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Efficient heterogeneous catalyst design primarily focuses on engineering the active sites or supports, often neglecting the impact of trace impurities on catalytic performance. Herein, we demonstrate that even trace amounts of sulfate (SO42−) residuals on Ru/TiO2 can totally change the CO2 reduction from methanation to reverse-water gas shift (RWGS) reaction under atmospheric pressure. We reveal that air annealing causes the trace amount of SO42− to migrate from TiO2 to Ru/TiO2 interface, leading to the significant changes in product selectivity from CH4 to CO. Detailed characterizations and DFT calculations show that the sulfate at Ru/TiO2 interface notably enhances the H transfer from Ru particles to the TiO2 support, weakening the CO intermediate activation on Ru particles and inhibiting the further hydrogenation of CO to CH4. This discovery highlights the vital role of trace impurities in CO2 hydrogenation reaction, and also provides broad implications for the design and development of more efficient and selective heterogeneous catalysts. The impact of trace impurities on catalytic performance is often overlooked. Here the authors show that trace amounts of sulfate residuals on Ru/TiO2 substantially enhance hydrogen transfer from Ru particles to the TiO2 support, shifting CO2 reduction from methanation to the reverse water-gas shift reaction. [ABSTRACT FROM AUTHOR]

High conversion rate and selectivity are challenges for CO2 utilization through catalytic reverse water gas shift (RWGS) reaction. Herein, a novel mesoporous biochar (MB) supported Cu-Mo2C nano-interface was prepared by consecutive physical activation of coconut shells followed by carbothermal hydrogen reduction of bimetal. As compared with traditional carbon materials, this MB exhibited ultra-high specific surface area (2693 m2 g–1) and mesopore volume of mesopore (0.81 cm3 g–1) with a narrow distribution (2–5 nm), responsible for the high dispersion of binary Cu-Mo2C sites, CO2 adsorption and mass transfer in the reaction system. Moderate carbothermal reduction led to the sufficient reduction of Mo ion with carbon matrix of MB and dispersive growth of nano Cu-Mo2C binary sites (~ 6.1 nm) on the surface of MB. Cu+ species were formed from Cu0 via electron transfer and showed high dispersion with simultaneous boosted bimetal loading due to the strong interaction between nano Mo2C and Cu. These were advantageous to the intrinsic activity and stability of the Cu-Mo2C binary sites and their accessibility to the reactant molecules. Under the RWGS reaction conditions of 500 °C, atmospheric pressure, and 300,000 ml/g/h gas hour space velocity, the CO2 conversion rate over Cu-Mo2C/MB reached 27.74 × 10–5 molCO2/gcat/s at very low H2 partial pressure, which was more than twice that over traditional carbon supported Cu-Mo2C catalysts. In addition, this catalyst exhibited 99.08% CO selectivity and high stability for more than 50 h without a decrease in activity and selectivity. This study offers a new development strategy and a promising candidate for industrial RWGS. Highlights: Coconut shell derived ordered mesoporous biochar with ultra-high SBET and mesopore volume was fabricated. Mesoporous biochar facilitates nano Cu-Mo2C interface formation, CO2 adsorption and mass transfer. Strong interaction between Mo2C and Cu leads to electron transfer and anchoring of Cu. CO2 conversion rate over Cu-Mo2C/MB was twice that over Cu-Mo2C/traditional carbon. The catalyst exhibited 99.1% CO selectivity and high stability for more than 50 h. [ABSTRACT FROM AUTHOR]

Inland waters are important sources of the greenhouse gases carbon dioxide (CO2) and methane (CH4). Ponds have amongst the highest CO2 and CH4 fluxes of all aquatic ecosystems, yet seasonal variation in fluxes remain poorly characterized, creating challenges for accurately estimating annual emissions. Further, ponds can exhibit a range of mixing regimes, yet the impact of mixing regimes on gas emissions remains unclear. Here, we assessed annual dynamics of CO2 and CH4 in four temperate ponds (Minnesota, USA) that varied in mixing regimes. The ponds ranged from annual sinks to sources of CO2 (−1 to 15 mol m−2 yr−1) and were all significant sources of CH4 (4.3–8.2 mol m−2 yr−1), with annual fluxes in CO2 equivalents of 1.8–4.1 kg CO2-eq. m−2 yr−1. Mixing regimes impacted CO2 and CH4 dynamics, as stratified periods were associated with more anoxia, greater accumulation of gases in the bottom waters, higher emissions of CH4, and lower fluxes of CO2. Ponds with stronger summer stratification also had increased CO2 and CH4 fluxes associated with fall turnover. Overall, the two ponds with the strongest stratification had higher annual fluxes (2.6, 4.1 kg CO2-eq. m−2 yr−1) compared to the two ponds that more frequently mixed (1.8, 2.2 kg CO2-eq. m−2 yr−1). [ABSTRACT FROM AUTHOR]

In response to the imperative for sustainable iron production with reduced CO2 emissions, this study delves into the intricate role of TiO2 in the direct reduction of iron oxide pellets. The TiO2-dependent reducibility of iron oxide pellets utilizing H2 and CO gas across varied temperatures and gas compositions is thoroughly investigated. Our findings unveil the nuanced nature of the TiO2 effect, underscored by its concentration-dependent behavior, revealing an optimal range between 1 and 1.5 pct TiO2, where a neutral or positive impact on reduction kinetics and diffusion coefficient is observed. Notably, the synergistic interplay of CO and H2 at 1000 °C emerges as particularly efficacious, suggesting complementary effects on the reduction process. The introduction of H2 into the reducing atmosphere regulated by CO not only extends the transition range but also markedly expedites the rate of reduction. Furthermore, our study highlights the temperature sensitivity of the TiO2 effect, with higher TiO2 content correlating with prolonged reduction time in a 100 pct H2 atmosphere at 900 °C. In a 100 pct H2 atmosphere, the non-contributory role of TiO2 stems from the water-gas shift reaction. Conversely, introducing H2 into a CO-controlled reducing atmosphere with TiO2 enhances the transition range and expedites the reduction rate. Additionally, our findings underscore the role of total iron content, revealing a direct correlation with the reduction process. [ABSTRACT FROM AUTHOR]

An analytical solution of the problem of heating a composite spherical droplet consisting of a liquid hydrocarbon and a microdroplet of water in a hot gas flow is presented. A microdroplet of water is located in the center of a droplet of hydrocarbon. At the hydrocarbon–water interface, the conjugation conditions are specified; at the outer boundary of the hydrocarbon droplet — a condition of convective heat exchange. The unsteady temperature of a drop is represented by an analytical formula, which is an expansion of the solution in terms of eigenfunctions of the Sturm–Liouville problem. The eigenvalues are found numerically from the characteristic equation. A condition for the orthogonality of eigenfunctios in a composite droplet with discontinuous thermophysical properties is derived. The results of calculations using the obtained analytical formula are in satisfactory agreement with the experimental data. Erroneous methods are discussed in previously presented publications by other authors. [ABSTRACT FROM AUTHOR]

The kinetics and equilibrium conditions of carbon dioxide hydrate formation in 'dry water" disperse system were studied using different types of hydrophobic silicon dioxide nanoparticles under isochoric conditions at 273.15 K temperature and 3 MPa initial pressure. Also studied was the effect of "dry water" on the kinetics of carbon dioxide hydrate dissociation under a pressure below the equilibrium and at 268.15 K temperature. [ABSTRACT FROM AUTHOR]

To study the influence of various factors on coal permeability in the process of coal seam water injection and the relationship between water injection parameters, an experimental system of highly pressurized water invasion and gas seepage is developed. The system consists of four parts: an overburden pressure loading unit, a micro water injection control unit, a gas injection, and vacuum pumping unit, data acquisition and real-time monitoring unit. It can not only be used for coal seam water injection radial seepage experiments. It can also be used as a set of experimental systems to simulate the geothermal exploitation of deep coal seams and explore the heat transfer law of geothermal exploitation. To verify its applicability, a coal seam water injection seepage experiment is carried out based on the experimental system. The results show that the coal permeability increases by 7–31% before and after water injection; at the same time, under different stress conditions, the internal and external pressure difference of the coal sample before and after water injection has a decrease of 0.01–0.05 MPa. The conclusion is consistent with previous studies, which shows that the experimental system is accurate and reliable. [ABSTRACT FROM AUTHOR]

