scholarly journals Direct and continuous generation of pure acetic acid solutions via electrocatalytic carbon monoxide reduction

2020 ◽  
Vol 118 (2) ◽  
pp. e2010868118
Author(s):  
Peng Zhu ◽  
Chuan Xia ◽  
Chun-Yen Liu ◽  
Kun Jiang ◽  
Guanhui Gao ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Density Functional ◽  
Liquid Electrolyte ◽  
Liquid Fuels ◽  
Acid Solutions ◽  
Faradaic Efficiency ◽  
Continuous Generation ◽  
Liquid Products ◽  
Cu Catalyst ◽  
Co Reduction

Electrochemical CO2 or CO reduction to high-value C2+ liquid fuels is desirable, but its practical application is challenged by impurities from cogenerated liquid products and solutes in liquid electrolytes, which necessitates cost- and energy-intensive downstream separation processes. By coupling rational designs in a Cu catalyst and porous solid electrolyte (PSE) reactor, here we demonstrate a direct and continuous generation of pure acetic acid solutions via electrochemical CO reduction. With optimized edge-to-surface ratio, the Cu nanocube catalyst presents an unprecedented acetate performance in neutral pH with other liquid products greatly suppressed, delivering a maximal acetate Faradaic efficiency of 43%, partial current of 200 mA⋅cm−2, ultrahigh relative purity of up to 98 wt%, and excellent stability of over 150 h continuous operation. Density functional theory simulations reveal the role of stepped sites along the cube edge in promoting the acetate pathway. Additionally, a PSE layer, other than a conventional liquid electrolyte, was designed to separate cathode and anode for efficient ion conductions, while not introducing any impurity ions into generated liquid fuels. Pure acetic acid solutions, with concentrations up to 2 wt% (0.33 M), can be continuously produced by employing the acetate-selective Cu catalyst in our PSE reactor.

scholarly journals Colloidal silver diphosphide (AgP2) nanocrystals as low overpotential catalysts for CO2 reduction to tunable syngas

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Hui Li ◽  
Peng Wen ◽  
Dominique S. Itanze ◽  
Zachary D. Hood ◽  
Xiao Ma ◽  
...  
Keyword(s):  
Density Functional ◽  
Co2 Reduction ◽  
Intermediate Formation ◽  
Density Functional Theory Calculations ◽  
Photocurrent Density ◽  
Faradaic Efficiency ◽  
Onset Potential ◽  
Fold Reduction ◽  
Co Conversion ◽  
Co Reduction

AbstractProduction of syngas with tunable CO/H2 ratio from renewable resources is an ideal way to provide a carbon-neutral feedstock for liquid fuel production. Ag is a benchmark electrocatalysts for CO2-to-CO conversion but high overpotential limits the efficiency. We synthesize AgP2 nanocrystals (NCs) with a greater than 3-fold reduction in overpotential for electrochemical CO2-to-CO reduction compared to Ag and greatly enhanced stability. Density functional theory calculations reveal a significant energy barrier decrease in the formate intermediate formation step. In situ X-ray absorption spectroscopy (XAS) shows that a maximum Faradaic efficiency is achieved at an average silver valence state of +1.08 in AgP2 NCs. A photocathode consisting of a n+p-Si wafer coated with ultrathin Al2O3 and AgP2 NCs achieves an onset potential of 0.2 V vs. RHE for CO production and a partial photocurrent density for CO at −0.11 V vs. RHE (j−0.11, CO) of −3.2 mA cm−2.

scholarly journals Hydroxide promotes carbon dioxide electroreduction to ethanol on copper via tuning of adsorbed hydrogen

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Mingchuan Luo ◽  
Ziyun Wang ◽  
Yuguang C. Li ◽  
Jun Li ◽  
Fengwang Li ◽  
...  
Keyword(s):  
Density Functional ◽  
Hydrogen Adsorption ◽  
Reduction Reaction ◽  
Liquid Fuels ◽  
Water Dissociation ◽  
Adsorbed Hydrogen ◽  
Functional Theory ◽  
Faradaic Efficiency ◽  
Complementary Approach ◽  
Cu Catalysts

