Water Gas Shift Research Articles

Thermodynamic Analysis of the Steam Reforming of Acetone by Gibbs Free Energy (GFE) Minimization

Steam reforming is an important industrial process for hydrogen production. Acetone, the by-product of phenol production from cumene peroxidation, is a useful source of hydrogen due to its availability and low value compared to hydrogen fuel. This study aimed to utilize the Gibbs free energy minimization method using the Soave–Redlich–Kwong (SRK) equation of state (EOS) to conduct a thermodynamic analysis of the steam reforming process for pure component acetone. The steam reforming process is temperature dependent, with increasing temperatures leading to higher hydrogen production. Competing reactions, particularly the exothermic reverse water–gas shift, impact hydrogen yields beyond 650 °C. The study identified 600 °C as the optimum temperature to strike a balance between maximizing hydrogen production and minimizing the reverse water–gas shift’s impact. The optimal hydrogen yield (70 mol%) was achieved at a steam-to-oil ratio (STOR) of 12. High STOR values shift the equilibrium of the water–gas shift reaction towards hydrogen production due to increased steam, effectively consuming acetone and favoring the desired product. Atmospheric pressure is optimum for hydrogen production because the equilibrium of gas phase reactions shifts in favor of the lighter components at lower pressures.

Maximizing H2 Production from a Combination of Catalytic Partial Oxidation of CH4 and Water Gas Shift Reaction

A single-bed and dual-bed catalyst system was studied to maximize H2 production from the combination of partial oxidation of CH4 and water gas shift reaction. In addition, the different types of catalysts, including Ni, Cu, Ni-Re, and Cu-Re supported on gadolinium-doped ceria (GDC) were investigated under different operating conditions of temperature (400–650 °C). Over Ni-based catalysts, methane can easily dissociate on a Ni surface to give hydrogen and carbon species. Then, carbon species react with lattice oxygen of ceria-based material to form CO. The addition of Re to Ni/GDC enhances CH4 dissociation on the Ni surface and increases oxygen storage capacity in the catalyst, thus promoting carbon elimination. In addition, the results showed that a dual-bed catalyst system exhibited catalytic activity better than a single-bed catalyst system. The dual-bed catalyst system, by the combination of 1%Re4%Ni/GDC as a partial oxidation catalyst and 1%Re4%Cu/GDC as a water gas shift catalyst, provided the highest CH4 conversion and H2 yield. An addition of Re onto Ni/GDC and Cu/GDC caused an increase in catalytic performance because Re addition could improve the catalyst reducibility and increase metal surface area, as more of their surface active sites are exposed to reactants.

Batch and semi-continuous fermentation with Parageobacillus thermoglucosidasius DSM 6285 for H2 production

BackgroundParageobacillus thermoglucosidasius is a facultatively anaerobic thermophile that is able to produce hydrogen (H2) gas from the oxidation of carbon monoxide through the water–gas shift reaction when grown under anaerobic conditions. The water–gas shift (WGS) reaction is driven by a carbon monoxide dehydrogenase–hydrogenase enzyme complex. Previous experiments exploring hydrogenogenesis with P. thermoglucosidasius have relied on batch fermentations comprising defined media compositions and gas atmospheres. This study evaluated the effects of a semi-continuous feeding strategy on hydrogenogenesis.ResultsA batch and two semi-continuous fermentations, with feeding of the latter fresh media (with glucose) in either 24 h or 48 h intervals were undertaken and H2 production, carbon monoxide dehydrogenase (CODH) activity, and metabolite consumption/production were monitored throughout. Maximum H2 production rates (HPR) of 0.14 and 0.3 mmol min−1, were observed for the batch and the semi-continuous fermentations, respectively. Daily feeding attained stable H2 production for 7 days, while feeding every 48 h resulted in high variations in H2 production. CODH enzyme activity correlated with H2 production, with a maximum of 1651 U mL−1 on day 14 with the 48 h feeding strategy, while CODH activity remained relatively constant throughout the fermentation process with the 24 h feeding strategy.ConclusionsThe results emphasize the significance of a semi-continuous glucose-containing feed for attaining stable hydrogen production with P. thermoglucosidasius. The semi-continuous fermentations achieved a 46% higher HPR than the batch fermentation. The higher HPRs achieved with both semi-continuous fermentations imply that this approach could enhance the biohydrogen platform. However, optimizing the feeding interval is pivotal to ensuring stable hydrogen production.

Repurposing E-Waste Cathodes as Catalysts for CO2 Reduction via Reverse Water-Gas Shift Reaction

Reverse water-gas shift (RWGS) reaction offers a promising pathway for utilising green H2 to reduce CO2 into CO, a valuable precursor for e-fuel production. Conventional catalyst synthesis methods, however, often...

Mechanism and catalytic activity of the water-gas shift reaction on a single-atom alloy Al1/Cu (111) surface.

