Formation Of CH Research Articles

Optimizing the content of Li2CO3, Na2SO4 and TEA in fly ash–cement system by response surface methodology

With an optimized dosage, hardening accelerators become a vital means of modifying fly ash-cement system (FAC). This study comprehensively investigated the mechanical properties of FAC modified by Li2CO3, Na2SO4, and triethanolamine (TEA) under different dosages, and optimized the dosage of accelerators through the response surface method (RSM). The synergistic effect of accelerators on the hydration of FAC was characterized by thermogravimetric differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results demonstrated that the factors and response value followed a quadratic polynomial model. The regression coefficients R2 of the model were all greater than 0.9, indicating good agreement with the experimental data. The content of Li2CO3 and Na2SO4 had an extremely significant effect on the compressive strength of 1d and 3d, followed by TEA. The optimal mix ratio predicted by RSM was 0.12% Li2CO3, 0.47% Na2SO4, and 0.40% TEA. Early hydration stages revealed that the combined action of these accelerators increased the formation of CH, CaCO3, and amorphous C-(A)-S-H gel. Microscopically, the surface of fly ash exhibited alkali-induced corrosion, thereby enhancing its pozzolanic reactivity.

Intrinsic reactivity of stoichiometric IrO2(1 1 0) surface toward oxidative coupling of methane

This study investigates the oxidative coupling of methane on the IrO2(110) surface using TPRS simulations informed by DFT-derived data. We discover that the efficiency of the IrO2(110) surface in generating ethylene is strongly influenced by methane surface coverage. Our simulations reveal that the presence of surface hydroxyl group enhances the yield of C2+ species from methane oxidation, but this effect is counteracted at high methane coverages due to the accelerated formation of CH2OH. In addition, the study reveals that slight modifications in energy barriers at the branching point (C2H4 formation vs. CH2OH formation) significantly affect C2H4(g) production from the simulation, underscoring the importance of precise energetic data for accurate catalytic reaction predictions. The results have broader implications for reactions and catalysts where branching point selectivity determines high-value product yields. Thus, combining surface science with computational analysis is crucial for accurately determining energy profiles of key steps at the branching points.

Sulfur-vacancy induced asymmetric active site for Bi19S27Br3 nanorods photocatalyzes CO2 conversion to ethylene

The photocatalytic conversion of CO2 into high value-added C2 products remains a significant challenge due to the limited active sites and high energy barrier of C-C coupling process. Herein, the sulfur-vacancy was established on the surface of Bi19S27Br3 nanorods, leading to the electron on residual S atoms become unstable and active. Under the light irradiation, the photoexcited electron transfer from S atoms to neighboring Bi atoms to generate in-situ charge-polarized Bi(3-x)+ asymmetric active sites, which can enhance CO2 adsorption-activation capacity and regulate C-C coupling process for the C1 intermediate. The experimental results and theoretical calculation confirm that more charges aggregate around the induced Bi atoms, reducing the energy barrier of the C-C coupling reaction and improving C2H4 formation. Consequently, the sulfur-vacancy Bi19S27Br3 nanorods achieve efficient C2H4 generation through photocatalytic CO2 reduction, which C2H4 formation rate is 17.80 µmol g−1 after 5-hour photocatalytic reaction, with the product selectivity and electron selectivity of 49 % and 85 %, respectively, outperforming the low sulfur-vacancy Bi19S27Br3 nanorods by four-folds. This research provides new insights into the design of photocatalysts.

