Water-line design and performance of Z

A new set of bi-plate transmission lines have been designed and installed in the water-section of PBFA-II for the Z-pinch experiments. Thirty-six aluminum flat-plate transmission lines submerged in a water dielectric deliver a timed electrical pulse from coaxial tube sections to a ring stack section. Each of the lines are electrically isolated from each other by transit-time effects. The water-lines are configured radially at four vertical levels. Each level has nine sets of bi-plates, with a transition section that is unique to that level. Mechanically, the bi-plate sections are designed to carry both static and dynamic loads. Electrically, the lines are designed to transport electrical pulses that average 200 nanoseconds with peak voltage of 2.5 to 3.0 MV. The peak fields exceed 200kV/cm. All line sections are a series of chromate coated aluminum plates, broken down into short, light weight sections. The design of the plates was meticulously developed using the Electro code for voltage break down, and NISA for mechanical analysis. Electrical losses associated with impedance mismatching and voltage breakdown were carefully reviewed. Changes in the bi-plate gap, surface shapes and electrical path discontinuities (mechanical joints) were precisely calculated to achieve maximum electrical performance and reliability. Several iterations of surface shapes and line gaps were reviewed to achieve the most desirable characteristics possible. Additional criteria required that minimal time and effort be required to remove and install the water-lines. Special hardware was developed to help meet this requirement

Enhancement Effect of Noble Metals on Manganese Oxide for the Oxygen Evolution Reaction

Catalysis and Surface Chemistr

Enhancing the connection between computation and experiments in electrocatalysis

Combining computational and experimental methods is a powerful approach to understand the variables that govern catalyst performance and ultimately design improved materials. However, the effectiveness of this approach rests on the strength of the relationships between calculated parameters and experimental measurements. These relationships are complicated by the intricacy and dynamic behaviour of catalytic active sites, and by the non-trivial relationship between calculated reaction energetics and observed rates. In this Perspective, we highlight opportunities to enhance the connection between computation and experiment in electrocatalysis. These include measuring the intrinsic kinetic behaviour of catalysts, creating precise models for the active site and its environment, and forming clear relationships between calculated reaction energetics and observed rates. As experimental and computational methods continue to become more powerful, clear connections between the two will maximize their utility to guide the design of efficient and selective electrocatalysts.Catalysis and Surface Chemistr

Development of Molybdenum Phosphide Catalysts for Higher Alcohol Synthesis from Syngas by Exploiting Support and Promoter Effects

Molybdenum phosphide (MoP) catalysts have recently attracted attention due to their robust methanol synthesis activity from CO/CO2. Synthesis strategies are used to steer MoP selectivity toward higher alcohols by investigating the promotion effects of alkali (K) and CO-dissociating (Co, Ni) and non-CO-dissociating (Pd) metals. A systematic study with transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy (XAS) showed that critical parameters governing the activity of MoP catalysts are P/Mo ratio and K loading, both facilitating MoP formation. The kinetic studies of mesoporous silica-supported MoP catalysts show a twofold role of K, which also acts as an electronic promoter by increasing the total alcohol selectivity and chain length. Palladium (Pd) increases CO conversion, but decreases alcohol chain length. The use of mesoporous carbon (MC) support has the most significant effect on catalyst performance and yields a KMoP/MC catalyst that ranks among the state-of-the-art in terms of selectivity to higher alcohols

Development of Molybdenum Phosphide Catalysts for Higher Alcohol Synthesis from Syngas by Exploiting Support and Promoter Effects

Molybdenum phosphide (MoP) catalysts have recently attracted attention due to their robust methanol synthesis activity from CO/CO2. Synthesis strategies are used to steer MoP selectivity toward higher alcohols by investigating the promotion effects of alkali (K) and CO-dissociating (Co, Ni) and non-CO-dissociating (Pd) metals. A systematic study with transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy (XAS) showed that critical parameters governing the activity of MoP catalysts are P/Mo ratio and K loading, both facilitating MoP formation. The kinetic studies of mesoporous silica-supported MoP catalysts show a twofold role of K, which also acts as an electronic promoter by increasing the total alcohol selectivity and chain length. Palladium (Pd) increases CO conversion, but decreases alcohol chain length. The use of mesoporous carbon (MC) support has the most significant effect on catalyst performance and yields a KMoP/MC catalyst that ranks among the state-of-the-art in terms of selectivity to higher alcohols

Revealing the Synergy between Oxide and Alloy Phases on the Performance of Bimetallic In-Pd Catalysts for CO₂ Hydrogenation to Methanol

In2O3 has recently emerged as a promising catalyst for methanol synthesis from CO2. In this work, we present the promotional effect of Pd on this catalyst and investigate structure–performance relationships using in situ X-ray spectroscopy, ex situ characterization, and microkinetic modeling. Catalysts were synthesized with varying In:Pd ratios (1:0, 2:1, 1:1, 1:2, 0:1) and tested for methanol synthesis from CO₂/H₂ at 40 bar and 300 °C. In:Pd(2:1)/SiO₂ shows the highest activity (5.1 μmol MeOH/gInPds) and selectivity toward methanol (61%). While all bimetallic catalysts had enhanced catalytic performance, characterization reveals methanol synthesis was maximized when the catalyst contained both In–Pd intermetallic compounds and an indium oxide phase. Experimental results and density functional theory suggest the active phase arises from a synergy between the indium oxide phase and a bimetallic In–Pd particle with a surface enrichment of indium. We show that the promotion observed in the In–Pd system is extendable to non precious metal containing binary systems, in particular In–Ni, which displayed similar composition–activity trends to the In–Pd system. Both palladium and nickel were found to form bimetallic catalysts with enhanced methanol activity and selectivity relative to that of indium oxide

A Highly Active Molybdenum Phosphide Catalyst for Methanol Synthesis from CO and CO₂

Methanol is a major fuel and chemical feedstock currently produced from syngas, a CO/CO2/H2 mixture. Herein we identify formate binding strength as a key parameter limiting the activity and stability of known catalysts for methanol synthesis in the presence of CO2. We present a molybdenum phosphide catalyst for CO and CO2 reduction to methanol, which through a weaker interaction with formate, can improve the activity and stability of methanol synthesis catalysts in a wide range of CO/CO2/H2 feeds