The mechanism and activity of the water-gas shift reaction (WGSR) on single-atom alloy Al1/Cu (111) and Cu (111) surfaces were studied using GGA-PBE-D3. Al1/Cu (111) exhibited bifunctional active sites, with the Al site being positively charged and the Cu site negatively charged due to electronic interactions. This led to selective adsorption of H2O and CO. Al1/Cu (111) promoted H2O adsorption and dissociation, reducing the energy barrier to 0.67 eV compared with 1.13 eV on the Cu (111) surface. Meanwhile, Cu served as the active site for H2 formation, which is the rate-determining step, with an energy barrier of 0.95 eV. The Al-O and Cu-C bonds cooperatively increased the interaction strength of O-containing intermediates. Al1/Cu (111) promoted the whole WGSR through cooperativity, reducing the overall apparent activation energy. This work gives insights for the design of single atom alloy (SAA) catalysts with p-p orbital energy level matching, which facilitates orbital interactions between Al and H2O, thus achieving excellent WGSR activity.

Visible light enhanced thermocatalytic reverse water gas shift reaction via localized surface plasmon resonance of copper nanoparticles

Visible light enhanced thermocatalytic reverse water gas shift reaction via localized surface plasmon resonance of copper nanoparticles

The influence of size, metal loading and oxygen vacancies on the catalytic performance of Au/CeO2−x in the sunlight-powered reverse water gas shift reaction

This study reports the conversion of CO2 and H2 to CO and H2O at low temperature and low pressure (up to 203 °C, p = 3.5 bar) using plasmonic Au/CeO2−x photocatalysts, with mildly concentrated sunlight as the sole energy source (up to 9 kW m−2).

High pressure microreactor for minute amounts of catalyst on planar supports: A case study of CO2 hydrogenation over Pd0.25Zn0.75Ox nanoclusters

High-pressure studies of well-defined catalysts, deposited on planar supports in ultra-high vacuum using physical methods, may bridge the gap between surface science and applied catalysis approaches in order to develop better catalysts for crucial reactions such as CO2 hydrogenation. However, the chemical reactors necessary for such investigations, typically involving catalyst quantities down to a few hundred nanograms, are lacking.We present the novel design and evaluation of a 50 µL rectangular microchannel reactor capable of testing small quantities of catalyst at pressures up to 40 bar and temperatures up to 240 °C. To evaluate the microreactor performance, Pd0.25Zn0.75Ox nanoclusters soft-landed on SiO2-coated mica sheets using the cluster beam deposition technique, were tested for CO2 hydrogenation via the reverse water–gas shift reaction through a series of kinetic experiments.Experimental results, combined with computational fluid dynamics and mass transport analysis, demonstrate that the proposed microreactor setup allows for testing minute quantities of catalysts with very high sensitivity at industrially relevant temperatures and pressures. Although not restricted to a particular catalyst preparation method, the setup is an excellent platform for conducting catalytic tests on composition-controlled, mass-selected, gas-phase nanoparticles deposited on planar substrates, facilitating the determination of reliable structure–activity relationships and enabling a more rational design of catalysts.

The catalytic mechanism for H2 production on MgO-CaO materials through the water gas shift reaction: A DFT study

The catalytic mechanism for H2 production on MgO-CaO materials through the water gas shift reaction: A DFT study

Highly dispersed copper-based nanocomposite synthesis via spray pyrolysis: towards waste-to-hydrogen production through the water-gas shift reaction

In this study, we synthesized a Cu–ZrCeO2 catalyst using spray pyrolysis, which exhibited high activity, stability, and reusability at high temperatures.

HIDRÓXIDOS DUPLOS LAMELARES EM PROCESSOS CATALÍTICOS PARA A QUÍMICA FINA, DEGRADAÇÃO DE POLUENTES E GERAÇÃO DE ENERGIA LIMPA: UMA BREVE REVISÃO

LAYERED DOUBLE HYDROXIDES IN CATALYTIC PROCESSES FOR FINE CHEMISTRY, POLLUTANT DEGRADATION AND CLEAN ENERGY GENERATION: A BRIEF REVIEW. Layered double hydroxides (LDHs) and related materials have been studied for a long time and their application in catalytic processes remain attractive due to the tuned properties, morphologies and metal-support interactions obtained from a variety of composition and synthesis route. In this mini-review, some important reactions, such as photocatalysis, electrocatalysis, reduction, carbon-carbon cross-couplings and water-gas shift will be emphasized along with the role of LDHs as catalysts, co-catalysts or catalytic precursors when it was clearly indicated.

Noble-metal like catalysts of carbide and nitride for low-temperature water gas shift reaction: A review

Noble-metal like catalysts of carbide and nitride for low-temperature water gas shift reaction: A review

Enhanced H2 recovery by coupling the water–gas shift reaction with in situ CO2 capture and mineralization using earth abundant Ca- and Mg-silicates and hydroxides

Decarbonization of clean energy carriers such as H2 by integrating multiphase chemical pathways with inherent carbon mineralization is a thermodynamically downhill approach designed for a sustainable energy and environmental future.