Cleaning up carbon monoxide (CO) in water gas shift feedstocks is crucial for fuel cell applications. The catalytic transformation of CO in hydrogen-rich feeds poses a significant challenge in environmental catalysis. To address this issue, a range of Cu–Mn-based monometallic and bimetallic catalysts with diverse supports (such as alumina, silica, zirconia, and titania) were employed. Temperature programming techniques were utilised to observe the reduction and oxidation behaviours of these catalysts. The investigation involved testing CO oxidation at various temperatures over copper and manganese-based supported catalysts in the presence of H2O and CO2 (simulating realistic conditions). A positive impact of H2O on catalytic performance was noted, whereas CO2 had a suppressive effect. Furthermore, the specific support materials (Al2O3, SiO2, TiO2, and ZrO2) were studied to understand their roles in CO oxidation under realistic conditions. In the presence of water, alumina catalysts containing bimetallic metals (Cu–Mn) exhibited 100% CO conversion even at a lower temperature of 160 °C. Conversely, under the predominant influence of CO2, alumina catalyst (Cu–Mn) showed 55% CO conversion. The exceptional performance was attributed to CO preferential adsorption on highly active Cu–Mn sites and a small H2-oxidative atmosphere of the catalysts. The activity results highlighted the strong dependence of CO conversion on reaction temperatures, the presence of metals, and the types of supports. Overall, these findings suggest the potential use of these catalysts for H2 purification under realistic conditions. [ABSTRACT FROM AUTHOR]

Highlights: Challenges and future directions for 3D-printed metal-organic frameworks (MOFs) monoliths in environmental applications are discussed. Various strategies for fabrication of 3D-printed MOF monoliths are summarized. Advancements in 3D printing enable customizable and high-performance MOF monoliths. 3D orienting of MOFs opens avenues for applications in water treatment and gas adsorption. Metal–organic frameworks (MOFs) have been extensively considered as one of the most promising types of porous and crystalline organic–inorganic materials, thanks to their large specific surface area, high porosity, tailorable structures and compositions, diverse functionalities, and well-controlled pore/size distribution. However, most developed MOFs are in powder forms, which still have some technical challenges, including abrasion, dustiness, low packing densities, clogging, mass/heat transfer limitation, environmental pollution, and mechanical instability during the packing process, that restrict their applicability in industrial applications. Therefore, in recent years, attention has focused on techniques to convert MOF powders into macroscopic materials like beads, membranes, monoliths, gel/sponges, and nanofibers to overcome these challenges.Three-dimensional (3D) printing technology has achieved much interest because it can produce many high-resolution macroscopic frameworks with complex shapes and geometries from digital models. Therefore, this review summarizes the combination of different 3D printing strategies with MOFs and MOF-based materials for fabricating 3D-printed MOF monoliths and their environmental applications, emphasizing water treatment and gas adsorption/separation applications. Herein, the various strategies for the fabrication of 3D-printed MOF monoliths, such as direct ink writing, seed-assisted in-situ growth, coordination replication from solid precursors, matrix incorporation, selective laser sintering, and digital light processing, are described with the relevant examples. Finally, future directions and challenges of 3D-printed MOF monoliths are also presented to better plan future trajectories in the shaping of MOF materials with improved control over the structure, composition, and textural properties of 3D-printed MOF monoliths. [ABSTRACT FROM AUTHOR]

Context: The capacities of V-Si72, V-C72, and V-Al36N36 nanocages to catalyze the ORR processes have been investigated. The acceptable pathways of ORR processes on V-Si72, V-C72, and V-Al36N36 nanocages have been examined by DSD-PBEPBE-D3/aug-cc-pVDZ, PW91PW91/aug-cc-pVDZ, and COSMO model in the gas phase and water. The ΔGreaction values of reaction steps of ORR pathways on V-Si72, V-C72, and V-Al36N36 nanocages are calculated. The Eadoption and Eformation of V-Si72, V-C72, and V-Al36N36 nanocages are negative values and these nanostructures are stable materials. The H2O has the lowest Eadsorption on V-Si72, V-C72, and V-Al36N36 nanocages. The *OH formation, creation of *OH-OH*, and formation of O* are rate-determining steps of ORR mechanisms. The overpotential values of ORR processes on V-Si72, V-C72, and V-Al36N36 nanocages are 0.41, 0.37, and 0.30 V, respectively. The V-Al36N36 nanocage have lower overpotential for ORR processes than V-Si72 and V-C72 nanocages by DSD-PBEPBE-D3/aug-cc-pVDZ, PW91PW91/aug-cc-pVDZ, and COSMO model in the gas phase and water. The V-Al36N36 nanocage have more negative ∆Greaction for reaction steps of ORR than V-Si72 and V-C72 nanocages. The V-Al36N36 nanocage with lower overpotential is proposed as an effective catalyst for ORR processes via studied pathways. Methods: The DSD-PBEPBE-D3/aug-cc-pVDZ method has been used to optimize and calculate the frequencies of V-Si72, V-C72, and V-Al36N36 nanocages in GAMESS software. The complexes of O, OH, OOH, and H2O with V-Si72, V-C72, and V-Al36N36 nanocages are optimized and frequencies are determined by the DSD-PBEPBE-D3/aug-cc-pVDZ method. The Gactivation and ∆Greaction of ORR pathways on V-Si72, V-C72, and V-Al36N36 nanocages are calculated by DSD-PBEPBE-D3/aug-cc-pVDZ, PW91PW91/aug-cc-pVDZ, and COSMO model in the gas phase and water. [ABSTRACT FROM AUTHOR]

The tight sandstone reservoirs in the Sulige Gas Field have complex pore structures and gas-water distribution, and the water production law in the complex gas-water distribution areas has not been clarified. The water production of gas wells in different regions varies greatly, and the water production of gas wells seriously affects the efficient development of natural gas. In order to improve the benefit of gas field development, this study takes stress-sensitive effects, gas-water immiscibility, and constant production conditions of gas wells under a certain gas-water ratio Rgw as constraints, and considers the fluid seepage as an isothermal seepage process, an evaluation model of the productivity of a theoretical water-producing gas well and a relative permeability model of the gas phase are constructed. Moreover, the influence of water production on the degree of pressure drop, gas well productivity, and gas well recovery was systematically analyzed. This study shows that when the water-gas ratio of gas wells is less than 1, 1-2, 2-3, 3-4, 4-5, and greater than 5, its influence on productivity is less than 40%, 52%, 50%, 58%, 61%, 65% and greater than 65%, respectively. The average water-gas ratio of the water-producing gas wells in the Sulige Gas Field is 1.27 m3/10 4 m3. The effect of water production on recovery is compared with the case of no water production: for water-producing gas wells, the recovery rate of Type I wells is reduced by 8.45%, that of Type II wells is reduced by 9.58%, and that of Type III wells is reduced by 11.54%. [ABSTRACT FROM AUTHOR]

Warning and controlling the water invasion in water-driving reservoirs is significant because water invasion will seriously hamper well productivity and gas recovery. Unfortunately, there are few comprehensive methods to control water invasion. First, we establish and verify a water invasion model of reservoir scale. Then, a new workflow for warning and controlling the water invasion is proposed using the numerical simulation method. The workflow first judges the water invasion characteristics, determines the water invasion index based on the production data, and then controls the water invasion by finding and closing the perforation layer of serious water production. Finally, the optimal water control scheme is obtained by comparing water and gas production. The results show that the accuracy of the geological reserves of the established water invasion model is 99% and has a good pressure fitting result. The early warning chart for the gas reservoir in the west of Amu Darya B area is drawn, including the early warning pressure and the level 1, level 2, and level 3 early warning water–gas ratio, which is convenient for field application. For the water-driving wells west of area B, the early warning value of the water–gas ratio increases with the increase of gas production rate during fixed production and decreases with the increase of bottom hole pressure during constant pressure production. Closing the harmful perforation from the water-finding study will significantly reduce the water while retaining the gas production. After water control technology, water production decreased by 90.9%, while gas production decreased by only 9.7%. [ABSTRACT FROM AUTHOR]

