Laser electrodispersion as a new chlorine-free method for the production of highly effective metal-containing supported catalysts

Abstract

Laser electrodispersion (LED) of metals is a promising technique for the preparation of heterogeneous catalysts as an alternative to wet impregnation of supports with the corresponding salt solutions. The LED technique can be used to deposit highly active chlorideand nitrate-free metal nanoparticles onto carbon or oxide supports. We report preparation and properties of new Ni-, Pd-, and Au-containing alumina-supported catalysts with low metal loadings (10 -3 -10 -4 % mass) and their comparison with the previously studied carbon (Sibunit) supported systems. The catalysts demonstrate high stability and extremely high specific catalytic activity (by 2-3 orders of magnitude higher than for traditional catalysts) in the gas-phase hydrodechlorination (HDC) of chlorobenzene (CB).

Bimetallic Nanostructured Catalysts Prepared by Laser Electrodispersion: Structure and Activity in Redox Reactions

“…LED catalysts strongly differ in structure, adsorption and catalytic properties from supported catalysts synthesized by "wet" chemical methods. [10][11][12] The scheme of the LED process is shown in Figure 1. A high power pulse laser is used to melt the metal target surface.…”

“…[9,13] The fast cooling of monodispersed nanodrops preliminarily produced in the laser plasma torch during their deposition on the support surface preserves their size, spherical shape and amorphous structure. Monometallic LED catalysts comprising Pd, Pt, Ni, Cu supported on carbon and oxide supports were widely studied in several classes of catalytic reactions, [9][10][11][12][13] and very promising results were achieved in environmentally important reactions of hydrodechlorination of chlorinated organic molecules. However bimetallic LED catalysts were synthesized only recently.…”

Формирование Аморфных Наночастиц Углерода Методом Лазерного Электродиспергирования

“…Отмеченные особенности рельефа поверхности свидетельствуют о том, что в условиях проведенного эксперимента на поверхности углеродной мишени происходит формирование жидкой фазы углерода. Соответ-ственно условия лазерного электродиспергирования углерода не долж-ны существенно отличаться от условий диспергирования металлов с высокой температурой плавления, в результате которого образуются аморфные металлические наночастицы [13]. Материал, эмитируемый с поверхности мишени, осаждался на по-лированную кремниевую подложку, которая располагалась в вакуумной камере на расстоянии 4 cm от мишени.…”

Grain boundaries in nanocrystalline catalytic materials as a source of surface chemical functionality

“…The HRTEM micrographs presented in Figure 10A shows consolidation of primary nanocrystals as grains with mismatching of atomic layers forming disordered GB areas at the aggregates surface (Savinova et al 2009). Implementation of laser electro-deposition (Lokteva et al 2012) changed the consolidation extent of Cu, Ni, Co, Au, Pd and Pt nanoparticles over a wide range by increasing the metals loading and keeping constant the size of nanoparticles on flat and granulated surface area of Si, C, SiO 2 or Al 2 O 3 supports (Rostovshchikova et al 2005a(Rostovshchikova et al ,b, 2013. Brought to you by | University of Pittsburgh Authenticated Download Date | 1/5/15 6:45 AM nanoparticles in consolidated nanocrystals covering the surface with islands of similar thickness ( Figure 1A).…”

“…Application of sol-gel and self-assembling technologies (Landau 2009, Lee et al 2012) as well as novel techniques [laser electro-dispersion (Lokteva et al 2012), reverse micelles (Nguyen 2013), decomposition of metal-surfactant complexes (Park et al 2007), and many others] led to manufacturing of supported, mono-dispersed, 2-10 nm nanoparticle assemblies with narrow particle size distribution and high loadings or even unsupported catalytic materials (λ = 1 in Eq. 1) as illustrated in Figure 1.…”