Liquid Products Research Articles

Synergetic effect of iron and tungsten on molybdenum‐doped HZSM‐5 zeolite in catalytic methane dehydroaromatization

AbstractMethane dehydroaromatization is a viable route for production of carbon and valuable petrochemicals. Unlike Fischer–Tropsch and methanol synthesis processes which have been scaled up to commercial level, development of methane dehydroaromatization to commercial level has been hampered by various challenges. In this work, a 5.4 wt. % trimetallic (Fe‐W‐Mo/HZSM‐5) catalyst has been synthesized, characterized, and applied in catalytic methane dehydroaromatization reaction. A gas chromatograph was used to analyze both liquid and gaseous products from the reactor. Based on 0.0013 moles of reacted methane after 240 min time on stream at 750, GHSV 960 mlg‐1cath‐1, and atmospheric pressure, a 5.4% Mo/HZSM‐5 catalyst recorded 7.9% methane conversion, 10.6% C2 hydrocarbon selectivity, 51.8% benzene selectivity, 9.8% toluene selectivity and 27.8% coke selectivity. Doping Mo/HZSM‐5 with Fe reduced methane conversion by 4.0%, increased C2 hydrocarbon selectivity by 1.7%, reduced benzene selectivity by 6.2% and increased toluene and coke selectivity by 1.8% and 2.8% respectively. Doping Mo/HZSM‐5 with W increased methane conversion by 7.3%, reduced C2 hydrocarbon selectivity by 2.1%, reduced benzene selectivity by 7.6% and increased toluene and coke selectivity by 0.3% and 9.4% respectively. When iron and tungsten were loaded onto Mo/HZSM‐5, catalytic activity of the tri‐metallic catalyst in methane conversion reduced by 2.0%, C2 hydrocarbon selectivity increased by 2.7%, benzene selectivity reduced by 3.1%, toluene selectivity reduced by 3.7%, and coke selectivity increased by 4.1%. Therefore, this present work demonstrates that metal synergy in a tri‐metallic catalyst plays a role in methane conversion and selectivity towards useful hydrocarbons.

Thermal Properties of Seed Cake Biomasses and Their Valorisation by Torrefaction

Seed cakes, by-products from the cold press extraction of vegetable oils, are valuable animal feed supplements due to their high content of proteins, carbohydrates, and minerals. However, the presence of anti-nutrients, as well as the rancidification and development of aflatoxins, can impede their intended use, requiring alternative treatment and valorisation methods. Thermal treatment as a procedure for the conversion of seed cakes from walnuts, hemp, pumpkin, flax, and sunflower into valuable products or energy has been investigated in this paper. Thermogravimetry shows the particular behaviour of seed cakes, with several degradation stages at around 230–280 and 340–390 °C, before and after the typical degradation of cellulose. These are related to the volatilisation of fatty acids, which are either free or bonded as triglycerides, and with the thermal degradation of proteins. Torrefaction at 250 °C produced ~75–82 wt% solids, with high calorific values of 24–26 kJ/g and an energy yield above 90%. The liquid products have a complex composition, with most parts of the compounds partitioning between the aqueous phase (strongly dominant) and the oily one (present in traces). The structural components of seed cakes (hemicelluloses, cellulose, and lignin) produce acetic acid, hydroxy ketones, furans, and phenols. In addition to these, most compounds are nitrogen-containing aromatic compounds from the degradation of protein components, which are highly present in seed cakes.

Solvolysis and oxidative liquefaction of the end-of-life composite wastes as an element of the circular economy assumptions