Geological carbon sequestration in jointed reservoirs will require the use of fracture network for the flow of CO2 plumes. However, acidic solution formed at the interface between brine and CO2 can cause chemical erosion of the local rock mass, especially in rocks with high carbonate content. The use of the water alternating gas technique for injection stimulation can exacerbate this issue, as the water–CO2 interface occurs in areas near the injection point. As a result, acidic flow can impact the surrounding rock mass, particularly around the main flow paths where fracture network conductivity is much higher than matrix permeability. To investigate the impact of acidic flow on fracture conductivity, we conducted an experiment on a fractured sandstone sample that was exposed to CO2-saturated water. Our findings revealed a nearly ten-fold increase in post-experimental water-relative permeability, and restriction of flow within established flow channels, which consist one third of the fracture surface. In conclusion, our study sheds light on the dynamic behavior of fractured sandstone under the influence of CO2–H2O flow, revealing significant changes in transmissivity and fracture geometry. These findings contribute to a better understanding of the hydraulic performance of fractures in the context of geological carbon sequestration. [ABSTRACT FROM AUTHOR]

High-temperature co-electrolysis is studied on electrolyte-supported NiO-YSZ/NiO-SDC/ScSZ/LSCF-GDC/LSCF (NiO: Nickel Oxide, YSZ: Yttria-stabilized zirconia, SDC: Samarium-doped ceria, ScSZ: Scandia-stabilized zirconia, LSCF: Lanthanum Strontium Cobalt Ferrite, GDC: Gadolinium-doped ceria) button cell. Electrochemical impedance spectroscopy (EIS) was recorded under open-circuit voltage (OCV) and co-electrolysis mode over various operating conditions, including temperature, water vapor content, and applied voltage. Interfacial polarization resistance (Rp) is obtained from peak arcs located in the three regions: gas conversion resistance (Region I (0.01 to 0.1 Hz)), gas diffusion resistance (Region II (0.1 to 100 Hz)) and air electrode charge transfer resistance (Region III (100 to 10,000 Hz)). As the temperature increased from 700 to 850 oC, Rp decreased from 18.15 to 3.32 Ω.cm2 at 1.3 V for 10%CO2/3%H2O. From the Distribution of relaxation times (DRT) studies, one additional peak, P5 (fuel gas conversion or gas-phase diffusion in the pores of the air electrode), is observed, and Region III (100 to 10,000 Hz) consists of two additional peaks: P1 (ionic transport coupled with gas diffusion close to triple phase boundaries (TPBs)) and P2 (fuel electrode charge transfer reaction), which were not clearly distinguished from EIS. Region II dominates in the overall polarization resistance. At 800 oC, for 10%CO2/3%H2O, the Rp decreased from 6.78 to 4.82 Ω.cm2, with an increase in the applied voltage from 1.3 to 1.5 V. At 800oC/1.5 V, the Rp values are 4.41, 8.09, and 6.77 Ω.cm2 for H2O, CO2, and co-electrolysis. At 800 ºC/1.5 V, with an increase in the water vapor content from 3%H2O to 15%H2O, there is not much change in the Rp value; therefore, 10%H2O is sufficient. H2 consumption is between 23 and 36%, depending on the temperature at OCV. At 800 °C for (10%H2/10%CO2/10%H2O), co-electrolysis occurs at applied voltage, along with Reverse water gas shift (RWGS) reaction. [ABSTRACT FROM AUTHOR]

We describe laboratory experiments in a 2D wave tank that aim at building up and monitor 2D shallow water soliton gas. The water surface elevation is obtained over a large ( ∼ 100 m 2 ) domain, with centimeter-resolution, by stereoscopic vision using two cameras. Floating particles are seeded to get surface texture and determine the wave field by image correlation. With this setup, soliton propagation and multiple interactions can be measured with a previously unreachable level of detail. The propagation of an oblique soliton is analyzed, and the amplitude decay and local incidence are compared to analytical predictions. We further present two cases of 2D soliton gas, emerging from multiple line solitons with random incidence ( | θ | < 30 ∘ ) and from irregular random waves forced with a JONSWAP spectrum ( | θ | < 45 ∘ ). To our knowledge, those are the first observations of random 2D soliton gas for gravity waves. In both cases, Mach reflections and Mach expansions result in solitons that mainly propagate in directions perpendicular to the wavemakers. [ABSTRACT FROM AUTHOR]

Solar thermochemical hydrogen (STCH) production from water splitting typically requires performing redox cycles at temperatures above 1200 °C to reduce and re-oxidize the bulk of a reversible material. Bulk processes such as oxygen vacancy formation and oxygen diffusion energies dictate the viability of a material for STCH. The surface plays an important role in the formation and destruction of vacancies and interacts with gas phase water and surface adsorbed species. These surface processes can lead to surface reconfigurations and even the formation of surface phases with stoichiometry and oxygen content very different from the bulk composition. Understanding in-situ the surface chemical state and its evolution under water splitting is important to design nonstoichiometric oxides capable of longer-lasting STCH generation at lower temperatures. In this work, we describe the water splitting active defect sites in LSM ((La0.65Sr0.35)0.95MnO3−δ) and Ga-doped LSM ((La0.6Sr0.4)0.95(Mn0.8Ga0.2)O3−δ) perovskites during Operando thermochemical water splitting conditions using ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) experiments at 800 °C under steam. We show that sub-stoichiometric La+3 in the oxygen-vacancy rich surface at operating conditions can be used to correlate surface water splitting activity and the creation of surface hydroxide intermediates. The addition of Ga in LSM is shown to drastically stabilize the surface chemical composition by preventing Sr segregation and stabilizing catalytically active surface defects that promote the binding of adsorbed hydroxides. We use Operando AP-XPS quantification of metastable surface hydroxide intermediates (La(OH)3) to determine the amount of catalytically active surface sites in LSM (2.9%) and in LSMG (7.8–8.1%, depending on the bulk oxidation state). [ABSTRACT FROM AUTHOR]

In terms of the collaborative optimization of CO2 flooding for Enhanced Oil Recovery (EOR) and CO2 sequestration, previous studies have co-optimized both cumulative oil production and CO2 sequestration by various algorithms. However, these solutions fail to optimize the CO2 injection schemes for high-water cut oil reservoirs. This paper presents an optimization methodology for CO2 flooding and sequestration in high-water cut oil reservoirs. The production optimization was carried out by adjusting the injection and production rate. To solve the proposed objective functions, the simultaneous perturbation stochastic approximation (SPSA) algorithm is applied in this paper, and the CMG-GEM module is utilized to simulate the reservoir production performance. A typical high-water cut reservoir in the Shengli oilfield was used to verify the feasibility of the presented methodology. In this paper, the production performance and net present value (NPV) for continuous gas injection under different water cuts were analyzed. The optimal timing of transforming from water flooding to gas displacement for the high-water cut reservoir was optimized. In addition, the optimal water–gas ratios for Water-Alternating-Gas (WAG) flooding were determined. The sensitivity of NPV to gas injection price and carbon subsidy was analyzed. The results show that when the gas price is 0.178 $/m3 and the carbon subsidy is 0.0169 $/m3, the optimal timing of transforming from water flooding to gas injection should be earlier than the time when the water cut is 0.82. Through the combination of NPV, cumulative oil production rate, and CO2 sequestration volume for WAG flooding, the optimal WAG ratio should be 1:2. The presented method in this paper considers various economic indicators and can optimize CO2 flooding and sequestration in high-water cut oil reservoirs efficiently, which can provide some guidance for the design of CO2 flooding schemes in high-water cut oil reservoirs. [ABSTRACT FROM AUTHOR]

