Gas Yield Research Articles

Valorizing disposable face masks into non-condensable hydrocarbon gases via optimal reactor configurations in thermal pyrolysis

Pyrolysis studies often overlook the potential of pyrolytic gas as a valuable hydrocarbon resource, thereby hindering the production of advanced carbonaceous nanomaterials (CNM). This study aims to explore various configurations of a multi-zone tubular reactor to upcycle disposable face masks into non-condensable hydrocarbons as potential CNM precursors. The highest gas yield (56.2 wt%) was achieved using a 3-zone configuration (Z-1,3,4), attributed to the end chain scission mechanism. The increased abundance of light hydrocarbons (≤C10) in the resulting liquid confirms a greater extent of end chain scission in the optimum reactor configuration with cold zone retainment. Employing this configuration, different face mask types, including 3ply (polypropylene-based), KF94 (polypropylene-based) and N95 (polyester-based), were utilized as individual feedstocks or in various ratios as mixtures to investigate the resultant composition of hydrocarbon gases. This composition was compared with existing literature studies to identify suitable hydrocarbon gas compositions for CNM production. Mixing 3ply and KF94 face masks produced a consistent gas composition predominantly comprising propylene (62.3 – 66.9%) and ethane (15.4 – 16.8%) via thermal pyrolysis at 500 ℃ with a constant heating rate of 20 ℃/min. However, the inclusion of N95 face masks increased CO2 level fivefold, diminishing the gas quality as a CNM precursor. These findings underscore the necessity of segregating polyester face mask material from polypropylene face mask material prior to pyrolysis to ensure a consistent quality and yield of CNM precursors.

CO2-mediated catalytic upcycling of plastic waste for H2-rich syngas and carbon nanomaterials

To establish a reliable disposal platform of plastic waste, this work developed a novel dual-stage CO2-medaited decomposition-catalysis route by applying multi-functional zeolite-supported bimetallic catalysts. Catalytic upcycling of plastic was first performed in Ar as a reference environment. Bimetallic Fe-Co/ZSM5 catalyst achieved the highest gas yield (53.98 mmol/g), with a H2 proportion of 62.17 vol%. It was evidenced that the Fe-Co alloy had an apparent positive synergistic effect on catalytic cracking and reforming of intermediate volatiles into H2-rich fuel gas and pure carbon nanotubes (CNTs). Regarding CO2-mediated decomposition-catalysis of plastic, there was an apparent synergistic effect between metallic Ni and Fe on gas production so that bimetallic Ni-Fe catalyst gained the maximum cumulative gas yield of 82.33 mmol/g, with a syngas purity of ∼74%. Ni-Fe/ZSM5 also achieved the maximum hydrogen efficiency (87.38%) and CO2-to-CO conversion efficiency (98.62%), implying hydrogen content in plastic and oxygen content in CO2 were essentially converted into gases. Additionally, bimetallic Ni-Fe catalyst revealed the highest carbon production (33.74 wt%), witnessing a synergistic enhancement of 43.45%; specially, approximately 257 mg/g CNTs were anchored on Ni-Fe/ZSM5, with a CNTs purity of over 76%. Overall, this study offers a superb solution in plastic waste valorization and greenhouse gas emission management.

Thermal conversion performance, kinetic mechanism, and products of electric vehicle lithium battery diaphragms

The proliferation of waste lithium batteries is on the rise; however, the thermal treatment attributes of these batteries are largely overlooked, and the conversion mechanism of lithium battery separators remains unclear. This study marks the first comprehensive to compare the thermal degradation characteristics, kinetic parameters and mechanisms, thermal degradation products, and degradation pathways of polypropylene (PP) and polyethylene (PE) lithium battery diaphragms. The pyrolysis temperatures for the PP and PE were 340–500 and 440–530 °C, respectively. PP and PE exhibited average activation energies of 65.19–73.04 and 207.62–209.40 kJ/mol, respectively. At 600–800 °C, the yields of PP and PE pyrolysis gases and gasoline products increased with increasing temperature, while the yields of diesel and paraffin products decreased. The most dominant products generated from the pyrolysis of PP and PE were olefins, and the amount of olefin products from PE increased with increasing pyrolysis temperature. CH3 fracture was the first reaction step that occurred during PP pyrolysis. Our study provides useful information for industrial recycling, disposal, and utilization of electric vehicle lithium battery separators as well as data on the pyrolysis behaviours and transformation mechanisms of polyolefin wastes.

