Cold Plasma for Synthesizing High Performance Bimetallic PdCu catalysts: Effect of Reduction Sequence and Pd/Cu Atomic Ratios

Treatment with atmospheric-pressure (AP) hydrogen cold plasma is an effective method for preparing highly active supported metal catalytic materials. However, this technique typically uses H2 as working gas, which is explosive and difficult to transport. This study proposes the use of PdCl2 as a Pd precursor and activated carbon as the support to fabricate Pd/C catalytic materials (Pd/C-EP-Ar) by using ethanol—which is renewable, easily stored, and safe—combined with AP cold plasma (AP ethanol cold plasma) followed by calcination in Ar gas at 550 °C for 2 h. Both Pd/C-EP and Pd/C-HP fabricated using AP ethanol and hydrogen cold plasma (without calcination in Ar gas) respectively, exhibit low CO oxidation reactivity. The activity of Pd/C-EP is lower than Pd/C-HP, which is mainly ascribed to the carbon layer formed by ethanol decomposition during plasma treatment. However, the 100% CO conversion temperature (T100) of Pd/C-EP-Ar is 140 °C, which is similar to that of Pd/C-HP-Ar fabricated using AP hydrogen cold plasma (calcined in Ar gas at 550 °C for 2 h). The characterization results of X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy indicated that the carbon layer formed by ethanol decomposition enhanced the interaction of metal nanoparticles to the support, and a high Pd/C atomic ratio was obtained. This was beneficial to the high CO oxidation performance. This work provides a safe method for synthesizing high-performance Pd/C catalytic materials avoiding the use of H2, which is explosive and difficult to transport.

Section: Resultsmentioning

confidence: 99%

Preparation of Pd/C by Atmospheric-Pressure Ethanol Cold Plasma and Its Preparation Mechanism

Zhang

Wang

et al. 2019

“…Interestingly, 0.4 eV redshift in the binding energy of Au4f 7/2 for Au/P25-H 2 P is observed, which can be explained by the following reasons. One the one hand, AP hydrogen cold plasma for synthesizing supported metal catalysts generally may lead to redshift of the binding energy due to the enhanced strong metal–support interaction [ 18 , 36 ]. On the other hand, Au/P25-H 2 P has the highest proportion of metallic Au 0 , which may also enhance the redshift of the binding energy [ 36 ].…”

Section: Resultsmentioning

confidence: 99%

“…The fast and low-temperature preparation process, and the Coulomb interaction between the charged species and metal precursors ions in cold plasma are conductive to fabrication of metal nanoparticles of small sizes with high dispersion [ 12 ]. In addition, the non-thermal equilibrium property of cold plasma is beneficial to enhanced metal–support interaction, amorphous metal nanoparticles [ 15 , 16 ], as well as metal alloy with specific structure [ 17 , 18 ], and metal nanoparticles with specific crystal facet [ 14 ]. Thanks to these properties, cold plasma has been successfully employed to prepare and activate gold catalysts, and it has been efficient to enhance the catalytic performance of the gold catalysts [ 19 , 20 , 21 , 22 , 23 , 24 , 25 ].…”

Section: Introductionmentioning

confidence: 99%

Atmospheric-Pressure Cold Plasma Activating Au/P25 for CO Oxidation: Effect of Working Gas

Zhang

et al. 2018

Commercial TiO2 (P25) supported gold (Au/P25) attracts increasing attention. In this work, atmospheric-pressure (AP) cold plasma was employed to activate the Au/P25-As catalyst prepared by a modified impregnation method. The influence of cold plasma working gas (oxygen, argon, hydrogen, and air) on the structure and performance of the obtained Au/P25 catalysts was investigated. X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), transmission electron microscopy (TEM), and X-ray spectroscopy (XPS) were adopted to characterize the Au/P25 catalysts. CO oxidation was used as model reaction probe to test the Au/P25 catalyst. XRD results reveal that supporting gold and AP cold plasma activation have little effect on the P25 support. CO oxidation activity over the Au/P25 catalysts follows the order: Au/P25-O2P > Au/P25-As > Au/P25-ArP ≈ Au/P25-H2P > Au/P25-AirP. Au/P25-AirP presents the poorest CO oxidation catalytic activity among the Au/P25 catalysts, which may be ascribed to the larger size of gold nanoparticles, low concentration of active [O]s, as well as the poisoning [NOx]s. The poor catalytic performance of Au/P25-ArP and Au/P25-H2P is ascribed to the lower concentration of [O]s species. 100% CO conversion temperatures for Au/P25-O2P is 40 °C, which is 30 °C lower than that over the as-prepared Au/P25-As catalyst. The excellent CO oxidation activity over Au/P25-O2P is mainly attributed to the efficient decomposition of gold precursor species, small size of gold nanoparticles, and the high concentration of [O]s species.

“…Di et al [17] prepared different single metal (Pt [18], Ag [19], Pd [20]) supported TiO 2 powders via DBD cold plasma. Moreover, they further prepared Pd/C [21], Pd/Al 2 O 3 [22] and bimetallic Pd-Cu/Al 2 O 3 [23,24] catalysts for CO oxidation. The photodegradation activity of methylene blue (MB) and CO oxidation activity were prominently improved.…”

Section: Preparation Of Catalyst By Dbd Plasmamentioning

confidence: 99%

A Review of Recent Advances of Dielectric Barrier Discharge Plasma in Catalysis

Zhu

et al. 2019

Dielectric barrier discharge plasma is one of the most popular methods to generate nanthermal plasma, which is made up of a host of high-energy electrons, free radicals, chemically active ions and excited species, so it has the property of being prone to chemical reactions. Due to these unique advantages, the plasma technology has been widely used in the catalytic fields. Compared with the conventional method, the heterogeneous catalyst prepared by plasma technology has good dispersion and smaller particle size, and its catalytic activity, selectivity and stability are significantly improved. In addition, the interaction between plasma and catalyst can achieve synergistic effects, so the catalytic effect is further improved. The review mainly introduces the characteristics of dielectric barrier discharge plasma, development trend and its recent advances in catalysis; then, we sum up the advantages of using plasma technology to prepare catalysts. At the same time, the synergistic effect of plasma technology combined with catalyst on methanation, CH4 reforming, NOx decomposition, H2O2 synthesis, Fischer–Tropsch synthesis, volatile organic compounds removal, catalytic sterilization, wastewater treatment and degradation of pesticide residues are discussed. Finally, the properties of plasma in catalytic reaction are summarized, and the application prospect of plasma in the future catalytic field is prospected.