plasma catalysis techniques
18 Apr 2020-
About: The article was published on 2020-04-18. It has received None citations till now.
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TL;DR: The present work focuses on the effects of pretreatment with glow-discharge plasma on cobalt dispersion and reducibility in alumina-supported catalysts and their performance in FT synthesis.
Abstract: In the last twenty years, remarkable advances in nanosciences and nanotechnology have given an impulse to the design of heterogeneous catalysts. Bell emphasized in 2003 the role of nanoparticle size in catalyst performance, and Schl#gl and Abd Hamid proposed in 2004 that the synthesis of nanosized catalysts may require multidimensional structural control. Glow-discharge (luminous) plasma is obtained by applying a potential difference between two electrodes placed in a gas. The plasma provides energy for decomposition of metal precursors. Several active catalysts have been developed by using glow discharge. The glow-discharge activation process is simple, quick, audio-visual, and easy to control. It does not require the high temperatures and significant amounts of compressed gases which are typically used in conventional catalyst pretreatments. The increasing interest in Fischer–Tropsch (FT) synthesis has been due to the growing demand for clean fuels and utilization of abundant natural gas, coal, and biomass-derived synthesis gas. Cobalt catalysts are preferred for FT synthesis due to their high productivity, high selectivity for heavy hydrocarbons, high stability, and low activity in the water-gas shift reaction. The catalytic performance of cobalt catalysts in FT synthesis appears to be strongly affected by the size of the cobalt metal particles. Conventional cobalt FT catalysts are prepared by aqueous impregnation of supports (silica, alumina, titania, etc.) with solutions of cobalt salts. After decomposition of the supported cobalt salts by calcination in an oxidizing atmosphere, the catalysts are reduced in hydrogen to generate cobalt metal sites. The present work focuses on the effects of pretreatment with glow-discharge plasma on cobalt dispersion and reducibility in alumina-supported catalysts and their performance in FT synthesis. Details of catalyst preparation are given in the Experimental Section. Cobalt and platinum contents in catalysts were 15 wt% and 0.1 wt%, respectively. The conventionally calcined catalysts are denoted Co(Pt)-Al2O3-T, where T indicates the temperature of the calcination pretreatment and Pt indicates promotion with Pt. The monometallic and Pt-promoted catalysts that were prepared using glowdischarge plasma (shortened to: plasma-assisted catalysts) are designated Co-Al2O3-PNH and CoPt-Al2O3-PNH respectively (Table 1).
156 citations
01 Jan 2007
TL;DR: In this article, the role and effectiveness of a plasma reactor for partial oxidation of methane is investigated using a rotating gliding arc which is a three dimensional version of a typical gliding arcs.
Abstract: Characteristics of a plasma reactor for partial oxidation of methane, especially focused on the role and effectiveness of plasma chemistry, is investigated. Partial oxidation of methane is investigated using a rotating gliding arc which is a three dimensional version of a typical gliding arc. The rotating gliding arc has both the characteristics of equilibrium and non-equilibrium plasma. Non-equilibrium characteristics of the rotating gliding arc can be increased by rotating an elongated arc string attached at both the tip of inner electrode and the edge of outer electrode. In this way, plasma chemistry can be enhanced and hydrogen selectivity can reach almost 100% that is much higher than thermal equilibrium condition. Also, the energy required to produce a unit mass of hydrogen (energy cost) is drastically reduced by increased effect of plasma chemistry. As a result, the present study enables the strategic approach of the plasma reforming process by means of through appropriate reactor design to maximize plasma effect and resulting in maximized reaction efficiency.
147 citations
TL;DR: In this paper, the authors report the beneficial effects of pretreatments of Tungsten carbide (WC) foil by atomic oxygen generated in an oxygen plasma source, and show that the graphitic carbon at the WC surface can be removed controllably by the atomic oxygen without causing oxidation of WC, and this improved performances for electrocatalytic methanol oxidation and hydrogen evolution.
Abstract: Tungsten carbide (WC) has been considered a promising replacement for precious metal-based catalysts and electrocatalysts; however, synthesis of high-quality WC that is free of surface carbon remains a major challenge. Surface carbon adversely influences the catalytic activity of WC and hinders direct interaction between metal adlayer modifiers and the WC substrate. In this letter, we report the beneficial effects of pretreatments of WC foil by atomic oxygen generated in an oxygen plasma source. We found that the graphitic carbon at the WC surface could be removed controllably by the atomic oxygen without causing oxidation of WC, and this improved performances for electrocatalytic methanol oxidation and hydrogen evolution.
58 citations
TL;DR: In this paper, a series of CoTMPP-based electrocatalysts were deposited on the porous gas diffusion substrate (titanium fibre felt) using plasma-enhanced impregnation method.
44 citations