Performance and synergistic effect of oil-coal co-hydrogenation with hydrogen-donor solvent enhancement

The synergistic effect of oil-coal co-hydrogenation and the relationship between H2 consumption and hydrogenation performance of heavy oil and low-rank coal were investigated. The feasibility of oil-coal co-hydrogenation with hydrogen-donor solvent (HDS) enhancement was studied. Results show a matching between the hydrogenation of CG residue and HS coal. H2 consumption is closely related to the severity of reaction, and positively related to the conversion of raw material and oil yield, which could be an essential index for evaluating and predicting the effectiveness of hydrogenation reactions. HDS, rich in partially hydrogenated polycyclic aromatic hydrocarbons, can enhance the synergistic effect of oil-coal co-hydrogenation, effectively inhibit coke formation and improve product distribution because of its ability to supply and transfer hydrogen. Compared to the superimposed product yield of single hydrogenation of residue and coal, the oil yield increases by a maximum of 9.18 wt%, while the gas yield and asphaltene yield decrease by a maximum of 2.72 wt% and 3.55 wt%, respectively, in the oil-coal co-hydrogenation with HDS enhancement. Under the condition of suitable H2 consumption, that is, suitable reaction severity, the synergistic effect of oil-coal co-hydrogenation with 35 wt% HDS is the optimum, and the best raw material conversion and oil yield can be obtained, which are 89.78 wt% and 67.46 wt% respectively.

Enhancement of volatile fatty acids production through anaerobic co-digestion of navel orange residue and waste activated sludge: Effect of pre-treatment and substrate proportions

In this study, the co-digestion system with Navel orange residues (NOR) and Waste activated sludge (WAS) was established, by pre-treating the NOR and setting different volatile solids (VS) ratios of NOR to WAS to motivate the production of volatile fatty acids (VFA). The pre-treatment method (pH 7 and temperature 70 °C) promoted the release of dissolved organic matter, and the concentration of soluble chemical oxygen demand (SCOD) increased by 45.56% compared with the untreated group (pH 3 and temperature 20 °C). In the co-digestion system, the highest VFA yield (5716.69 mg/L) was obtained at VS ratio of 2. When the VS ratio was increased to 4, the imbalance in proportions of carbon and nitrogen affected VFA production, and the high concentration of essential oils (EO) present in the NOR inhibited the methane production; the cumulative yield of methane gas decreased by 24.10% compared with the yield obtained when the VS ratio was 2. Analysis of microbial community revealed that an increase in the number of VFA-producing microbial populations and the abundance of Methanobacteria resulted in the accumulation of acetic acid. This study demonstrated that co-digestion of NOR with WAS improve VFA production, thus realizing the utilization of solid wastes and reducing environmental pollution.

Computational prediction of green fuels from crude palm oil in fluid catalytic cracking riser

Fluid catalytic cracking could convert crude palm oil into valuable green fuels to substitute fossil fuels. This study aimed to predict the phenomenon and green fuels yield in the industrial fluid catalytic cracking riser using computational fluid dynamics. A three-dimensional transient simulation using the Eulerian-Lagrangian with the multiphase particle-in-cell is to investigate reactive gas-particle hydrodynamics and the four-lump kinetic network model with the rare earth-Y catalyst for crude palm oil cracking behaviors. The study results show that the fluid and catalyst velocity profile increase in the middle of the riser reactor because the cracking reaction process that produces OLP and Gas products has a lighter molecular weight. The endothermic reaction causes the temperature profile to decrease because the heat of the reaction comes from the catalyst. This analysis shows that the simulation accurately predicts green fuel products from crude palm oil. As a result, the crude palm oil conversion, organic liquid product yield, and Gas yield correspond to 70 wt%, 28.8 wt%, and 27.5 wt%, respectively. Compared to the experimental study, the computational prediction of yield products showed good agreement and determined the optimal riser dimension. The methodology and results are guidelines for optimizing the FCC riser process using CPO.