A multi-input–multi-output artificial neuron network (MIMO-ANN) model has been developed for process monitoring and improvement on a natural gas glycol dehydration process. The MIMO-ANN model was based on a steady-state process simulation model constructed in commercial software Aspen HYSYS. A set of training data was generated with the converged simulation model for the training of the MIMO-ANN model in Python. The process input of the model includes lean glycol recirculation rate and purity along with wet gas inlet pressure. On the other hand, the process output considered includes dehydrated gas water and aromatics content, dehydrated gas hydrate formation temperature and water dew point, stripping gas flow rate as well as reboiler duty. The overall mean squared error (MSE) of the MIMO-ANN model was calculated as 1.79. The best-fit line that highly overlaps with a 45° diagonal line is constructed with a correlation coefficient (R2) score of more than 0.999 for all studied process output testing datasets. The mean absolute percentage error (MAPE) of the predicted outputs is generally less than 1%, except for dehydrated gas water dew point (16.63%) and stripping gas flow rate (11.55%), due to error predictions attempted on pseudo-zero values. This successfully displays an exceptional predictive performance of the MIMO-ANN model developed in this work which can be further deployed as an online dashboard for real-time monitoring tool. [ABSTRACT FROM AUTHOR]

Sediment re-suspension plays a crucial role in releasing endogenous nitrogen and greenhouse gases in shallow urban waters. However, the impacts of repeated re-suspension and photo-induced processes on migration and transformation from endogenous nitrogen, as well as the emission of greenhouse gases, remain unclear. This study simulated three conditions: re-suspension (Rs), re-suspension combined with ultravioletirradiation (Rs + UV), and ultraviolet irradiation (UV). The findings revealed that both repeated sediment re-suspension and exposure to UV light altered the characteristics of surface sediments. Decrease of convertible nitrogen in sediments, leading to the release of ion-exchangeable nitrogen (IEF-N) into NH4+-N and NO3−-N, influenced greenhouse gas production differently under various conditions. The study observed the highest concentration of dissolved N2O in under UV irradiation, positively correlated with NO2−-N and NO3−-N. Re-suspension increased the turbidity of the overlying water and accelerated nitrification, resulting in the highest NO3−-N concentration and the lowest dissolved N2O concentration. Additionally, in the Rs + UV dissolved N2O maintained the higher concentrations than in Rs, with greatest amount of N conversion in surface sediments, and a 59.45% reduction in IEF-N. The production of N2O during re-suspension was mainly positively correlated with NH4+-N in the overlying water. Therefore, this study suggest that repeated re-suspension and light exposure significantly influence nitrogen migration and transformation processes in sediment, providing a theoretical explanation for the eutrophication of water and greenhouse gas emissions. [ABSTRACT FROM AUTHOR]

In this study, a hybrid absorption chiller was proposed as a part of the energy supply facility for a building with a rooftop greenhouse. Using the exhaust gas and the cooling water from the gas engine, the hybrid absorption chiller supplies the cooling and heating in summer and winter, respectively. Starting from the reference cycle, optimization processes were performed in three steps to maximize the improvements in the cooling capacity and the COP. The COP and the cooling capacity of the finally optimized cycle could be substantially improved compared to those of the initial reference cycle. Additionally, the performance characteristics in off-design conditions were investigated. The hybrid absorption cycle displayed a unique feature, that is, the overall COP decreased with the increasing temperature and the mass flow rate of the hot water due to the crucial role of the single-effect cycle with a low COP. Using the proposed hybrid absorption chiller, a COP of approximately 1.1 can be achieved, which is substantially higher than that of a single-effect absorption chiller. If the present hybrid absorption system is widely applied to places where gas- and liquid-phase waste heat is available, then this system is expected to contribute to energy savings and the reduction of CO2 emissions. [ABSTRACT FROM AUTHOR]

To reveal the characteristics of overlying rock movement in hard and thick volcanic rock mining areas, a typical volcanic rock occurrence was used as a model. Similar simulation experiments were conducted, combined with on-site monitoring data, to systematically analyze the variations of surface and overlying rock deformation and damage with different mining steps, and compared with the model without hard and thick volcanic rocks. The results showed that compared to the model without hard and thick volcanic rocks, the presence of hard and thick volcanic rocks in the overlying strata led to an increased range of subsidence basin and a decrease in maximum subsidence value. The hard and thick volcanic rocks easily formed larger fractured spaces, which served as the main locations for the accumulation of gas and water in fractures. The "O"-shaped fractured circle formed after the rupture of the hard and thick volcanic rocks provided a favorable pathway for gas outbursts and water surges in the fractures. The rupture of hard and thick volcanic rocks easily triggered intense overlying rock movement and surface subsidence, leading to occurrences of underground and surface disasters such as dynamic ground pressure, outbursts of gas and water in fractures, and damage to surface structures and ecological environments. [ABSTRACT FROM AUTHOR]

In this study, the installation of an airlift pump with inner diameter of 102 mm and length of 5.64 m was utilized to consider the conveying process of non-spherical coal particles with density of 1340 kg/m3 and graining 25–44.5 mm. The test results revealed that the magnitude of increase in the solid transport rate due to the changes in the three tested parameters between compressed air velocity, submergence ratio, and feeding coal possibility was not the same, which are stand in range of 20%, 75%, and 40%, respectively. Hence, creating the optimal airlift pump performance is highly dependent on submergence ratio. More importantly, we measured the solid volume fraction using the method of one-way valves in order to minimize the disadvantages of conventional devices, such as fast speed camera and conductivity ring sensor. The results confirmed that the volume fraction of the solid phase in the transfer process was always less than 12%. To validate present experimental data, the existing empirical correlations together with the theoretical equations related to the multiphase flow was used. The overall agreement between the theory and experimental solid delivery results was particularly good instead of the first stage of conveying process. This drawback can be corrected by omitting the role of friction and shear stress at low air income velocity. It was also found that the model developed by Kalenik failed to predict the performance of our airlift operation in terms of the mass flow rate of the coal particles. [ABSTRACT FROM AUTHOR]

Plastic waste is being manufactured for the production of hydrogen. The amount of plastic waste collected annually is 189,953 tonnes from adjacent nations like Indonesia and Malaysia. Polyethylene (PE), Polypropylene (PP), Polyethylene Terephthalate (PET), Polyvinyl chloride (PVC), and Polystyrene (PS) are the five most prevalent forms of plastic found in most waste. Pyrolysis, water gas shift and steam reforming reaction, and pressure swing adsorption are the three main phases utilized and studied. In this research, authors examines the energy consumption on every stage. The plastic waste can be utilized to manufacture many hydrocarbons using the pyrolysis reaction. For this process, fast pyrolysis is being used at a temperature of 500 °C. A neutralization process is also needed due to the presence of Hydrochloric acid from the pyrolysis reaction, with the addition of sodium hydroxide. This is being carried to prevent any damage to the reactor during the process. Secondly, the steam reforming process continues after the water gas shift reaction has produced steam and carbon monoxide, followed by carbon dioxide and hydrogen formation. Lastly, pressure swing adsorption is designed to extract H2S and CO2 from the water gas shift and steam reforming reaction for greater purity of hydrogen. From the simulation study, it is observed that using various types of plastic waste procured (total input of 20,000 kg per hour of plastics) from, Brunei Darussalam, Malaysia and Indonesia, can produce about 340,000 tons of Hydrogen per year. Additionally, the annual profit of the Hydrogen production is estimated to be between $ 271,158,100 and $ 358,480,200. As per the economic analysis, it can be said that its a good to start hydrogen production plant in these regions. [ABSTRACT FROM AUTHOR]