Effect of CeO2 morphology and Ru impregnation method on CH4 selectivity reduction in polyethylene waste conversion to liquid fuels and lubricants

Hydrogenolysis of polyolefins offers a sustainable pathway by giving plastic waste a second life as valuable resources, transforming it into fuels and lubricants. Supported Ru catalysts have shown potential for depolymerizing polyolefins under mild conditions; however, depolymerization via terminal C-C bond cleavage can lead to the excessive formation of CH4. This study investigated the effects of CeO2 morphology and Ru impregnation method on the suppression of CH4 formation and increasing liquid and wax proportions (C5-C41) in the production of liquid fuels and lubricants through polyethylene hydrogenolysis. Controlling the morphology of CeO2 and impregnating Ru via electrostatic adsorption can enhance the formation of oxygen vacancies and strengthen the interaction between Ru and CeO2. The presence of defects in CeO2 also correlated with smaller particle size of Ru and a higher hydrogen reservoir site, which effectively suppress CH4 formation.

Anionic Ionomer: Released Surface-Immobilized Cations and an Established Hydrophobic Microenvironment for Efficient and Durable CO2-to-Ethylene Electrosynthesis at High Current over One Month.

Electrosynthesis of multicarbon products, such as C2H4, from CO2 reduction on copper (Cu) catalysts holds promise for achieving carbon neutrality. However, maintaining a steady high current-level C2H4 electrosynthesis still encounters challenges, arising from unstable alkalinity and carbonate precipitation caused by undesired ion migration at the cathode under a repulsive electric field. To address these issues, we propose a universal "charge release" concept by incorporating tiny amounts of an oppositely charged anionic ionomer (e.g., perfluorinated sulfonic acid, PFSA) into a cationic covalent organic framework on the Cu surface (cCOF/PFSA). This strategy effectively releases the hidden positive charge within the cCOF, enhancing surface immobilization of cations to impede both outward migration of generated OH- and inward migration of cations, inhibiting carbonate precipitation and creating a strong alkaline microenvironment. Meanwhile, the ionomer's hydrophobic chains create a hydrophobic environment within the cCOF, facilitating efficient gas transport. In situ characterizations and theoretical calculations demonstrate that the cCOF/PFSA catalyst establishes a hydrophobic strong alkaline microenvironment, optimizing the adsorption strength and configuration of *CO intermediates to promote the C2H4 formation. The optimized catalyst achieves a 70.5% Faradaic efficiency for C2H4 with a partial current density over 470 mA cm-2. Notably, it delivers a high single-pass carbon efficiency of 96.5% for CO2RR and sustains an exceptional stability over 760 h. When implemented in a large-area MEA electrolyzer and a 5-cell MEA stack, the system achieves an industrial current of 15 A and continuous C2H4 production exceeding 19 mL min-1, marking a significant step toward industrial feasibility in CO2RR-to-C2H4 conversion.

Evaluating diffusivity for efficient electrocatalytic conversion of carbon dioxide into multicarbon products using dealloyed hierarchically nanoporous copper

Hierarchical nanoporous copper (Hi-NPC) is a promising catalyst for carbon dioxide reduction reaction (CO2RR) due to its high surface area and excellent mass transport properties. To evaluate the effect of its architecture, eutectic-phased Cu18Al82 and single-phased Cu33Al67 were potentiostatically dealloyed to produce Hi-NPC and homogeneous nanoporous copper (Ho-NPC), respectively. At a comparable overpotential, the Hi-NPC electrocatalyst exhibited a significantly higher C2+ partial current density (jC2+) in CO2RR, reaching 510 mA/cm2, compared to both Ho-NPC (72 mA/cm2) and Cu electrodes (23 mA/cm2). When the current density was normalized by the electrochemically active surface area, the CO production among three electrodes demonstrated similar electrochemical behavior. However, notable differences were observed in the formation of C2H4 and C2H5OH, which can be attributed to the hierarchical structure of Hi-NPC facilitating C–C coupling to form C2 products. Although the Tafel plot indicated the CO2RR kinetics were identical for all three electrodes, linear sweep voltammetry experiments revealed that Hi-NPC exhibited the steepest current variation slope. Furthermore, the improved diffusivity was further confirmed by conducting oxygen reduction reactions with varying partial O2/N2 flow rates and electrochemical impedance spectroscopies. The hydrophobic properties of the electrode under various CO2RR current densities were also evaluated by water contact angle test.

