Gas-air Mixture Research Articles

Периоперационное кондиционирование оксидом азота для предотвращения острого почечного повреждения при кардиохирургических вмешательствах у пациентов с хронической болезнью почек: промежуточные результаты рандомизированного контролируемого исследования DEF

INTRODUCTION: Acute kidney injury (AKI) is a common and serious complication after cardiac surgery performed under cardiopulmonary bypass (CPB). Patients with chronic kidney disease (CKD) are particularly vulnerable to cardiac surgery-associated AKI. Nitric oxide (NO) has great potential for implementing multi-organ protection in cardiac surgery. OBJECTIVES: To test the hypothesis that perioperative nitric oxide conditioning has a good safety profile and reduces the incidence of acute kidney injury during cardiac surgery under cardiopulmonary bypass in patients with chronic kidney disease. MATERIAL AND METHODS: An interim analysis of the results of the single-center prospective randomized controlled trial DEFENDER was conducted. Currently, the study included 96 patients with CKD who underwent cardiac surgery under CPB. Patients was randomized into 2 equal groups consisting of 48 people each. In the experimental group, during the operation and 6 hours after it, 80 ppm NO was delivered through the ventilator and CPB circuits. In the control group, during the operation and 6 hours after it, a standard oxygen-air mixture without NO was delivered through the ventilator and CPB circuits. The end points of the study were: the difference between groups in the incidence of AKI, the incidence of postoperative complications, outcomes and the safety profile of NO therapy. RESULTS: In the experimental group, the incidence of AKI was significantly lower compared to the control group (16,7 и 35,4 %, p = 0.036). In the experimental group, nitrogen dioxide concentration in the gas-air mixture and methemoglobin level were not above the reference range. The groups did not differ in the frequency of blood transfusions, the amount of postoperative bleeding, or the number of platelets on the first day after surgery. CONCLUSIONS: Perioperative nitric oxide conditioning has a good safety profile and reduces the incidence of acute kidney injury during cardiac surgery with CPB in patients with chronic kidney disease.

ОБҐРУНТУВАННЯ КОМПЛЕКСНОГО ПРОЕКТУ ВИРОБНИЦТВА ТЕП-ЛОВОЇ ТА ЕЛЕКТРИЧНОЇ ЕНЕРГІЇ З ВИКОРИСТАННЯМ МЕТАНУ ЗА-КРИТИХ ШАХТ

The article deals with the issue of methane extraction from closed mines for its further use as an alternative energy source. A substantiated and developed method of methane extraction from the dome of the collapse of closed mines, while a mobile surface degassing unit is used to extract methane from the installed places of gas collectors. The use of the proposed method of methane extraction will improve the environmental safety of the man-made and natural environment, solve the issue of disposal and use of methane as fuel for cogeneration plants. To ensure the company's own production of electricity and thermal energy, a gas-piston cogeneration power plant has been justified and selected.At the first stage of the project, methane reserves of closed mines are calculated. As a result of the collapse of the roof layers above the created space in the mountain massif, a displacement vault and a "collapse dome" are formed. Methane accumulates under the collapse dome. The parameters of the vault depend on the depth of the cleaning work and the size of the created space. At the second stage, a mobile surface degassing unit is used to extract methane from closed mines from established places of methane accumulation. The advantage of a mobile surface degassing unit is its mobility, which makes it possible to install it in the necessary places, as well as carry out degassing and achieve significant volumes of capted gas with a methane content of up to 80%. To obtain a gas-air mixture of the required concentration (from 25% to 40%), a methane concentration increaser is used. The third stage is the substantiation of the type of power plant for the design of a gas turbine or gas piston mini thermal power station, taking into account individual conditions and technical tasks.

Coarse-grained modeling of high-enthalpy air flows based on the updated vibrational state-to-state kinetics

