CO Production Yield Research Articles

GFP Chromophore Integrated Conjugated Microporous Polymers toward Bioinspired Photocatalytic CO2 Reduction to CO.

The development of highly active, durable, and low-cost metal-free catalysts for the photocatalytic CO2 reduction reaction (CO2RR) is an efficient and environmentally friendly solution to address significant problems like global warming and high energy demand. In the present study, we have demonstrated the design and synthesis of a donor-acceptor based conjugated microporous polymer (CMP), TPA-GFP, by integrating an electron donor, tris(4-ethynylphenyl)amine (TPA), with a green fluorescent protein chromophore analogue (Z)-4-(2-hydroxy-3,5-diiodobenzylidene)-1-(4-iodophenyl)-2-methyl-1H-imidazol-5(4H)-one (o-HBDI-I3) (GFP). In comparison to nondonor 1,3,5-triethynylbenzene (TEB) based TEB-GFP CMP, photocatalytic CO2 reduction using donor-acceptor based TPA-GFP CMP displays a 3-fold increment of CO production yield with a maximum CO yield of 1666 μmol g-1 at 12 h. Further, the CO selectivity increases significantly from a mere 54% in TEB-GFP to an impressive 95% in TPA-GFP. The impressive CO2 reduction efficiency and selectivity for TPA-GFP can be attributed to the efficient light-harvesting capability and facile charge separation and migration through donor-acceptor building units of the CMP. The mechanistic aspect of the photocatalytic CO2 reduction process is explored using in situ DRIFTS and DFT calculation, and a plausible photocatalytic mechanism is proposed.

Impact of mixing grain sorghum with corn on ethanol and coproduct yields

Impact of mixing grain sorghum with corn on ethanol and coproduct yields

Photocatalytic CO2 Reduction Using Zinc Indium Sulfide Aggregated Nanostructures Fabricated under Four Anionic Conditions.

Zinc indihuhium sulfide (ZIS), among various semiconductor materials, shows considerable potential due to its simplicity, low cost, and environmental compatibility. However, the influence of precursor anions on ZIS properties remains unclear. In this study, we synthesized ZIS via a hydrothermal method using four different anionic precursors (ZnCl2/InCl3, Zn(NO3)2/In(NO3)3, Zn(CH3CO2)2/In(CH3CO2)3, and Zn(CH3CO2)2/In2(SO4)3), resulting in distinct morphologies and crystal structures. Our findings reveal that ZIS produced from Zn(CH3CO2)2/In2(SO4)3 (ZIS-AceSO4) exhibited the highest photocatalytic CO2 reduction efficiency, achieving a CO production yield of 134 μmol g-1h-1. This enhanced performance is attributed to the formation of more zinc and indium vacancy defects, as confirmed by EDS analysis. Additionally, we determined the energy levels of the valence band maximum (VBM) and the conduction band minimum (CBM) via UPS and absorption spectra, providing insights into the band alignment essential for photocatalytic processes. These findings not only deepen our understanding of the anionic precursor's impact on ZIS properties but also offer new avenues for optimizing photocatalytic CO2 reduction, marking a significant advancement over previous studies.

Construction of Bi2WO6/g-C3N4/Cu foam as 3D Z-scheme photocatalyst for photocatalytic CO2 reduction

Photocatalytic CO2 reduction to hydrocarbon fuels represents a promising solution to CO2 emission challenges. However, photocatalytic CO2 reduction systems face hurdles in practical utilization for the low efficiency of photocatalysts and challenge in catalyst immobilization. Therefore, a novel monolithic three-dimensional Z-scheme photocatalyst was synthesized by fabricating Bi2WO6/g-C3N4 heterojunction on Cu foam substrate (Bi2WO6/g-C3N4/Cu foam) via thermal polymerization and electrophoresis deposition. A series of characterization results, including X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and N2 adsorption–desorption, illustrate the crystalline properties, pore structure, and morphology of the composite photocatalyst. Consequently, Bi2WO6/g-C3N4/Cu foam achieved CO production yield of 33.84 μmol/g cat under visible light illumination for 6 h and retained 96.2 % of initial photocatalytic activity after 30 h of reaction. UV–Vis diffuse reflection spectra, photoluminescence spectra and photoelectrochemical analysis was involved to reveal the mechanism of the photocatalytic activity of composite photocatalyst.The synergistic effect of the Z-scheme mechanism and the hierarchical macroporous structure improves the light absorption, light-induced electron-hole pair separation, and charge transmission. This catalyst construction strategy provides a viable approach for facilitating practical photocatalytic CO2 reduction.

