Syngas Research Articles

Gasification of Coal and Biomass Mixtures

The results of an analysis of the state of developments in the field of gasification of coal and biomass mixtures are presented. It is shown that this is a promising direction for diversifying the areas of coal application and a new area for using biomass as a renewable natural resource. The specific features of the process of gasification of coal and biomass mixtures are considered. A comparison of gasifiers of various types was carried out, and the technology and the type of gasifiers that are of particular interest for the production of synthesis gas from the mixtures of coal and biomass were identified.

Gasification of Coffee Parchment as Potential Method for Coffee Agro-Industry Waste Utilization

Coffee parchment is a lignocellulosic waste material which has a potential to transform into synthesis gas. This research aims to study the feasibility of coffee parchment conversion under downdraft gasification with ‘auto-heating’ supply method. The temperature profile in each zone of the reactor was investigated as the effect of different equivalence ratio (ER) as well as the producer gas characteristics such as ignition time, flame duration, colour and temperature, carbon conversion and producer gas composition. Initially, coffee parchment collected from dehulling process was sun-dried three to four days. The gasification was ignited by firing ca. 300 g of wood charcoal inside the reactor before the coffee parchment loaded, then the reactor was tighly closed. Once the combustible gas was produced, the gasification time was measured. The result shows that the highest operational temperature inside the reactor was 715.66 °C within the combustion zone. The biomass conversion tends to increase by the increasing of ER, but the producer gas might dilute by more carbon dioxide production, and nitrogen input into the producer gas which indicated by the flame duration, colour, and temperature. Introducing an ER of 0.3 into the gasification reactor has provided adequate amount of oxygen to convert the coffee parchment into producer gas. This investigation suggests that coffee parchment is feasible to be converted into syngas. However, providing an advance process integrated to cleaning system would be required in the future to obtain a fuel grade syngas.

A Waste-to-Energy Technical Approach: Syngas–Biodiesel Blend for Power Generation

In this study, a technical analysis of synthesis gas (syngas) and biodiesel blend utilized in an internal combustion engine is presented. The experimental setup is composed of an engine workbench coupled with a downdraft gasifier which was fed with forest biomass and municipal solid waste at a blending ratio of 85:15, respectively. This research paper aims to contribute to the understanding of using fuel blends composed of synthesis gas and biodiesel, both obtained from residues produced in a municipality, since the waste-to-energy approach has been trending globally due to increasing waste generation allied with rising energy demand. The experiments’ controlling parameters regarding the engine are rotation and torque, exhaust gas temperature, and fuel consumption. The gasification parameters such as the oxidation and reduction temperatures, pressures at the filter, hood, and reactor, and the volume of tars and chars produced during the thermochemical process are also presented. Ultimate and proximate analyses of raw materials and fuels were performed, as well as the chromatography of produced syngas. The syngas produced from forest biomass and MSW co-gasification at a blending ratio in mass of 85:15 presented an LHV of around 6 MJ/m3 and 15% of H2 in volume. From the experiment using syngas and biodiesel blend in the engine, it is concluded that the specific consumption at lower loads was reduced by 20% when compared to the consumption of the same engine operating with regular diesel. The development of co-gasification of forest and municipal waste may then be an interesting technology for electrical energy decentralized generation.

Modeling and Experimental Investigation of Sulfurous Compounds Removal from Gas Condensate through Ultrasound-Assisted Oxidative Desulfurization Method.

