metallic catalyst
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2022 ◽  
Author(s):  
Yi Xue ◽  
Chengjin Li ◽  
Xiaoxia Zhou ◽  
Zhaoyu Kuang ◽  
Wanpeng Zhao ◽  
...  

2021 ◽  
Author(s):  
Guodong David Zhan ◽  
Bodong Li ◽  
Timothy Eric Moellendick ◽  
Duanwei He ◽  
Jianhui Xu

Abstract PDC drill bits are the primary drilling tools for oil and gas in most of formations. In a PDC drill bit, PDC cutters are key cutting components to engage with these formations. However, there is often a big challenge for today's PDC drill bits when drilling very hard and abrasive formation. The main weakness in the PDC cutter is due to the unavoidable use of metallic catalyst which is used to bond the diamond grains in the PDC cutters. The thermal expansion of the metallic catalysts resulting from high frictional heat at the cutter/rock interface during drilling operation is higher than that of diamond grains, causing the thermal stress between the metallic catalyst and diamond grain which can break the PDC cutter. Therefore, development of catalyst-free PDC cutters would be a game-changing technology for drill bit by delivering significant increase in performance, durability, and drilling economics. In this study, an innovative ultra-high pressure and ultra-high temperature technology was developed with ultra-high pressures up to 35 GPa, much higher than current PDC cutter technology. We report a new type of catalyst-free PDC cutting material, synthesized under one of conditions using ultra-high pressure of 16 GPa. The new material breaks all single-crystal-diamond indenters in Vickers hardness testing which sets a new world record as the hardest diamond material as of today. Also, the material shows the highest thermal stability in the family of diamonds in air at 1,200°C, which is about 600 °C higher than current PDC cutters. As a consequence of these superior properties, this new material exhibited industry-recorded wear resistance, which is four times of that of current PDC cutters. All of these achievements demonstrated a breakthrough in PDC cutter technology development and presented a feasibility for the goal of "One-Run-To-TD" game-changing drilling technology.


2021 ◽  
Vol 105 (1) ◽  
pp. 87-96
Author(s):  
Michail O Danilov ◽  
Galina I Dovbeshko ◽  
Igor A Rusetskii ◽  
Uliana K Afonina ◽  
Valerii V Bykov ◽  
...  

A thermo chemical method for the synthesis of layered composites of graphite-like carbon nitride from urea and melamine has been developed. The production of graphite-like carbon nitride has been proven, SEM, X-ray diffraction, Raman spectroscopy and elemental analysis. Electrochemical studies have established that the obtained composites are promising materials as metal-free catalysts for oxygen electrodes for fuel cells.


2021 ◽  
Author(s):  
Dengxin Yan ◽  
Henrik Kristoffersen ◽  
Jack Pedersen ◽  
Jan Rossmeisl

Rational design of catalysts by tailoring specific surface sites with different elements could result in catalysts with high activity, selectivity and stability. In this work, we show that *CO on-top and O* on-top adsorption energies are good descriptors for catalysis of the CO oxidation reaction (COOR) on pure metals and binary alloys. The observed Brønsted-Evans-Polanyi (BEP) and scaling relations for COOR on different surfaces are incorporated into a predictive model that uses the binding strength of the four adjacent metal atoms making up the active site for COOR catalysis to estimate reaction and activation energies. The model is used to screen 161 multi-metallic catalyst candidates made by combining Ru, Pt, Pd, Cu and Au at these four sites. The screening and subsequent calculations suggest that Ru-Pt-Cu alloys are good catalysts for COOR. Our study shows that it is possible to use information from pure metals and binary alloys to predict the catalytic behavior of more complex alloys, and hereby reduce the computational cost of identifying new catalyst candidates for COOR.


2021 ◽  
Author(s):  
Dengxin Yan ◽  
Henrik Kristoffersen ◽  
Jack Pedersen ◽  
Jan Rossmeisl

Rational design of catalysts by tailoring specific surface sites with different elements could result in catalysts with high activity, selectivity and stability. In this work, we show that *CO on-top and O* on-top adsorption energies are good descriptors for catalysis of the CO oxidation reaction (COOR) on pure metals and binary alloys. The observed Brønsted-Evans-Polanyi (BEP) and scaling relations for COOR on different surfaces are incorporated into a predictive model that uses the binding strength of the four adjacent metal atoms making up the active site for COOR catalysis to estimate reaction and activation energies. The model is used to screen 161 multi-metallic catalyst candidates made by combining Ru, Pt, Pd, Cu and Au at these four sites. The screening and subsequent calculations suggest that Ru-Pt-Cu alloys are good catalysts for COOR. Our study shows that it is possible to use information from pure metals and binary alloys to predict the catalytic behavior of more complex alloys, and hereby reduce the computational cost of identifying new catalyst candidates for COOR.


Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2679
Author(s):  
María Núñez ◽  
Sebastián Muñoz-Guerra ◽  
Antxon Martínez de Ilarduya

This work explores for the first time the enzymatic synthesis of poly(butylene-co-ε-caprolactone) (PBSCL) copolyesters in bulk using commercially available monomers (dimethyl succinate (DMS), 1,4-butanediol (BD), and ε-caprolactone (CL)). A preliminary kinetic study was carried out which demonstrated the higher reactivity of DMS over CL in the condensation/ring opening polymerization reaction, catalyzed by Candida antarctica lipase B. PBSCL copolyesters were obtained with high molecular weights and a random microstructure, as determined by 13C NMR. They were thermally stable up to 300 °C, with thermal stability increasing with the content of CL in the copolyester. All of them were semicrystalline, with melting temperatures and enthalpies decreasing up to the eutectic point observed at intermediate compositions, and glass transition temperatures decreasing with the content of CL in the copolyester. The use of CALB provided copolyesters free from toxic metallic catalyst, which is very useful if the polymer is intended to be used for biomedical applications.


Author(s):  
Chung-Seop Lee ◽  
Sujin Guo ◽  
Hojung Rho ◽  
Juliana Levi ◽  
Sergi Garcia-Segura ◽  
...  

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1878
Author(s):  
Béla Pécz ◽  
Nikolaos Vouroutzis ◽  
György Zoltán Radnóczi ◽  
Nikolaos Frangis ◽  
John Stoemenos

Si whiskers grown by Ni-Metal-Induced-Lateral-Crystallization (Ni-MILC) were grown at 413 °C, intentionally below the threshold for Solid State Crystallization, which is 420 °C. These whiskers have significant common characteristics with whiskers grown by the Vapor Liquid Solid (VLS) method. The crystalline quality of the whiskers in both methods is the same. However, in VLS, a crystalline substrate is required, in contrast to the amorphous one in Ni-MILC for the growth of single crystalline whiskers. Moreover, whiskers grown by VLS have a polygonal cross-section with their diameter determined by the diameter of the hemispherical metallic catalysts. On the other hand, in the Ni-MILC, the cross-section of the whiskers depends on the size of the NiSi2 grain from which they are emanated. This was confirmed by observing the crossing whiskers and the rotational Moiré patterns in the crossing area. The structure of disturbed short and thin nonlinear branches on the side-walls of the whiskers was studied. In the whiskers grown by the VLS method, significant contamination occurs by the metallic catalyst degrading the electrical characteristics of the whisker. Such Si whiskers are not compatible with the current CMOS process. Whiskers grown by Ni-MILC at 413 °C are also contaminated by Ni. However, the excess Ni is in the form of tetrahedral NiSi2 inclusions which are coherent with the Si matrix due to the very low misfit of 0.4% between them. These whiskers are compatible with current CMOS process and Thin Film Transistors (TFTs).


2021 ◽  
pp. 131140
Author(s):  
Jing Li ◽  
Junli Wu ◽  
Ziyi Xie ◽  
Xinlei Zhang ◽  
Songlei Lv ◽  
...  

2021 ◽  
Author(s):  
Dengxin Yan ◽  
Henrik Kristoffersen ◽  
Jack Pedersen ◽  
Jan Rossmeisl

Rational design of catalysts by tailoring specific surface sites with different elements could result in catalysts with high activity, selectivity and stability. In this work, we show that *CO on-top and O* on-top adsorption energies are good descriptors for catalysis of the CO oxidation reaction (COOR) on pure metals and binary alloys. The observed Brønsted-Evans-Polanyi (BEP) and scaling relations for COOR on different surfaces are incorporated into a predictive model that uses the binding strength of the four adjacent metal atoms making up the active site for COOR catalysis to estimate reaction and activation energies. The model is used to screen 234 multi-metallic catalyst candidates made by combining Ru, Pt, Pd, Cu and Au at these four sites. The screening and subsequent calculations suggest that Ru-Cu-Au and Ru-Pt-Cu alloys are good catalysts for COOR. Our study shows that it is possible to use information from pure metals and binary alloys to predict the catalytic behavior of more complex alloys, and hereby reduce the computational cost of identifying new catalyst candidates for COOR.


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