In pursuit of sustainable development, recycling composite waste is a crucial challenge as well as an opportunity to support the progress towards eco-friendly materials management and circular economy practices. The current study brings together two modern recycling techniques solvolysis and oxidative liquefaction to recycle five types of composite waste materials including wind turbine blades (WTBs), composite pipes, personal protective equipment (PPEs) used in the medical sector, photovoltaic (PV) panels and municipal solid waste (MSW). Following a well-structured experimental design for each type of waste the solvolysis was performed at a temperature range of 100–190 °C, process time within the range of 1–3 h, and catalyst (TBD) concentration within the range of 0.015–0.025 mol, end with ethylene glycol and 1-methyl-2-pyrrolidinone in a 1:1 M ratio, while depending on the material evaluated, the oxidative liquefaction process was conducted at temperatures between 250 and 350 °C for WTB and between 200 and 300 °C for PPE, MSW, and PV. Oxidant concentrations, reaction time and pressure (15–45%, 30–90 min, 20–40 bar for WTBs, 30–60%, 45 min, 30 bar for remaining waste types) were studied in addition to highly variant waste-to-liquid ratio from 5 to 25% for WTB, 3–7% for PPE and MSW, and 12.5–37.5 for PV. Prior to experimental investigation, surface morphologies and chemical studies of the waste material were performed by scanning electron microscope (SEM) and Fourier transform infrared FT-IR spectroscopy, while after experimentation total polymer degradation (TPD) was calculated and liquid products were analysed through gas chromatography with flame ionisation detection (GC-FID). Following the solvolysis, 50–60% TPD was obtained, allowing for the recovery of glass fibres (GF) with average lengths of 50–60 mm and a maximum length of 650 mm. This allowed for the recovery of GFs with average lengths of 50–60 mm and a maximum length of 650 mm. In the case of oxidative liquefaction, total polymer degradation of 72–100%, 52–100% and 55–100% was achieved, depending on the investigated waste, i.e. WTB, PPE and MSW, respectively. The yield of oxygenated chemical compounds depended upon the types and composition of waste, but acetic acid was the main acid while WTB, PPE, and MSW, the liquid samples contained phenol also. Involved chemistry and possible degradation pathways of complex composite wastes are discussed in detail to enhance the recycling process and material recovery.

Intrinsic Metal Component-Assisted Microwave Pyrolysis and Kinetic Study of Waste Printed Circuit Boards

Waste printed circuit boards (WPCBs) hold great recycling value, but improper recycling can lead to environmental issues. This study combines pyrolysis and microwave technologies, leveraging the unique phenomenon where metal materials tend to “spark” in a microwave field, to develop a microwave pyrolysis process for WPCBs that incorporates metal fillers. The research analyzes the effects of microwave power, metal filler addition, and pyrolysis time on the efficiency of microwave pyrolysis. It explores the mechanisms of microwave pyrolysis and the pathways of pyrolysis product formation, and the kinetics of the pyrolysis reaction of WPCBs. The results indicate that microwave-assisted pyrolysis greatly improves efficiency. Within the experimental range, the optimal conditions are found to be a microwave power of 1600–1800 W, a metal filler addition of 10%, and a pyrolysis time of 10 min. Under these conditions, the yield of pyrolysis liquid was 12.8%, with approximately 5–12 different components, while the yield of pyrolysis gas was 12.7–13.4%, with about 9–11 different components. Compared to conventional pyrolysis products, the liquid products from microwave pyrolysis are simpler and more advantageous for resource utilization. Theoretical calculations show that the average activation energy for the microwave pyrolysis process is 81.05 kJ/mol, with an average reaction order of 0.93, which is greatly better than the 147.75 kJ/mol of the conventional pyrolysis process.

Hydrothermal Catalytic Transformations of Polymeric Wastes over Zeolite Catalysts Modified with Molybdenum and Tungsten

The article is devoted to the study of the adsorption properties and morphology of new composite catalysts based on acid-activated zeolite heulandite-clinoptilolite of the Kazakhstan Taizhuzgen deposit modified with molybdenum salts (NH4)MoO·4H2O and tungsten (NH4)5H5[H2(WO4)6]·H2O, for the process of thermocatalytic hydrogenation of plastic waste. The study of the developed catalyst by the method of adsorption nitrogen porometry demonstrated the presence of typical type IV isotherms, which indicated the formation of a porous adsorbent by multilayer nitrogen adsorption in the mesopores of the catalyst. The adsorption capacity of the structure formed by the catalyst based on zeolite modified with molybdenum and tungsten, due to the presence of predominantly mesoporous cavities, is able to selectively influence the process of hydrothermocatalytic processing of waste polymers based on polyethylene and polypropylene. The pore size distribution indicates the presence of mesopores and an insignificant number of micropores at low pressure. The catalyst samples were tested in the thermocatalytic hydrogenation reaction of polymer waste. Significant gas formation and predominant content of alkanes, isoalkanes, alkenes and aromatic hydrocarbons in liquid products are shown. It is obviously that the main contribution to the transformations made by mesoporous inclusions in the cavities of the zeolite under study formed during their treatment with molybdenum and tungsten salts.