A C-modified engineering strategy of porous In2O3 catalysts for point-concentrated solar-driven photothermal CO2 hydrogenation

The solar-driven photothermal CO2 conversion serves as an effective approach for addressing the substantial challenges of energy crises and global environmental issues. In this work, various forms of In2O3 catalysts, including In2O3-c, In2O3-r, In2O3-s, and porous spherical In2O3, along with a C-modified porous spherical In2O3 catalyst (C-In2O3), were successfully synthesized through a hydrothermal method. An in-depth analysis was conducted to evaluate the performance of these catalysts in the point-concentrated solar-driven photothermal CO2 hydrogenation. As a result, the porous C-In2O3 catalyst exhibited a superior CO2 conversion rate of approximately 13.2 % under simulated sunlight irradiation, with a light intensity of 44.6 mW/cm2. Notably, all catalysts demonstrated nearly 100 % selectivity towards CO (CO production rate of around 8.51 mmol gcat−1h−1) during the photothermal catalytic reaction, without any formation of CH4. The outstanding performance of the C-In2O3 catalyst was attributed to the modification of In2O3 band structure by the incorporation of C, which significantly enhanced the intensive solar light absorption of the catalyst. Furthermore, incorporating C into In2O3 substantially augments its basic strength and significantly elevates the quantity of basic sites, thereby endowing it with outstanding CO2 adsorption and conversion capabilities. This work provides a C-modified engineering strategy to design efficient photothermal catalysts for boosting point-concentrated photothermal CO2 hydrogenation.

Amorphous Strategy and Doping Copper on Metal-Organic Framework Surface for Enhanced Photocatalytic CO2 Reduction to C2H4.

Amorphous photocatalysts are characterized by numerous grain boundaries and abundant unsaturated sites, which enhance reaction efficiency from both kinetic and thermodynamic perspectives. However, amorphization strategies have rarely been used for photocatalytic CO2 reduction. Doping copper onto a metal-organic framework (MOF) surface can regulate the electronic structure of photocatalysts, promote electron transfer from the MOF to Cu, and improve the separation efficiency of electron-hole pairs. In this study, an amorphous photocatalyst MOFw-p/Cu containing highly dispersed Cu (0, I, II) sites was designed and synthesized by introducing a regulator and in situ copper species during the nucleation process of MOF (UiO-66-NH2). Various characterizations confirmed that the Cu species were anchored to the organometallic skeleton of the surface amorphization MOF structure. The synergistic effect of Cu doping and surface amorphization in MOFw-p/Cu can significantly enhance the CO and CH4 yields while promoting the formation of the multicarbon product C2H4. The approach holds promise for developing novel, highly efficient MOFs as photocatalysts for CO2 photoreduction, enabling the production of high-value-added C2 products.

Macroscopic behavior and kinetic mechanism of ammonium dihydrogen phosphate for suppressing polyethylene dust deflagration

In this paper, the inhibition effect of ammonium dihydrogen phosphate (NH4H2PO4) on the deflagration of polyethylene dust (C100H202) is studied by combining experimental tests with reaction molecular dynamics simulation (ReaxFF MD). The mechanism by which NH4H2PO4 inhibits C100H202 deflagration is revealed at the microscopic level. The experimental results demonstrate that the inhibition effect of NH4H2PO4 on C100H202 deflagration is positively correlated with its concentration, and the addition of NH4H2PO4 equivalent to 50 % of the mass of C100H202 can completely suppress the deflagration. The apparent activation energies for the decomposition of C100H202 and C100H202/50 %NH4H2PO4 are calculated using ReaxFF MD to be 97.11 kJ/mol and 124.78 kJ/mol, respectively, which are in agreement with the results obtained from thermogravimetric tests. Furthermore, ReaxFF MD is employed to calculate the types and quantities of deflagration products and free radicals before and after the addition of NH4H2PO4. The results indicate that the number of the main intermediate C2H4 decreases with the increasing addition of NH4H2PO4. Based on this, the generation and consumption pathways of C2H4 are traced. It is found that phosphorous groups such as HOPO and PO2 scavenge active free radicals like ·O and ·OH, thereby altering the formation and consumption pathways of C2H4, leading to a reduction in both its formation and consumption. Additionally, H2O and inert gases produced by the thermal decomposition of NH4H2PO4 also contribute to inhibiting the progression of C100H202 deflagration.