AbstractProducing liquid fuels such as ethanol from CO2, H2O, and renewable electricity offers a route to store sustainable energy. The search for efficient electrocatalysts for the CO2 reduction reaction relies on tuning the adsorption strength of carbonaceous intermediates. Here, we report a complementary approach in which we utilize hydroxide and oxide doping of a catalyst surface to tune the adsorbed hydrogen on Cu. Density functional theory studies indicate that this doping accelerates water dissociation and changes the hydrogen adsorption energy on Cu. We synthesize and investigate a suite of metal-hydroxide-interface-doped-Cu catalysts, and find that the most efficient, Ce(OH)x-doped-Cu, exhibits an ethanol Faradaic efficiency of 43% and a partial current density of 128 mA cm−2. Mechanistic studies, wherein we combine investigation of hydrogen evolution performance with the results of operando Raman spectroscopy, show that adsorbed hydrogen hydrogenates surface *HCCOH, a key intermediate whose fate determines branching to ethanol versus ethylene.

scholarly journals Selective reduction of CO to acetaldehyde with CuAg electrocatalysts

2020 ◽  
Vol 117 (23) ◽  
pp. 12572-12575 ◽  
Author(s):  
Lei Wang ◽  
Drew C. Higgins ◽  
Yongfei Ji ◽  
Carlos G. Morales-Guio ◽  
Karen Chan ◽  
...  
Keyword(s):  
Density Functional ◽  
Selective Reduction ◽  
Density Functional Theory Calculations ◽  
Hydrogen Electrode ◽  
Reaction Conditions ◽  
Faradaic Efficiency ◽  
Catalyst Composition ◽  
Alkaline Reaction ◽  
Fuels And Chemicals ◽  
Co Reduction

Electrochemical CO reduction can serve as a sequential step in the transformation of CO2into multicarbon fuels and chemicals. In this study, we provide insights on how to steer selectivity for CO reduction almost exclusively toward a single multicarbon oxygenate by carefully controlling the catalyst composition and its surrounding reaction conditions. Under alkaline reaction conditions, we demonstrate that planar CuAg electrodes can reduce CO to acetaldehyde with over 50% Faradaic efficiency and over 90% selectivity on a carbon basis at a modest electrode potential of −0.536 V vs. the reversible hydrogen electrode. The Faradaic efficiency to acetaldehyde was further enhanced to 70% by increasing the roughness factor of the CuAg electrode. Density functional theory calculations indicate that Ag ad-atoms on Cu weaken the binding energy of the reduced acetaldehyde intermediate and inhibit its further reduction to ethanol, demonstrating that the improved selectivity to acetaldehyde is due to the electronic effect from Ag incorporation. These findings will aid in the design of catalysts that are able to guide complex reaction networks and achieve high selectivity for the desired product.

High-Entropy Alloys as Catalysts for the CO2 and CO Reduction Reactions

2019 ◽  
Author(s):  
Jack Pedersen ◽  
Thomas Batchelor ◽  
Alexander Bagger ◽  
Jan Rossmeisl
Keyword(s):  
Density Functional ◽  
Rational Design ◽  
Hydrogen Adsorption ◽  
Co Adsorption ◽  
Reduction Reaction ◽  
Supervised Machine Learning ◽  
High Entropy Alloys ◽  
High Entropy ◽  
Co Reduction ◽  
Disordered Alloy