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.

Upgrading of kraft lignin pyrolysis products: Managing sulfur impurities

Pyrolysis stands as a powerful method for the valorization of biomass like kraft lignin, an aromatic-rich and sulfur-containing polymeric by-product from the pulping industry. Sulfur in the raw matrix is released during thermal processes and is redistributed in pyrolysis products. However, the presence of sulfur lowers the quality of products due to its corrosive and toxic character. In this work, commercial activated carbons have been used as adsorbents to remove the main sulfur compounds from the gas phase (i.e., CH3SH, COS, H2S). The analysis of sulfur content in biochar has been performed through SEM-EDXS, while the sulfur content in oils has been obtained by GC–MS analysis. The adsorption of sulfur on the activated carbon bed results in an enhancement of the release of sulfur in the gas phase from 34 % without activated carbon to 44 %. Up to 88 % of H2S removal is achieved after the adsorption step, together with a reduction of the overall sulfur content in the bio-oil rich in intermediates such as guaiacols and alkylated phenols. The residual sulfur contained in the liquid product is lowered to 3 % of the total sulfur in the system, thus improving the quality of the liquid pyrolysis product. This process limits the amount of sulfur in the gas and improves its quality and market value. At the same time, this results in a redistribution of sulfur in pyrolysis products such as bio-oil, improving its range of application as a source of chemical intermediates from kraft lignin.

Calculation of the Critical Liquid Production of Cyclic Steam Stimulation in Heavy Oil Reservoir with Edge Water

Abstract For heavy oil reservoirs with edge water, when the liquid production of cyclic steam stimulation is excessively high, there is a risk of edge-water invasion. Therefore, the liquid production of cyclic steam stimulation is of great significance to the prevention of edge-water invasion in heavy oil reservoir with edge water. Currently, many studies on the critical liquid production in oil reservoir by water flooding are conducted. However, there is few research on the critical liquid production in heavy oil reservoir by cyclic steam stimulation. To fill this gap, The formation after cyclic steam stimulation is divided into the heated zone and the unheated zone. A characterization method for the flow field parameters after cyclic steam stimulation is established. By transforming the length of the thermal swept zone, the comprehensive mobility of the heated zone is equivalently represented as the comprehensive mobility of the unheated zone. On this basis, considering the threshold pressure gradient in heavy oil, a calculation method for the critical liquid production after cyclic steam stimulation in oil reservoir is developed based on the theory of mirror reflection and the superposition of potentials. The results show: (1) Permeability being constant, the critical liquid production rate increases with the increase in cyclic steam injection quality. With a constant cyclic steam injection quality, the critical liquid production rate increases with the increase in permeability; (2) Guided by the established relationship curve diagram between critical liquid production and crude oil mobility, the development plan is designed. As a result, the comprehensive water cut in the oilfield is 8.1%, and no water invasion has occurred; (3) Guided by the established relationship curve diagram between the cumulative liquid production and cumulative heat injection corresponding to different critical liquid production rates, adjustments were made to the oilfield development plan. As a result, the critical liquid production rate for well A1 increased from 110 t/d in the first cycle to 150 t/d in the second cycle.

Enhancement of liquid/gas production during co-pyrolysis of vacuum residue and plastics due to synergistic interactions

Vacuum residue (VR) was copyrolysed with polyethylene (PE) or polystyrene (PS) in a batch reactor to investigate the corresponding synergistic pyrolytic interactions. The synergistic interactions between VR and plastic pyrolysates enhanced liquid and gas production while reducing coke formation, as compared with VR-only and plastic-only pyrolysis. The pyrolysis of 9:1 w/w VR: PE3M (PE with Mw = 3 MDa) and 9:1 w/w VR/PS350K (PS with Mw ≈ 350 kDa) mixtures produced oil in yields of 28.6 and 38.4 wt%, respectively, which exceeded those expected in the absence of synergistic interactions 1.12- and 1.29-fold, respectively. The corresponding coke yields were ~ 0.9 times lower than those expected in the absence of synergistic interactions. Moreover, copyrolysis synergistically increased the yields of oil-phase paraffins and olefins while decreasing that of aromatic compounds and was therefore concluded to enable effective VR utilisation and plastic recycling by enhancing liquid and gas production.

