Feedstock For Production Of Chemicals Research Articles

Review on integrated green hydrogen polygeneration system——Electrolysers, modelling, 4 E analysis and optimization

Green hydrogen production by water electrolysis is sustainable and carbon-free for energy storage. This paper introduces recent development in integrated green hydrogen polygeneration. Throughout this review, theoretical concepts, design types, and recent developments related to the integration of Alkaline Electrolysis (AE), Proton Exchange Membrane Electrolysis (PEME), and the Solid Oxide Electrolysis Cell (SOEC) are summarised. This review evaluates the thermodynamic efficiency and economic impact of green hydrogen production integrated with different energy sources, energy storage and power cycles. Compared with two kinds of commercially applied methods (AE and PEME), SOEC is the state-of-the-art method to produce hydrogen, which can be integrated with external heat to reduce energy consumption. SOEC avoids the inevitable energy loss in AE and PEME, which leads to low-temperature waste heat evaluated as exergy destruction rather than utilized. The overall efficiency improvement of SOEC systems is over 10%. In most cases, the efficiency is always over 70%, and over 80% in some cases, which exceeds the typical values of 20%–60% from AE and PEME systems. The produced hydrogen can be stored and transported, as well as being used as a feedstock for chemical production, forming a polygeneration system with multiple energy sources, desalination, and fuel production. The latest lifetime of SOEC was predicted at 50,000 h or more, which is the minimum requirement to be commercially competitive. In the literature review, 80.4% of papers chose exergy efficiency as assessment index, compared with 67.9% of energy efficiency. And 58.9% of them chose genetic algorithm to complete multi-objective optimization.

SiC-based structured catalysts for a high-efficiency electrified dry reforming of methane

The process of dry reforming of methane (DRM) can allow the conversion of methane and carbon dioxide, the two main greenhouse gases (GHG), into syngas which can be either used as feedstock for chemicals production or it can undergo through separation step for H2 recovery. However, the heat required for the reaction is obtained by combustion of fossil fuels, so CO2 footprint of the process is significant. Another problematic aspect of the process concerns the heat transfer to the catalytic volume: for allowing the catalytic bed to reach and maintain the reaction temperature, the heating medium outside the tubes containing the catalyst must have a temperature higher than 1000 °C. A process intensification could be performed by combining two innovative technologies: (i) the use of electrification for the energy supply (microwave heating and direct electrification) and (ii) the adoption of structured catalysts with high thermal conductivity.This work proposed the study of electrified DRM process using two Ni-based structured catalysts prepared starting by different carriers, a Silicon carbide (SiC) honeycomb monolith and a Si–SiC open-cell foam. The electrification of the DRM process has been realized by using either microwave heating or electrification through Joule (or ohmic) heating, and the experimental tests have been performed at different space velocity values. The configuration of the carriers has been carefully chosen in order to enhance the heat and mass transport phenomena, allowing to assure a flat temperature profile along the entire catalytic bed.The results have shown that the SiC monolith is more suitable than the Si–SiC foam for a microwave-assisted catalytic test. In fact, the higher fraction of void in the foam determines a lower heat absorption, and a consequently higher energy consumption (8.29 kWh/Nm3 H2 and 4.2 kWh/Nm3 H2, for the foam and the monolith respectively). Moreover, the monolith-based catalyst approached the thermodynamic equilibrium values in terms of CH4 conversion in all the investigated temperature range, while in the same tests the foam-based catalyst reached these values only at the higher temperatures. Conversely, the foam-based catalyst has shown the best performance in the electrification tests through Joule heating: the CH4 conversion approached the equilibrium values in the investigated temperature range and, more important, the energy consumption value was of 2.6 kWh/Nm3 H2, very close to the theoretical one (1.90 kWh/Nm3 H2) and equal to about ¼ of that obtained with microwaves.

Confinement effects over Ni-based catalysts for methane dry reforming

Advances in application of the confinement effect in improving the resistance to sintering and coking of Ni-based catalysts for methane dry reforming were summarized.