Assessment of Iron(III) chloride as a catalyst for the production of hydrogen from the supercritical water gasification of microalgae

Alkali metal salts and supported transition metals have been the dominant catalysts used to maximise hydrogen production from supercritical water gasification (SCWG). Recently, FeCl3 has emerged as an alternative to these that has been found to be more effective in some cases reported in literature. However, to these authors’ knowledge, few studies exist that study this catalyst with none that involve microalgae as the feedstock. Investigation is reported into the effect of FeCl3 on the SCWG of Chlorella vulgaris for a range of temperatures (400–600°C) and biomass concentrations (1–3wt%), with comparisons made to other catalysts (KOH, Ru/C and their combinations). A significant decrease in hydrogen yield, carbon conversion and energy efficiency was observed with the addition of FeCl3, due to a reduced pH which suppressed the water gas shift reaction and catalysed of char forming reactions. This was in contrary to Ru/C and KOH catalysts, where those outcomes increased. Additionally, when FeCl3 was used with Ru/C, the ruthenium was poisoned, nullifying its positive effects. Consequently, FeCl3 is not a suitable catalyst for hydrogen production from microalgae, either alone or in conjunction with a ruthenium catalyst.

Research progress on mechanism and catalysts for reverse water-gas shift reaction

Research progress on mechanism and catalysts for reverse water-gas shift reaction

CO2 conversion to CO by reverse water gas shift and dry reforming using chemical looping

Chemical looping technology provides an efficient means of sustainable CO2 conversion to the important chemical intermediate of CO or syngas by changing conventional co-feeding of reactant into alternating feeding. It...

Role of SiO2 in enhancing CO yield by using silica-supported La0.5Ba0.5FeO3 in reverse water–gas shift chemical looping

Perovskite oxides facilitate CO2 conversion by reverse water–gas shift chemical looping at moderate conditions by employing an oxygen vacancy at the surface to aid CO2 adsorption and then to scavenge an oxygen atom from it to fill the vacancy.

Identifying the ideal thermodynamics of non-stoichiometric oxygen-carrier materials for chemical looping water-gas shift

As temperature and heat content matching is important in heat exchange, chemical potential and capacity matching is key to chemical looping processes.

Theoretical Study on Copper Adsorption on Zinc Oxide Surfaces

The study of copper on zinc oxide surfaces is a topic of ongoing research due to the importance of copper as a promoter in the low-temperature synthesis of methanol, the water-gas shift process and methanol steam reforming. The role of zinc oxide in supporting the stabilisation of the copper atoms and promoting the CO2 hydrogenation reaction is multifaceted and involves a range of physical and chemical factors. In this work, we used density functional theory (DFT) calculations to investigate the copper adsorption on zinc oxide surfaces on different sites. Bader charge analysis, adsorption energy and phonon inelastic neutron scattering (INS) associated with most stable systems were calculated and compared with previous theoretical and experimental results. We found that atomic copper adsorption on hollow site of ZnO(111) is the most stable and favourable site for copper adsorption compared to other zinc oxide surfaces. This is due to the strong metal-oxygen interaction between copper and the zinc oxide surface. We concluded that further studies are needed to investigate the catalytic activity of this catalyst under realistic reaction conditions with realistic models of copper supported on zinc oxide.

Engineering Lattice Dislocations of TiO2 Support of PdZn-ZnO Dual-Site Catalysts to Boost CO2 Hydrogenation to Methanol.

CO2 hydrogenation to methanol using green hydrogen derived from renewable resources provides a promising method for sustainable carbon cycle but suffers from high selectivity towards byproduct CO. Here, we develop an efficient PdZn-ZnO/TiO2 catalyst by engineering lattice dislocation structures of TiO2 support. We discover that this modification orders irregularly arranged atoms in TiO2 to stabilize crystal lattice, and consequently weakens electronic interactions with supported active phases. It facilitates the transformation of metallic Pd into PdZn alloy, effectively suppressing CO production through inhibiting the reverse water-gas shift reaction mediated by the carboxylate pathway on Pd0 sites. Moreover, it enables the efficient transfer of hydrogen species via hydrogen spillover from PdZn alloy to ZnO for compensating the poor hydrogen dissociation ability of ZnO, thereby creating both more oxygen vacancies essential for CO2 activation and a hydroxyl-rich environment conducive to hydrogenation of intermediates. These collective modifications on PdZn-ZnO dual sites synergistically induce the propensity of the formate pathway for methanol synthesis. Consequently, compared to the unmodified catalyst, our as-designed catalyst increases methanol selectivity from 64.2 to 80.0 %, reduces CO selectivity from 35.0 to 19.8 %, and achieves an impressive methanol space-time yield of 9028.0 mgMeOH gPd+Zn -1 h-1 at a similar CO2 conversion (~8.0 %).