Convert food waste into easily biodegradable liquid substrate: New insights into wet oxidation as a pretreatment for anaerobic digestion

This study is the first comprehensive investigation into the industrial application of wet oxidation (WO) for food waste (FW) valorization. We analyzed the physicochemical properties of WO products and performed a material flow analysis. WO achieved a 25.7 % reduction in chemical oxygen demand and produced liquid and solid products suitable for high-value applications. The liquid product featured high biodegradability (B/C ratio of 0.65), significant BOD5 (33 ± 9 g/L), low total solids (3.5 % ± 0.4 %), and low metal concentrations, making it ideal for high-efficiency anaerobic digestion or as a carbon source in wastewater treatment. The solid product, with a total solids content of 63.9 % ± 1.4 %, is a potential organic fertilizer alternative. Life cycle assessment showed that WO-related scenarios offered superior greenhouse gas (GHG) reduction compared to conventional anaerobic digestion (11.30 kg CO2-eq/t FW slurry). The most effective scenario, combining WO with a carbon source and organic fertilizer alternative, achieved a GHG reduction of −21.80 kg CO2-eq/t FW slurry. Consequently, this study demonstrates that WO, as a pretreatment for food waste valorization, is both technically feasible and environmentally sound, offering valuable engineering references for the implementation of high-efficiency anaerobic digestion processes for food waste.

Laboratory-scale simulation study of pyrolysis process in a fixed-bed gasifier for municipal solid waste pellets: Effects of temperature distribution and residence time

In this study, stepwise heating pyrolysis was designed to simulate the pyrolysis process of municipal solid waste (MSW) pellet in an updraft fixed bed gasifier at a laboratory scale. Differences in pyrolysis product between fixed bed stepwise heating pyrolysis (FBS, ranging from 300 °C to 800 °C) and continuous heating pyrolysis (FBC, maintained at 800 °C) were revealed. The impact of residence time at various temperature ranges on MSW pyrolysis was also investigated. Results indicated that compared to FBC, the gas yield of FBS decreased by 30.74%, while its liquid yield increased by 11.96%. It was primarily due to the lower heating rate reduced the secondary conversion of aliphatic hydrocarbons, oxygenated compounds, and monoaromatic hydrocarbons (MAHs) within liquid products. In addition, the composition of MSW pyrolysis products was changed by adjusting the residence time. Maintaining a uniform residence time of 5min for MSW pellets at each temperature was considered optimal for gas yield, which was mainly attributed to the enhanced cracking of long-chain aliphatic and polycondensation of MAHs and polycyclic aromatic hydrocarbons (PAHs). Besides, the volatiles (C- and O-containing compounds) of the char were almost completely released. The underlying influence mechanism of residence time on the pyrolysis behavior of MSW was also proposed, which could provide insights for the implementation of MSW gasification.

Cellulose pyrolysis via liquid metal catalysis

Liquid metals are largely unexplored as catalytic media for biomass conversion. Unlike conventional solid-state catalysts which are prone to deactivation, liquid metals, i.e., low-melting metals operated above their melting point, can show resilience against coking, high thermal conductivity, and enhanced liquid-solid contact between catalyst and biomass feedstocks. This promise motivated the present investigation of liquid metals as catalysts for cellulose pyrolysis. Bismuth, tin, and indium were selected as liquid metal candidates, and their impact on cellulose devolatilization kinetics is studied via thermogravimetric analysis. The results indicate that all three metals show catalytic activity, with bismuth catalyzing volatiles formation, while indium and tin enhance char formation. Quantitative analysis of liquid product reveals that bismuth is selective to dehydration and functional rearrangement reactions, leading to anhydro sugars and functionalized furans formation. In contrast, indium and tin are selective towards dehydration, fragmentation reactions, and Diels Alder chemistry, leading to formation of C2-C4 fragments and aromatic compounds, as further confirmed via infrared spectroscopic analysis of the obtained chars. Finally, the Sn and Bi liquid metals’ stability against deactivation via coking is examined against conventional solid-state zeolite catalyst through multiple cellulose pyrolysis runs in the thermogravimetric analyzer (TGA) with the same batch of catalyst. While ZSM-5 zeolite catalyst's activity and selectivity declined and approached non-catalytic sand results (both the TGA curve and the liquid product distribution) within the first few runs, both Sn and Bi fairly maintained their robustness against coking for the conducted durability runs. Overall, the results show significant promise for this new class of catalysts for biomass pyrolysis.

