scholarly journals Material Discovery and High Throughput Exploration of Ru Based Catalysts for Low Temperature Ammonia Decomposition

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1869 ◽  
Author(s):  
Katherine McCullough ◽  
Pei-Hua Chiang ◽  
Juan D. Jimenez ◽  
Jochen A. Lauterbach
Keyword(s):  
Low Temperature ◽  
High Throughput ◽  
Bimetallic Catalysts ◽  
Active Sites ◽  
Operating Conditions ◽  
Ammonia Decomposition ◽  
Turnover Frequency ◽  
Surface Sites ◽  
Equivalent Number ◽  
Apparent Activation Energies

High throughput experimentation has the capability to generate massive, multidimensional datasets, allowing for the discovery of novel catalytic materials. Here, we show the synthesis and catalytic screening of over 100 unique Ru-Metal-K based bimetallic catalysts for low temperature ammonia decomposition, with a Ru loading between 1–3 wt% Ru and a fixed K loading of 12 wt% K, supported on γ-Al2O3. Bimetallic catalysts containing Sc, Sr, Hf, Y, Mg, Zr, Ta, or Ca in addition to Ru were found to have excellent ammonia decomposition activity when compared to state-of-the-art catalysts in literature. Furthermore, the Ru content could be reduced to 1 wt% Ru, a factor of four decrease, with the addition of Sr, Y, Zr, or Hf, where these secondary metals have not been previously explored for ammonia decomposition. The bimetallic interactions between Ru and the secondary metal, specifically RuSrK and RuFeK, were investigated in detail to elucidate the reaction kinetics and surface properties of both high and low performing catalysts. The RuSrK catalyst had a turnover frequency of 1.78 s−1, while RuFeK had a turnover frequency of only 0.28 s−1 under identical operating conditions. Based on their apparent activation energies and number of surface sites, the RuSrK had a factor of two lower activation energy than the RuFeK, while also possessing an equivalent number of surface sites, which suggests that the Sr promotes ammonia decomposition in the presence of Ru by modifying the active sites of Ru.

Novel Microfabricated Pd-Au/SiO2 Model Catalysts for the Hydrogenation of 1,3-Butadiene

1994 ◽  
Vol 368 ◽  
Author(s):  
Anthony C. Krauth ◽  
Eduardo E. Wolf
Keyword(s):  
Activation Energy ◽  
Atmospheric Pressure ◽  
Bimetallic Catalysts ◽  
Low Temperatures ◽  
Room Temperature ◽  
Pd Catalyst ◽  
Turnover Frequency ◽  
Exponential Factor ◽  
Apparent Activation Energies ◽  
Monometallic Catalyst

ABSTRACTModel Pd-Au/SiO2 catalysts were prepared via a microfabrication methodology and their catalytic activity was evaluated using the hydrogenation of 1,3-butadiene as a probe reaction. The catalytic particles of the microfabricated catalyst were Pd-Au squares, ranging in composition, each approximately 4 µm in size and separated by 4 µm on a silica/silicon support. The reaction was carried out at atmospheric pressure with a hydrogen to hydrocarbon ratio of 125. The bimetallic catalysts exhibited lower apparent activation energies than the pure Pd catalyst with a minimum occurring at ˜65 at% Pd. Corresponding to the decrease in activation energy, there is an increase in the turnover frequency over the monometallic catalyst at low temperatures, i.e. room temperature. At high temperatures (above 200°C) the pure Pd catalyst has the highest conversion (0.61) and the largest pre-exponential factor (4.71×1016 cc/g Pd/s), while the 73 at% Pd catalyst has the lowest conversion (0.45) and the smallest pre-exponential factor (5.59 × 10 6 cc/g Pd/s). The bimetallic catalysts also showed a higher selectivity towards 1-butene than the monometallic catalyst; however, at lower conversions (less than 25%) the pure Pd catalyst was more selectivity towards 1-butene. AFM was used to characterize the surface morphology of each of the samples.

scholarly journals A Review of Low Temperature NH3-SCR for Removal of NOx

Catalysts ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 349 ◽  
Author(s):  
Devaiah Damma ◽  
Padmanabha Ettireddy ◽  
Benjaram Reddy ◽  
Panagiotis Smirniotis
Keyword(s):  
Low Temperature ◽  
Transition Metal ◽  
Transition Metal Oxides ◽  
Active Sites ◽  
Catalytic Reduction ◽  
Operating Conditions ◽  
Advanced Materials ◽  
Research Progress ◽  
Nh3 Scr ◽  
Mixed Transition

The importance of the low-temperature selective catalytic reduction (LT-SCR) of NOx by NH3 is increasing due to the recent severe pollution regulations being imposed around the world. Supported and mixed transition metal oxides have been widely investigated for LT-SCR technology. However, these catalytic materials have some drawbacks, especially in terms of catalyst poisoning by H2O or/and SO2. Hence, the development of catalysts for the LT-SCR process is still under active investigation throughout seeking better performance. Extensive research efforts have been made to develop new advanced materials for this technology. This article critically reviews the recent research progress on supported transition and mixed transition metal oxide catalysts for the LT-SCR reaction. The review covered the description of the influence of operating conditions and promoters on the LT-SCR performance. The reaction mechanism, reaction intermediates, and active sites are also discussed in detail using isotopic labelling and in situ FT-IR studies.