Investigation of gasification reactions and H2/CO ratio analysis for rice husk air gasification simulation

The syngas generated during gasification process is used for industrial process heat, power generation and chemical feedstock production. Gas composition, H2/CO and CO/CO2 ratios are the deciding factors for producer gas end-use. In the present work, rice husk air gasification simulation is carried out by non-stoichiometric equilibrium model using Gibbs free energy minimization by FactSage 6.3 software. Influence of gasification reactions and effect of temperature, equiv?alence ratio on gas composition was studied. The analysis was carried out to study the effect of operating conditions on producer gas heating value and gasification efficiency at various H2/CO ratios. Increase in temperature improves H2 and CO formation in water gas reaction and reduction of H2 formation was observed in water gas shift reaction due to endothermic behavior change. For all the values of the equivalence ratio, ?, an increase in temperature reduces the H2/CO and enhances the CO/CO2 ratio due to higher CO formation. For a particular, ?, value, maximum gas heating value and gasification efficiency were obtained at low H2/CO ratio.

Advanced Electrochemical Impedance Analysis Using Distribution of Relaxation Times for in Operando Mechanistic Insights of Fuel Cell and Water Electrolyzer Designs

The development of sustainable and carbon-neutral alternative energy frameworks and chemical feedstocks requires rapid production of scalable water electrolyzer designs for hydrogen production.[1] Coupling electrolyzers to renewable energy supplies can provide a ‘green’ hydrogen production pathway, enabling clean production of chemical feedstocks as well as an energy storage framework. Current acid-based electrolyzer designs, however, integrate precious metals for stable operation, where drastic reductions in iridium use and increased cell durability are required for scalable deployment.[2] This requires the ability to monitor changes to the cell in operando for rapid diagnostics during initial and long-term operation under sustained or intermittent profiles. One technique proposed is electrochemical impedance spectroscopy (EIS), which can provide a breakdown of the cell resistances based on the timescale of the process.[3] Further analysis by circuit modeling, however, requires significant insight into the system for accurate interpretations. By coupling conventional EIS methods with distribution of relaxation times (DRT) analysis, the number of processes impacting cell operation can be determined without a priori knowledge of the system.[4] This has improved circuit modeling analysis of Li-ion batteries and solid oxide fuel cells.[5] Here, we demonstrate the power of EIS-coupled DRT analysis by analyzing the operation porous cathode and anode films of Nafion-based electrolyzer cells in half-cell and full cell configuration. Analysis of the electrodes in half-cell configurations provides estimates of kinetic parameters, active area, ionic conductivity, and diffusion coefficients associated with the electrode from a single EIS spectrum that are comparable to values obtained from in situ values.[6] Further analysis of the full cell operation with variable cathode gas composition provides insight as to the effect of the cathode gas composition on both the cathode and anode operation and stability. The work presented here will show the versatility and limitations of DRT-coupled EIS analysis of novel fuel cell and electrolyzer designs as well as present key findings for improving electrolyzer performance and stability.[1]Ayers, K. et al. Annu. Rev. Chem. Biomolec. Eng. 2019, 10, 219-239.[2]Pham, C. et al Adv. Energy Mater. 2021, 11, 2101998.[3]Liu, H. et al. J. Phys. Chem. Lett. 2022, 13, 6520-6531.[4]Wan, T. et al. Electrochimica Acta 2015, 184, 483-499.[5]Dierickx, S., Ivers-Tiffee, E. Electrochimica Acta 2020, 355, 136764.[6]Giesbrecht, P.K., Freund, M.S. J. Phys. Chem. C 2022, 126, 132-150.

What Shall We Do with Steel Mill Off-Gas: Polygeneration Systems Minimizing Greenhouse Gas Emissions.