Demethoxylation was kinetically and spectroscopically studied over three catalysts with different Ru0/Ruδ+ ratios. In-situ spectroscopic tests demonstrated that the synergy between Ru0 and Ruδ+ was crucial, and Ru0 was in charge of H2 activation and adsorption of aromatic ring while Ruδ+ adsorbed with O in methoxyl. A Langmuir–Hinshelwood kinetic model was proposed, and ratio of Ru0/Ruδ+ was the key in deciding the rate-determining step (RDS): i) desorption of toluene was RDS over catalyst with high Ru0 ratio; ii) dissociation of H2 was RDS over Ruδ+ enriched catalyst; iii) demethoxylation was rate-determined by CO water–gas shift (WGS) when Ru0/Ruδ+ approached ~ 1. The best performance was obtained over Ru/NiAl2O4-200, which effectively enabled both C-O bond activation and rapid recovery of adsorption sites for aromatic rings. Finally, in-situ DRIFT studies on methoxy decomposition and CO-WGS unraveled that the electronic composition of Ru was more stable in Ru/NiAl2O4-200 which contributes to its excellence. [ABSTRACT FROM AUTHOR]

This paper reports on results of bathymetric and seismoacoustic studies of the shelf in the western part of Peter the Great Bay. Five flooded coastlines, formed in the Late Pleistocene–Holocene, were revealed on the shelf. It was found that a significant part of the shelf is occupied by a zone of irregular sedimentation. This zone is underlain by an erosion surface buried under sediments of ebb–flood tidal deltas in the areas of active sedimentation and is exposed on the seafloor within the area of active modern erosion. The abrasion and formation of the irregular sedimentation zone on the shelf intensified about 11 500–11 700 years ago. Acoustic anomalies, associated with gas occurrences in sediments and gas plumes in the water column, were recorded on the shelf of the bay. Types of anomalies were classified, and a map of their areal distribution was compiled. It is concluded that the trigger mechanism that provides gas migration into sediments and to the water column is associated with a group of factors: the change of the postglacial sea level and abrasion processes, as well as the meteorological and hydrological regimes. [ABSTRACT FROM AUTHOR]

The preparation method for the heterogeneous catalysts makes a crucial role in catalytic activities. Here, we applied the co-precipitation, sol–gel, and impregnation method to prepare a series of MnOx–CeO2 supports with different Ce: Mn atom ratios at 9:1 and 8:2. After loaded with 1 wt% of Au, the obtained Au/MnOx–CeO2 were evaluated for low-temperature CO oxidation and water–gas shift reaction. Nitrogen adsorption, X-ray diffraction (XRD), Raman spectroscopy, temperature-programmed reduction (TPR), and Transmission Electron Microscopy Energy Dispersive Spectroscopy (TEM-EDS) showed that co-precipitation gave the formation of homogeneous distribution of active sites of MnOx–CeO2 oxides and the doping of Mn led to the formation of fluorite-type solid. The Au/C8M2-C catalyst prepared by co-precipitation performed best in low-temperature CO oxidation and water–gas shift reaction, which may be due to the homogeneous distribution of active sites. The doped Mn also demonstrated a great improvement over the low-temperature CO oxidation, implying the strengthened redox-oxidation capabilities. [ABSTRACT FROM AUTHOR]

The preparation method for the heterogeneous catalysts makes a crucial role in catalytic activities. Here, we applied the co-precipitation, sol–gel, and impregnation method to prepare a series of MnOx–CeO2 supports with different Ce: Mn atom ratios at 9:1 and 8:2. After loaded with 1 wt% of Au, the obtained Au/MnOx–CeO2 were evaluated for low-temperature CO oxidation and water–gas shift reaction. Nitrogen adsorption, X-ray diffraction (XRD), Raman spectroscopy, temperature-programmed reduction (TPR), and Transmission Electron Microscopy Energy Dispersive Spectroscopy (TEM-EDS) showed that co-precipitation gave the formation of homogeneous distribution of active sites of MnOx–CeO2 oxides and the doping of Mn led to the formation of fluorite-type solid. The Au/C8M2-C catalyst prepared by co-precipitation performed best in low-temperature CO oxidation and water–gas shift reaction, which may be due to the homogeneous distribution of active sites. The doped Mn also demonstrated a great improvement over the low-temperature CO oxidation, implying the strengthened redox-oxidation capabilities. [ABSTRACT FROM AUTHOR]

Over the last decade, there have been significant advancements in the different aspects of produced water (PW) management and disposal. These methods include internal application, surface discharge, subsurface discharge, and beneficial reuse (or external uses). While the petroleum industry is focused on using PW internally, the call for other external applications reverberates in agricultural, chemical, and manufacturing industries. Recently, beneficial reuse has gained momentum as a two-way solution for reusing treated PW instead. It promises to alleviate the use of freshwater, tackle drought, and reduce the amount of PW waste disposed of at the end of the process. Despite those mentioned earlier, the petroleum industry prefers using PW internally or discharging it into the subsurface. There seems to be a missing link between all the previously proposed recommendations about beneficial reuse and the actual execution of the external reuse of PW by the major stakeholders. This work provides a holistic account of the state of knowledge by incorporating the oil and gas perspectives and the challenges responsible for the gap in implementing external uses of PW as proposed as a solution to PW management. Based on life cycle assessment and life cycle cost methods, the challenges related to beneficial reuse are highlighted, and the reason for the hesitancy of the petroleum industry to venture into external solutions is presented. This work proposes progressive recommendations that provide insight into achieving long-term environmental sustainability by exploring external uses of PW and harnessing its merit. [ABSTRACT FROM AUTHOR]

As global initiatives pivot toward more sustainable industrial processes, the conversion of carbon dioxide (CO2) into high-value chemicals offers a promising path forward. Ionic liquids (ILs), in particular, show the potential in boosting the efficacy of related reactions. However, their thermodynamic influence on the chemical equilibrium of reactive processes requires further exploration. This study presents a detailed assessment of three specific ILs—[BMIm][BF4], [BMIm][PF6], and [BMIm][NTf2]—on the equilibrium of the CO2 hydrogenation to carbon monoxide (CO) via the Reverse Water–Gas Shift (RWGS) reaction. Both predictive and non-predictive methods based on the Predictive Soave–Redlich–Kwong equation of state were employed to represent the pure ILs' densities and vapor pressure. The non-predictive approach provided a more accurate representation, further utilized for describing the phase equilibria of mixtures encompassing ILs, CO2, H2, CO, and H2O. Through extensive evaluation, the effects of temperature, pressure, and IL content on CO2 hydrogenation were elucidated. Results indicate that higher molar ratios of ILs amplify the equilibrium conversion. Additionally, the system sensitivity to pressure changes was observed, leading to enhanced CO2 conversion at elevated pressures. With varying temperatures, systems containing hydrophobic ILs ([BMIm][PF6] or [BMIm][NTf2]) displayed increased conversion rates at high temperatures, while the hydrophilic IL [BMIm][BF4] demonstrated superior CO production at lower temperatures. This behavior is linked to temperature's profound influence on water sorption in the IL. Notably, the system with hydrophilic IL [BMIm][BF4] exhibited a striking increase in CO2 conversion, from 1.1 to 54.1% at 348 K and 2.0 MPa, almost 50-fold higher than the original conversion. This study illuminates the pivotal role of thermodynamics in driving the future of IL-based CO2 conversion technology, highlighting the potential for further advancements in sustainable industry practices. [ABSTRACT FROM AUTHOR]

Water Alternated Gas (WAG) flooding is largely used as an Enhanced Oil Recovery (EOR) method in oil fields. It is based on the high sweep efficiency of the water phase and the high displacement efficiency of the gas phase. Additionally, other components may be dissolved in both displacing phases, increasing the oil recovery factor and leading to modern WAG schemes such as PWAG (Polymer WAG), MWAG (Miscible WAG), and others. In this paper, we present approximate analytical solutions for the linear immiscible Water Alternated Gas problem. The mathematical model is composed by a 2×2 system of nonlinear hyperbolic Partial Differential Equations (PDE), solved by the Method of Characteristics (MOC) for a set of reservoir properties. The analytical solution is compared with numerical simulation showing the accuracy and robustness of the method under different WAG configurations. The presented solutions can be used to select the best recovery technique for a particular field in a fast and efficient way. [ABSTRACT FROM AUTHOR]