Using the high-entropy alloys (HEAs) CoCuGaNiZn and AgAuCuPdPt as starting points we provide a framework for tuning the composition of disordered multi-metallic alloys to control the selectivity and activity of the reduction of carbon dioxide (CO2) to highly reduced compounds. By combining density functional theory (DFT) with supervised machine learning we predicted the CO and hydrogen (H) adsorption energies of all surface sites on the (111) surface of the two HEAs. This allowed an optimization for the HEA compositions with increased likelihood for sites with weak hydrogen adsorption{to suppress the formation of molecular hydrogen (H2) and with strong CO adsorption to favor the reduction of CO. This led to the discovery of several disordered alloy catalyst candidates for which selectivity towards highly reduced carbon compounds is expected, as well as insights into the rational design of disordered alloy catalysts for the CO2 and CO reduction reaction.

scholarly journals Production of Fuels and Chemicals from a CO2/H2 Mixture

Reactions ◽  
2020 ◽  
Vol 1 (2) ◽  
pp. 130-146
Author(s):  
Yali Yao ◽  
Baraka Celestin Sempuga ◽  
Xinying Liu ◽  
Diane Hildebrandt
Keyword(s):  
Co2 Hydrogenation ◽  
Water Gas Shift ◽  
Liquid Fuels ◽  
Saturated Hydrocarbons ◽  
Reverse Water Gas Shift ◽  
Cu Catalyst ◽  
In Series ◽  
Fuels And Chemicals ◽  
Water Gas ◽  
Aspen Simulation

In order to explore co-production alternatives, a once-through process for CO2 hydrogenation to chemicals and liquid fuels was investigated experimentally. In this approach, two different catalysts were considered; the first was a Cu-based catalyst that hydrogenates CO2 to methanol and CO and the second a Fisher–Tropsch (FT) Co-based catalyst. The two catalysts were loaded into different reactors and were initially operated separately. The experimental results show that: (1) the Cu catalyst was very active in both the methanol synthesis and reverse-water gas shift (R-WGS) reactions and these two reactions were restricted by thermodynamic equilibrium; this was also supported by an Aspen plus simulation of an (equilibrium) Gibbs reactor. The Aspen simulation results also indicated that the reactor can be operated adiabatically under certain conditions, given that the methanol reaction is exothermic and R-WGS is endothermic. (2) the FT catalyst produced mainly CH4 and short chain saturated hydrocarbons when the feed was CO2/H2. When the two reactors were coupled in series and the presence of CO in the tail gas from the first reactor (loaded with Cu catalyst) significantly improves the FT product selectivity toward higher carbon hydrocarbons in the second reactor compared to the standalone FT reactor with only CO2/H2 in the feed.

Durability of Red Mud Based Geopolymer Paste in Acid Solutions

2016 ◽  
Vol 866 ◽  
pp. 99-105 ◽  
Author(s):  
Smita Singh ◽  
M.U. Aswath ◽  
R.V. Ranganath
Keyword(s):  
Mechanical Properties ◽  
Acetic Acid ◽  
Fly Ash ◽  
Red Mud ◽  
Acetic Acid Solution ◽  
Strength Loss ◽  
Acid Solutions ◽  
Test Results ◽  
Acid Attack ◽  
Geopolymer Paste

The present investigation is on the effect of red mud on the mechanical properties and durability of the geopolymer paste in sulphuric and acetic acid solution. Red mud and fly ash were used to form the geopolymer paste along with the alkalies. The variation of red mud in the paste composition was from 0% to 90%. Cylindrical shaped specimens of 1 inch diameter and 1 inch height were prepared. The specimens were immersed in 5% sulphuric acid and 5% acetic acid for 1, 7, 14, 28, 56 and 84 days and tested for weight loss, visual deformation, strength loss and colour of the solvent, based on the procedure specified by ASTM C 267 – 01. SEM/EDX Tests were performed on the geopolymer specimens. Test results show that initially, the strength of the geopolymer increased upon the addition of red mud. The strength was maximum when the percentage of red mud was 30%. The maximum strength obtained was 38 MPa for the paste containing 30% red mud using 10M alkali solution as against 31.69 MPa, when only fly ash was used. Geopolymer paste containing 30% and 50% red mud showed better resistance to acid attack. The strength loss was minimum for the samples containing 30% red mud in both inorganic and organic acid i.e. sulphuric and acetic acid.