Construction of Bi2O3−x/NiAl-LDH S-scheme heterojunction for boosting photothermal-assisted photocatalytic CO2 reduction

In this study, a new type of 2D/2D Bi2O3−x/NiAl-LDH (BO/NA-LDH) S-scheme photocatalyst was prepared by combining NiAl-LDH with Bi2O3−x by wet chemical deposition for obtaining efficient photothermal-assisted photocatalytic reduction of CO2 under simulated sunlight irradiation. In particular, the as-prepared optimal 50-BO/NA-LDH sample exhibited the CO production yield of 83.55 ± 2.76 μmol/g/h, which was 9 and 27 times that of BO (9.32 ± 0.62 μmol/g/h) and NA-LDH (3.09 ± 0.38 μmol/g/h), respectively. The enhancement of photothermal-assisted activity over the 50-BO/NA-LDH system was mainly attributed to the coupling of the photothermal conversion performance of Bi2O3−x and improving the migration efficiency of interface carriers of S-scheme heterojunction and 2D/2D structure. This study presents a promising strategy for the development of high-efficient photothermal-assisted photocatalysts.

Efficient Photoreduction of CO2 to CO with 100% Selectivity by Slowing Down Electron Transport.

It remains challenging to obtain a single product in the gas-solid photocatalytic reduction of CO2 because CO and CH4 are usually produced simultaneously. This study presents the design of the I-type nested heterojunction TiO2/BiVO4 with controllable electron transport by modulating the TiO2 component. This study demonstrates that slowing electron transport could enable TiO2/BiVO4-4 to generate CO with 100% selectivity. In addition, modifying TiO2/BiVO4-4 by loading a Cu single atom further increased the CO product yield by 3.83 times (17.33 μmol·gcat-1·h-1), while maintaining 100% selectivity for CO. Characterization and density functional theory (DFT) calculations revealed that the selectivity was mainly determined by the electron transport of the support, whereas CO2 was efficiently adsorbed and activated by the Cu single atom. Such a two-step regulation strategy of combining heterojunction with single atom enhances the possibility of simultaneously obtaining high selectivity and high yield in the photocatalytic reduction of CO2.

Exploring the Mechanism of the Electrochemical Polymerization of CO2 over CeO2(110)

The reduction of CO2 is a promising route for the synthesis of renewable energy carriers and the removal of CO2 from the atmosphere to limit global warming. These negative emission technologies (NETs) require the conversion of carbon dioxide into a stable and easily storable form[1]. However, despite its potential, the development of suitable CO2 reduction catalysts is still in its infancy. Indeed state of the art catalysts suffer from high overpotentials, a low selectivity between possible products and a generally low yield of post CO products with two or more carbon atoms. Catalysts which even allow for the electrochemical polymerization of CO2 and thus, the direct formation of hard carbon were completely absent until the work of Esrafilzadeh et al.[2]. Using a liquid electrocatalyst consisting of Ga, In, Sn and Ce in a n,n-dimethylformamide (DMF) electrolyte they were able to polymerize CO2 electrochemically to a carbonaceous material. They hypothesized that the active catalyst consists of a cerium oxide which is reduced to metallic Ce in the process. However, no direct proof for this hypothesis was provided. Also a possible mechanism which could lead to the reported products is so far unknown.In this contribution we will explore the reaction mechanisms for the electrochemical polymerization of CO2 using density functional theory (DFT) modelling. In the initial step, the most likely active sites at Ce oxide are identified. This is then followed by a detailed analysis of the reaction route which is based on well known mechanisms in organic chemistry. We find that an oxygen defect rich CeO2(110) surface is most likely present under reaction conditions. [3] The reaction over this surface is initialized at oxygen defect sites. Chain propagation is then achieved through an electrochemical aldol condensation type mechanism (Figure 1). [3] References 1 J. Hilaire, J. C. Minx et al., Climatic Change, 2019, 157, 189.2 D. Esrafilzadeh, A. Zavabeti et al., Nature. Commun., 2019, 10, 865.3 F. Keller, J. Döhn, A. Groß, M. Busch, in preparation. Figure 1