Understanding the behaviour of active catalyst sites at the atomic level is crucial for optimizing catalytic performance. Here, the evolution of Pt and Cu dopants in Au25 clusters on CeO2 supports is investigated in the water-gas shift (WGS) reaction, using operando XAFS and DRIFTS. Different behaviour is observed for the Cu and Pt dopants during the pretreatment and reaction. The Cu migrates and builds clusters on the support, whereas the Pt creates single-atom active sites on the surface of the cluster, leading to better performance. Doping with both metals induces strong interactions and pretreatment and reaction conditions lead to the growth of the Au clusters, thereby affecting their catalytic behaviour. This highlights importance of understanding the behaviour of atoms at different stages of catalyst evolution. These insights into the atomic dynamics at the different stages are crucial for the precise optimisation of catalysts, which ultimately enables improved catalytic performance. Understanding the atomic dynamics of active catalyst sites is crucial for the precise optimization of catalyst performance. Here, the authors employ operando XAFS and DRIFTS to study the dynamics of the mobility of platinum and copper dopants in bimetallic and trimetallic gold nanoclusters supported on ceria, using the water-gas shift process as a model reaction. [ABSTRACT FROM AUTHOR]

Background: The leaf epidermis plays an important role in the transmission of light and the regulation of water and gas exchange, which influences the photosynthesis of mesophyll cells. Small papillae (SP) are one of the important structural elements of the leaf epidermis. The mechanism of the effect that small papillae have on rice leaf photosynthetic performance remains unclear. Results: In this study, a small papilla deficient 25 (spd25) mutant was isolated from japonica rice Longjin1. Small papillae were absent on the adaxial and abaxial leaf surfaces of the spd25 mutant and the silicon and cuticular wax content in the spd25 mutant leaves decreased. Map-based cloning and functional analysis revealed that SPD25, encoding a guanine nucleotide exchange factor for Rop, is a novel allele of OsRopGEF10. The spd25 mutant showed an increased water loss rate and reduced relative water content. The lower stomatal conductance in the spd25 mutant prevented water loss but decreased the intercellular CO2 concentration and net assimilation rate. The fluorescence parameters showed that the inhibited CO2 assimilation reaction feedback regulated the photochemical electron-transfer reaction, but the performance of Photosystem II was stable. Further analysis indicated that the excess light energy absorbed by the spd25 mutant was dissipated in the form of non-photochemical quenching to avoid photodamage through the optical properties of small papillae. Conclusions: SPD25 regulates the development of small papillae on the surface of rice leaves, which play an important role in balancing photosynthetic gas exchange and water loss. This study deepens our understanding of the physiological mechanisms by which small papillae affect photosynthetic performance. [ABSTRACT FROM AUTHOR]

Single-atom catalysts (SACs) are particularly sensitive to external conditions, complicating the identification of catalytically active species and active sites under in situ or operando conditions. We developed a methodology for tracing the structural evolution of SACs to nanoparticles, identifying the active species and their link to the catalytic activity for the reverse water gas shift (RWGS) reaction. The new method is illustrated by studying structure-activity relationships in two materials containing Pt SACs on ceria nanodomes, supported on either ceria or titania. These materials exhibited distinctly different activities for CO production. Multimodal operando characterization attributed the enhanced activity of the titania-supported catalysts at temperatures below 320 ˚C to the formation of unique Pt sites at the ceria-titania interface capable of forming Pt nanoparticles, the active species for the RWGS reaction. Migration of Pt nanoparticles to titania support was found to be responsible for the deactivation of titania-supported catalysts at elevated temperatures. Tracking the migration of Pt atoms provides a new opportunity to investigate the activation and deactivation of Pt SACs for the RWGS reaction. Platinum dispersed on metal oxide supports is widely used for industrially important catalysis such as the reverse water gas shift reaction, but active site migration and subsequent alterations in catalytic performance are still not fully understood. Here, the use of platinum on ceria nanodomes shows the detrimental effect of migration of platinum nanoparticles to titania supports at elevated temperatures. [ABSTRACT FROM AUTHOR]

The present paper considers the processes occurring in a failed fuel element during fuel cladding failure detection in the mast sipping system of the refueling machine. The time taken for water and fission gas products to leak from a failed fuel element during its lifting was estimated depending on the size of the defect. A period of 10–12 min exposure prior to bubbling was demonstrated to be applicable for detecting defects with a size of about 30 μm. The sizes of gas bubbles leaving the fuel element during the failure detection were estimated along with their rate of ascent. An algorithm for conducting fuel element failure detection that increases the sensitivity of the method without extending the refueling is proposed. [ABSTRACT FROM AUTHOR]

Synthesis gas is the cornerstone of many chemical processes for manufacturing a broad range of petrochemical products. In this work, a mathematical model was developed for investigation of the CO2 reforming of methane in a catalytic packed bed reactor. To simulate the reformer, a pseudo homogenous two-dimensional mathematical model was developed and the resulting nonlinear second order partial differential equations were solved using the finite difference method. It was assumed that equilibrium reverse water-gas shift reaction always takes place in the reactor to adjust H2/CO ratio (≤1). The effect of operating conditions, including bulk density, porosity, inlet gas and wall temperature, reactor diameter, total molar flow of gas and inlet CH4/CO2 ratio on the reactor performance were investigated. Finally, the study investigated the effect of H2/CO ratio on the outlet synthesis gas product at the range of 0.7–1. The validity of the model was investigated and the deviation between the model results and the experimental data was acceptable. [ABSTRACT FROM AUTHOR]

Subsurface reservoirs are large complex systems. Reservoir flow models are defined on complex grids that follow geology with relatively large block sizes to make consistent simulations feasible. Reservoir engineers rely on established reservoir simulation software to model fluid flow. Nevertheless, fluid front position inaccuracies and front smearing on large grids may cause significant errors and make it hard to predict hydrocarbon production efficiency. We investigate higher-order methods that reduce these undesired effects without refining the grid, thus making reservoir simulation more accurate and robust. For this paper, we implemented a second-order finite volume method with linear programming (LP) reconstruction in the open-source industry-grade reservoir simulator OPM Flow (part of the open porous media initiative, OPM). We benchmark it against the first-order method on full-scale cases with standard coarse and refined grids. We prepared open refined-grid models of a synthetic reservoir with an unstructured grid and refined Norne field example. Our results confirm that the LP method predicts front positions as accurately as the first-order method on the refined grid for problems dominated by transport. These include the water alternating gas scenario on the synthetic reservoir and piston-type injection on the Norne field. Moreover, we study the gains from the LP method for CO 2 injection problems on the Norne field with full multi-phase complexity beyond transport. We observe the relevant difference between the first- and the second-order methods in these cases. However, in some configurations, the reservoir complexity overshadows the gains from the second-order methods. [ABSTRACT FROM AUTHOR]

Designing novel catalysts is key to solving many energy and environmental challenges. Despite the promise that data science approaches, including machine learning (ML), can accelerate the development of catalysts, truly novel catalysts have rarely been discovered through ML approaches because of one of its most common limitations and criticisms—the assumed inability to extrapolate and identify extraordinary materials. Herein, we demonstrate an extrapolative ML approach to develop new multi-elemental reverse water-gas shift catalysts. Using 45 catalysts as the initial data points and performing 44 cycles of the closed loop discovery system (ML prediction + experiment), we experimentally tested a total of 300 catalysts and identified more than 100 catalysts with superior activity compared to those of the previously reported high-performance catalysts. The composition of the optimal catalyst discovered was Pt(3)/Rb(1)-Ba(1)-Mo(0.6)-Nb(0.2)/TiO2. Notably, niobium (Nb) was not included in the original dataset, and the catalyst composition identified was not predictable even by human experts. Despite the promise that machine learning (ML) can accelerate catalyst development, truly novel catalysts are challenging to find through ML approaches because of their inability to extrapolate. Here, the authors show an extrapolative ML approach to develop new multi-elemental catalysts. [ABSTRACT FROM AUTHOR]