This study employed an ultrasound-assisted oxidative desulfurization process (UAOD) to investigate the degradation of three sulfurous compounds in the synthetic gas condensate. Various parameters, including oxidizers (hydrogen peroxide, sodium peroxide, potassium superoxide), promoters (formic acid, acetic acid), catalysts (phosphotungstic acid, ferrous(II) sulfate, zirconium dioxide, vanadium pentoxide, aluminum oxide γ, copper(II) oxide), and phase transfer agents (isobutanol, tetraoctylammonium bromide, and tetra-n-butylammonium fluoride), were examined to identify the optimal combination for reducing sulfurous compounds in the UAOD process. The influence of the extraction stage and reactor vessel material on the desulfurization efficiency was also investigated. Results revealed that hydrogen peroxide, formic acid, phosphotungstic acid, and isobutyl alcohol were the most effective oxidizers, promoters, catalysts, and phase transfer agents, respectively. Response surface methodology was used to determine the optimal conditions by evaluating different concentrations of these reagents within specific ranges. The study considered ranges such as 10-70 vol % of hydrogen peroxide, 5-70 vol % of formic acid, 1-30 wt % of phosphotungstic acid, 1-30 vol % of isobutanol, and 5-40 min of ultrasonic ripple time. Empirical models were developed for each sulfurous compound type, providing optimal conditions for sulfur removal with an error margin of less than 0.1%. The validity of the suggested models was confirmed through an industrial data analysis. Additionally, it was observed that increasing the number of extraction stages improved desulfurization efficiency, and using a stainless-steel reactor vessel was more suitable than using a glass vessel.

Modeling and analysis of air combustion and steam regeneration in methanol to olefins processes

Light olefins is the incredibly important materials in chemical industry. Methanol to olefins (MTO), which provides a non-oil route for light olefins production, received considerable attention in the past decades. However, the catalyst deactivation is an inevitable feature in MTO processes, and regeneration, therefore, is one of the key steps in industrial MTO processes. Traditionally the MTO catalyst is regenerated by removing the deposited coke via air combustion, which unavoidably transforms coke into carbon dioxide and reduces the carbon utilization efficiency. Recent study shows that the coke species over MTO catalyst can be regenerated via steam, which can promote the light olefins yield as the deactivated coke species can be essentially transferred to industrially useful synthesis gas, is a promising pathway for further MTO processes development. In this work, we modelled and analyzed these two MTO regeneration methods in terms of carbon utilization efficiency and technology economics. As shown, the steam regeneration could achieve a carbon utilization efficiency of 84.31%, compared to 74.74% for air combustion regeneration. The MTO processes using steam regeneration can essentially achieve the near-zero carbon emission. In addition, light olefins production of the MTO processes using steam regeneration is 12.81% higher than that using air combustion regeneration. In this regard, steam regeneration could be considered as a potential yet promising regeneration method for further MTO processes, showing not only great environmental benefits but also competitive economic performance.

Radiation-induced dry reforming: A negative emission process

The reaction between the most abundant greenhouse gases (GHG) to produce hydrogen might represent the most powerful and effective decarbonizing opportunity, if a low-carbon energy source is used to drive it. This is the case of methane (CH4) dry reforming (MDR) where its reaction with carbon dioxide (CO2) produces synthesis gas (syngas, a mixture of carbon monoxide and hydrogen). This study explores the feasibility of using ionizing radiation to induce the MDR reaction, at low temperatures and/or less energy demanding conditions. Additionally, the ionizing radiation is proposed to be supplied by nuclear power plants (NPPs), which are low-carbon reliable energy generation sources. Thus, the radiolysis of CO2, CH4 and their mixtures, under γ-irradiation was evaluated in the absence and presence of nickel catalysts. The radiation-induced MDR reaction and radiation-induced catalytic promotion were proven to take place at temperatures close to ambient though at low conversion, with yields below 1%. Since irradiation and heat can be provided by a nuclear power plant, this radiation-induced reaction establishes a connection between nuclear energy to renewable resources and enables a pathway for a decarbonized cleaner chemical industry, for producing green chemicals.

Combining methane clumped and bulk isotopes, temporal variations in molecular and isotopic composition, and hydrochemical and geological proxies to understand methane's origin in the Ronda peridotite massifs (Spain)