The state-to-state (StS) model can accurately describe high-temperature thermochemical nonequilibrium flows. For the five-species air gas mixture, we develop a comprehensive database for the state-specific rate coefficients for temperatures 300–25 000 K in this paper. The database incorporates recent molecular dynamics simulations (based on the ab initio potential energy surfaces) in the literature, and theoretical methods, including the forced harmonic oscillator model and the Marrone–Treanor model, are employed to complement the rate coefficients that are unavailable from molecular dynamics calculations. The post-shock StS simulations using the present database agree with the experimental NO infrared radiation. Based on this updated StS kinetics database, we investigate the post-shock high-enthalpy air flows by employing both the StS and coarse-grained models (CGM). The CGM, which lumps molecular vibrational states into groups, shows results that align with the StS model, even utilizing only two groups for each molecule. However, the CGM-1G model, with only one group per molecule and belonging to the multi-temperature model (but uses StS kinetics), fails to reproduce the StS results. Analysis of vibrational energy source terms for different kinetic processes and fractions of vibrational groups reveals that the deficiency of the CGM-1G model stems from the overestimation of high-lying vibrational states, leading to higher dissociation rates and increased consumption of vibrational energy in dissociation. Furthermore, the presence of the Zeldovich-exchange processes indirectly facilitates energy transfer in N2 and O2, a phenomenon not observed in binary gas systems. These findings have important implications for developing the reduced-order model based on coarse-grained treatment.

Ventilation of large section blind headings under conditions of changing ore load size

Relevance. The need to ensure safe working conditions in the working areas of underground mines. Stagnant zones with low air velocities can be formed in large section blind heading behind the ore bulk when ore is shipped by mining machines. There is a possibility of the formation of local gas accumulations and their abrupt removal later in such stagnant zones due to the unsteadiness of accumulation and transfer of gas impurities in a blind heading. A sharp removal of gas will lead to contamination of the load-haul-dump operators’ workplace. Aim. To identify removal of exhaust gases in large section blind headings in conditions of changing ore load size. Objects. Large section blind headings with of complex geometry. Methods. Three-dimensional numerical simulation of unsteady turbulent flow of a gas-air mixture in the Ansys CFX, visualization and analysis of simulation data in the Wolfram Mathematica. Results. The paper presents the results of mathematical modeling of ventilation of large section blind headings of complex geometry under conditions of changing ore load size formed during mining operations by the load-haul-dump machines with an internal combustion engine. It is shown that either a single vortex is formed that ventilates the blind headings space, or a stagnant zone behind the bulk ore, which is characterized by a relatively low intensity of mass transfer. Vortex formation depends on the height of the ore bulk. The authors have obtained the dependences of the change in the average concentration of exhaust gases at the outlet of the blind headings space on the operating time of the machine. They determined the dependence of the correction volume coefficient on the geometric parameters of the blind headings. An analytical model of the removal of gases from the blind headings space under conditions of changing bulk ore volume is obtained. The expression of increment in gas concentration on an operator’s workplace makes it possible to derive formula to find maximum time of load-haul dump operation in a stope such that gas concentration is never higher than maximum allowable concentration.

Modeling and Mitigating Gas Hazards during Potash Mine Closure

The planned closure of potash mines achieved through the injection of highly mineralized brines into the worked-out area is a complex process. A critical concern arises when brines obstruct the aerodynamic connections between the flooded mine’s airspace and the atmosphere, potentially leading to the formation of closed cavities where explosive gases can accumulate. To address this hazard, it is imperative to develop systems capable of extracting the gas–air mixture from the unflooded part of the worked-out area. Two distinct scenarios are examined: the first involves controlled flooding with saturated brines, while the second contemplates flooding resulting from a hypothetical breakthrough of supra-salt strata, leading to the ingress of groundwater into the worked-out area. A novel mathematical model is introduced to predict the evolution of gas–air mixture parameters in the unflooded part of the worked-out area. Utilizing this model, we assess the effectiveness of proposed measures designed to eliminate explosive gases from the worked-out area. Specifically, a pipeline system is proposed for the removal of gases. The findings from this study contribute valuable insights into ensuring the safe and efficient closure of potash mines, shedding light on potential risks and effective mitigation strategies for gas-related hazards during planned flooding.