Study of metal sequenced spray impregnation method towards Co-Mo/γ-Al2O3 catalytic performance in hydrotreating of used coconut oil to liquid biohydrocarbon

A series of bifunctional catalyst CoMo on γ-Al2O3 have been successfully prepared using the spray impregnation (dry impregnation), with the variation in the metal sequence (Co-Mo and Mo-Co) and metal impregnation time gap (1-h, 24-h, and simultaneous). XRF indicated that the developed method causes a minimal amount of metal loss during the impregnation process. XRD shows that 24-h treatment reduces crystallinity compared to the 1-h and simultaneous catalysts. Co and Mo existed as CoAl2O4, CoO, and MoO3 as reported by XANES and XPS. The preparation technique signified the catalyst's acidity and surface area. The Co-Mo/γ-Al2O3 24H has a high surface area (118.32 m2 g−1), with a pore volume of 0.22 cm3 g−1, and a pore diameter of 7.48 nm. It has a high proportion of weak acid sites (41.32 %) which is crucial to perform HDO reactions. Co-Mo/γ-Al2O3 24H showed high catalytic activity (40.32 wt% liquid product) and selectivity (85.61 % of biogasoline and 9.75 % of diesel fractions) from the hydrotreatment. Kimi@UGM2010.

Hydrocarbon Generation Characteristics of Coal‐measure Source Rocks and their Contribution to Natural Gas: A Case Study of Middle and Lower Jurassic Targets from the Southern Junggar Basin Margin

AbstractIn order to study the hydrocarbon generation (HCGE) characteristics of coal‐bearing basins, the coal‐measure source rocks of the Middle Jurassic–Lower Jurassic (MLJ) of the piedmont thrust belt in the southern margin of the Junggar Basin in Northwest China are taken as research objects. More than 60 MLJ samples were collected from outcrops and wells. Total organic carbon (TOC), rock pyrolysis (Rock–Eval), organic petrological, vitrinite reflectance (%Ro), and hydrous pyrolysis were performed to analyze the relevant samples. The pyrolysis gases and liquid products were measured, and then the chemical composition, as well as carbon isotopes of the gases, were analyzed. The results indicate that the MLJ source rocks have the capacity for large‐scale gas generation. In addition, for coal‐measure source rocks, the heavier the carbon isotope of kerogen (δ13Ckerogen), the lower the liquid hydrocarbon and hydrocarbon gas yield, and the easier it is to produce non‐hydrocarbon gas. It is worth noting that when the δ13Ckerogen in organic matter (OM) is relatively heavier, the fractionation of its products may become weaker in the evolutionary process. The vital contribution of the MLJ source rock to natural gas resources in the study area was further confirmed by comparing it with the Jurassic source gas.

Research on oil well production analysis based on long-term slow-release tracer

Abstract Downhole monitoring the production profile is crucial for the development of oil and gas reservoirs. Currently, the commonly methods for monitoring the production profile include logging tools and using tracer monitoring. The tracer monitoring method is more popular in oil field operations due to its wide applicability, simple process, low cost, low risk, and long monitoring time. However, compared to traditional logging tool monitoring methods, tracer monitoring has drawbacks such as data lag, difficulty in downhole installation, and unstable long-term effects. Bohai Oilfield has developed a new type of solid tracer and solved the problem of downhole installation by improving the structure of the downhole screen tube. This tracer uses polymer material as the skeleton. After entering the designated position, the internal tracer can slowly diffuse into the solvent through the pores in the skeleton, achieving slow release and long-term monitoring of the production profile of the oil well. In 2023, this new type was first applied in the D6 well in Bohai Sea, and a half month stable production stage liquid production profile was obtained through sampling. The monitoring results showed that: (1) Solid slow-release tracer monitoring technology can continuously obtain production layer information in complex environments and can be used for short-term rapid water exploration and long-term water production monitoring, identifying water breakthrough time and main water breakthrough location, (2) The distance between water injection well and D6 production wells is small, and the water injection volume in the injection wells is large. The tracer monitoring results show that there is a certain degree of water flooding in all 6 sections of each test layer, (3) The first test layer is the main liquid production section, the first and sixth test layers are the main oil production sections, and the first and second test layers are the main water production sections. The research results can determine the oil and water production situation of each section of oil well, identify the water breakthrough time and water outlet position, and provide a basis for the next development adjustment.

