Liquid Fuels Research Articles

Thermal pyrolysis behavior and mechanisms of kraft lignin using methane, H2, and H2O as reactive medium: A ReaxFF molecular dynamics simulation

Biomass has become an alternative to fossil fuels due to its capacity to provide carbon-neutral energy. However, the conversion of kraft lignin into high-value chemicals remains challenging. Hydrotreatment, utilizing CH4, H2, or H2O, enables the production of high-quality liquid hydrocarbon fuels while enhancing hydrogen utilization. Reactive molecular dynamics was employed to investigate the influence of CH4, H2, and H2O as reactive medium of kraft lignin at the atomic scale. The three reactive mediums increased the maximum heavy tar yield by 8.34%, 8.07%, and 8.53% respectively, and increased the hydrogen content of pyrolysis products. Steam conditions promote the decomposition of ether bonds, while H2 and CH4 exhibit stronger inhibitory on the decomposition of carbon hexagonal rings. A crucial role of pentagonal carbon rings as intermediates in the lignin cracking process was found. These findings provide valuable insights for optimizing the pyrolysis conditions of kraft lignin to achieve the desired product yields.

Combustion of liquid hydrocarbon fuels sprayed into gas generation chamber with superheated steam as low emission technology for energy production

Experimental and numerical studies were conducted to scientifically validate the Steam Injection Method with Gas Generation chamber (SIMGG) as a low-emission combustion technology for energy production in low and medium power boilers using different types of fuels. For the first time, a fully functional prototype of a burner implementing SIMGG was tested under the conditions of a standard low-power boiler installation, and combustion characteristics of fuels with various physical properties (diesel fuel and a mixture of used automotive oils) were obtained under different operating parameters. The results of the studies show that using SIMGG reduces carbon monoxide (CO) and nitrogen oxides (NOx) emissions by up to half or more under closed-combustion conditions for various fuels. The lowest total emissions of CO and NOx are achieved at an air excess coefficient of 1.2 and a steam-to-fuel ratio of greater than 0.66.

Aquathermolysis of polyolefin plastic wastes over a MOF-derived TiO2 anatase catalyst: Enhancing C–N bond cleavage and coke suppression

Plastics are ubiquitous in modern society owing to their cost-effectiveness, low weight, and durability. However, the disposal and recycling of plastic waste remain significant challenges. Aquathermolysis has emerged as a promising strategy for converting contaminant-rich polyolefin plastic waste into value-added liquid fuels. This study investigates the plastic-waste aquathermolysis potential of a TiO2 catalyst derived from the sacrificial precursor Ti-containing MIL-125 via a MOF-mediated synthesis pathway combined with calcination. The TiO2 catalyst retained its mesoporous properties and predominantly anatase phase on calcination at 450 ℃. The aquathermolysis catalysis and stability of the newly synthesized catalyst for plastic-waste conversion were evaluated and compared with those of other catalytic systems. Additionally, the role of water in the N removal efficiency and coke suppression properties of the catalyst were analyzed. Water significantly improved the removal of N and S impurities, with a N reduction of 80–95% at the optimal water content (20–40 wt%). The robustness of the as-synthesized catalyst was confirmed by deconvoluted X-ray photoelectron spectroscopy patterns, which indicated the persistence of the TiO2 phase, even after prolonged catalysis in aqueous environments, and transmission electron microscopy results, which showed that the anatase phase remained well-dispersed under aquathermolysis conditions with a significant reduction in the C/Ti ratio and a corresponding increment in the N/C ratio. The results of this study could guide future research on the development of catalysts, similar to the MIL-125-derived TiO2 catalyst investigated here, with high potential for efficient plastic-waste conversion and impurity removal in aqueous environments.