SELECTION OF GAS MIXER PARAMETERS FOR DIESEL CONVERSION GENERATOR MOTOR IN GAS DIESEL

According to literary sources, options for converting diesel engines into dual-fuel engines for operation on any fuel, in particular, natural gas (NG), were analyzed. The conversion method with external mixture formation and an ignition dose of liquid fuel involves the preparation of a gas-air mixture of the required composition in a special device. The methodology for choosing the design parameters of the gas mixer for the organization of the work process of a V-shaped diesel engine type 12Ch 15/17.5, converted into a gas diesel, which works as part of a motor-generator unit of backup power supply, is given. The basic design of the diesel motor-generator was analyzed. A comparative calculation of the working processes of diesel and gas-diesel variants of execution (with an ignition dose of diesel fuel of 10%) was carried out. The requirements for the design and location of the gas mixer have been formed. In the work, using 3D modeling technologies, the geometry of the gas mixer and its flow part were formed. Using the method of finite volumes, the calculation grid was synthesized and its adaptation near solid walls was carried out. Next, a series of numerical experiments was conducted in a three-dimensional setting to evaluate the throughput and quality of mixing network methane with air (when the robot is operating at typical operating modes). The distribution of flow velocities in the vertical and horizontal planes of the flow part of the gas mixer was evaluated, the change in pressure along the height of the gas mixer and the distribution of the mass fraction of methane in the flow part of the engine intake tract were analyzed, and scientific and practical recommendations were developed to ensure the efficient operation of gas diesel as part of a motor-generator installation. It is shown that the proposed design of the gas mixer allows effective mixing of methane with air when operating in the entire power range of the considered engine. The use of 3D modeling technologies, with the use of modern numerical methods, allows you to assess the operating conditions of the mixture by macro indicators and in local sub-regions, which allows, in the future, to develop recommendations for increasing the efficiency of the process of preparing the fuel-air mixture.

Design and optimization of a combi boiler heat exchanger: A CFD-based approach

Heat exchangers are widely used in various fields, emphasizing the importance of efficiency and mass/dimensional improvements. Aluminum boiler heat exchangers play a crucial role in systems, where the natural gas-air fuel mixture is burned and heat transfer to water occurs. In such heat exchanger designs, the region where the air-gas mixture burns is referred to as the “combustion chamber,” and the thermal energy produced is transferred to the circulating water in the body.In this study, it was aimed to improve the heat transfer per unit surface by using novel pin–fin geometries in DAIKIN NDJ 24 kW aluminum cast boiler heat exchanger, thus reducing and lightening the dimensions of the combi heat exchanger for the same thermal performance. This approach targets cost reduction in production and downsizing of the boiler dimensions for more compact units. Cleanability limit was also established, and a unique symmetric droplet model was optimized utilizing a Computational Fluid Dynamics (CFD) based Response Surface Methodology (RSM) approach. Predictions of thermal performance through CFD simulations were subsequently validated experimentally using test bench available at DAIKIN’s facility in Sakarya, Türkiye. The results demonstrated a remarkable of 14% reduction in the overall weight, which was achieved by shortening the combi boiler height by 26 mm, while preserving the same efficiency levels. This research underscores the potential of the innovative pin geometry and optimized droplet model to enhance the efficiency and performance of the heat exchanger, with implications for cost savings and improved manufacturing processes. Also the effect of the new pin-fin geometry on the condensation performance was investigated as a multiphase phenomenon for the first time in the international literature. The results showed an excellent agreement between predicted and measured performance data.

Bubble-graft coverage after Descemet Membrane Endothelial Keratoplasty depending on gaze angle.

In Descemet Membrane Endothelial Keratoplasty (DMEK) a gas bubble is usually used to attach the graft to the host cornea. In this study, we observed the bubble size and bubble-graft coverage at different gaze angles following DMEK. This observational prospective study analyzed 465 images of patients who underwent an uneventful DMEK. Intraoperatively, the anterior chamber was filled up to 90% of its volume with a 20% Sulfur Hexafluoride (SF6) gas-air mixture. Postoperatively, the bubble was photographed daily in different gaze angles ranging from a supine position (0°) to an upright position (90°) and a slightly inclined position (105°). The primary outcomes were bubble-graft coverage and bubble diameters depending on the gaze angle and time after DMEK. The highest bubble-graft coverage was achieved at a 0° gaze angle at all times of measurement. In the first 48 h after DMEK, the mean bubble-graft coverage was over 85% at a gaze angle between 0° and 45°. Starting 72 h after DMEK, the graft coverage declined at all gaze angles. The graft coverage at a 0° gaze angle was 88.61 ± 10.90% after 96 postoperative hours, while the graft coverage was below 85% at all other gaze angles. Our clinical results provide novel insight into variation in bubble-graft coverage as a function of gaze angle and may be used to aid in patient counselling for appropriate body positioning following DMEK to prevent early graft detachment. Maintaining supine positioning seems to be most advantageous starting 48 h after DMEK.

