scholarly journals Turning a Methanation Catalyst into a Methanol Producer: In-Co Catalysts for the Direct Hydrogenation of CO2 to Methanol

2018 ◽  
Author(s):  
Anastasiya Bavykina ◽  
Irina Yarulina ◽  
Lieven Gevers ◽  
Mohamed Nejib Hedhili ◽  
Xiaohe Miao ◽  
...  
Keyword(s):  
Fossil Fuels ◽  
Close Contact ◽  
Active Phase ◽  
Reaction Conditions ◽  
Hydrogenation Of Co2 ◽  
Co Catalysts ◽  
Wide Range ◽  
Direct Hydrogenation ◽  
Co Precipitation

<div> <div> <div> <p>The direct hydrogenation of CO2 to methanol using green hydrogen is regarded as a potential technology to reduce greenhouse gas emissions and the dependence on fossil fuels. For this technology to become feasible, highly selective and productive catalysts that can operate under a wide range of reaction conditions near thermodynamic conversion are required. Here, we demonstrate that indium in close contact with cobalt catalyses the formation of methanol from CO2 with high selectivity (>80%) and productivity (0.86 gCH3OH.gcatalyst-1.h-1) at conversion levels close to thermodynamic equilibrium, even at temperatures as high as 300 °C and at moderate pressures (50 bar). The studied In@Co system, obtained via co- precipitation, undergoes in situ transformation under the reaction conditions to form the active phase. Extensive characterization demonstrates that the active catalyst is composed of a mixed metal carbide (Co3InC0.75), indium oxide (In2O3) and metallic Co. </p> </div> </div> </div>

scholarly journals Turning a Methanation Catalyst into a Methanol Producer: In-Co Catalysts for the Direct Hydrogenation of CO2 to Methanol

2018 ◽  
Author(s):  
Anastasiya Bavykina ◽  
Irina Yarulina ◽  
Lieven Gevers ◽  
Mohamed Nejib Hedhili ◽  
Xiaohe Miao ◽  
...  
Keyword(s):  
Fossil Fuels ◽  
Close Contact ◽  
Active Phase ◽  
Reaction Conditions ◽  
Hydrogenation Of Co2 ◽  
Co Catalysts ◽  
Wide Range ◽  
Direct Hydrogenation ◽  
Co Precipitation

<div> <div> <div> <p>The direct hydrogenation of CO2 to methanol using green hydrogen is regarded as a potential technology to reduce greenhouse gas emissions and the dependence on fossil fuels. For this technology to become feasible, highly selective and productive catalysts that can operate under a wide range of reaction conditions near thermodynamic conversion are required. Here, we demonstrate that indium in close contact with cobalt catalyses the formation of methanol from CO2 with high selectivity (>80%) and productivity (0.86 gCH3OH.gcatalyst-1.h-1) at conversion levels close to thermodynamic equilibrium, even at temperatures as high as 300 °C and at moderate pressures (50 bar). The studied In@Co system, obtained via co- precipitation, undergoes in situ transformation under the reaction conditions to form the active phase. Extensive characterization demonstrates that the active catalyst is composed of a mixed metal carbide (Co3InC0.75), indium oxide (In2O3) and metallic Co. </p> </div> </div> </div>

Preparation of TiO2-Al2O3 Support and Hydrodenitrogenation over Ni2P/TiO2-Al2O3 Catalyst

2014 ◽  
Vol 881-883 ◽  
pp. 245-250
Author(s):  
Jing Sen Yan ◽  
Hai Yan Wang ◽  
Feng Wei He
Keyword(s):  
Reduction Method ◽  
Bond Cleavage ◽  
Great Influence ◽  
Active Phase ◽  
Molar Ratio ◽  
Incipient Wetness Impregnation ◽  
Aluminium Nitrate ◽  
Titanium Sulfate ◽  
Co Precipitation

A series of TiO2-Al2O3 composite supports were prepared by co-precipitation of titanium sulfate and aluminium nitrate , and the nickel phosphide catalysts were prepared by incipient wetness impregnation and in situ H2 reduction method. The catalysts were characterized by XRD, N2 adsorption, TPR, TEM and XPS techniques. Their hydrodenitrogenation (HDN) performances were evaluated by using quinoline as model molecules . The results show that TiO2 was evenly dispersed on massive γ-Al2O3 surface. The introduction of TiO2 weakened the strong interaction between Al2O3 and phosphate, and improved the reducibility of the precursors , facilitating to the formation of Ni2P active phase. TiO2 acted as an electronic promoter for the Ni-P catalyst and enhanced both the hydrogenation and C-N bond cleavage activities. Different Ti / Al molar ratio had great influence on HDN activity of the catalyst. The Ni2P /TiO2-Al2O3 with Ti/Al ratio of 1/8, exhibited the highest activity for quinoline HDN.