An efficient carbon-neutral power and methanol polygeneration system based on biomass decarbonization and CO2 hydrogenation: Thermodynamic and economic analysis

This study presents a novel approach to enhance methanol synthesis (MS) efficiency through integration with an MEA-based decarbonized biomass direct-fired power plant (BFPP-CCS). The integration optimizes the utilization of chemical energy from feedstocks by combining exothermic MS reactions with diverse thermal energies, which effectively captures chemical energy through synergistic utilization from MS and various thermal inputs. Gradual methanol conversion maximizes both its chemical and fuel properties. Through such integration, the enhancement of waste heat and purge gas utilization in MS and BFPP carbon capture processes results in a 3.42 MW improvement in power generation and a 26.0 % reduction in associated energy penalties from CCS. Analysis of a 150 kton/yr MS facility and a 35 MW BFPP-CCS demonstrates 2.87 % increase in overall efficiency and reduction in CCS heat consumption by 1.03 GJ/tCO2. Moreover, this integrated approach yields a 33.1 M$ NPV increase and 3.4 years DPP decrease, achieving carbon-neutral power and liquid fuels production. Sensitivity analysis indicates the polygeneration system performs optimally around 250 °C and 60 bar, with a preference for 0.90 MS recycle ratio. Additionally, factors such as carbon recovery rate, electrolysis efficiency, and fixed carbon content in biomass are quantitatively revealed as crucial for maximizing carbon mitigation potential.

Three-part superposition quasi-static stress model for PTFE across a broad low-temperature range based on ZWT and higher-order stress corrections

The widespread application of cryogenic liquid fuels in aerospace necessitates an accurate description of the mechanical properties of sealing materials such as Polytetrafluoroethylene (PTFE) at low temperatures. This study aims to develop a stress prediction model to describe the tensile stress response of PTFE across a broad low-temperature range. Quasi-static tensile tests on PTFE samples were conducted to obtain the uniaxial tensile properties of PTFE in the low-temperature range. Data fitting revealed significant errors and a loss of physical significance in the classical Zhu–Wang–Tang (ZWT) constitutive model and its modified versions when describing PTFE's mechanical response at low temperatures or large strains. Based on these theoretical models, a three-part superposition (TPS) model, incorporating asymptotic growth, linear growth, and exponential growth terms, is proposed. The TPS model demonstrates excellent predictive accuracy for PTFE's mechanical response from 77 K to 293 K, and from initial strain to fracture. Additionally, the physical connections and interpretations between the three parts of the TPS model and the macroscopic mechanical behavior and microscopic crystalline characteristics of semi-crystalline polymers are analyzed, providing a unified description and a comprehensive understanding of PTFE's mechanical behavior over this temperature range.

A molecular dynamics study on the supercritical evaporation of liquid ammonia under forced convection conditions

Although the behavior of the supercritical transition during the evaporation of liquid fuels in engine combustion chambers has been studied by many researchers, the effects of convection on the phase transition of liquid fuel in supercritical environments have been little studied. Previous studies mainly focused on hydrocarbon fuels for supercritical evaporation, with fewer on the zero-carbon liquid ammonia fuel. Aiming at the above deficiencies, this study used molecular dynamics simulations (MD) to explore the phase transition of liquid ammonia in a nitrogen supercritical environment under forced convection conditions. The Peng-Robinson equation of state (PR-EoS) was used to calculate the vapor–liquid equilibrium of the ammonia–nitrogen system to determine the supercritical transition time of liquid ammonia under forced convection conditions. The effects of forced convection on the heat and mass transfer process and the evolution of the liquid-phase region and the vapor–liquid interface region were analyzed. It was found that forced convection can promote the mass and heat transfer process and accelerate the phase transition of liquid ammonia to some extent. Forced convection may have a greater effect on the single-phase diffusive mixing process compared to the two-phase evaporation process. The increase in the interfacial thickness under forced convection conditions is mainly attributed to the temperature increase promoted by convection. The interfacial temperature dominates the development of its thickness and the thickness is approximately linear with temperature during the diffusive mixing stage. The shear effect induced by convection has an inhibitory effect on the diffusion of ammonia molecules within the interface region along the vertical convection direction. The cases in this study indicate that forced convection may promote the supercritical transition of liquid ammonia. In addition, a dimensionless number κ was proposed to explore the possibility of scaling up the MD results to the engineering scale.