Both the global steel and chemical industries contribute largely to industrial greenhouse gas (GHG) emissions. For both industries, GHG emissions are strongly related to the consumption of fossil resources. While the chemical industry often releases GHGs as direct process emissions, steel mills globally produce 1.78 Gt of off-gases each year, which are currently combusted for subsequent heat and electricity generation. However, these steel mill off-gases consist of high value compounds, which also can be utilized as feedstock for chemical production and thereby reduce fossil resource consumption and thus GHG emissions. In the present work, we determine climate-optimal utilization pathways for steel mill off-gases. We combine a nonlinear, disjunctive model of the steel mill off-gas separation system with a large-scale linear model of the chemical industry to perform environmental optimization. The results show that the climate-optimal utilization of steel mill off-gases depends on electricity's carbon footprint: For the current electricity grid mix, methane, hydrogen, and synthesis gas are recovered as feedstocks for conventional chemical production and enable a methanol-based chemical industry. For low electricity footprints in the future, the separation of steel mill off-gases supports CO2-based production processes in the chemical industry, supplying up to 30% of the required CO2. By coupling the global steel and chemical industry, industrial GHG emissions can be reduced by up to 79 Mt CO2-equivalents per year. These reductions provide up to 4.5% additional GHG savings compared to a stand-alone optimization of the two industries, showing a limited potential for this industrial symbiosis.

Life cycle greenhouse gas emissions of biomass- and waste-derived hydrocarbons considering uncertainties in available feedstocks

Sustainable chemical production requires renewable feedstocks. Biomass- and waste-derived production is a method for producing chemical products from renewables. In this study, we explore sustainable chemical production applying renewable feedstocks crude palm oil, rapeseed oil, palm fatty acid distillate, used cooking oil, inedible animal fat, inedible fish fat, and algae oil. Hydrotreated vegetable oil has been applied as the raw material for cracking on petrochemical sites and conversion into chemicals based on existing technology patents. A life cycle assessment was used to examine whether this production route can support a reduction in nonbiogenic greenhouse gas (GHG) emission by the production and use of renewable-derived hydrocarbons (RDHC) as the functional unit (FU). The life cycle GHG of the FU ranged between 2.87 and 3.29 kg-CO2eq/FU for three types of feedstock mix, considering their availability and RDHC production capacity, whereas that of fossil-based life cycle is 4.59 kg-CO2eq/FU. Due to the limited availability and wide range of needs, the sourcing of renewable feedstocks could become competitive in the near future. The development and implementation of technologies applying various resources as feedstocks for chemical production are strongly needed toward a carbon-neutral chemical production.

On the influence of hydrothermal treatment pH on the performance of Bi2WO6 as photocatalyst in the glycerol photoreforming.

Solar driven semiconductor-based photoreforming of biomass derivatives, such as glycerol is a sustainable alternative towards green hydrogen evolution concerted with production of chemical feedstocks. In this work, we have investigated the influence of the pH of the hydrothermal treatment on the efficiency of Bi2WO6 as photocatalyst in the glycerol photoreforming. Bi2WO6 is pointed as a promising material for this application due its adequate band gap and the ability to promote hole transfer directly to glycerol without formation of non-selective ⋅OH radicals. Samples prepared at neutral to moderate alkaline conditions (pH = 7-9) are highly crystalline, while those prepared in acidic media (pH = 0-2) exhibit higher concentrations of oxygen vacancies. At pH = 13, the non-stoichiometric Bi(III)-rich phase Bi3.84W0.16O6.24 is formed. All samples were fully characterized towards their optical and morphological properties. UV-Vis irradiation of the photocatalysts modified with 1% m/m Pt and in the presence of 5% v/v aqueous glycerol solution leads to H2 evolution and glycerol oxidation. The sample prepared at pH = 0 exhibited the highest photonic efficiency (ξ) for H2 evolution (1.4 ± 0.1%) among the investigated samples with 99% selectivity for simultaneous formic acid formation. Similar performance was observed for the non-stoichiometric Bi3.84W0.16O6.24 sample (ξ = 1.2 ± 0.1% and 88% selectivity for formic acid), whereas the more crystalline sample prepared at pH = 9 was less active (ξ = 0.9 ± 0.1%) and leads to multiple oxidation products. The different behaviors were rationalized based on the role of oxygen vacancies as active adsorption and redox sites at the semiconductor surface, stablishing clear relationships between the semiconductor structure and its photocatalytic performance. The present work contributes for the rational development of specific photocatalysts for glycerol photoreforming.