Power-to-liquid versus biomass-derived kerosene: a comparative study

Power-to-Liquid (PtL) kerosene is considered by many experts as the only viable option to achieve a large scale decarbonization of the aviation sector in the near-medium term. In the PtL process carbon dioxide of renewable origin or from ambient air and green hydrogen are combined to produce a liquid fuel that can replace fossil kerosene. For this purpose the Fischer-Tropsch pathway and the methanol pathway are available. On the other hand, more production pathways are available when using a biomass feedstock. The aim of this work is to compare the power and biogenic routes for the production of sustainable kerosene in terms of performance and requirements. Indeed, there is a lack of studies in the literature that directly compare the two options, i.e. biofuels and e-fuels, on a common basis. Accordingly, simulation models are built in this work for both routes to calculate the yield of kerosene and co-products, the hydrogen demand, the flows of carbon dioxide, the electricity and thermal energy demands. The simulation outputs are compared against the results of the relevant studies in the literature. The expectation from this comparative study is to highlight the criticalities of each route and, possibly, any opportunity to overcome them by exploring any synergy between the different routes.

Mesoporous α‑Fe2O3 nanostructures decorated with perovskite Cs3Bi2Br9 quantum dots as an S-scheme photocatalyst for efficient charge transfer and CO2 conversion

In view of the greenhouse effect caused by excessive CO2 emission in the atmosphere, the efficient capture and conversion of CO2 to chemical feedstock is imminent. Herein, a novel Cs3Bi2Br9/α‑Fe2O3 (CBB/α‑Fe2O3) composite was constructed by decorating lead-free perovskite Cs3Bi2Br9 quantum dots (QDs) on the pores of mesoporous α‑Fe2O3 nanostructures. The developed CBB/α‑Fe2O3 composite possesses bifunctional advantages for both the efficient capture and conversion of CO2, with a CO production yield of 84.12 μmol g−1h−1 for the optimized sample. Experimental results and theoretical predictions indicate that the electrons transfer via an S-scheme route in the CBB/α‑Fe2O3 composite, which not only boosts the charge separation but also retains the strong reduction ability of Cs3Bi2Br9. By combination of in-situ diffuse reflectance infrared Fourier transform spectra (DRIFTS) with theoretical calculations, the mechanism of the photocatalytic CO2 reduction over the CBB/α‑Fe2O3 composite was explored in depth. This study opens a new avenue for the exploitation of photocatalysts with high CO2 capture ability and conversion efficiency.

Steam Explosion of Eucalyptus grandis Sawdust for Ethanol Production within a Biorefinery Approach

In this work, Eucalyptus grandis sawdust was subjected to steam explosion as the first step in cellulosic ethanol production within a biorefinery approach. The effect of the moisture content in the eucalypt sawdust (8 and 50%) and pretreatment process variables, such as temperature and residence time, were evaluated along with the influence of the water washing of steam-exploded solids on enzymatic hydrolysis and C6 fermentation yields. All other process streams were characterized to evaluate the recovery yield of valuable co-products. A recovery of nearly 100% glucans in the solid fraction and 60% xylans in the liquid fraction, mainly as partially acetylated oligomers, was obtained. The best enzymatic hydrolysis efficiencies (66–67%) were achieved after pretreatment at 205 °C for 10 min. The washing of pretreated sawdust with water improved the hydrolysis efficiencies and ethanol production yields by 10% compared to the unwashed pretreated solids under the same experimental condition. The highest ethanol yields were achieved after pretreatment of the sawdust with an 8% moisture content at 205 °C for 10 min, enzymatic hydrolysis at 13 wt% total solids with 25 FPU/g glucans, and fermentation with S. cerevisiae PE-2. In this case, 227 L ethanol and 40 kg total xylose (including xylo-oligomers) were obtained per ton of dry eucalypt sawdust.