In serpentinised peridotite and ultramafic rock systems, methane (CH4) origin is frequently considered abiotic, but variable microbial and thermogenic components can also exist. Typically, the origin of CH4 is studied using bulk, 13C/12C and 2H/H isotopic composition, molecular gas composition, occasionally radiocarbon (14C), microbiology and geological context. Recent advances in CH4-clumped isotope methods have yielded novel insights into the formation of CH4: nonetheless, their interpretation in natural gas samples is often uncertain and requires additional research. Here, we study the origin of the gas released in hyperalkaline (pH > 10) springs in the Ronda Peridotite Massifs (southern Spain), combining bulk and clumped CH4 isotopes with molecular gas composition, hydrochemical (Total Organic Carbon and Platinum Group Elements in water), geothermal and geo-structural data. Five springs analysed in 2014 have been re-examined for changes in gas chemistry over time, and three newly discovered gas-bearing springs are analysed for the first time. Regardless of whether springs have microbial or abiotic isotopic fingerprints, we find that bulk CH4 isotopes are fairly stable over a seven-year period. This suggests that the CH4 source(s) or postgenetic processes (such as oxidation and diffusion) have not undergone significant temporal changes. Major variations in H2 and CH4 concentrations in certain springs may be the result of changes in gas pressure and migration intensity. Paired CH4 clumped isotopes (Δ12CH2D2 - Δ13CH3D) were analysed in two bubbling springs, where the presence of CH4 can be interpreted as non-microbial based on 13C enrichment, absence of 14C, and the presence of ethane and propane. However, these isotopes are in disequilibrium, which prevents the quantification of the gas formation temperature. Within the Δ12CH2D2 - Δ13CH3D diagram, the data lie within both the microbialgenic zone, suggested by previous authors, and the abiotic zone that results combining data from laboratory gas synthesis and other natural gas samples. Therefore, attributing a microbial origin to CH4 based only on clumped isotopes is less definite than previously assumed. The amount of Total Organic Carbon appears to be correlated with the origin of CH4, as it is higher in 13C-depleted CH4 samples and lower in 13C-enriched samples. Palladium (Pd) and Rhodium (Rh) dissolved in water (the more soluble Platinum Group Elements) can be a proxy for the chromitite ore deposits contained in plagioclase tectonite layers throughout the investigated area, which may act as catalysts for abiotic CO2 hydrogenation. Clumped isotope disequilibrium and the reported absence of diffuse CH4-bearing fluid inclusions in the peridotites appear to rule out high temperature gas genesis in post-magmatic inclusions. These observations, along with the moderate temperatures at the base of the peridotite massifs and the consistent occurrence of gas along tectonic contacts between serpentinised (H2-bearing) peridotite and carbon-bearing rocks, are compatible with the theory of low-temperature CO2 hydrogenation.

Real-Time Electrochemical Monitoring of the Progress of Sulfate Reducing Bacterially Induced Corrosion of Carbon Steel

Microbiologically influenced corrosion (MIC) is a widespread problem in the oil and gas industry, and sulfate reducing bacteria (SRB) cause the most aggressive kind of corrosion. A sulfate-reducing enrichment culture was obtained from a natural gas transmission line, and incubated in split chamber-zero resistance ammetry incubations. Here, carbon steel electrodes were placed in a synthetic gas field brine in opposing chambers that were connected with a salt bridge. To mimic the heterogeneous metal coverage of a metal surface that causes MIC, one chamber was experimentally manipulated with the addition of the SRB culture, while the other was uninoculated. Initial measurement of positive current between the electrodes in incubations with an organic electron donor (lactate) indicated a period of priming of the metal surface by planktonic SRB, before the current transitioned to negative, indicating that the cathodic corrosive reaction was occurring on the electrode exposed to SRB activities. This negative current is consistent with hypothesized mechanisms of SRB-induced corrosion and was observed in lactate-free incubations and in uninoculated incubations amended with sulfide. These observations, combined with SRB metabolic patterns and mass loss analyses indicate the dynamic nature of SRB-mediated corrosion and illustrate the utility of real-time monitoring of MIC activities.