Development and Application of Unsealed Borehole Leakage Detection Device Based on Flow Method

Poor sealing of gas extraction boreholes is one key to restrict gas extraction efficiency. In this paper, a novel borehole sealed quality detection device for the gas extraction of a coal mine is developed based on the theory of air leakage. By comparing the amount of gas extracted at different test points, it is possible to determine whether there is air leakage around the borehole, and the specific leakage position and leakage amount. Moreover, this device has the advantages of simple operation and a short test period. Based on the above analysis, a corresponding air leakage disposal method was proposed to handle the leaky boreholes. Field tests showed that the air–gas mixture flow in the test borehole was reduced by a factor of approximately 1.55 and the concentration of pure seam gas was increased approximately six times after the disposal of the air leaks. The combination of the leakage disposal method and the leakage detection device can accurately seal the borehole at the position of the leak, thus effectively ensuring the effectiveness of gas extraction from the borehole. The findings have important implications for improving the efficiency of gas extraction in coal mining operations.

Laser ignition versus conventional spark ignition system performance for hydrogen-enriched natural gas-air mixtures in a constant volume combustion chamber

This study compares the performance of a laser ignition system vis-à-vis a conventional electrical spark ignition system in a constant volume combustion chamber. A custom-built constant-volume combustion chamber was used to compare the performance of the laser and spark ignition systems. A combination of three lenses in the optical path was used to create laser plasma in the constant volume combustion chamber. Initial chamber pressure and temperature were maintained constant at 4 bar and 150 °C during the experiments. The effect of hydrogen enrichment of compressed natural gas on combustion was assessed for three relative air–fuel mixture strengths (λ: 1.0, 1.2 and 1.4) to compare the performance of both ignition systems. The laser ignition system exhibited superior combustion characteristics to the spark ignition system. The combustion duration of laser ignition was considerably lower than spark ignition. Three hydrogen-enriched natural gas blends (10HCNG, 20HCNG and 40HCNG) were assessed and compared with baseline compressed natural gas. Hydrogen enrichment improved the combustion characteristics, increasing the excess chamber pressure and reducing the combustion duration. Two locations were taken for assessing the performance of the laser ignition system in this study. The first location was the same as the spark from a conventional electrical spark ignition system, and the second was at the centre of the constant volume combustion chamber. The central location of laser ignition showed a higher reduction in the combustion duration than baseline spark ignition and its corresponding laser ignition, indicating its superiority. The ability to choose an ignition location centrally in the engine combustion chamber emerged to be a main advantage of laser ignition systems.

Investigations on conical lean turbulent premixed hydrogenated natural gas flames

Hydrogen's ability to enhance carbon neutrality in combustion processes puts forward the use of hydrogenated fuels, both in the form of fuel and an energy carrier as a potential decarbonization solution. However, because of the nature of hydrogen, blending it with hydrocarbons causes crucial structural changes in the flame structure, including higher flame propagation velocities and higher flame temperatures, decreased instantaneous flame thickness, and increased risks of flame flashback and an increasing potential of NOx emissions due to higher flame temperatures. These attributes encourage a thorough examination of hydrogenated blends of hydrocarbon fuels. Using lean premixed fuels is another technique to achieve efficient and cleaner combustion. However, due to the problem of flame instability in lean premixed combustion, forecasting the design points in terms of flame attributes is critical for better combustor designs.In this study, conical (Bunsen type) lean premixed turbulent flames of hydrogenated natural gas-air mixtures are experimentally studied. Through chemiluminescence measurements of the OH* and CH* radicals and laser-induced Mie scattering, lean natural gas-air premixed flames are examined with subsequently increasing hydrogen addition rates up to 20% by volume and keeping the premixture velocity constant. The obtained data is utilized for exploring the dynamics of the turbulent flame front. The main turbulent premixed flame parameters we identified relate to the instantaneous and average topology of the flame such as the turbulent flame brush thickness and flame height. We also inferred global combustion parameters like the turbulent flame propagation speed from the experimental findings.

Preparation of low-concentration H2 test gas mixtures in ambient air for calibration of H2 sensors

Abstract. Using electrochemical gas sensors for quantitative measurements of trace gas components in ambient air introduces several challenges, of which interference, drift and aging of the sensor are the most significant. Frequent and precise calibration as well as thorough characterization of the sensor helps to achieve reliable and repeatable results. We therefore propose the use of a simple, lightweight and inexpensive setup to produce hydrogen calibration gases with precisely known concentrations in ambient air. The hydrogen is produced by electrolysis with electric current monitoring, and the output can be set to any value between ∼ 3 and ∼ 11 µgH2min-1. With a dilution flow of 500 mL min−1, for example, this results in a concentration range from ∼ 70 up to ∼ 240 ppm, but concentrations significantly below or above this range can also be covered with accordingly modified dilution flows. This setup can be used not only for calibration, but also for thorough and long-term characterization of electrochemical gas sensors to evaluate sensitivity, zero voltage and response time over extended periods of time.