scholarly journals REGULATORY MECHANISMS OF CELLULAR RESPIRATION

1950 ◽  
Vol 34 (2) ◽  
pp. 211-224 ◽  
Author(s):  
E. S. Guzman Barron ◽  
Maria Isabel Ardao ◽  
Marion Hearon
Keyword(s):  
Acetic Acid ◽  
Pyruvic Acid ◽  
No Oxidation ◽  
Yeast Cells ◽  
Acid Formation ◽  
Cellular Respiration ◽  
Acid Oxidase ◽  
Acid Solutions ◽  
Fluoroacetic Acid ◽  
A Cell

The rate of the aerobic metabolism of pyruvic acid by bakers' yeast cells is determined mainly by the amount of undissociated acid present. As a consequence, the greatest rate of oxidation was observed at pH 2.8. Oxidation, at a slow rate, started at pH 1.08; at pH 9.4 there was no oxidation at all. The anaerobic metabolism, only a fraction of the aerobic, was observed only in acid solutions. There was none at pH values higher than 3. Pyruvic acid in the presence of oxygen was oxidized directly to acetic acid; in the absence of oxygen it was metabolized mainly by dismutation to lactic and acetic acids, and CO2. Acetic acid formation was demonstrated on oxidation of pyruvic acid at pH 1.91, and on addition of fluoroacetic acid. Succinic acid formation was shown by addition of malonic acid. These metabolic pathways in a cell so rich in carboxylase may be explained by the arrangement of enzymes within the cell, so that carboxylase is at the center, while pyruvic acid oxidase is located at the periphery. Succinic and citric acids were oxidized only in acid solutions up to pH 4. Malic and α-ketoglutaric acids were not oxidized, undoubtedly because of lack of penetration.

Ultrastable Cu Catalyst for CO2 Electroreduction to Multicarbon Liquid Fuels by Tuning C−C Coupling with CuTi Subsurface

2021 ◽  
Author(s):  
Fei Hu ◽  
Li Yang ◽  
Yawen Jiang ◽  
Chongxiong Duan ◽  
Xiaonong Wang ◽  
...  
Keyword(s):  
Liquid Fuels ◽  
Co2 Electroreduction ◽  
Cu Catalyst

Molecular Dynamic Simulation of Hydrogen Production by Catalytic Gasification of Key Intermediates of Biomass in Supercritical Water

2017 ◽  
Vol 140 (4) ◽  
Author(s):  
Hui Jin ◽  
Bin Chen ◽  
Xiao Zhao ◽  
Changqing Cao
Keyword(s):  
Supercritical Water ◽  
Active Sites ◽  
Density Functional ◽  
Free Carbon ◽  
Ni Catalyst ◽  
Catalytic Gasification ◽  
Syngas Production ◽  
Reactor Optimization ◽  
Cu Catalyst ◽  
Microscopic Reaction

Supercritical water gasification (SCWG) is an efficient and clean conversion of biomass due to the unique chemical and physical properties. Anthracene and furfural are the key intermediates in SCWG, and their microscopic reaction mechanism in supercritical water may provide information for reactor optimization and selection of optimal operating condition. Density functional theory (DFT) and reactive empirical force fields (ReaxFF) were combined to investigate the molecular dynamics of catalytic gasification of anthracene and furfural. The simulation results showed that Cu and Ni obviously increased the production of H radicals, therefore the substance SCWG process. Ni catalyst decreased the production of H2 with the residence time of 500 ps while significantly increased CO production and finally increased the syngas production. Ni catalyst was proved to decrease the free carbon production to prohibit the carbon deposition on the surface of active sites; meanwhile, Cu catalyst increased the production of free carbon.

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