Novel Chemical Routes for Carbon Dioxide and Methane Production from Lignin Photodegradation: The Role of Environmental Free Radicals.

Sunlight irradiation significantly mediates plant litter's carbon dynamics and volatile carbon release in semi-arid and arid ecosystems. In this process, carbon loss is controlled by lignin, but the mechanisms of production of CO2 and CH4 during lignin photolysis are ambiguous. In this study, the photomineralization of plant litter and the lignocellulosic component collectively indicate that lignin is a major source of CO2 and CH4 emissions. Characterization and free radical analysis reveal that the production of CO2 is due to the oxidation and ring-opening reaction of the coniferyl alcohol unit, with the subsequent decarboxylation of carboxylic acid as an oxidation product. This reaction involves o-quinone formation by the reactions between O2, superoxide radical (O2·-), and persistent free radicals (PFRs)-bearing lignin. Of this, O2·- contributes to 43.2% of the photogenerated CO2, as a new pathway, derived from the electron transfer from PFRs to O2. Interestingly, photoinduced demethylation of the dimethoxybenzene-type compounds as the photolysis products of lignin results in a never-before-reported CH4 formation chemical route independent of that of O2. This mechanistic insight into the role of lignin in volatile carbon production from the irradiative plant litter will contribute to a deeper understanding of carbon balance in water-limited ecosystems.

Catalytic hydrogenation of magnesite to methane and magnesium oxide using magnesium carbonate hydroxide as model compound

The hydrogenation of magnesite to CH4 and MgO offers a powerful approach for CO2 direct utilization. To deepen the understanding of the reaction mechanisms, (Mg5(CO3)4(OH)2(H2O)4 was selected as a model compound to gain insights into carbonate hydrogenation. A novel Ni/Fe/ZrO2 catalyst with ferromagnetic properties was employed to facilitate the magnetic separation of the catalyst from the solid products. Thermodynamic simulation and experiments were conducted to address key issues such as gas evolution during catalytic hydrogenation, the effects of catalyst on CH4 selectivity, and the separation of solid products and catalyst. The results indicate that lower temperatures favor CH4 formation, whereas higher temperatures favor CO formation. Increasing Ni loading can enhance the CH4 selectivity. With the presence of 10Ni/Fe/ZrO2 catalyst, 100% CH4 selectivity can be achieved at 300 °C. Moreover, 10Ni/Fe/ZrO2 catalyst exhibits high magnetic responsiveness, facilitating the solid separation and the recycle of the catalyst.

Unraveling the mechanistic interplay between CO and CO2 hydrogenation over Ni, Co, and NiCo catalysts

