Papers by Keyword: Catalyst Support

Abstract: A thin-wall 410L Stainless metallic honeycomb has been fabricated successfully by extruding and sintering processing. The extruded pastes are a combination of two phases: a solid phase composed of metallic powder carried by a fluid solution of water, binder and additives. The key to forming high quality, defect free honeycombs lies in the optimization of paste properties and is contingent on solids loading and fluid-phase rheology. To develop a model that predicts paste rheology, capillary rheometry was used to characterize powder pastes and binder gels used as the fluid phase. Suspension viscosity models were successfully applied to permit rapid optimization of solids content and binder gel solution for extrusion of honeycombs.

Abstract: Pure 410L powder is used to mix with an additive to prepare a powder mixed paste. 410L honeycombs are fabricated by extruding the powder mixed paste, then dried and sintered. With sintering temperature increasing from 1120°C to1150°C, the density of sintered honeycombs increasing, powder particles bind together and become grains. The structure parameters and properties of sintered honeycombs were obtained by measuring and calculating. Results show that wall thickness 0.13~0.18mm, cell number (1/in2) 350~385, clear cross section (%) 73~80, specific surface Sv(sq m/cu dm）2.68~2.85； specific heat capacity Cp(J/g.K) 0.50~0.56, heat conductivity κ(W/m.K) 11.2~12.5. SEM/EDS analysis shows that the structure of sintered honeycombs consists of matrix phase α-Fe(Cr) and small particles which are complex compounds of silicon, iron and inclusion elements distributed in matrix. Chromium oxide is formed on surface of sintered honeycombs.

Abstract: Pure 304L powder is used to mix with an additive to prepare a powder mixed paste. 304L honeycombs are fabricated by extruding the powder mixed paste, then dried and sintered. When sintering at 1150°C, 30minite, powder particles bind together and become grains. The structure parameters of and properties of sintered honeycombs were obtained by measuring and calculating. Results show that wall thickness 0.15~0.20mm, cell number (1/in2) 330~365, clear cross section (%) 73~79, specific surface Sv(sq m/cu dm）2.52~2.68; specific heat capacity Cp(J/g.K) 0.6~0.7, heat conductivity κ(W/m.K) 10~12; transverse compression strength 40~50 Mpa, longitudinal compression strength 140~150 Mpa. SEM/EDS analysis shows that the surface of sintered honeycombs is really rough, the structure of sintered honeycombs consists of matrix phase α-Fe(Cr,Ni) , complex compounds of silicon, iron and inclusion elements distributed in matrix . There is oxide film forming on surface of sintered honeycombs.

Abstract: Porous catalyst support was prepared using gangue of bauxite tailing which was a solid waste material. It was found that the mass ratio of gangue of bauxite and knar clay was 4: 1. The masses of cellulose and water were individually 1 wt% and 25 wt% of the total mass of gangue of bauxite tailing and knar clay. The pore forming agent M was optimum among the selected pore forming agents. The pore forming agent M didn’t residue in support after sintering so that the support wasn’t polluted. The appropriate addition of the pore forming agent M was 4%, and the catalyst support with the porosity of 41.3% was preparated. The appropriate sintering temperature and holding time were 1250 °C and 2.0 h, respectively. Mullite and quartz were the main mineral phase of the porous catalyst support and the catalyst support have good chemical stability and heat-resisting property.

Abstract: The porous metal fiber sintered felt (PMFSF), a new catalyst support, was successfully used to construct a methanol steam reforming microreactor for hydrogen production. To study the transport characteristics of PMFSFs, a three-dimensional model with the cubic pore cell structure for PMFSFs was established. Using computational fluid dynamics fluent software, the velocity and pressure distribution when the fluid through the PMFSFs was investigated by changing the porosity of PMFSFs and inlet velocity of the fluid. In addition, fluid temperature distribution was analyzed under different inlet velocities by setting the temperature of fluid and wall. The result shows that the PMFSFs greatly enhance the transport characteristics because of its three-dimensional network structure and microchannel structure, it will become an ideal candidate for catalyst support material.

Abstract: Pure 316L powder is used to mix with an additive to prepare a powder mixed paste. 316L honeycombs were fabricated by extruding the powder mixed paste, then dried and sintered. The volume shrinkage and the apparent density of extruded honeycombs after drying and sintering were measured. The effect of sintering temperature on the volume shrinkage, the apparent density and the structure of honeycombs had been studied. The results show that the volume shrinkage and the apparent density of sintered honeycombs increase with sintering temperature from 1120°C to 1200°C , the volume shrinkage varying from 42% to 57%, and the apparent density from 1.9 to 2.9g/cm3 for 80% solids fraction. The volume shrinkage decreases and the apparent density increases with solid fractions increasing. The structure of sintered honeycombs consists of matrix phase α-Fe(Cr,Ni) , complex compounds of silicon, oxygen and inclusion elements. There is oxide film forming on surface of sintered honeycombs.

Abstract: We introduce the concept of functional microchannel lining. As an example, we describe the composition and structure of a Ni-Al intermetallic layer lining the inner wall of the microchannel produced by a powder-metallurgical process utilizing microscopic reactive infiltration and/or diffusion. The Ni-Al lining layer is a thick film consists of multiple sub-layers and has a peculiar porous structure, in which long and thin micropores had grown along the thickness direction of the film. In our experiment, a nickel-powder compact containing shaped aluminum wire was sintered at temperatures between the melting points of nickel and aluminum. Molten aluminum migrated into the surrounding nickel powder and reacted with nickel, and thus a microchannel and a Ni-Al intermetallic lining layer were produced. In this process, nickel powder composed the device body, and the aluminum wire gave the shape of the microchannel and act as the aluminum source for the lining layer. Metallographical examinations revealed that both aluminum concentration and voidage in the Ni-Al lining layer show a graded distribution along the thickness direction of the layer. Such a porous structure is appropriate for a catalyst support used for high-temperature reactions.

Abstract: A microchanneling process utilizing microscopic reactive infiltration produces microchannels and alloy lining layers in metal bodies. We examined the composition and structure of a Ni-Al intermetallic lining layer with a peculiar porous structure produced by Ni-Al reactive infiltration. The Ni-Al lining layer is a thick film consists of multiple sub-layers and has many micropores. Such a porous structure and the heat resistance of Ni-Al intermetallic compound are appropriate for a catalyst support in high-temperature use. Image analysis and EPMA revealed that both aluminum concentration and voidage in the Ni-Al lining layer show a graded distribution along the thickness direction of the lining layer.

Abstract: Carbon Nanofibers (CNF) layers were synthesized nickel-based thin-films on flat fused silica substrates. CNF synthesis was performed via thermal catalytic chemical vapor deposition of ethylene using nickel as metal catalyst. Different underlayer metal thin films, viz. titanium, tantalum and titanium-tungsten were tested in order to obtain stable and well-attached CNF films on fused silica substrates. It is found in case of titanium CNFs are formed on the nickel, but due to severe Ni/Ti inderdiffusion the titanium film looses its adhesive function, as a consequence of which the formed CNF film detaches from the substrate. The use of tantalum or titanium-tungsten as adhesion layer resulted in stable and well-adhered CNF films on fused silica substrates, of which the morphology can be controlled by the growth time.

Abstract: Metallic and ceramic foam catalyst supports and catalysts were manufactured. Comparative studies of the foam-structure catalyst supports and straight-channel catalysts supports were performed. Affect of the catalyst support pore structure upon the catalyst operational performance was analyzed.