Impact of supply and exhaust ventilation system on gas concentrations in a compartment during thermal decomposition and combustion of materials

Experiments were conducted on the detection of fires when using different operation modes of an indoor supply and exhaust ventilation system. The operating conditions of the supply and exhaust ventilation system were identified that exclude the formation of hazardous concentrations of products of thermal decomposition, gasification and combustion of class A materials (wood, cardboard and linoleum). The changes in the concentrations of the gas-air mixture components (CO, O2, CO2) were recorded in different operation modes of the supply and exhaust ventilation system and for different mechanisms of thermal decomposition and flame combustion initiation. The performance characteristics of the supply and exhaust ventilation system were determined that are necessary and sufficient for efficient operation of fire detection, containment and suppression systems.

MATHEMATICAL MODELING OF THE AUTONOMOUS HEAT SUPPLY SYSTEM WITH TUBULAR GAS HEATERS IN BUILDING STRUCTURES WHEN OPERATING IN THE CONDENSATION MODE

Problem statement. The application of modern autonomous heat supply systems is one of the directions of reducing the consumption of natural energy resources. There are many different autonomous systems of heat supply of objects. One of the variants of such systems is the system with tubе gas heaters. A tube gas heater consists of a gas burner, a radiating tube and a fan. One of the technical solutions for such heat supply systems is a tubular heater located inside the building structure. Increase of the efficiency of gas equipment can be achieved by operating this equipment in the condensation mode. Therefore, the operation of tubular gas heaters in building structures in the condensation mode is quite interesting in terms of increasing the efficiency of utilisation of the thermal potential of gaseous fuel and ensuring its saving. For research and practical design of autonomous heat supply systems with gas tube heaters in building structures with regard to the condensation mode of operation it is essential to develop a mathematical model for calculating the thermal and hydraulic modes of the system. The purpose of the article is to develop a mathematical model of an autonomous heat supply system with tubular gas heaters in building structures when operating in the condensation mode. Conclusion. The mathematical model of hydraulic and thermal modes of autonomous heat supply system with tubular gas heaters in building structures when operating in the condensation mode was developed. It is presented in the form of differential equations. The model is based on the equations of conservation of mass, motion and energy for the gas-air mixture inside the canal in two-phase flow, the equation of heat transfer inside the building structure, the equation of heat transfer from the external surface of the heater to the environment. The mathematical model of hydraulic and thermal modes of autonomous heat supply system with tubular gas heaters in building structures when operating in the condensation mode will be used to calculate and design such systems.

Comparative assessment of methods for determining hydrocarbon weight content in gas-air mixture

Comparative assessment of methods for determining hydrocarbon weight content in gas-air mixture

Самовоспламенение пылегазовоздушных смесей в атмосфере горных выработок

The underground mining of coal deposits is usually accompanied by manifestation of a number of negative factors, one of which is the presence of dust and gas-air mixtures consisting of fine coal dust, methane released from the broken coal and the air of the mine atmosphere. Despite modern methods and means of dust suppression and dust collection, it has not yet been possible to achieve complete neutralization of dust and gas-air mixtures in the atmosphere of mine workings. The negative effects of dust and gas-air mixtures can manifest themselves in different ways. On the one hand, deposits of coal dust in the worked-out spaces, under certain conditions, form foci of spontaneous combustion, which are the causes of endogenous fires. On the other hand, dust and gas-air mixtures are predisposed to ignition from external sources or to spontaneous ignition followed by combustion in the form of deflagration, which, under certain conditions, turns into detonation, spreading in the atmosphere of mine workings at supersonic speed. This article considers a nonstationary one-dimensional problem of selfignition of dust and gas-air mixtures in the air flows of mine workings. The temperature and the period of spontaneous ignition of dust-gas-air mixtures are found based on the solution of this problem, expressed numerically using the Geer method. An analysis of the mixture self-ignition process is performed and some patterns of the influence of the parameters of mixtures on the period of their self-ignition are revealed.