A simplified and a numerical mathematical models of gas cooling and water heating in a thin turbulent bubbling layer on a tray with cross-phase flow are presented. The thermal efficiency of gas cooling is found using the ideal displacement model, and the temperature profile in the liquid phase is found from the solution of a cell model or a two-dimensional differential equation of convective heat exchange with an interfacial heat source. Examples of calculating the efficiency of water cooling of gas with different humidity on sieve and valve trays are given. The results of calculations of the thermal efficiency of gas cooling depending on the height of the gas–liquid layer, as well as on the gas velocity in the column are compared with known experimental data. Conclusions are drawn about the adequacy of the mathematical model and of the developed algorithm for calculating the heat and mass transfer characteristics of the bubbling layer. Comparative characteristics of the thermal efficiency of sieve and valve trays are given depending on the gas velocity and different heights of the liquid column. The influence of the variable mass of valves along the length of the tray on the increase in thermal efficiency is shown. Conclusions are drawn on the most efficient designs and modes of operation of bubbling trays. [ABSTRACT FROM AUTHOR]

Water-based enhanced oil recovery methods have been developed to improve the oil production rate from ultra-tight reservoirs. By coupling the effect of surfactant as wettability alteration and water alternating gas injection method, we aimed to determine the most efficient enhanced oil recovery technique. We performed seven injectivity scenarios to measure the oil recovery factor by introducing the alkylbenzene sulfonic acid (LABSA) as a surfactant agent during the active carbonated water alternating gas (ACWAG) injection. To consider the effect of slug size during water alternating gas injection, we used two different slug sizes (0.3, and 0.6). After the water breakthrough, a little oil volume was produced, and the maximum oil recovery factor at 1.5 Pore Volume (PV) was 26%. This issue corresponded to the water channeling after the breakthrough point. For smaller slug sizes (0.3), the maximum oil recovery factor (78%) was reached in smaller pore volumes. One of the exciting results wass the considerable influence of slug ratio during the water alternating gas (WAG) injection, in which it provided more oil recovery factor (83%) when the gas volume is higher than the water volume. Finally, by introducing the coupling effect of active carbonated water (made by LABSA surfactant) and WAG injection, the maximum oil recovery factor was 85%, corresponding to the better efficiency of active carbonated water in interfacial tension reduction. The results of this comprehensive investigation can be extended in ultra-tight sandstone reservoirs and can be applied as a further guideline in numerical simulations. [ABSTRACT FROM AUTHOR]

The study is presented on the influence of the composition of a ceria-zirconia support on the structure and the activity in water-gas shift reaction of platinum catalysts (Pt/Ce0.75Zr0.25O2 and Pt/Ce0.4Zr0.5Y0.05La0.05O2). The structure diagnostics of the samples were performed using high-resolution transmission electron microscopy, powder X-ray diffraction, CO chemisorption and X-ray atomic pair distribution function method. It was shown that the catalysts contain highly dispersed platinum particles not exceeding 2 nm in size. Platinum particles supported on Ce0.75Zr0.25O2 are smaller due to the higher specific surface area of the support. The catalysts Pt/Ce0.75Zr0.25O2 and Pt/Ce0.4Zr0.5Y0.05La0.05O2 proved to have similar efficiency while having the same platinum content. It was assumed that the catalysts supported on Ce0.4Zr0.5Y0.05La0.05O2 demonstrate a slightly higher turnover frequency per platinum surface atom, but it is likely compensated by the difference in the supported metal particle size. [ABSTRACT FROM AUTHOR]

The transport of water and gas is the most important process for the performance evaluation of landfill cover. However, the transport behaviors of these two components have been calculated separately (i.e., ignoring their coupling effect) in analytical solutions due to the complexity, although this coupling effect has been widely demonstrated in numerical studies, laboratory tests, and field tests. This study presents an analytical solution for coupled water–gas transport in a single-layer landfill cover, which can consider transient diffusive–advective transport of gas under steady-state water transport. The proposed analytical solution is verified against the field data, laboratory data, and numerical simulations. Parametric study is conducted to investigate the effects of four important parameters (i.e., infiltration rate, evaporation rate, desaturation coefficient, and saturated coefficient of water permeability) on the coupled water–gas transport behaviors, and the results indicate that these parameters all have a significant impact on the coupled water–gas transport (e.g., the gas emission flux for the case with desaturation coefficient α = 0.9 m–1 is 11.9 times greater than that with α = 0.3 m–1). For the simulations considered, ignoring the coupling effect would underestimate the steady-state gas emission flux by about 10.9– 54.2%, due to the changes of gas transport properties induced by water transport. The magnitude of this underestimation (i.e., error induced by ignoring the coupling effect) increases with decreasing infiltration rate, increasing evaporation rate, increasing desaturation coefficient, and decreasing saturated coefficient of water permeability. [ABSTRACT FROM AUTHOR]

Context: How to elucidate the effect of alkali metal promoters on gold-catalyzed water-gas shift reaction intrinsically remains a challenging, because that the complex synergy effects such as strong metal-support interactions, interfacial effects, and charge transfer of supported metal catalysts makes people difficulty in the understanding the alkali promotion phenomenon in nature. Herein, we report a systematically study of whole water-gas shift reaction mechanism on pure and the K-modified defected-Au(211) (i.e., by removing one surface Au atom from perfect Au(211) and make one model with the Au-Au coordination number is six) by using the microkinetic modeling based on first principles. Our results indicate that the presence of K can increase the adsorption ability of oxygen-containing species via the attractive coulomb interaction, has no significant effect on the adsorption of H species, but inhibits the adsorption of CO due to the steric effect. K promoter stabilizes the water adsorption by ~0.3 eV, which results in one order increasing of whole reaction rate. Interestingly, the strong promotion effect of the K can be assigned to the significant direct space interaction between K and the adsorbate H2O* through the inducted electric field, which can be further confirmed by the posed negative electric field on the unpromoted D-Au(211). Microkinetic modeling results revealed that the carboxyl mechanism is the most likely to occur, redox mechanism is the next one, and the formate mechanism is the least likely to occur. For different kinds of alkali metal additives, the adsorption strength of water molecules gradually weakens from Li to Cs, but Na shows the best promoter behavior at the low temperature. By considering the effect of K contents on the reactivity of water-gas shift reaction, we found that the K with the medium coverage (~0.2~0.3 ML) has the strongest promoting effect. It is expected that the conclusion of this work can be extended to other WGSR catalytic systems like Cu(or Pt). Methods: All calculations were performed by using the plane-wave based periodic method implemented in Vienna ab initio simulation package (VASP, version 5.4.4), where the ionic cores are described by the projector augmented wave (PAW) method. The exchange and correlation energies were computed using the Perdew, Burke and Ernzerhof functional with the vdw correction (PBE-D3). The transition states (TSs) were searched using the climbing image nudged elastic band (CI-NEB) method. Some electronic structure properties like work function was predicated by the DS-PAW software. Microkinetic simulation was carried out using MKMCXX software. [ABSTRACT FROM AUTHOR]