Numerical Simulation of Processes in an Electrochemical Cell Using COMSOL Multiphysics

Fuel cells are a promising source of clean energy. To find optimal parameters for their operation, modeling is necessary, which is quite difficult to implement taking into account all the significant effects occurring in them. We aim to develop a previously unrealized model in COMSOL Multiphysics that, on one hand, will consider the influence of electrochemical heating and non-isothermal fluid flow on the temperature field and reaction rates, and on the other hand, will demonstrate the operating mode of the Solid Oxide Fuel Cell (SOFC) on carbonaceous fuel. This model incorporates a range of physical phenomena, including electron and ion transport, gas species diffusion, electrochemical reactions, and heat transfer, to simulate the performance of the SOFC. The findings provide a detailed view of reactant concentration, temperature, and current distribution, enabling the calculation of power output. The developed model was compared with a 1-kW industrial prototype operating on hydrogen and showed good agreement in the volt-ampere characteristic with a deviation not exceeding 5% for the majority of the operating range. The fuel cell exhibits enhanced performance on hydrogen, generating 1340 W/m2 with a current density of 0.25 A/cm2. When fueled by methane, it produces 1200 W/m2 at the same current density. Using synthesis gas, it reaches its peak power of 1340 W/m2 at a current density of 0.3 A/cm2.

Effects of a Cyclone Dimensions on Quality of Syngas Produced with a Wood-fired Biomass Gasifier

Charcoal gasification was widely used during the second World War to deal with petroleum scarcity. When petroleum was again available after the war, gasification was neglected afterwards. However, fossils resources are know as non-renewable and there are several reseach carried out all over the world to develop renewable sources of energy. Under that scope gasifiers are of great interest in the developing countries for developing individual or decentralised sources of energy. Even in developed countries, several research and implementation of gasification units are in progress.
 In a previous work, we designed and fabricated a downdraft biomass gasifier with a relatively big cyclone and filtration units. Produced syngas was full of moisture and carbon dioxyde (CO2) when the gasifier was feed with wood, but moisture content was lesser with charcoal. Therefore further work should be carried out in order to use low density wood itself from agricultural, furniture makers or sawmill wastes.
 We compared different cyclone separator design methods, adopted the Lapple’s cutt of model and found that to obtain good removal efficiency of unwanted particles, it is better to work with small cyclones. The new cyclone that we built allowed us on the one hand to reduce the humidity of the synthesis gas obtained, and on the other hand to reduce the quantity of tars in the liquid collected at the bottom of the cyclone. These improvements have led to the production of cleaner and better fuel syngas.

Ni-WC/Al2O3 and Ni-WC/MgWO4/MgAl2O4 catalysts for resource recovery via pyrolysis combined with the dry reforming of plastics (PCDR)

Plastic waste (PW) is currently one of an environmental threat. Despite the increasing share of recycled plastics, their disposal remains high. Therefore, there is a high demand for new PW management systems. Among them, pyrolysis combined with dry reforming (PCDR) is an advantageous solution because it allows for resource recovery in the form of gas and liquid fuels, with simultaneous utilization of CO2. To date, catalysts based on Ni, Co, and noble metals supported on metal oxides have been examined. However, these catalysts suffer from quick deactivation due to coking and sintering. Therefore, testing other materials for PCDR is of particular importance. In this regard, Ni-WC/Al2O3 and Ni-WC/MgWO4/MgAl2O4 were investigated as potential PCDR catalysts. The catalysts were characterized by BET, BJH, XRD, CO2-TPD, H2-TPR, SEM, TEM, TG and DTG. The catalytic activity was evaluated in a two-step PCDR process using low-density polyethylene (LDPE), polystyrene (PS), polyethylene terephthalate (PET), and simulated waste plastic (SWP). The structure of the polymer strongly determines the yields of gas, liquid, and solid products. The highest yield of synthetic gas generation was observed for Ni-WC/MgWO4/MgAl2O4 and was 48.20 ± 2.41 mmol/gp. Different origins of the structural changes including oxidation or coking were observed for different plastics. PCDR of PET led mainly to oxidation, LDPE to the coking deposition. Catalysts after the process with PS were characterized by preservation of crystalline structure. The results indicate a high potential of carbide catalysts in the recovery of gaseous and liquid raw materials.