Although CO and CO2 hydrogenation reactions have been extensively studied, there is still significant controversy regarding the mechanism of methane formation and the routes for byproducts, especially when both carbon sources are simultaneously present. This work combines kinetic, operando-spectroscopic, isotopic techniques and DFT calculations to elucidate the relationships between CO and CO2 hydrogenation over mono Ni, Co and bimetallic NiCo catalysts with similar metal dispersion. The bimetallic catalysts showed a slight synergistic effect for methane formation from CO, while from CO2 the effect was opposite, showing a negative shift of activity as compared with those observed on the monometallic catalysts. The kinetic analysis shows similar apparent order with respect to H2 (∼0.5) and an inverse secondary isotope kinetic effect (<1) for both methanation reactions, suggesting that CH4 formation proceeds via C-O bond breaking in an H*-assisted mechanism, where the rate-determining step was not shown to be sensitive to the carbon source. The anti-synergistic effect observed on the bimetallic catalysts during CO2 hydrogenation is explained by the formation of unreactive HCOO* species (spectator), which generate a lower density of methane intermediates. On the other hand, the formation of the undesired products, i.e., CO or CO2 during CO2 or CO hydrogenation, respectively, shows relevant differences since the CO formation during CO2 hydrogenation proceeds through the desorption of the carbonyl species adsorbed on weak sites, meanwhile the CO2 formation from CO hydrogenation is due to a minority route of direct dissociation of CO, allowing the rejection of O* with CO* to produce CO2. This study contributes to elucidate the routes that determine the selectivity and reactivity for CO and CO2 hydrogenation and their mechanistic relationship. This information is valuable for the rational design and development of new materials with high performance during hydrogenation processes.

Early age accelerated carbonation of cementitious materials surface in low CO2 concentration condition

Accelerated carbonation curing contributes to the carbon sequestration effect of cementitious materials and enhances surface density. However, in large-scale applications, traditional high CO2 concentration conditions (>5 % CO2) are constrained by economic costs. This study traces the early-stage accelerated carbonation process of cement mortar under low CO2 concentration (3 % CO2) condition from the perspectives of the evolution of CaCO3 crystal types, phase transformations, and microstructural changes, and compares the results with those under the 20 % CO2 condition. The results show that the carbonation depth of mortar specimens cured under the 3 % CO2 condition is shallower, but the cumulative concentration of CaCO3 within the surface 3 mm is not significantly lower than that under the 20 % CO2 condition; The carbonation zone generates more low-crystalline forms of CaCO3; The accelerated carbonation process does not affect the formation of CH and ettringite. Microscopic results indicate that under the 3 % CO2 condition, the synergistic effects of hydration and carbonation are better, and appropriately extending the curing time helps to refine the pore structure of the carbonation zone and improve the density of the substrate surface.

Formation of acetonitrile and ethylene from activation of ethane over cobalt-exchanged aluminosilicates: Active sites and reaction pathways

Cobalt-exchanged ZSM-5 catalyzes the ammoxidation of ethane (2 C2H6 + 3 O2 + 2 NH3 → 2 CH3CN + 6 H2O), yet the active form of cobalt, the role of the Brønsted acidic zeolite, and the reaction pathways remain elusive. Comparisons of rates and selectivities of reactions at distinctive cobalt sites (Co2+ at Al pair sites (CoZ2), Co3O4, cobalt phyllosilicate, and cobalt aluminate) suggest sites that form from CoZ2 provide the greatest rates and selectivities for CH3CN and C2H4 formation. Significantly, we revealed a large fraction of CH3CN appears to form directly through a trimolecular reaction at cobalt ions without desorption of intermediates. In parallel, a more conventional sequential pathway dehydrogenates C2H6, aminates C2H4, and oxidatively dehydrogenates C2H5NH2 to produce CH3CN. Combined rate measurements with temperature programmed reactions and in situ infrared spectra demonstrate that O2-derived intermediates at cobalt ions initiate both reaction sequences by abstracting H-atom from C2H6.

Revisiting the influence of Ni particle size on the hydrogenation of CO2 to CH4 over Ni/CeO2

Nickel nanoparticles were supported on CeO2 and evaluated in the hydrogenation of CO2 to CH4 at 538 K and 1 atm. Chemisorption of H2 was used to estimate the average Ni particle size, which ranged from 1.3 to 17 nm. The apparent activation energy for CH4 formation and turnover frequency for CO2 conversion was independent of Ni particle size. The smallest Ni particles (1.3 nm) were less selective to CH4. Comparisons to alumina-supported Ni reveal the same performance as Ni/CeO2 when normalized to active Ni atoms counted by H2 chemisorption. A beneficial effect of ceria relative to alumina is the enhanced reducibility of Ni as evaluated by H2 temperature-programmed reduction. The constancy of the turnover frequency on Ni particles suggests the acid-base and/or redox properties of the support do not play a significant role in the CO2 methanation reaction under the conditions of study, which contrasts many earlier works.