Sub-Millisecond Laser-Irradiation-Mediated Surface Restructure Boosts the CO Production Yield of Cobalt Oxide Supported Pd Nanoparticles.

The catalytic conversion of CO2 into valuable commodities has the potential to balance ongoing energy and environmental issues. To this end, the reverse water-gas shift (RWGS) reaction is a key process that converts CO2 into CO for various industrial processes. However, the competitive CO2 methanation reaction severely limits the CO production yield; therefore, a highly CO-selective catalyst is needed. To address this issue, we have developed a bimetallic nanocatalyst comprising Pd nanoparticles on the cobalt oxide support (denoted as CoPd) via a wet chemical reduction method. Furthermore, the as-prepared CoPd nanocatalyst was exposed to sub-millisecond laser irradiation with per-pulse energies of 1 mJ (denoted as CoPd-1) and 10 mJ (denoted as CoPd-10) for a fixed duration of 10 s to optimize the catalytic activity and selectivity. For the optimum case, the CoPd-10 nanocatalyst exhibited the highest CO production yield of ∼1667 μmol g-1catalyst, with a CO selectivity of ∼88% at a temperature of 573 K, which is a 41% improvement over pristine CoPd (~976 μmol g-1catalyst). The in-depth analysis of structural characterizations along with gas chromatography (GC) and electrochemical analysis suggested that such a high catalytic activity and selectivity of the CoPd-10 nanocatalyst originated from the sub-millisecond laser-irradiation-assisted facile surface restructure of cobalt oxide supported Pd nanoparticles, where atomic CoOx species were observed in the defect sites of the Pd nanoparticles. Such an atomic manipulation led to the formation of heteroatomic reaction sites, where atomic CoOx species and adjacent Pd domains, respectively, promoted the CO2 activation and H2 splitting steps. In addition, the cobalt oxide support helped to donate electrons to Pd, thereby enhancing its ability of H2 splitting. These results provide a strong foundation to use sub-millisecond laser irradiation for catalytic applications.

Bio-oil and biochar from the pyrolytic conversion of biomass: A current and future perspective on the trade-off between economic, environmental, and technical indicators.

Over the years, the transformation of biomass into a plethora of renewable value-added products has been identified as a promising strategy to fulfil high energy demands, lower greenhouse gas emissions, and exploit under-utilized resources. Techno-economic analysis (TEA) and life-cycle assessment (LCA) are essential to scale up this process while lowering the conversion cost. In this study, trade-offs are made between economic, environmental, and technical indicators produced from these methodologies to better evaluate the commercialization potential of biomass pyrolysis. This research emphasizes the necessity of combining LCA and TEA variables to assess the performance of the early-stage technology and associated constraints. The important findings based on the LCA analysis imply that most of the studies reported in literature focussed on the global warming potentials (GWP) under environmental category by considering greenhouse gases (GHGs) as evaluation parameter, neglecting many other important environmental indices. In addition, the upstream and downstream processes play an important role in understanding the life cycle impacts of a biomass based biorefinery. Under upstream conditions, the use of a specific type of feedstock may influence the LCA conclusions and technical priority. Under downstream conditions, the product utilization as fuels in different energy backgrounds is crucial to the overall impact potentials of the pyrolysis systems. In view of the TEA analysis, investigations towards maximizing the yield of valuable co-products would play an important role in the commercialization of pyrolysis process. However, comprehensive research to compare the conventional, advanced, and emerging approaches of biomass pyrolysis from the economic perspective is currently not available in the literature.

Surface anchored atomic cobalt-oxide species coupled with oxygen vacancies boost the CO-production yield of Pd nanoparticles

The high density of oxygen vacancies and adjacent Pd domains promote CO2 activation and H2 dissociation, respectively.