Synergistic effect of macroporosity and crystallinity on catalyst deactivation behavior over macroporous Ni/CexZr1-xO2–Al2O3 for dry reforming of methane

Dry reforming of methane (DRM) is an outstanding process for transforming methane and carbon dioxide into synthesis gases (H2 and CO). In this study, a special geometrical modification on Ni/CexZr1-xO2–Al2O3 catalyst was applied by introducing a macroporous structure into the support to accelerate the metal support interaction that optimized the distribution of the active sites over the catalyst. Furthermore, we investigated a synergistic effect of the macroporosity and CexZr1-xO2 (CZ) crystallinity over the Ni/CexZr1-xO2–Al2O3 catalyst on its catalytic performance in DRM. Macroporous Ni/CexZr1-xO2–Al2O3 catalysts were prepared via washing (Ni-MaCZA-W) and hydrothermal (Ni-MaCZA-H) methods. Non-macroporous Ni-CZA-H with crystalline CZ was prepared for comparison. The crystalline CZ over macroporous Ni-MaCZA-H had a strong interaction with Ni due to easy accessibility of Ni species to CZ in the macroporous support, resulting in highly dispersed Ni nanoparticles and abundant oxygen vacancies. The unique properties of Ni-MaCZA-H increased catalytic activity and stability in DRM, suppressing coke formation via efficient coke gasification. The Ni species and amorphous CZ over Ni-MaCZA-W resulted in a bimodal Ni size distribution and fast catalyst deactivation. However, even though the crystalline CZ over Ni-CZA-H generated a unimodal distribution of Ni nanoparticles, the non-macroporous Ni-CZA-H resulted in gradual deactivation in the catalytic activity and the production of a different type of coke.

Synthesis gas fermentation at high cell density: How pH and hydrogen partial pressure affect productivity and product ratio in continuous fermentation

For the first time, syngas fermentation was operated continuously with total cell retention and process pressures up to 4barg in long-term runs of up to 3000 hours. Throughout this time, the process was stable. The measured data have shown that hydrogen uptake and ethanol space-time yield are highest at a slightly reduced pH of 5.7 compared to pH5.9. Even lower pH values lead to higher acetic acid to ethanol product ratios, while C2space-time yields remain constant. Increasing the hydrogen partial pressure to 1.52bar resulted in a significant increase in hydrogen uptake rate and ethanol formation. An ethanol space-time yield of 10mmolL-1h-1 was short-term achieved, being the highest space-time yield measured to date for the wild type of C. ljungdahlii. Hydrogen uptake above a theoretical equilibrium concentration of 1.2mmolH2L-1 is significantly reduced, indicating an inhibition of an enzymatic reaction.

Demonstration and scale‐up of high‐temperature electrolysis systems

AbstractHigh‐temperature electrolysis (HTE) is a key to link the electricity sector with other industries and to evolve the electricity transition into a full energy transition. After years of development, HTE is now on the threshold to reach market readiness. The present work shows the latest achievements of Sunfire's development based on the results of the project GrInHy2.0 demonstrating hydrogen production (solid oxide electrolysis cell [SOEC]) in an industrial environment and the project SynLink demonstrating co‐electrolysis (Co‐SOEC) for renewable synthesis gas production. The GrInHy2.0 system is a 720 kWAC electrolyzer operating in the iron‐and‐steel works Salzgitter (Germany). It is now in operation for approx. 14,500 h and achieved a mean degradation rate below 23 mOhm cm2 kh−1 and an electrical efficiency of up to 84%LHV. It also proved that HTE now reached industrial‐relevant availability of over 90%. While the HTE system in Salzgitter consists of eight modules, a single module was tested in co‐electrolysis mode within the project SynLink. It demonstrated synthesis gas generation via Co‐SOEC with a flexible H2/CO ratio between 1 and 4. The work provides insight into how HTE will play a major role in the near future to efficiently produce renewable feedstock for an economy with a drastically reduced carbon footprint.