Water-Insoluble Copper Complexes As Electrocatalysts for CO2 Reduction

The electrochemical reduction of carbon dioxide (CO2R) constitutes a promising CO2 utilization technology, allowing the production of valuable fuels and chemicals by using electrical energy from renewable sources. Nevertheless, poor selectivity and high required overpotentials hamper practical applications of the CO2R, which highlights the need for the development of more efficient electrocatalysts. Different copper-based materials have been extensively studied as electrocatalysts for CO2R. Particularly, copper complexes exhibited interesting properties under operational conditions: many of them undergo structural modifications (e.g. changes in oxidation state and/or coordination number), which potentially affect activity, selectivity and stability. Interestingly, some complexes exhibit reversible restructuring under specific conditions, which can be an interesting property to reach higher stability. In this presentation, we will show the results obtained for the electrocatalysis of water-insoluble copper complexes for the CO2R. The activity, selectivity and stability of both [Cu(bzimpy)Cl2] and [Cu(pyrben)2(NO3)]NO3 were investigated in K2SO4 0.1 mol L-1 (CO2 sat.) under different electrochemical conditions. Here, bzimpy and pyrben stand for 2,6-bis(2-benzimidazolyl)pyridine and 2-(2-pyridyl)benzimidazole, respectively. Qualitative EC-MS (Electrochemistry Coupled to Mass Spectrometry) analysis evidenced that both complexes are active for CO2 reduction and that product distribution changes according to the applied potential. Quantitative gas chromatography measurements revealed that, at -1.24 V vs. RHE, [Cu(bzimpy)Cl2] promotes the formation of H2, CO, CH4 and C2H4 with faradaic efficiencies of 26, 3.4, 9.2 and 31%, respectively. On the other hand, [Cu(pyrben)2(NO3)]NO3 shows FE values of 24, 8.8, 15 and 24% for H2, CO, CH4 and C2H4, respectively. After 1.6 h of electrolysis, the former exhibited stable current and FE of ~42% towards ethylene formation.

INTENSITY OF GREENHOUSE GAS FORMATION DUE TO LIVESTOCK FARMING ACTIVITIES – AS AN ENVIRONMENTAL FACTOR

According to numerous expert assessments by international organizations and specialists, animal husbandry makes a significant negative contribution to global climate change due to the emission of greenhouse gases (GHG), which are formed at different stages of livestock production as a result of various chemical and biological processes in the body of animals and in livestock waste. The domestic animal husbandry is developing mainly due to the intensification of production in the industry, but traditional farming methods as well as small-scale production in the individual sector also take place. Since the use of various technologies in animal husbandry has different effects on the level of environmental pollution and GHG emissions, the aim of the research was to study the differences in the intensity of GHG gas formation by one animal reared with individual features of animal rearing technologies and business activities. The intensity of gas formation and emission of CH4 and N2O in typical farms for pork production and milk production by one animal reared was determined, analyzed and substantiated. A significant variation in this indicator was found depending on the individual economic and technological features of the studied farms. The average weighted annual intensity of CH4 emission from animal manure in pig farms varied within the range of 0.95–25.71, in cattle farm – 2.74; CH4 from intestinal fermentation of dairy cows – 110.8–148.4; N2O (direct) in pig farms – 0.0–0.106, in cattle farm – 0.229; N2O (indirect) in pig farms – 0.071–0.097, in cattle farm – 0.174. The emission intensity is characterized separately in each age and sex group of animals in the herd structure of farms and the average weighted emission intensity in pork producing farms depending on the season. Based on the research results, it is proposed to use the generalized average annual indicator of greenhouse gas emissions per one average weighted animal reared (kg/head/year) as an indicator of the environmental load of livestock farms on the environment, which will allow planning production volumes with minimal environmental risks in the context of climate change.