Life cycle water consumption of bio-oil fermentation for bio-ethanol production based on a distributed-centralized model

Life cycle water consumption of bio-ethanol production via bio-oil direct fermentation or indirect fermentation based on a distributed-centralized model was investigated. The life cycle water consumption results separately are 202 and 888 L water per GJ bio-ethanol for bio-oil indirect fermentation, and 206 and 2200 L water per GJ bio-ethanol for bio-oil direct fermentation when the economic value-based allocation method and the process purpose-based method are separately used. 32 different parameters related to material use, energy consumption, waste emission, and product yields were varied in a sensitivity analysis. The sensitivity analysis shows bio-ethanol yield and co-product yield have the greatest impact on the life cycle water consumption results. According to an uncertainty analysis, the maximum and minimum water consumption results separately are 1225 (the process purpose-based method) and 156 L water per GJ bio-ethanol (the economic value-based allocation method) for bio-oil indirect fermentation. A contribution analysis shows that the distributed-centralized model can really contribute to a slight reduction in water consumption in comparison with the non-distributed model. Overall, bio-ethanol production via bio-oil indirect fermentation based on the distributed-centralized model is green and clean from the standpoint of water resource consumption.

CsPbBr3 perovskite based tandem device for CO2 photoreduction

The design of efficient photocatalytic devices is of great significance to achieve low-cost carbon dioxide reduction into solar fuels. Herein, directional charge-carrier migration is realized by introducing a CO2 reduction device with a tandem structure made up of g-C3N4 and an inorganic lead-perovskite (CsPbBr3). This photocatalytic device shows a significantly increased CO2 photoreduction rate in a humid gaseous CO2 system when compared to the parental g-C3N4 layer. This “full artificial photosynthesis” thereby generates fuel molecules and oxygen from water and CO2, only, without any co-catalysts or sacrificial agents. To our surprise, the device maintains greater than 90% of the CO production yield after 5 days continuous irradiation. The existence of internal electric field is confirmed, which drive the directional movement of photogenerated charge-carriers with the perovskite being reductive, while the carbon nitride with its enormous oxidation stability is covering the oxidation processes. This represents a promising possibility for the practical application of CO2 photoreduction with scalable devices.

Oxygen vacancy engineering of BiOBr/HNb3O8 Z-scheme hybrid photocatalyst for boosting photocatalytic conversion of CO2

Photo-chemical conversion of CO2 into solar fuels by photocatalysts is a promising and sustainable strategy in response to the ever-increasing environmental problems and imminent energy crisis. However, it is unavoidably impeded by the insufficient active site, undesirable inert charge transfer and fast recombination of photogenerated charge carriers on semiconductor photocatalysts. In this work, all these challenges are overcome by construction of a novel defect-engineered Z-scheme hybrid photocatalyst, which is comprised of three-dimensional (3D) BiOBr nanoflowers assembled by nanosheets with abundant oxygen vacancies (BiOBr-VO) and two-dimensional (2D) HNb3O8 nanosheets (HNb3O8 NS). The special 3D-2D architecture structure is beneficial to preventing photocatalyst stacking and providing more active sites, and the introduced oxygen vacancies not only broaden the light absorption range but also enhance the electrical conductivity. More importantly, the constructed Z-scheme photocatalytic system could accelerate the charge carriers transfer and separation. As a result, the optimal BiOBr-VO/HNb3O8 NS (50%-BiOBr-VO/HNb3O8 NS) shows a high CO production yield of 164.6 μmol·g−1 with the selectivity achieves to 98.7% in a mild gas-solid system using water as electron donors. Moreover, the BiOBr-VO/HNb3O8 NS photocatalyst keeps high photocatalytic activity after five cycles under the identical experimental conditions, demonstrating its excellent long-term durability. This work provided an original strategy to design a new hybrid structure photocatalyst involved VOs, thus guiding a new way to further enhance CO2 reduction activity of photocatalyst.

Saccharomyces cerevisiae Fermentation of 28 Barley and 12 Oat Cultivars

As barley and oat production have recently increased in Canada, it has become prudent to investigate these cereal crops as potential feedstocks for alcoholic fermentation. Ethanol and other coproduct yields can vary substantially among fermented feedstocks, which currently consist primarily of wheat and corn. In this study, the liquified mash of milled grains from 28 barley (hulled and hull-less) and 12 oat cultivars were fermented with Saccharomyces cerevisiae to determine concentrations of fermentation products (ethanol, isopropanol, acetic acid, lactic acid, succinic acid, α-glycerylphosphorylcholine (α-GPC), and glycerol). On average, the fermentation of barley produced significantly higher amounts of ethanol, isopropanol, acetic acid, succinic acid, α-GPC, and glycerol than that of oats. The best performing barley cultivars were able to produce up to 78.48 g/L (CDC Clear) ethanol and 1.81 g/L α-GPC (CDC Cowboy). Furthermore, the presence of milled hulls did not impact ethanol yield amongst barley cultivars. Due to its superior ethanol yield compared to oats, barley is a suitable feedstock for ethanol production. In addition, the accumulation of α-GPC could add considerable value to the fermentation of these cereal crops.