Optimal design of a coal-based synthetic natural gas (SNG) process with different coal ranks and gasification technologies via techno-economic analysis

Natural gas is regarded as a cleaner fuel and could be a feedstock for chemicals production. In some regions where petroleum resources are limited, the coal-based synthetic natural gas (SNG) process could be an alternative option. Generally, the coal-based SNG process begins with the gasification of coal to produce crude syngas, implying that coal rank and gasification technology would have a significant impact on the process performance and product quality. Within this work, a series of coal-based SNG processes with different coal ranks and gasification technologies are investigated and analyzed based on rigorous process modeling and simulation. Sensitivity analysis is carried out to optimize key parameters and explore their effects on process performance. The results indicate that the low-rank coal with the Lurgi gasifier could effectively improve the energy conversion efficiency when compared with various combinations of coal ranks and gasification technologies. The lignite coal with the Lurgi gasifier could improve the energy efficiency up to 61% with a Wobbe index of 52 MJ/m3, a carbon yield of 44%, and the minimum CO2 emission of 3.5 kgCO2/kgSNG. The economic evaluation suggests that the total equipment investment for the process based on lignite is 20% and 27% lower than that based on bituminous and anthracite, respectively. Furthermore, the Lurgi gasifier could save 12% equipment investment compared with the Texaco gasifier when the process is based on the same coal rank. The research could provide quantitative guidance for the design and optimization of coal-based SNG processes.

A New Approach to Modeling Solid Oxide Cell Reactors with Multiple Stacks for Process System Simulation

Reactors with solid oxide cells (SOC) are highly efficient electrochemical energy converters, which can be used for electricity generation and production of chemical feedstocks. The technology is in an upscaling phase. Thereby demanding development of strategies for robust and efficient operation or large SOC reactors and plants. The present state of technology requires reactors with multiple stacks to achieve the appropriate power. This study aims to establish and apply a simulation framework to investigate process systems containing SOC reactors with multiple stacks. Focusing especially on the operating behavior of SOC reactors under transient conditions, by observing the performance of all cells in the reactor. For this purpose, a simulation model of the entire SOC reactor consisting of multiple stacks, pipes, manifolds, and thermal insulation was developed. After validation on stack and reactor level, the model was used to investigate the fundamental behavior of the SOC reactors and the individual stacks in various operation modes. Additionally, the influences of local degradation and reactor scaling on the performance were examined. The results show that detailed investigation of the reactors is necessary to ensure operability and to increase efficiency and robustness. Furthermore, the computing performance is sufficient to develop and validate system controls.

Chemical upgrade of carbon monoxide to acetate on an atomically dispersed copper catalyst via CO-insertion

Electrochemical conversion of small molecules such as carbon dioxide (CO2) and carbon monoxide (CO) to high-value multi-carbon products (C2+) offers a chemical upgrade approach for fuels and chemical feedstock production using renewable energy, in the possible absence of the petrochemical industry under the new energy system such as hydrogen economy. Identifying robust and efficient electrocatalysts to selectively produce C2+ products remains a challenge. Herein, we report a synthetic strategy of atomically dispersing copper atoms on nitrogen-rich porous carbon (Cu–N–C) through pyrolysis of a supramolecular assembly. Benefitting from the unsaturated coordination structure, in KOH electrolyte, the Cu–N–C with a Cu content of 6.9 wt% exhibits a maximum acetate Faradaic efficiency (FE) of 30% with an acetate partial current density as high as 48 mA cm−2 in electrochemical CO reduction. Different from the C–C coupling mechanism on metallic copper, we propose a CO insertion mechanism for the acetate production on the single site copper catalyst.