Evaluation of waste plastic and waste cooking oil as a potential alternative fuel in diesel engine

The generation of plastic waste and waste cooking oil is a serious environmental concern because of worldwide waste disposal issues. At the same time, increasing demand and contemporary geopolitics make fossil fuels a significant worldwide problem. As a result, there has been an increase in demand for alternate fuel for CI engines. To overcome these twin problems can be addressed by converting waste into liquid fuels. This research explores an intriguing area by mixing waste cooking oil biodiesel and waste plastic oil to create a mixture that remarkably seems like the physico-chemical properties of diesel fuel in a society that is looking for sustainable alternatives. So, in this investigation, a ternary fuel blend of Petro-diesel, waste cooking oil biodiesel (WCOB), and waste plastic oil (WPO) was used in the diesel engine. To enhance the properties of fuel, combustion, emission, and performance parameters of diesel engines, a ternary blend of B20P20D60 was employed in the CI engine as an alternative fuel. In the ternary fuel blends, WCOB, WPO, and diesel content were 20%, 20%, and 60%, respectively. The results were compared with conventional diesel fuel, showing that the ternary fuel blend B20P20D60 has an improved brake thermal efficiency of up to 1.71% at 80% loading and reduced emissions (HC, CO, NOx) compared to conventional diesel. Because of this, the ternary blends have significant potential for use in diesel engines.

Impact of CO2 on the Pyrolysis of Mixed Polymer Wastes into Combustible Fuel: A Case Study for Footwear Waste

Plastic waste is a promising resource for producing liquid fuels that can be integrated into existing hydrocarbon infrastructures. However, the heterogeneous nature of plastic-derived liquid fuels limits direct application in internal combustion engines, necessitating their refinement into a usable form. To address these issues, this study explored the enhancement of combustible gaseous fuels derived from plastic waste, footwear waste, as a viable alternative. This approach involves the introduction of carbon dioxide as a reactive feedstock during the pyrolysis process. Analytical techniques were employed to precisely determine the types and compositions of four polymers present in footwear waste. The compositional matrices of the primary pyrogenic products were also identified. However, incorporating carbon dioxide into pyrolysis leads to its interaction with volatile compounds, converting them into lighter gaseous products, particularly carbon monoxide. The homogeneous reactivity of carbon dioxide was further enhanced by the application of heat and a nickel-based catalyst. The gaseous product yield from catalytic pyrolysis in the presence of carbon dioxide increased proportionally with the test temperature. Specifically, the use of carbon dioxide led to a 1.92-fold increase in gaseous product yield at 700 ˚C, in reference to the results from nitrogen. This study demonstrates a technical advancement in pyrolytic valorisation of footwear waste by incorporating carbon dioxide and provides a detailed investigation into its mechanical role in maximising the production of combustible gaseous fuels.

Waste to Energy; Conversion of Plastic Waste into Liquid Fuel Equivalent to Diesel and Gasoline Using the Pyrolysis Method

Abstract The aim of this research is to produce oil equivalent to diesel and gasoline from plastic waste using the pyrolysis method, examining its physico-chemical properties and comparing it with conventional diesel and gasoline. The production of diesel oil and gasoline from plastic waste is a topic that has received increasing attention in recent years, due to increasing awareness of the environmental problems caused by plastic waste and the need for alternative energy sources. Methods for converting plastic waste into liquid fuel, separating diesel and gasoline equivalents and examining their physico-chemical properties are the main focus of this research. Pyrolysis is the process chosen because the technology is simpler than other methods, such as gasification for example. A total of 6000 grams of plastic chips were pyrolyzed in an LPG-fueled reactor. Pyrolysis was carried out at temperatures of 200, 250, 300, 350, 400 °C, then the yield of oil produced at each temperature was weighed. It was found that the optimum temperature for pyrolysis was 300 because the increase in yield afterwards was very small. Next, 2000 grams of pyrolysis oil was distilled by gradually increasing the temperature from 100 to 300. The resulting 1520 grams or 79.17% gasoline equivalent fraction, 320 grams or 16.67% diesel fraction, the remaining 80 grams or 4.17% residual oil. The results of the physico-chemical properties examination showed that the diesel and gasoline fractions were similar to conventional diesel and gasoline.