Influence of organic cocoa agroforestry on soil physico-chemical properties and crop yields of smallholders’ cocoa farms, Ghana

AbstractThe success of sustainable Theobroma cacao (cocoa) production depends on the physical and chemical properties of the soils on which they are established but these are possibly moderated by the management approach that farmers adopt. We assessed and compared soil physico-chemical properties of young, mature and old organic and conventional cocoa agroforestry systems at two depths (0–15 and 15–30 cm) and evaluated the production of cocoa pods, banana and plantain in the two farm types. Cocoa farms under organic management had 20, 81, 88 and 323% higher stocks of soil organic carbon, P, Mn and Cu, respectively, compared to those under conventional management. Higher soil moisture content, electrical conductivity and pH were found on organic systems than the conventional farms. Annual cocoa pod production per tree was similar in both cocoa systems (Org. 10.1 ± 1.1 vs Con. 10.1 ± 0.6 pods per tree). The annual production of banana and plantain was higher on organic farms (186.3 ± 34.70 kg ha−1 yr−1) than conventional systems (31.6 ± 9.58 kg ha−1 yr−1). We concluded that organic management of cocoa agroforestry systems result in soils with the greater overall quality for cocoa production than conventional management and it increases the yield of co-products. Studies focusing on the impact of organic management on cocoa agroforestry systems at the landscape and regional scales are urgently needed to further deepen our understanding and support policy.

Effect of “Magnetized Water” on Size of Nickel Oxide Nanoparticles and their Catalytic Properties in Co2 Reforming of Methane

It was shown that the particle size of NiO nanoparticles has been controlled through the homogeneous precipitation process by using “magnetized water” which, according to the authors, is due to a change in the surface tension and viscosity of water under the influence of a magnetic field. The textural properties, shape, recovery behavior, and size distribution of NiO nanoparticles were determined using BET, XRD, TPR, and TEM methods. The effect of NiO particle size on the catalytic reaction of carbon dioxide reforming of methane into synthesis gas was studied. The CO2 and CH4 conversions and the yield of CO and H2 products possess higher values for the treated NiO sample.

Coupling CO2 separation with catalytic reverse water-gas shift reaction via ceramic-carbonate dual-phase membrane reactor

Coupling of CO2 separation and CO2 utilization in membrane reactor is an ideal way to solve CO2 emission problem. In this study, we report an effective catalytic reverse water-gas shift (RWGS) process to produce CO with simultaneous CO2 capture from CO2-containing gas mixture using a ceramic-carbonate dual-phase membrane in a single reactor. The dual-phase membrane is comprised of a ceramic phase of oxygen-ion conductor and molten carbonate phase. The catalytic bed contains a LaNiO3 (LNO) or La0.9Ce0.1NiO3-δ (LCNO) catalyst. The RWGS reaction process can be catalytically activated by a single membrane without additional catalyst. CO2 permeation flux of the separation process and CO2 conversion of the RWGS reaction display significant increase after packing with catalysts in the membrane reactor. The results show that the reactor with LCNO catalyst generally precedes the LNO counterpart in CO2 conversion rate and the CO production yield. The membrane reactor yields a CO2 flux of 4.25 ml min−1 cm−2, which is around 4 times higher than that of the single membrane separation with pure He sweep gas. A CO2 conversion of 56.8% and a CO production rate of 2.41 ml min−1 cm−2 can be obtained at 750 °C using the membrane reactor with LCNO catalyst. Long-term stability test shows no obvious sign of degradation within 70 h. Overall, this work presents the technical exploration of a combined CO2 capture and conversion membrane-reactor for RWGS reaction process.