Aluminum Metal–Organic Framework-Ligated Single-Site Nickel(II)-Hydride for Heterogeneous Chemoselective Catalysis

The development of chemoselective and heterogeneous earth-abundant metal catalysts is essential for environmentally friendly chemical synthesis. We report a highly efficient, chemoselective, and reusable single-site nickel(II) hydride catalyst based on robust and porous aluminum metal–organic frameworks (MOFs) (DUT-5) for hydrogenation of nitro and nitrile compounds to the corresponding amines and hydrogenolysis of aryl ethers under mild conditions. The nickel-hydride catalyst was prepared by the metalation of aluminum hydroxide secondary building units (SBUs) of DUT-5 having the formula of Al(μ2-OH)(bpdc) (bpdc = 4,4′-biphenyldicarboxylate) with NiBr2 followed by a reaction with NaEt3BH. DUT-5-NiH has a broad substrate scope with excellent functional group tolerance in the hydrogenation of aromatic and aliphatic nitro and nitrile compounds under 1 bar H2 and could be recycled and reused at least 10 times. By changing the reaction conditions of the hydrogenation of nitriles, symmetric or unsymmetric secondary amines were also afforded selectively. The experimental and computational studies suggested reversible nitrile coordination to nickel followed by 1,2-insertion of coordinated nitrile into the nickel-hydride bond occurring in the turnover-limiting step. In addition, DUT-5-NiH is also an active catalyst for chemoselective hydrogenolysis of carbon–oxygen bonds in aryl ethers to afford hydrocarbons under atmospheric hydrogen in the absence of any base, which is important for the generation of fuels from biomass. This work highlights the potential of MOF-based single-site earth-abundant metal catalysts for practical and eco-friendly production of chemical feedstocks and biofuels.

Enhancement of fuel properties of yard waste through dry torrefaction

Yard waste or green waste is an abundant yet underutilized source of biomass around the world. Yard waste is rich in complex organic compounds, which is beneficial when used as feedstock for chemicals production, but undesirable components within the biomass are detrimental to the quality of the products. In this work, the prospect of yard waste upgrading as a solid fuel source by dry torrefaction (DT) was studied. Dry torrefaction of yard waste was conducted at 170 °C, 200 °C, 250 °C, and 300 °C under N2, CO2, and flue gas (25:75 vol% mixture of CO2:N2) atmosphere in a tubular reactor. As temperature was increased, the mass yield of the torrefied yard waste decreased while the HHV increased. The mass yields obtained were in the order of nitrogen < carbon dioxide < flue gas. HHV was in the order of flue gas < nitrogen < carbon dioxide. Overall, carbon dioxide was shown to be the best carrier gas for energy intensification, where HHV was enhanced from 15.6 to 22.2 MJ/kg at 300 °C, with an energy yield of 98.1%. Flue gas showed no visible improvement in properties up to temperatures of 250 °C. Thermogravimetric analysis (TGA) highlighted that within the given temperature range, hemicellulose was completely degraded as temperature approach 300 °C, while cellulose was partially degraded. Fourier transform infrared spectroscopy (FTIR) emphasised that flue gas was unable to degrade various functional groups to the same degree as the other gases. Field Emission scanning electron microscopy with Energy Dispersive X-ray analysis (FESEM-EDX) revealed that flue gas was unable to degrade the biomass as much as nitrogen or carbon dioxide.

Production of Value-Added Chemicals by Bacillus methanolicus Strains Cultivated on Mannitol and Extracts of Seaweed Saccharina latissima at 50°C.

The facultative methylotroph Bacillus methanolicus MGA3 has previously been genetically engineered to overproduce the amino acids L-lysine and L-glutamate and their derivatives cadaverine and γ-aminobutyric acid (GABA) from methanol at 50°C. We here explored the potential of utilizing the sugar alcohol mannitol and seaweed extract (SWE) containing mannitol, as alternative feedstocks for production of chemicals by fermentation using B. methanolicus. Extracts of the brown algae Saccharina latissima harvested in the Trondheim Fjord in Norway were prepared and found to contain 12–13 g/l of mannitol, with conductivities corresponding to a salt content of ∼2% NaCl. Initially, 12 B. methanolicus wild type strains were tested for tolerance to various SWE concentrations, and some strains including MGA3 could grow on 50% SWE medium. Non-methylotrophic and methylotrophic growth of B. methanolicus rely on differences in regulation of metabolic pathways, and we compared production titers of GABA and cadaverine under such growth conditions. Shake flask experiments showed that recombinant MGA3 strains could produce similar and higher titers of cadaverine during growth on 50% SWE and mannitol, compared to on methanol. GABA production levels under these conditions were however low compared to growth on methanol. We present the first fed-batch mannitol fermentation of B. methanolicus and production of 6.3 g/l cadaverine. Finally, we constructed a recombinant MGA3 strain synthesizing the C30 terpenoids 4,4′-diaponeurosporene and 4,4′-diapolycopene, experimentally confirming that B. methanolicus has a functional methylerythritol phosphate (MEP) pathway. Together, our results contribute to extending the range of both the feedstocks for growth and products that can be synthesized by B. methanolicus.