Continuous processing of JP-10 production: Hydroisomerization of endo-tetrahydrodicyclopentadiene to exo-tetrahydrodicyclopentadiene using a novel bimetal catalyst of Ba/Se supported on TiO2/SO4

High-energy-density liquid fuels can be utilized as an energetic supplement to conventional fuels and are essential for volume-limited aerospace vehicles to boost payload and flying range. JP-10 has attracted much attention because of its high density, flash point, high volumetric heat, and low freezing point. Here we report the hydroisomerization of endo-tetrahydrodicyclopentadiene to exo-tetrahydrodicyclopentadiene (the main component of JP-10) was investigated over the TiO2/SO4 supported Ba(10 %)/Se(5–20 %) catalysts. This work aims to examine changes in continuous processing settings to maximize exo-THDCPD production, selectivity, and conversion. It was discovered that the synthesized TiO2/SO4/Ba(10 %)/Se(5–20 %) heterogeneous catalysts were novel, more effective, affordable, environmentally friendly, and simple to produce. The catalyst’s physicochemical characteristics were examined using FT-IR, BET, XRD, HR-SEM, HR-TEM, TGA and NH3-TPD. The produced TiO2/SO4/Ba(10 %)/Se(5–20 %) nano-catalysts have good catalytic activity and a wide range of active Lewis and Brønsted acid sites. Evaluation of the isomerization of endo-THDCPD to exo-THDCPD was conducted in a high-pressure fixed-bed continuous reactor operating at 200 °C, 20 bar of pressure, and 4.0mol/h of H2 flow rate. According to the investigations, the synthesized catalyst with a 15 % Se load performs exceptionally well, exhibiting 100 % conversion, 98.5 % selectivity, and 98.5 % yield at an H2 flow rate of 10 ml/min. The isomerized product is used in Jet Propellant-10, a high-density fuel. Under ideal circumstances, exo-THDCPD with a high degree of purity (>98 wt%) was produced without the need for any sort of separation technique.

Exploring the potential of fast pyrolysis of invasive biomass species for the production of chemicals

The pyrolysis of five invasive plants crowded in Colombia (Liquidambar styraciflua, Sambucus nigra, Cecropia telenitida, Ruta greveolens, and Clusia orthoneura) has been studied for the first time in order to assess their potential for the production of liquid and solid fuels and chemical products. The volatiles produced from the fast pyrolysis of these biomass species at three different temperatures (500, 600 and 700 ºC) were analyzed by Py-GC/MS. In spite of the different nature of the feedstock, the bio-oil produced from the pyrolysis of all the biomasses at the three temperatures studied is mainly composed of phenols (with a relative content in the 19–26.5 % range), acids (14.6–19.5 %), ketones (13.4–19.2 %) and levoglucosan (6.7–15.4 %). Temperature has a moderate effect, leading to a decrease in the relative content of all component families, except aldehydes and hydrocarbons, when it is increased. Biochars produced at 500 ºC show high calorific values, as well as low H/C and O/C ratios, which prove their high stability in the soil. These results are clear evidence that the valorization of these invasive plants by pyrolysis may be an effective strategy for the mitigation of their associated impacts.

Stability of supported Pd-based ethanol oxidation reaction electrocatalysts in alkaline media

This study evaluates the dissolution of the supported electrocatalysts Pd/C, PdSn/C, PdNb/C, and PdFe3O4/C during ethanol oxidation reaction for Alkaline Direct Liquid Fuel Cells (ADLFC) applications. A scanning flow cell (SFC) combined to an inductively coupled plasma mass spectrometry (online ICP-MS) is used to assess the dissolution stability in a broad potential window. Accelerated stress tests with and without ethanol are developed using a rotating disk electrode (RDE) with dissolution products analysis by ex-situ ICP-MS. Potential profiles simulating those experienced by the catalyst during regular fuel cell operation were used. Sn and Fe catalysts demonstrate improved activity and stability compared with the material with Pd alone. For these reasons, PdSn/C and PdFe3O4/C are suitable for ADLFC applications. Severe Nb dissolution destabilizes Pd, increasing its leaching. This work demonstrates that while additional metals and oxides can improve the alcohol oxidation kinetics of Pd, these additives’ dissolution stability must already be considered at the catalyst design stage.