Assessment of biogas and syngas production from sugarcane vinasse: A sustainable alternative for the production of renewable fuels

AbstractThe increasing demand for renewable energy sources as a substitute for fossil fuels has driven researchers to develop sustainable processes for biomass energy reuse in biofuel production. Based on this premise, the present study aimed to simulate the production process of synthesis gas (syngas) from vinasse, a by‐product of the sugar and alcohol industry, highlighting the applicability of this gas in transitioning toward a more renewable and sustainable energy future. The simulation was conducted in four distinct stages using the Aspen HYSYS® software. The first stage involved obtaining hydrated ethanol from sugarcane juice, followed by anaerobic digestion of vinasse to produce biogas. The third stage involved purifying the biogas to obtain biomethane. Finally, the simulation of steam methane reforming was performed to generate syngas. The modeling and simulation results demonstrated the feasibility of the process, as it generated 20.68 Nm3 of biogas (~55% vol CH4 and 45% vol CO2) per 1 Nm3 of vinasse, corresponding to 11.66 Nm3 of biomethane (~96.5% mol CH4), which aligns with national regulatory standards and the literature presented. Regarding syngas, both evaluated configurations yielded satisfactory results. The first configuration resulted in syngas with an H2/CO molar ratio of three, making it a viable source of pure hydrogen and a raw material for biofuel production, such as dimethyl ether and methanol. The second configuration, with an H2/CO molar ratio of two, holds great potential for its application in the synthesis of liquid fuels (Fischer‐Tropsch), serving as a direct substitute for gasoline, diesel, and jet fuel.

Nickel oxide/copper nanocluster anchored in carbon-nitride nanosheets realizing ultrahigh stability and broad potential range for zero-gap membrane flow reactor towards CO2-into-CO electroreduction

CO2 electrochemical reduction is a sustainable approach to achieve chemical fixation of CO2 and storage of renewable energy. However, the catalyst which has the ability of mediating CO2 to a single product with a relatively high current density is highly demand. Herein, we reported a metallic nitrogen-carbon catalyst based on two kinds of metal phthalocyanines by a facile synthesis method. The synergistic effect of Cu and Ni and the active sites of nickel oxide/copper nanocluster endow the catalyst excellent performance towards CO2-into-CO electroreduction. Typically, the Cu-Ni bimetallic catalyst achieves high selectivity (85.2 %) at positive potential (−0.72 VRHE), with the stability of current density and product selectivity beyond 72 h. The volume ratio of CO/H2 can be effectively tuned (from 2:1, 1:1 to 1:2) by controlling the electrolysis potential, which is promising for synthesis gas in the Fischer-Tropsch reactions and methanol synthesis. Furthermore, the advantages are further amplified by applying it to zero-gap membrane flow reactor, which can enhance the selectivity over 90 % at a broad potential range (−2.5 ∼ −2.7 V) and achieve an current density of 9-fold of H-type cell. Our work proves a way for optimizing the CO2 electrocatalyst and electrolyzers.

An analysis of waste/biomass gasification producing hydrogen-rich syngas: A review

In the last few decades, the population growth level has increased exponentially so the waste disposal level has increased gradually. Wastes like biodegradable wastes, kitchen wastes, hotel wastes, and other agro wastes can be processed through bio methanation and composting technology but non-biodegradable materials like plastics, rubber, industrial sludge, and other wastes cannot be processed in simple ways or technologies. These wastes are critical to handle and need robust technology. Gasification and incinerators are a technology to utilize these waste materials and convert them into useful energy. However, the incinerator has a drawback of control over emissions generated by waste material combustion. Gasification is the best-suited technology which can convert the waste material into gaseous form and this gas provides heat to the prime movers to generate energy/power. Carbon monoxide, hydrogen, methane, carbon dioxide, oxygen, and nitrogen are the main components of synthetic gas (syngas), which has a low calorific value. Increased hydrogen and carbon monoxide concentrations improve this gas's calorific value. Different gasification methods like gasification using agent as steam, catalytic gasification, and gasification using different combination of fuels (waste-coal/biomass) are used to enrich the hydrogen content of the syngas. This paper reviewed the theory of waste-to-energy technologies, incineration technology, gasification technology, methods for increasing hydrogen in syngas, also different methods. This review discusses waste gasification disposal methods and hydrogen enrichment.