Synthesis Gas Composition Prediction for Underground Coal Gasification Using a Thermochemical Equilibrium Modeling Approach

Underground coal gasification (UCG) is an in situ conversion technique that enables the production of high-calorific synthesis gas from resources that are economically not minable by conventional methods. A broad range of end-use options is available for the synthesis gas, including fuels and chemical feedstock production. Furthermore, UCG also offers a high potential for integration with Carbon Capture and Storage (CCS) to mitigate greenhouse gas emissions. In the present study, a stoichiometric equilibrium model, based on minimization of the Gibbs function has been used to estimate the equilibrium composition of the synthesis gas. Thereto, we further developed and applied a proven thermodynamic equilibrium model to simulate the relevant thermochemical coal conversion processes (pyrolysis and gasification). Our modeling approach has been validated against thermodynamic models, laboratory gasification experiments and UCG field trial data reported in the literature. The synthesis gas compositions have been found to be in good agreement under a wide range of different operating conditions. Consequently, the presented modeling approach enables an efficient quantification of synthesis gas quality resulting from UCG, considering varying coal and oxidizer compositions at deposit-specific pressures and temperatures.

Introduction of a green algal squalene synthase enhances squalene accumulation in a strain of Synechocystis sp. PCC 6803

Squalene is a triterpene which is produced as a precursor for a wide range of terpenoid compounds in many organisms. It has commercial use in food and cosmetics but could also be used as a feedstock for production of chemicals and fuels, if generated sustainably on a large scale. We have engineered a cyanobacterium, Synechocystis sp. PCC 6803, for production of squalene from CO2. In this organism, squalene is produced via the methylerythritol-phosphate (MEP) pathway for terpenoid biosynthesis, and consumed by the enzyme squalene hopene cyclase (Shc) for generation of hopanoids. The gene encoding Shc in Synechocystis was inactivated (Δshc) by insertion of a gene encoding a squalene synthase from the green alga Botryococcus braunii, under control of an inducible promoter. We could demonstrate elevated squalene generation in cells where the algal enzyme was induced. Heterologous overexpression of genes upstream in the MEP pathway further enhanced the production of squalene, to a level three times higher than the Δshc background strain. During growth in flat panel bioreactors, a squalene titer of 5.1 ​mg/L of culture was reached.

Impacts of Pyrolytic Interactions during the Co-pyrolysis of Biomass/Plastic: Synergies in Lignocellulose-Polyethylene System

Multiple pyrolytic interactions in the cellulose-hemicellulose-lignin-polyethylene system were thoroughly investigated using a novel approach, which evaluates the pyrolytic interaction impacts through product recovery tests and the in-situ pyrolysate monitoring by evolved gas analysis-mass spectrometry. Fast pyrolysis of neat cellulose, xylan, milled wood lignin, beech wood, polyethylene, and their mixtures was conducted at 650 °C using the combined approach. Interactions in the cellulose/polyethylene, xylan/polyethylene, and milled wood lignin/polyethylene systems enhanced the production of CO and C2-C3 hydrocarbons, and simultaneously inhibited that of solids such as heavy tar, wax, and coke. Polyethylene worked as a dispersant of biomass upon injection, and the improved gasification was mainly due to the enhanced hydrogen-exchange between hydrogen-rich polyethylene pyrolysates and carbon-centered radicals in vapor phase. The results suggested that pyrolytic interactions in the biomass components (cellulose-hemicellulose-lignin) occur preferentially before contact with polyethylene, and then the beech wood pyrolysates further interact with the polyethylene pyrolysates. Thus, this novel approach allowed advanced evaluation of pyrolytic interactions and can be applied to different combinations and compositions in the cellulose-hemicellulose-lignin-plastic system. It will help understand the nature of co-pyrolysis systems and predict the significance of co-pyrolysis in practical energy and chemical feedstock production.