Molecular Engineering of Poly(Ionic Liquid) for Direct and Continuous Production of Pure Formic Acid from Flue Gas.

Electrochemical CO2 reduction reaction (CO2RR) offers a promising approach to close the carbon cycle and reduce reliance on fossil fuels. However, traditional decoupled CO2RR processes involve energy-intensive CO2 capture, conversion, and product separation, which increases operational costs. Here, we report the development of a bismuth-poly(ionic liquid) (Bi-PIL) hybrid catalyst that exhibits exceptional electrocatalytic performance for CO2 conversion to formate. The Bi-PIL catalyst achieves over 90% Faradaic efficiency for formate over a wide potential range, even at low 15% v/v CO2 concentrations typical of industrial flue gas. The biphenyl in PIL backbone affords hydrophobicity while maintaining high ionic conductivity, effectively mitigating the flooding issues. The PIL layer plays a crucial role as a CO2 concentrator and co-catalyst that accelerates the CO2RR kinetics. Furthermore, we demonstrate the potential of Bi-PIL catalysts in a solid-state electrolyte (SSE) electrolyzer for the continuous and direct production of pure formic acid solutions from flue gas. Techno-economic analysis suggests that this integrated process can produce formic acid at a significantly reduced cost compared to the traditional decoupled approaches. This work presents a promising strategy to overcome the challenges associated with low-concentration CO2 utilization and streamline the production of valuable liquid fuels and chemicals from CO2.

Spray combustion characteristics of boron slurry fuel in high particle loading conditions

Enhancing the energy density of hydrocarbon fuels is indeed crucial, especially in the context of addressing energy needs. Incorporating energetic particles as additives into conventional liquid fuels garners increased attention due to its potential to enhance energy density. Due to its high energy potential, boron is the most promising additive in several energetic particles. However, the study focusing on the boron-loaded slurry fuels are limited. Therefore, the present work focuses on the effect of boron loading on the spray combustion of boron-loaded slurry fuel, especially at higher loadings (10%, 20% & 30% boron + Jet A-1 fuel) using a swirl-stabilized spray combustor. The research scrutinizes the feed and exhaust particles' surface morphology, chemical composition and active boron content through diverse particle characterization techniques. Furthermore, the study investigates the influence of boron loading on the combustion characteristics of slurry fuel using methods such as colour flame imaging, spectroscopy, and BO2* Chemiluminescence imaging. The impact of boron loading on the positive thermal contribution of the slurry was examined by analyzing temperature measurements at various locations within the combustor. The BO2* chemiluminescence imaging and spectroscopy results indicate that the intensity of BO2 emission increases with a rise in particle loading. The temperature results reveal an increase in temperature compared to pure Jet A-1 for all the boron-loaded cases. In particular, JB10 and JB20 achieved nearly 90% and 85% of the theoretical temperature increase. The diffractogram and thermogravimetric results of the burnt particles collected show that the particles were burnt thoroughly for the boron-loaded cases.

Experimental study on the burning rate and flame dynamics of oil reservoir pool fire under cross-wind: Effect of lip height

The study of combustion characteristics and heat feedback mechanisms of liquid fuels is important for fire safety engineering, particularly in the context of energy utilization. In thiswork, the effect of lip height on the evolution of n-heptane pool fire burning rates and flame heights, as well as the thermal feedback control mechanism, were investigated in a series of experiments in the presence of cross-wind. The results showed that the lip height of pool and cross-wind speed have a significant effect on the flame characteristics and heat feedback mechanism. For a given wind speed condition, the radiative feedback fraction and the convective feedback fraction showed non-monotonic changes with an increase in the lip height of pool. With the increase of lip height and cross-wind speed, the lift off phenomenon gradually appeared inside the oil pool, while the flame height outside the oil pool gradually decreased. A new correlation is proposed, which can well describle the relationship between the flame height and the ratio of the air entrainment caused by the cross airflow to that caused by the flame buoyancy, which can provide references for the utilization and management of energy storage strategies nowadays.