Upgrading vacuum residue in a supercritical CO2 environment with polypropylene and steam: Insights into products distribution and characterization of liquid products

The pyrolysis of vacuum residue (VR) using polypropylene (PP) under supercritical carbon dioxide (scCO2) conditions represents a novel approach to converting this abundant and difficult-to-process feedstock into lighter liquid products. In this paper, a set of experiments was performed to analyze the impact of scCO2, PP and steam on the yields of pyrolysis products (i.e., liquid, gas and coke) and characteristics of the liquid fractions. The findings indicated notable improvements when scCO2 was used instead of subcritical CO2 in the pyrolysis of VR with PP. These included decreased viscosity and improved API gravity, alongside increased maltene yield and reduced coke yield. Furthermore, the inclusion of PP markedly elevated the quality of the obtained liquid, whereas steam + scCO2 primarily affected the product distribution by raising the yield of coke and gas fractions. VR pyrolysis under scCO2 conditions at 380 °C, 8 MPa, PP/VR ratio of 0.23 for 60 min in a batch system, without the use of catalyst, resulted in the highest liquid yield of 83.7 ± 1.9 wt%, and minimum coke yield of 9.8 ± 1.3 wt%. Under these conditions, the upgraded liquid consisted of 75.2 wt% light and middle distillates with boiling points below 350 °C. Additionally, the proportion of oxygenates in the pyrolysis oil reduced by 60.5 %, improving its heating value. Moreover, adding PP to the upgrading process resulted in a higher proportion of isoparaffins, cycloparaffins, and aromatics, coupled with a decrease in olefins, aligning the liquid specifications more closely with fuel standards.

Study on Production in Different Layers of Tight Reservoir

Abstract In rencent years, the tight oil blocks in our factory are all developed without injectio n and put into production by large-scale fracture network. There are problems of low initial pro duction and fast decline, and the development effect is poor. Because of the large inclination A ngle of the vertical well, it is impossible to obtain the test results of stratified fluid production b y conventional test methods. At the same time, the understanding of tight oil reservoir utilizatio n status after large-scale reconstruction is not clear enough. Therefore, the test of liquid product ion profile in inclined vertical Wells is explored. Meanwhile, the results of conventional liqui d production profile are applied to in-depth analysis of reservoir utilization status in convention al blocks and test blocks respectively, and the relationship between different reservoir types an d fracturing scale and liquid production capacity is determined. The influencing factors and app lication principles of CDFT test results were clarified, the understanding of different reservoi r utilization conditions was obtained, and the main direction of the optimal design of fracturin g program was clarified, which provided technical support for the subsequent design and optim ization of fracturing program in the new district.

Thermodynamics and kinetics of evaporation and thermal decomposition of 1-ethyl- and 1-butyl-3-methylimidazolium methanesulfonate ionic liquids: Experimental and computational study

