic materials with high activity were prepared by reduction of the Au precursor using atmospheric-pressure DBD cold plasma method, as well as a way of calcination in air, respectively. Furthermore, Au/C and Pd/C catalytic materials were also prepared by impregnation method followed with cold plasma reduction using chloroauric acid and Pd Cl2 as Au and Pd sources, respectively. The main researches are as follows:1.Ti O2 with different crystal phase proportions were prepared by hydrothermal method, and were adopted as the support to inspect the influences of the ratio of anatase and rutile on the catalytic activity of Au/Ti O2. The results showed that: the best ratio of anatase and rutile is close to 4:6 for the Au/Ti O2 samples prepared by plasma treatment combined with calcination under air atmosphere, while the ratio is about 8:2 for the samples prepared by directly calcination in air for 2 h.2. Commercial Ti O2 P25(fA: fR=7:3) and anatase Ti O2 prepared by hydrothermal method which had almost the same specific surface area(50m2?g-1) were adopted as the supports for preparing Au/P25 and Au/Ti O2 catalytic materials by atmospheric-pressure DBD cold plasma, and the effect of treating time was also investigated. The results showed that Au/P25 exhibited higher CO oxidation acitivity than Au/Ti O2 with support of pure anatase Ti O2, and the appropriate time for plasma treatment was 4 min.3. Activated carbon, which is favorable for recovery of precious metals by simple calcination and dispersion of the metal nanoparticles due to the abundant oxygen-containing groups, was adopted for preparing Au/C and Pd/C catalytic materials by impregnation method assisted with atmospheric–pressure DBD cold plasma. The Cl- ions in gold precursor were harmful for dispersion of gold nanoparticles; therefore the Au/C materials exhibited low CO oxidation activity. However, the Pd/C catalytic materials prepared in this way contain smaller size and high dispersion of Pd nanoparticles, and thereby exhibiting high CO oxidation activity.Atmospheric–pressure DBD cold plasma is highly efficient for preparing supported Au, Pd catalytic materials, which is significant for the development of a simple and environmentally friendly technology for preparing other supported metal catalysts.