scholarly journals High-throughput computational-experimental screening protocol for the discovery of bimetallic catalysts

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Byung Chul Yeo ◽  
Hyunji Nam ◽  
Hyobin Nam ◽  
Min-Cheol Kim ◽  
Hong Woo Lee ◽  
...  
Keyword(s):  
High Throughput ◽  
Bimetallic Catalysts ◽  
High Throughput Screening ◽  
Direct Synthesis ◽  
Catalytic Performance ◽  
Platinum Group Metals ◽  
Pt Catalyst ◽  
Electronic Density ◽  
Bimetallic Alloy ◽  
Screening Protocol

AbstractTo accelerate the discovery of materials through computations and experiments, a well-established protocol closely bridging these methods is required. We introduce a high-throughput screening protocol for the discovery of bimetallic catalysts that replace palladium (Pd), where the similarities in the electronic density of states patterns were employed as a screening descriptor. Using first-principles calculations, we screened 4350 bimetallic alloy structures and proposed eight candidates expected to have catalytic performance comparable to that of Pd. Our experiments demonstrate that four bimetallic catalysts indeed exhibit catalytic properties comparable to those of Pd. Moreover, we discover a bimetallic (Ni-Pt) catalyst that has not yet been reported for H2O2 direct synthesis. In particular, Ni61Pt39 outperforms the prototypical Pd catalyst for the chemical reaction and exhibits a 9.5-fold enhancement in cost-normalized productivity. This protocol provides an opportunity for the catalyst discovery for the replacement or reduction in the use of the platinum-group metals.

scholarly journals Searching novel complex solid solution electrocatalysts in unconventional element combinations

Nano Research ◽  
2021 ◽  
Author(s):  
Olga A. Krysiak ◽  
Simon Schumacher ◽  
Alan Savan ◽  
Wolfgang Schuhmann ◽  
Alfred Ludwig ◽  
...  
Keyword(s):  
High Throughput ◽  
High Throughput Screening ◽  
Active Sites ◽  
Search Space ◽  
Reduction Reaction ◽  
Film Material ◽  
X Ray ◽  
High Entropy ◽  
Catalyst Composition ◽  
Scanning Transmission

AbstractDespite outstanding accomplishments in catalyst discovery, finding new, more efficient, environmentally neutral, and noble metal-free catalysts remains challenging and unsolved. Recently, complex solid solutions consisting of at least five different elements and often named as high-entropy alloys have emerged as a new class of electrocatalysts for a variety of reactions. The multicomponent combinations of elements facilitate tuning of active sites and catalytic properties. Predicting optimal catalyst composition remains difficult, making testing of a very high number of them indispensable. We present the high-throughput screening of the electrochemical activity of thin film material libraries prepared by combinatorial co-sputtering of metals which are commonly used in catalysis (Pd, Cu, Ni) combined with metals which are not commonly used in catalysis (Ti, Hf, Zr). Introducing unusual elements in the search space allows discovery of catalytic activity for hitherto unknown compositions. Material libraries with very similar composition spreads can show different activities vs. composition trends for different reactions. In order to address the inherent challenge of the huge combinatorial material space and the inability to predict active electrocatalyst compositions, we developed a high-throughput process based on co-sputtered material libraries, and performed high-throughput characterization using energy dispersive X-ray spectroscopy (EDS), scanning transmission electron microscopy (SEM), X-ray diffraction (XRD) and conductivity measurements followed by electrochemical screening by means of a scanning droplet cell. The results show surprising material compositions with increased activity for the oxygen reduction reaction and the hydrogen evolution reaction. Such data are important input data for future data-driven materials prediction.

Effect of Film Cooling on Low Temperature Hot Corrosion in a Coal Fired Gas Turbine

2003 ◽  
Author(s):  
Vaidyanathan Krishnan ◽  
J. S. Kapat ◽  
Y. H. Sohn ◽  
V. H. Desai
Keyword(s):  
Low Temperature ◽  
Corrosion Rate ◽  
Hot Corrosion ◽  
Film Cooling ◽  
Gas Turbines ◽  
Primary Source ◽  
Operating Conditions ◽  
Coal Gas ◽  
A Chain ◽  
Lower Corrosion Rate

In recent times, the use of coal gas in gas turbines has gained a lot of interest, as coal is quite abundant as a primary source of energy. However, use of coal gas produces a few detrimental effects that need closer attention. This paper concentrates on one such effect, namely hot corrosion, where trace amounts of sulfur can cause corrosion (or sulfidation) of hot and exposed surfaces, thereby reducing the life of the material. In low temperature hot corrosion, which is the focus of this paper, transport of SO2 from the hot gas stream is the primary process that leads to a chain of events, ultimately causing hot corrosion. The corrosion rate depends on SO2 mass flux to the wall as well as wall surface temperature, both of which are affected in the presence of any film cooling. An analytical model is developed to describe the associated transport phenomena of both heat and mass in the presence of film cooling The model predicts how corrosion rates may be affected under operating conditions. It is found that although use of film cooling typically leads to lower corrosion rate, there are combinations of operating parameters under which corrosion rate can actually increase in the presence of film cooling.

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