Knudsen cell mass spectrometry was used to study the evaporation of two ionic liquids, 1-ethyl-3-methylimidazolium methanesulfonate ([EtMIm][MS], MS = CH3SO3) and 1-butyl-3-methylimidazolium methanesulfonate ([BuMIm][MS]), accompanied by thermal decomposition (thermolysis). The independent occurrence of evaporation and thermolysis reactions made it possible to determine their thermodynamic and kinetic characteristics under identical experimental conditions. The saturated vapor pressures were measured and the standard enthalpies of vaporization of [EtMIm][MS](l) and [BuMIm][MS](l) were obtained. The standard thermodynamic functions of formation in the liquid and gaseous states at 298.15 K were estimated from the available experimental data and the results of quantum chemical calculations. The gaseous decomposition products of ionic liquids were identified and the pressures of the thermolysis products of [EtMIm][MS](l) were determined. According to the experimental data and quantum chemical calculations, the thermolysis of [EtMIm][MS](l) occurs through heterogeneous reactions far from the equilibrium state. The kinetics of the reactions is described in two ways. When the degree of sample conversion is used as a variable, the constant reaction rates at the initial stage of thermolysis correspond to a pseudo-zero order reaction with a monotonic increase in the degree of conversion. In the proposed alternative approach, the reaction rates are estimated from the fluxes of thermolysis products and are expressed in terms of ionic liquid concentration.

Thermoeconomic modeling of new energy system based on biogas upgrading to multigenerational purpose

The following article outlines an integrated approach toward the valorization of biogas for energy, chilled water, hot water, freshwater, and liquid carbon dioxide production. The suggested system includes a biogas upgrading unit with a biomethane-fueled burner, a Kalian cycle, an LNG regasification process, and a multi-effect desalination unit that can provide CO2, electricity, cooling, and heating. The new ideas in the proposed system include a cryogenic biogas upgrading process that can be used in many industrial settings, the production of liquid carbon dioxide through biogas upgrading, and the use of biomethane in the integrated combustion process. Furthermore, the grey wolf optimization technique is applied in various multi-objective optimization contexts to achieve optimal operating conditions and preferred performance outcomes. In this simulation, the generation of electricity reaches a value of 755 kW. Attached to it is a cooling load of about 5102 kW, with a heating load of 4725 kW, freshwater capacity about 1.33 kg/s, production rate of liquid CO2 at 0.58 kg/s, and natural gas at 3.1 kg/s. Thermodynamic results reveal that the proposed multigeneration performance scheme providently enhances energy and exergy efficiencies up to 59.82 % and 5.74 %, respectively, compared to the condition of a single product. The performed exergy analysis shows that the overall irreversibility of the suggested configuration is equal to 18,047 kW while about 42.6 % of this value is contributed from the heat exchanger E-104. Moreover, the CO2 emission intensity of the process can be kept as 0.35 kg/kWh. Cryogenic separation can obtain about 88 % of CO2 in biogas and turn it into its liquid phase. The performed economic assessment has resulted in the following total cost rate as well as cost per unit exergy: 321.38 $/h and 83.06 $/GJ, respectively. Under optimal conditions, an exergy efficiency of 13.40 % and a net power output of 2034.39 kW are attained.

Research on the dynamics and mechanism of thermal cracking of coal-based endothermic hydrocarbon fuels

Thermal cracking of endothermic hydrocarbon fuels (EHF) plays an important role in the endothermic process when the fuel temperature exceeds the supercritical temperature. To gain a deeper understanding of the thermal cracking behavior of EHF, this work discusses the thermal cracking law and reaction mechanism of coal-based EHF at different temperatures through static thermal cracking experiments, and establishes a total molecular reaction dynamics model containing 34 species and 24-step reactions based on product distribution. The results show that in the temperature range of 450℃ to 500℃, the gas phase yield of the fuel increases linearly from 8% to 56%, and the conversion rate reaches up to 96.1%. The kinetic reaction of thermal cracking conforms to the primary kinetic equation, the cracking rate constant k is between 1.08×10-4~7.92×10-4s-1, the activation energy Ea=184.47±11.5kJ∙mol-1, and the precursor factor lnA=21.61±3.0. Gas phase products include hydrogen, methane, ethane, ethylene, propane and butane. Liquid phase products include paraffins, alkyldecahydronaphthalenes and aromatic hydrocarbons. As the cracking depth increases, the degree of fuel branching first increases and then decreases, up to 0.33. Paraffins and alkyldecahydronaphthalenes are gradually converted into olefins, cyclic olefins, benzene, naphthalene, indene, fluorene and pyrene and other compounds. Based on the product distribution, the reaction mechanism of thermal cracking of coal-based EHF is speculated to include single-molecule β-cracking, bimolecular F-S-S, intramolecular H-transfer, cyclization and isomerization mechanisms.