CARBON DIOXIDE CONVERSION OF METHANE ON LaNiO3 AND La0.9Ce0.1NiO3 PEROVSKITE CATALYSTS

Introduction. Perovskite type catalysts are becoming more and more relevant due to their stability to high temperature and sintering in the process of obtaining synthesis gas. Modification of perovskite catalysts with cerium can improve oxygen mobility and intensity of interaction with active metal particles. The purpose of this work is to study the activity of perovskite type catalysts LaNiO3 and La0.9Ce0.1NiO3 in the process of carbon dioxide conversion from methane to synthesis gas. Methodology. The catalyst was synthesized by the Pechini method, studied using the X-ray phase method and chromatographic analysis. Results of work. Catalyst La0.9Ce0.1NiO3 prepared by Pechini method can provide almost complete conversion of methane and carbon dioxide gas at the reaction temperature of 850°C (XCH4 98%, XCO2 93.6%). X-ray phase analysis shows that the synthesized LaNiO3 and La0.9Ce0.1NiO3 are oxide catalysts of the perovskite type, and have a typical structure of perovskites, forming phases LaNiO3 and CeO2. Conclusion. Studies have shown that varying the temperature of the reaction makes it possible to purposefully control the reaction in the direction of obtaining synthesis gas with a given ratio, to obtain valuable products such as acetic acid, acetic anhydride and ethylene glycol.

Catalytic activity of Ni-MgAl2O4 modified with transition metal (Ti, Mo, W) carbides as potential catalysts for resource recovery via dry reforming of waste plastics

The growing amounts of plastic waste and CO2 emissions are two environmental threats that require urgent attention. Pyrolysis combined with dry reforming (PCDR) is a technology that allows both CO2 utilization and resource recovery from waste plastic. New catalysts for PCDR are crucial for developing efficient and stable processes that can be widely implemented in the industry. In this study, Ni/MgAl2O4 catalysts modified using different transition metal (Ti, Mo, W) carbides were investigated in the PCDR of low-density polyethylene (LDPE) and polystyrene (PS) with emphasis on syngas yield, H2/CO ratio, product distribution, and catalyst deactivation. In addition, the effect of reforming temperature and process pressure was investigated. The catalysts were characterized using H2-TPR, CO2-TPD, N2 physisorption, XRD, TEM, XPS and TGA. The combined characterization and activity tests demonstrated that modification with different metal carbides affects the structure and activity of Ni/MgAl2O4 catalysts in relation to product yields, syngas composition, and catalyst stability. The investigation revealed that modification of nickel catalysts with different transition metal carbides enables manipulation of syngas composition, which is of great importance because different industrial processes require synthesis gas with different H2:CO ratios. Moreover, mixed outcomes were observed when different plastic feedstocks were used in the PCDR, indicating that different metal carbide-modified catalysts may be suitable for the process depending on the feedstock used. Regarding the effectiveness of synthesis gas production and catalyst stability, the most promising catalyst was the Ni-TiC/MgAl2O4 catalyst. According to the obtained results, modification with TiC resulted not only in increased synthesis gas production but also in reduced carbon deposition in PCDR of both LDPE and PS.

Determination of Thermophysical Properties of Alternative Motor Fuels as an Environmental Aspect of Internal Combustion Engines

The article analyzes the state of the global problem of the fuel and energy crisis and environmental pollution by the combustion products of hydrocarbon fuels of industrial and transport power plants. To ensure the energy security of the state, the Cabinet of Ministers of Ukraine developed and adopted the «Energy Strategy of Energy Saving of Ukraine for the period until 2030», which was updated in 2008, to protect the country from energy risks. In addition, the Cabinet of Ministers of Ukraine approved the «Concept of a targeted scientific and technical program for the development of the production and use of biological fuels». To increase the efficiency of using alternative motor fuels, as one of the aspects of solving the problem, an original method and results of calculating the thermophysical properties of a wide class of such motor fuels (hydrogen, natural gas, biogas, mine gas, coke, blast furnace and synthesis gas, etc.) are proposed. A description of the developed mathematical model for determining parameters of phase equilibria and thermophysical properties of dense molecular systems (dense gases and liquids) is given. Calculation procedures are based on the thermodynamic theory of disturbances without the involvement of empirical parameters. Features of the proposed method are: limitation of initial information, high accuracy, the possibility of application in any practically important ranges of states. Calculation errors are at the level of traditional experimental errors.