scholarly journals Methanol Synthesis from CO2: A Review of the Latest Developments in Heterogeneous Catalysis

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3902 ◽  
Author(s):  
R. Guil-López ◽  
N. Mota ◽  
J. Llorente ◽  
E. Millán ◽  
B. Pawelec ◽  
...  
Keyword(s):  
Methanol Synthesis ◽  
Heterogeneous Catalysts ◽  
Fossil Fuels ◽  
Value Added ◽  
Active Phase ◽  
Catalyst Design ◽  
Transportation Fuel ◽  
Catalytic Systems ◽  
Effective Utilization ◽  
Direct Hydrogenation

Technological approaches which enable the effective utilization of CO2 for manufacturing value-added chemicals and fuels can help to solve environmental problems derived from large CO2 emissions associated with the use of fossil fuels. One of the most interesting products that can be synthesized from CO2 is methanol, since it is an industrial commodity used in several chemical products and also an efficient transportation fuel. In this review, we highlight the recent advances in the development of heterogeneous catalysts and processes for the direct hydrogenation of CO2 to methanol. The main efforts focused on the improvement of conventional Cu/ZnO based catalysts and the development of new catalytic systems targeting the specific needs for CO2 to methanol reactions (unfavourable thermodynamics, production of high amount of water and high methanol selectivity under high or full CO2 conversion). Major studies on the development of active and selective catalysts based on thermodynamics, mechanisms, nano-synthesis and catalyst design (active phase, promoters, supports, etc.) are highlighted in this review. Finally, a summary concerning future perspectives on the research and development of efficient heterogeneous catalysts for methanol synthesis from CO2 will be presented.

scholarly journals Preparation, Characterization, and Optimization of an In Vitro C30 Carotenoid Pathway

2005 ◽  
Vol 71 (11) ◽  
pp. 6578-6583 ◽  
Author(s):  
Bosung Ku ◽  
Jae-Cheol Jeong ◽  
Benjamin N. Mijts ◽  
Claudia Schmidt-Dannert ◽  
Jonathan S. Dordick
Keyword(s):  
Phase System ◽  
Reaction Conditions ◽  
Two Phase ◽  
Gene Encoding ◽  
In Situ Extraction ◽  
Steady State Kinetics ◽  
Wide Range ◽  
Carotenoid Synthesis

ABSTRACT The ispA gene encoding farnesyl pyrophosphate (FPP) synthase from Escherichia coli and the crtM gene encoding 4,4′-diapophytoene (DAP) synthase from Staphylococcus aureus were overexpressed and purified for use in vitro. Steady-state kinetics for FPP synthase and DAP synthase, individually and in sequence, were determined under optimized reaction conditions. For the two-step reaction, the DAP product was unstable in aqueous buffer; however, in situ extraction using an aqueous-organic two-phase system resulted in a 100% conversion of isopentenyl pyrophosphate and dimethylallyl pyrophosphate into DAP. This aqueous-organic two-phase system is the first demonstration of an in vitro carotenoid synthesis pathway performed with in situ extraction, which enables quantitative conversions. This approach, if extended to a wide range of isoprenoid-based pathways, could lead to the synthesis of novel carotenoids and their derivatives.

scholarly journals Organozinc Pivalates for Cobalt-Catalyzed Difluoroalkylarylation of Alkenes and Mechanistic Insights

2021 ◽  
Author(s):  
Xinyi Cheng ◽  
Xingchen Liu ◽  
Shengchun Wang ◽  
Ying Hu ◽  
Bingjing Hu ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Functional Groups ◽  
Halogen Atom ◽  
Cobalt Catalyst ◽  
Bond Formation ◽  
Single Electron Transfer ◽  
Mechanistic Studies ◽  
Reaction Conditions ◽  
Wide Range

Abstract A set of cobalt-catalyzed regioselective difluoroalkylarylation of both activated and unactivated alkenes with bench-stable solid arylzinc pivalates and difluoroalkyl bromides through a cascade Csp3‒Csp3/Csp3‒Csp2 bond formation has been developed under mild reaction conditions. Indeed, a wide range of functional groups on difluoroalkyl bromides, olefins, 1,3-dienes as well as (hetero)arylzinc pivalates are well tolerated by the cobalt-catalyst, thus furnishing three-component coupling products in good yields and with high regio- and diastereoselectivity. Kinetic experiments comparing arylzinc pivalates and conventional arylzinc halides highlight the unique reactivity of these new organozinc pivalates. Detailed mechanistic studies strongly support that the reaction involves direct halogen atom abstraction via single electron transfer to difluoroalkyl bromides from the in situ formed cobalt(I) species, thus realizing a Co(I)/Co(II)/Co(III) catalytic cycle.