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

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

Experimental characterization on injection and spray of coal-derived liquid fuel

Coal-derived liquid fuels (CDLs) are petroleum diesel's (PD) alternatives produced by coal liquefaction. The injection and non-evaporating spray characteristics of CDLs, including diesel from direct coal liquefaction (DDCL), diesel from indirect coal liquefaction (DICL), and their blends (DBCL), were discussed. The high-pressure common rail test bench was used to evaluate the injection delay, injection rate, injection quantity, single injection heat value, and injector inlet pressure. A constant volume chamber along with high-speed camera was used to visualize the spray, then measuring the spray tip penetration distance, spray cone angle, and spray area. Besides, injection tests were conducted using injectors removed from engines that had finished durability tests fueled with DBCL and PD. The results revealed that DDCL had shorter injection delays and more mass injection quantity than PD, with an injection heat value 7 % higher at a rail pressure of 140 MPa. Regarding the spray, PD had a longer spray tip penetration distance and smaller cone angle than CDLs. On test conditions, the spray Sauter mean diameters of DDCL and DICL were over 30 % less than that of PD. Inferring from the reduction in injection rate and quantity, PD generated more clog in the injector hole than DBCL.

Haemoprevalence of Salmonellae Infections in Sheep in Maiduguri, Nigeria: A study Using Abattoir Samples

Haemoprevalence of Salmonellae Infections in Sheep in Maiduguri, Nigeria: A study Using Abattoir Samples

Highly efficient hydrogenation of CO2 to heavy hydrocarbons via NaFeGa catalysts

Transforming CO2 into heavy hydrocarbons via thermal catalytic hydrogenation has garnered interest for its potential to address resource shortages and reduce atmospheric CO2. In this research, NaFeGa catalysts enriched with Ga additives were synthesized by the coprecipitation method. Various characterization techniques, including Mössbauer spectroscopy, were employed alongside reverse water-gas shift and Fischer-Tropsch synthesis experiments to elucidate the Fe-Ga interaction. This interaction effectively modulated the ratio of active sites Fe5C2 and enhanced CO species adsorption. The Ga additive's anti-hydrogenation effect limited intermediate hydrogenation, leading to increased carbon-hydrogen product yields. The catalyst underwent direct hydrogenation of CO2 under high throughput conditions (space velocity of 50,000 h−1), resulting in efficient CO2 conversion as well as remarkable heavy hydrocarbon selectivity. The catalyst demonstrated a remarkable heavy hydrocarbon space-time yield (STY) of 1460.2 g·kgcat−1·h−1, surpassing the threshold for commercial viability and offering a promising solution for large-scale production of liquid fuels from CO2.

Electronegativity- induced cobalt-doped platinum hollow nanospheres with high CO tolerance for efficient methanol oxidation reaction

Although Platinum (Pt)-based alloys have garnered significant interest within the realm of direct methanol fuel cells (DMFCs), there still exists a notable dearth in the exploration of the catalytic behavior of the liquid fuels on well-defined active sites and unavoidable Pt poisoning because of the adsorbed CO species (COads). Here, we propose an electronegativity-induced electronic redistribution strategy to optimize the adsorption of crucial intermediates for the methanol oxidation reaction (MOR) by introducing the Co element to form the PtCo alloys. The optimal PtCo hollow nanospheres (HNSs) exhibit excellent high-quality activity of 3.27 A mgPt−1, which is 11.6 times and 13.1 times higher than that of Pt/C and pure Pt, respectively. The in-situ Fourier transform infrared reflection spectroscopy validates that electron redistribution could weak CO adsorption, and subsequently decrease the CO poisoning adjacent the Pt active sites. Theoretical simulations result show that the introduction of Co optimize surface electronic structure and reduce the d-band center of Pt, thus optimized the adsorption behavior of COads. This study not only employs a straightforward method for the preparation of Pt-based alloys but also delineates a pathway toward designing advanced active sites for MOR via electronegativity-induced electronic redistribution.