Directional motion of discharge filaments pattern in a ratchet dielectric barrier discharge system

The directional motion of the discharge filaments pattern with controllable motion speed is achieved by using a novel dielectric barrier discharge device with a ratcheting asymmetric boundary. It can be observed in a gas mixture of argon and air over a considerably wide parameter range of gas pressure from 12 to 55 kPa and argon content from 0% to 90%. The motion speeds are adjustable with a maximum range of 1.25°/s to 6.25°/s by altering the argon concentration and gas pressure. Notably, the discharge filaments move along the ratchet-tilting direction while maintaining a hexagonal arrangement. The filaments of the hexagonal structure, that is, the main part of the pattern discharge simultaneously as demonstrated by the results of the intensified charge-coupled device measurements. The transverse electric field (parallel to the dielectric plate) simulated by solving the Poisson equation exhibits an asymmetric spatial distribution. A net tangential force from the asymmetric transverse electric field is exerted on the pattern, driving it to a directional motion.

TEST RESULTS OF DOMESTIC RECUPERATIVE COALS

Adsorption steam recovery plants (VRS) of oil and petroleum products are among the most common in the world. This is facilitated by their relatively high throughput, low energy consumption, and a sufficiently high achievable degree of purification of the gas-air mixture (GAM) from hydrocarbons. The main consumable material in this case is an adsorbent – a substance capable of first selectively attaching hydrocarbon gases contained in hot water to its surface, and when thermodynamic conditions change, it detaches them. Most often, recuperative (activated) coal is used as an adsorbent. During operation, the adsorption capacity of recuperative coal gradually decreases. This is facilitated by the mechanical destruction heavy hydrocarbons contained in the hot water, which cannot be fully isolated during the desorption operation. Therefore, periodically recuperative coal requires replacement.Until recently, it was purchased abroad. Usually, recuperative coal was supplied complete with the recuperation units themselves, supplied from abroad. However, to date, adsorption VRS have begun to be produced in Russia. In addition, the endless sanctions of the West are forcing us to look for sources of supply of this adsorbent inside the country.The article presents the results of comparative laboratory tests of a number of recuperative coals for use in the adsorption of hydrocarbons from hot water. According to the of coal granules, as well as water vapor and value of the integral efficiency indicator, the best of them was the Sorber-30 brand coal. In addition, the enterprise at which it is produced has the necessary production facilities, human resources, capabilities for conducting input quality control of raw materials and the quality of finished products, and also supplies recuperative coal to consumers in sufficiently large volumes, i.e. is a reliable supplier.The article also describes the results of comparative industrial tests of the recovery coal «Sorber-30» and imported coal of the brand «CGF4 plus», operated in the adsorption VRSin LLC «Transneft – Port Kozmino» since 2014.

Ascending Performance of Scientific Balloons with Buoyant Gas–Air Mixture Inflation for Designated Ceiling Height

This paper aims to investigate a new method that uses buoyant gas mixed with air to control the floating height of scientific balloons. Firstly, the static characteristics and thermophysical properties of mixed-gas balloons are analyzed. Subsequently, the inflation model and the thermal-dynamic coupled model are established. Furthermore, based on theoretical research, a GUI program is compiled to simulate the ascent of mixed-gas balloons. Finally, flight tests are conducted. As the balloon volume expands to the maximum, the vertical velocity begins to decay and eventually oscillates around 0 m/s, which is consistent with the simulation. In addition, there is a noticeable shift in which the balloon starts to float after climbing to the target altitude, and the difference values between the test and the simulation are less than 350 m. Moreover, the trajectory results are similar to the prediction, and the errors of the end position are less than 2.5 km in horizontal distance. Consequently, this paper provides guidance for balloon-designated ceiling height technology which can allow a single balloon system to be used for tests at multiple heights.

An experimental and theoretical approach for the biogas dry reforming reaction using perovskite-derived La0.8X0.2NiO3-δ catalysts (X = Sm, Pr, Ce)

The work presented herein reports on the investigation of the biogas dry reforming catalytic performance of LaNiO3 (LNO), La0.8Sm0.2NiO3 (LSNO), La0.8Pr0.2NiO3 (LPNO) and La0.8Ce0.2NiO3 (LCNO). The perovskite-type materials were synthesized via citrate sol-gel and characterized using XRD, N2 physisorption H2-TPR, H2-TPD, TEM, HAADF-STEM and XPS. The performance of all catalysts in terms of both activity and stability was examined in order to assess the effect of temperature on the CH4 and CO2 conversion, as well as on the H2 and CO yield and the H2/CO molar ratio of the produced gas mixture. Experimental results showed that modification of LaNiO3 with Sm and Pr enhanced the catalytic performance in terms of catalytic stability and reduced the order/crystallinity of the deposited coke. A theoretical model was also produced in Python with the purpose of simulating the catalytic performance. Modelling results showed a good agreement with the experimental values and therefore confirm the validity of the model for predicting the dry reforming catalytic performance.