scholarly journals Late-stage C–H thiolation via sulfonium salts using β-sulfinylesters as the versatile sulfur source

2021 ◽  
Author(s):  
Yanhui Chen ◽  
Si Wen ◽  
Qingyu Tian ◽  
Yuqing Zhang ◽  
Guolin Cheng
Keyword(s):  
Michael Reaction ◽  
Bond Cleavage ◽  
Sulfur Source ◽  
Reaction Conditions ◽  
Sulfonium Salts ◽  
Drug Molecules ◽  
Organic Sulfides ◽  
Wide Range ◽  
Successful Capture

Abstract Organic sulfides form the core scaffold of a wide range of pharmaceuticals, natural products, and materials, and serve as key intermediates in synthesis. Prior methods to organic sulfides require the use of transition metal (TM) catalysts, prefunctionalized or chelating group-containing substrates, and elevated reaction temperatures. A general TM-free C–H thiolation protocol using readily accessible sulfur source is highly desirable. Herein, we disclose a direct C(sp)–, C(sp2)–, and C(sp3)–H thiolation reaction using β-sulfinylesters as the versatile sulfur source. The key step of this protocol is chemoselective C–S bond cleavage of the sulfonium salts that is in situ formed from the corresponding (hetero)arenes, alkenes, alkynes, and 1,3-dicarboxyl compounds with β-sulfinylesters. The successful capture of acrylate byproduct supports a retro-Michael reaction mechanism. This method is expected to be used widely because of several advantageous aspects including TM-free, mild reaction conditions, and broad substrate scope including drug molecules.

scholarly journals High-Performance Chlorine-Doped Cu2O Catalysts for the Ethynylation of Formaldehyde

Processes ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 198
Author(s):  
Jie Gao ◽  
Guofeng Yang ◽  
Haitao Li ◽  
Mei Dong ◽  
Zhipeng Wang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Bond Strength ◽  
Reaction Temperature ◽  
Active Sites ◽  
High Performance ◽  
Lattice Structure ◽  
Reaction Conditions ◽  
Simple Strategy ◽  
Co Precipitation

The in situ formed Cu+ species serve as active sites in the ethynylation of formaldehyde. The key problem that needs to be solved in this process is how to avoid excessive reduction of Cu2+ to inactive metallic Cu, which tends to decrease the catalytic activity. In this work, Cl−-modified Cu2O catalysts with different Cl content were prepared by co-precipitation. The characterization results demonstrated that Cl− remained in the lattice structure of Cu2O, inducing the expansion of the Cu2O lattice and the enhancement of the Cu–O bond strength. Consequently, the reduction of Cu+ to Cu0 was effectively prevented in reductive media. Moreover, the activity and stability of Cu2O were significantly improved. The Cl− modification increased the yield of 1,4-butynediol (BD) from 73% to 94% at a reaction temperature of 90 °C. More importantly, the BD yield of Cl− modified Cu2O was still as high as 86% during the ten-cycle experiment, whereas the BD yield of Cu2O in the absence of Cl− decreased sharply to 17% at the same reaction conditions. This work provides a simple strategy to stabilize Cu+ in reductive media.

scholarly journals Organozinc pivalates for cobalt-catalyzed difluoroalkylarylation of alkenes

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xinyi Cheng ◽  
Xingchen Liu ◽  
Shengchun Wang ◽  
Ying Hu ◽  
Binjing Hu ◽  
...  
Keyword(s):  
Cobalt Catalyst ◽  
Bond Formation ◽  
Vital Role ◽  
Transition Metal Catalysis ◽  
Single Electron Transfer ◽  
Mechanistic Studies ◽  
Reaction Conditions ◽  
Metal Catalysis ◽  
Wide Range