Enhancing oil recovery in reservoirs with light oil and high gas content relies on optimizing the miscible water alternating gas (WAG) injection profile. However, this can be costly and time-consuming due to computationally demanding compositional simulation models and numerous other well control variables. This study introduces WAGeq, a novel approach that expedites the convergence of the optimization algorithm for miscible water alternating gas (WAG) injection in carbonate reservoirs. The WAGeq leverages production data to create flexible solutions that maximize the net present value (NPV) of the field, while providing practical implementation of individual WAG profiles for each injector. The WAGeq utilizes an injection priority index to rank the wells and determine which should inject water or gas at each time interval. The index is built using a parametric equation that considers factors such as producer and injector relationship, water cut (WCUT), gas–oil ratio (GOR), and wells cumulative gas production, to induce desirable effects on production and WAG profile. To evaluate WAGeq's effectiveness, two other approaches were compared: a benchmark solution named WAGbm, in which the injected fluid is optimized for each well over time, and a traditional baseline strategy with fixed 6-month WAG cycles. The procedures were applied to a synthetic simulation case (SEC1_2022) with characteristics of a Brazilian pre-salt carbonate field with karstic formations and high CO2 content. The WAGeq outperformed the baseline procedure, improving the NPV by 6.7% or 511 USD million. Moreover, WAGeq required fewer simulations (less than 350) than WAGbm (up to 2000), while delivering a slightly higher NPV. The terms of the equation were also found to be essential for producing a WAG profile with regular patterns on each injector, resulting in a more practical solution. In conclusion, WAGeq significantly reduces computational requirements while creating consistent patterns across injectors, which are crucial factors to consider when planning a practical WAG strategy. [ABSTRACT FROM AUTHOR]

Active areas of research on chemical looping technologies for the conversion of CO2 to CO are contrasted and discussed, including current performance, methods for material design, and next steps in expanding their development. Generation of CO from CO2 is of interest in sustainable chemistry and engineering to convert anthropogenic CO2 emissions into feedstock for Fischer–Tropsch (FT), methanol to gasoline (MTG), gas-to-liquid (GTL), and other synthesis pathways for fuels and materials. Chemical looping strategies have been identified which not only produce CO, but also H2 from H2O and methane sources, supplying the other key component of syngas. Configurations of these chemical looping technologies into the materials economy potentially constitute sustainable carbon loop cycles for fuels as well as carbon sequestration into industrial and commercial materials. Major areas of research in CO2 conversion by chemical looping, collectively referred to here as CO2CL, including Solar-Thermal Chemical Looping (STCL), Reverse Water Gas Shift Chemical Looping (RWGS-CL), Chemical Looping Reforming (CLR), Super Dry Reforming (SDR), Autothermal Catalyst Assisted Chemical Looping (ACACL), and Reverse Boudouard Reforming (RBR) are discussed in terms of their process characteristics, historical development of oxygen carrier (OC) material, state of the art methods for material design, and future work needed to advance the scale-up of these technologies. This perspective centers around the non-methane utilizing processes for CO2CL, focusing on the phenomena of oxygen transfer between gas molecules and the oxygen carrier (OC). [ABSTRACT FROM AUTHOR]

In order to estimate the effect of hydrogen bond network isomerism on the thermodynamic functions and concentrations of water clusters in the gas phase, the structural and thermodynamic parameters of all 133 possible isomeric structures of water hexamer (H 2 O) 6 in the initial conformations of the book, cage and prism types have been studied using the DFT (B3LYP/6-311++G(2d,2p)), DFT-D3 (B3LYP/6-311++G(2d,2p)), G4, W1BD, DFTB, and MB-pol calculations. It was found that accounting of the orientational isomerism leads to the values of water cluster gas-phase concentrations different by 1 or 3 orders of magnitude (depending on the method of energy calculation and averaging) from the results obtained when only single energetically favorable structure is considered. The absolute Boltzmann-averaged estimates of the hexamer binding enthalpy per monomer are of 5.50 (G4 results) and 5.77 (DFT results) kcal/mol. The total concentration of H 2 O 6 including all isomers in the saturated water vapor at standard conditions are estimated as 1.61 · 10 3 (G4) and 8.17 · 10 5 (DFT) molecules/cm 3 with W1BD indirect estimates lying between these values. [ABSTRACT FROM AUTHOR]

In fractured reservoirs, the seismic response characteristics are more complex than in conventional reservoirs because of their inherent properties of anisotropy and dispersion-attenuation, increasing the multiplicity of the prediction solutions and making fluid identification more difficult. Since fluid saturation is a crucial parameter that can directly affect these inherent properties, its effect on F-AVAZ (frequency-dependent amplitude versus angle-azimuth) seismic response characteristics of fractured reservoirs is studied in this article. Using Norris and KG models, an effective partially saturated fractured porous medium is established. Based on the anisotropic reflectivity algorithm, the deterministic relationship between F-AVAZ and fluid saturation is obtained. The numerical simulation results of the three-layer model show that when oil–water coexists in fractured reservoirs, F-AVAZ gradually changes with growing water saturation. While the fluid changes from fully water saturated to gas bearing, F-AVAZ suddenly jumps because of the rapidly decreasing effective P-wave modulus. This abrupt increase of P-wave amplitude is the classic 'bright spot' phenomenon, which verifies the validity of the anisotropic reflectivity algorithm based on the Norris-KG model for fractured reservoirs. This study lays a solid theoretical foundation for the analysis of seismic response characteristics of multi-phase fluid saturated fractured reservoirs and provides a reliable theoretical basis for improving reservoir prediction and fluid identification accuracy. [ABSTRACT FROM AUTHOR]

Applications of the traditional static material-balance method in gas reservoirs become a challenge with production maturity due to variability in aquifer influx, infill drilling, and production-operational changes in offset wells, among others. Besides, some existing modeling approaches involve a trial-and-error method, making the solution outcomes nontrivial. This study proposes a new methodology for analyzing production data involving water-drive gas reservoirs. The main findings of this study include the following: (1) A straight-line plot that yields gas and water in-place volumes, (2) A modified-(pav/z)* plot exhibits a straight-line with an x-intercept of gas initially-in-place, similar to that in a conventional-(pav/z) plot, (3) A new definition of degree of aquifer support that is quantifiable using production data. Synthetic data verified the proposed modeling approach, whereas a field dataset provided validation. [ABSTRACT FROM AUTHOR]

The perforation of shale gas transportation pipelines occurred frequently in the form of pitting corrosion because of microbiologically influenced corrosion (MIC). In this study, the pitting corrosion behavior of L245N pipeline steel in shale gas produced water with sulfate reducing bacteria (SRB) and iron oxidizing bacteria (IOB) was studied. The results indicate that the development of pitting corrosion can be divided into three stages. The compact biofilm was formed in the second stage and facilitated the appearance of pits. The major mechanism of pit growth was electron uptake from elemental iron by sessile SRB settled in the biofilm. The corrosion prevention strategy was briefly discussed. [ABSTRACT FROM AUTHOR]

Some methods were considered to remove tritium-containing hydrogen compounds from various gas flows from scientific and production facilities in the nuclear and thermonuclear power industry. The possibilities of tritium removal from a gas flow in the form of hydrogen were analyzed, and it was concluded that these methods can be applied at low flow rates of the gas being purified. At high gas flow rates, the main detritiation methods are adsorption and water phase isotope exchange. Both these methods include the preliminary catalytic oxidation of tritium-containing molecules to water with the further removal of tritiated water from the gas. The main technological parameters of these methods were compared, and it was inferred that phase isotope exchange has great advantages. [ABSTRACT FROM AUTHOR]

The objective of this work was to study the effect of water stress on the physio-morphological and biochemical characters of green kohlrabi (Brassica oleracea var. gongylodes L.) and to identify its various adaptive strategies to counter stress. The greenhouse germination and cultivation of kohlrabi were conducted under various water stress conditions (0, 25, 50, and 75% Field Capacity (FC)) or without as a control. A rehydration (100% FC) of the treated plants was carried out, in order to highlight the capacity of the growth recovery and normal development in this variety. The adaptive strategies, tolerance mechanisms and resistance limits of this plant to drought were discussed. The results have shown that B. oleracea var. gongylodes adopts several strategies to counter water stress. It activates the tolerance mechanisms by actuating the biosynthetic pathways of osmolytes, such as proline and soluble sugars to ensure osmotic adjustment, as well as phenolic compounds and flavonoids. It also adopts the avoidance strategy as a mechanism for countering drought stress. In fact, kohlrabi limits the losses of water by perspiration (decrease of the number and surface of the leaves and reduction of the stomatic conductance), and it improves the absorption of water, by the establishment of a long and vigorous root system. [ABSTRACT FROM AUTHOR]