Core Metabolism Shifts during Growth on Methanol versus Methane in the Methanotroph Methylomicrobium buryatense 5GB1.

Methylomicrobium buryatense 5GB1 is an obligate methylotroph which grows on methane or methanol with similar growth rates. It has long been assumed that the core metabolic pathways must be similar on the two substrates, but recent studies of methane metabolism in this bacterium suggest that growth on methanol might have significant differences from growth on methane. In this study, both a targeted metabolomics approach and a 13C tracer approach were taken to understand core carbon metabolism in M. buryatense 5GB1 during growth on methanol and to determine whether such differences occur. Our results suggest a systematic shift of active core metabolism in which increased flux occurred through both the Entner-Doudoroff (ED) pathway and the partial serine cycle, while the tricarboxylic acid (TCA) cycle was incomplete, in contrast to growth on methane. Using the experimental results as constraints, we applied flux balance analysis to determine the metabolic flux phenotype of M. buryatense 5GB1 growing on methanol, and the results are consistent with predictions based on ATP and NADH changes. Transcriptomics analysis suggested that the changes in fluxes and metabolite levels represented results of posttranscriptional regulation. The combination of flux balance analysis of the genome-scale model and the flux ratio from 13C data changed the solution space for a better prediction of cell behavior and demonstrated the significant differences in physiology between growth on methane and growth on methanol.IMPORTANCE One-carbon compounds such as methane and methanol are of increasing interest as sustainable substrates for biological production of fuels and industrial chemicals. The bacteria that carry out these conversions have been studied for many decades, but gaps exist in our knowledge of their metabolic pathways. One such gap is the difference between growth on methane and growth on methanol. Understanding such metabolism is important, since each has advantages and disadvantages as a feedstock for production of chemicals and fuels. The significance of our research is in the demonstration that the metabolic network is substantially altered in each case and in the delineation of these changes. The resulting new insights into the core metabolism of this bacterium now provide an improved basis for future strain design.

Two-dimensional copper nanosheets for electrochemical reduction of carbon monoxide to acetate

Upgrading carbon dioxide to high-value multicarbon (C2+) products is one promising avenue for fuel and chemical production. Among all the monometallic catalysts, copper has attracted much attention because of its unique ability to convert CO2 or CO into C2+ products with an appreciable selectivity. Although numerous attempts have been made to synthesize Cu materials that expose the desired facets, it still remains a challenge to obtain high-quality nanostructured Cu catalysts for the electroreduction of CO2/CO. Here we report a facile synthesis of freestanding triangular-shaped two-dimensional Cu nanosheets that selectively expose the (111) surface. In a 2 M KOH electrolyte, the Cu nanosheets exhibit an acetate Faradaic efficiency of 48% with an acetate partial current density up to 131 mA cm−2 in electrochemical CO reduction. Further analysis suggest that the high acetate selectivity is attributed to the suppression of ethylene and ethanol formation, probably due to the reduction of exposed (100) and (110) surfaces. Upgrading CO to high-value multicarbon products is a promising avenue for fuel and chemical feedstock production. Here triangular Cu nanosheets that selectively expose the (111) surface exhibit a high acetate partial current density (131 mA cm–2) and Faradaic efficiency (48%) in CO electroreduction.

Direct Liquefaction of Victorian Brown Coal for Effective and Noble Utilization: Production of Chemical Feedstocks by Modified BCL Process

Direct Liquefaction of Victorian Brown Coal for Effective and Noble Utilization: Production of Chemical Feedstocks by Modified BCL Process