AbstractInstallation of fluorine into pharmaceutically relevant molecules plays a vital role in their properties of biology or medicinal chemistry. Direct difunctionalization of alkenes and 1,3-dienes to achieve fluorinated compounds through transition-metal catalysis is challenging, due to the facile β-H elimination from the Csp3‒[M] intermediate. Here we report a cobalt-catalyzed regioselective difluoroalkylarylation of both activated and unactivated alkenes with solid arylzinc pivalates and difluoroalkyl bromides through a cascade Csp3‒Csp3/Csp3‒Csp2 bond formation under mild reaction conditions. Indeed, a wide range of functional groups on difluoroalkyl bromides, olefins, 1,3-dienes as well as (hetero)arylzinc pivalates are well tolerated by the cobalt-catalyst, thus furnishing three-component coupling products in good yields and with high regio- and diastereoselectivity. Kinetic experiments comparing arylzinc pivalates and conventional arylzinc halides highlight the unique reactivity of these organozinc pivalates. Mechanistic studies strongly support that the reaction involves direct halogen atom abstraction via single electron transfer to difluoroalkyl bromides from the in situ formed cobalt(I) species, thus realizing a Co(I)/Co(II)/Co(III) catalytic cycle.

In-situ electrical-resistivity measurements in the high-voltage electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 68-69
Author(s):  
W. E. King
Keyword(s):  
Electrical Resistivity ◽  
Electron Microscope ◽  
High Voltage ◽  
Resistivity Measurements ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron ◽  
Wide Range ◽  
Helium Gas

A side-entry type, helium-temperature specimen stage that has the capability of in-situ electrical-resistivity measurements has been designed and developed for use in the AEI-EM7 1200-kV electron microscope at Argonne National Laboratory. The electrical-resistivity measurements complement the high-voltage electron microscope (HVEM) to yield a unique opportunity to investigate defect production in metals by electron irradiation over a wide range of defect concentrations.A flow cryostat that uses helium gas as a coolant is employed to attain and maintain any specified temperature between 10 and 300 K. The helium gas coolant eliminates the vibrations that arise from boiling liquid helium and the temperature instabilities due to alternating heat-transfer mechanisms in the two-phase temperature regime (4.215 K). Figure 1 shows a schematic view of the liquid/gaseous helium transfer system. A liquid-gas mixture can be used for fast cooldown. The cold tip of the transfer tube is inserted coincident with the tilt axis of the specimen stage, and the end of the coolant flow tube is positioned without contact within the heat exchanger of the copper specimen block (Fig. 2).

Catalysts for hydrogenation of CO2 into components of motor fuels

2020 ◽  
pp. 1-18
Author(s):  
Yu.V. Bilokopytov ◽  
◽  
S.L. Melnykova ◽  
N.Yu. Khimach ◽  
◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Heterogeneous Catalysts ◽  
Fossil Fuels ◽  
Catalyst Stability ◽  
Co2 Conversion ◽  
Active Components ◽  
Synthesis Conditions ◽  
Hydrogenation Of Co2 ◽  
Mesoporous Zeolites ◽  
Motor Fuels

CO2 is a harmful greenhouse gas, a product of chemical emissions, the combustion of fossil fuels and car exhausts, and it is a widely available source of carbon. The review considers various ways of hydrogenation of carbon dioxide into components of motor fuels - methanol, dimethyl ether, ethanol, hydrocarbons - in the presence of heterogeneous catalysts. At each route of conversion of CO2 (into oxygenates or hydrocarbons) the first stage is the formation of CO by the reverse water gas shift (rWGS) reaction, which must be taken into account when catalysts of process are choosing. The influence of chemical nature, specific surface area, particle size and interaction between catalyst components, as well as the method of its production on the CO2 conversion processes is analyzed. It is noted that the main active components of CO2 conversion into methanol are copper atoms and ions which interact with the oxide components of the catalyst. There is a positive effect of other metals oxides additives with strong basic centers on the surface on the activity of the traditional copper-zinc-aluminum oxide catalyst for the synthesis of methanol from the synthesis gas. The most active catalysts for the synthesis of DME from CO2 and H2 are bifunctional. These catalysts contain both a methanol synthesis catalyst and a dehydrating component, such as mesoporous zeolites with acid centers of weak and medium strength, evenly distributed on the surface. The synthesis of gasoline hydrocarbons (≥ C5) is carried out through the formation of CO or CH3OH and DME as intermediates on multifunctional catalysts, which also contain zeolites. Hydrogenation of CO2 into ethanol can be considered as an alternative to the synthesis of ethanol through the hydration of ethylene. High activation energy of carbon dioxide, harsh synthesis conditions as well as high selectivity for hydrocarbons, in particular methane remains the main problems. Further increase of selectivity and efficiency of carbon dioxide hydrogenation processes involves the use of nanocatalysts taking into account the mechanism of CO2 conversion reactions, development of methods for removing excess water as a by-product from the reaction zone and increasing catalyst stability over time.

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