Enhanced selective hydrogenation of CO2 to CH4 on molybdenum carbide hollow sphere catalyst

AbstractHerein, methane (CH4) production in carbon dioxide (CO2) hydrogenation by hydrogen (H2) is enhanced by reducing surface carbon deposits on molybdenum carbide (Mo2C) hollow spheres. When surface carbon deposits present on Mo2C hollow spheres, CO2 conversion is 9.9%, and CO and CH4 are both produced from CO2 hydrogenation, with CO and CH4 selectivity of 58.4% and 41.6%, respectively. When surface carbon deposits absent on Mo2C hollow spheres, CO2 conversion increases to 18.6%, and CO2 hydrogenation to CH4 is enhanced, with a 100% CH4 selectivity. Reducing surface carbon deposits on Mo2C hollow spheres changes the CO2 adsorbed on Mo2C hollow spheres from a monodentate structure to a bidentate structure which prefers to undergo hydrogenation to CH4, thus enhancing CH4 formation from CO2 hydrogenation. These results open a new way to fabricate more efficient noble‐metal‐free catalysts for selective CO2 hydrogenation.

Temporal analysis of products (TAP) reactor study of the dynamics of CO2 interaction with a Ru/γ-Al2O3 supported catalyst II: Interaction strength, formation of intermediates and oxygen exchange

Continuing a comprehensive study of the reduction of COx over supported Ru catalysts, we explored the interaction of CO2 with Ru/γ-Al2O3 by TAP reactor measurements, focusing on dynamic aspects in adsorption/desorption, reaction and oxygen exchange processes. Pulse shape analysis in H2/CO2 multipulse sequences provides information on the interaction of reactant/product species with the catalyst. The measurements provide information on the dynamic build-up of reaction intermediates and more stable adspecies during pulsing, and its relation to CH4 formation. Facile oxygen exchange between CO2 and catalyst, followed by isotope labeling experiments, is quantitatively reconciled in a simple model, relating the ratio between different CO2 isotopologues to the 18O:16O ratio in the total exchangeable oxygen on the surface and in the CO2 pulse. The results provide detailed insight into various aspects of the interaction between CO2 and Ru/Al2O3 catalysts important for a mechanistic understanding of various catalytic reactions involving CO2.

A comprehensive thermodynamic analysis of hydrogen and synthesis gas production from steam reforming of propionic acid: Effect of O2 addition and CaO as CO2 sorbent

A thermodynamic analysis was performed for the production of synthesis gas and hydrogen gas from steam reforming of propionic acid, one of the constituents of the bio-oil, using ASPEN Plus v8.8. The aim of the study was to perform a global analysis on steam reforming of propionic acid focusing on several parameters such as steam-to-propionic acid ratio, reaction temperature, addition of O2 in the feed stream and presence of CaO as a CO2 sorbent in the reaction environment. The results showed that higher amounts of steam/propionic acid ratio resulted in higher H2 and CO2 yields. It was also observed that high H2O/PA molar ratios led to reduced coke production as WGS reaction was favored with excess steam, causing CO in the reaction mixture to be consumed through the WGS reaction rather than the Boudouard reaction. Addition of O2 in the reaction environment was observed to negatively affect yield of H2. Yet, coke formation was deprived and increasing the O2 amount in the feed stream decreased the energy required for the process. Furthermore, the presence of CaO enhanced H2 yield and energy requirements of the process compared to conventional steam reforming process. 100 % yield of H2 production with a heat generation of −83.4 MJ/kmol of PA and almost zero formation of CO2, CO, CH4 and coke is achieved at 600 °C for sorption enhanced steam reforming of propionic acid.