Experimental investigation on in-situ hydrogen generation from depleted heavy oil reservoir by gasification

Fossil energy has been confirmed as the primary raw material for hydrogen generation in chemical factories. In-situ hydrogen generation from depleted oil reservoirs has been considered a prominent technology for hydrogen generation, accompanied by harmful gas storage, over the past few years. In this study, the effects of temperature, reaction time, distinct porous media, and oil/water ratio on hydrogen generation were investigated by simulating in-situ heavy oil gasification using high-temperature and high-pressure reactors. As indicated by the results, besides hydrogen, methane and carbon dioxide were also largely generated in the gasification process through water gas shift, oxidation, aquathermolysis, pyrolysis, and so forth. The result suggested that temperature and oil/water ratio exerted relatively significant effects on hydrogen generation due to the boosted forward reaction of water gas shift and steam reforming. Moreover, oxygen would prefer an oxidation reaction with oil instead of hydrogen. It was expressed that the hydrogen fraction decreased and remained constant as residence time went on due to less carbon monoxide generation, and arriving at equilibrium, whereas the gas yield tend to increase. The metallic oxides notably catalyzed hydrogen generation. Some novel insights gained in this study are conducive to achieving high-efficiency hydrogen generation through in-situ heavy oil gasification.

Impact of hail-netting on Vitis vinifera L. canopy microclimate, leaf gas exchange, fruit quality, and yield in a semi-arid environment

Hail events have the potential to destroy grapevine shoots, reduce yield, and inflict economic loss upon growers. As a result, many grape growers have adopted the use of hail-netting to mitigate potential vine damage. Although hail-netting has been observed to prevent hail damage, Texas High Plains grape growers have expressed concerns regarding effects hail-netting may have on vine canopy microclimate, grapevine health, fruit maturity, fruit quality and yield. Therefore, over three growing seasons (2018 – 2020), field-grown vines (Vitis vinifera L. ‘Malbec’ and ‘Pinot gris’) were exposed to hail-netting, or grown without hail-netting. Each growing season canopy microclimate, leaf gas exchange, fruit maturity, yield parameters, and vegetative growth were monitored. Netting reduced canopy air and leaf temperature and decreased canopy vapour pressure deficit. By modifying light infiltration and leaf temperature, hail-netting altered leaf gas exchange. In addition, gas exchange differences were found between cultivars. Although fruit pH and total acidity were not different at harvest, fruit maturity measurements revealed total soluble solid development was influenced by netting and cultivar. Vine cluster numbers were greater for vines without netting and yield parameters were generally lower for ‘Malbec’ vines. Pruning weights indicate decreased vegetative growth for hail-netting and ‘Pinot gris’ vines. Results suggest grape-growers' use of hail-netting may allow growers to achieve fruit production goals. However, when using hail-netting, growers should consider possible management modifications due to changes in vine physiology, fruit maturation, and harvest schedules.

Impact of hail-netting on Vitis vinifera L. canopy microclimate, leaf gas exchange, fruit quality, and yield in a semi-arid environment

Hail events have the potential to destroy grapevine shoots, reduce yield, and inflict economic loss upon growers. As a result, many grape growers have adopted the use of hail-netting to mitigate potential vine damage. Although hail-netting has been observed to prevent hail damage, Texas High Plains grape growers have expressed concerns regarding effects hail-netting may have on vine canopy microclimate, grapevine health, fruit maturity, fruit quality and yield. Therefore, over three growing seasons (2018 – 2020), field-grown vines (Vitis viniferaL. ‘Malbec’ and ‘Pinot gris’) were exposed to hail-netting, or grown without hail-netting. Each growing season canopy microclimate, leaf gas exchange, fruit maturity, yield parameters, and vegetative growth were monitored. Netting reduced canopy air and leaf temperature and decreased canopy vapour pressure deficit. By modifying light infiltration and leaf temperature, hail-netting altered leaf gas exchange. In addition, gas exchange differences were found between cultivars. Although fruit pH and total acidity were not different at harvest, fruit maturity measurements revealed total soluble solid development was influenced by netting and cultivar. Vine cluster numbers were greater for vines without netting and yield parameters were generally lower for ‘Malbec’ vines. Pruning weights indicate decreased vegetative growth for hail-netting and ‘Pinot gris’ vines. Results suggest grape-growers' use of hail-netting may allow growers to achieve fruit production goals. However, when using hail-netting, growers should consider possible management modifications due to changes in vine physiology, fruit maturation, and harvest schedules.

Effects of various carbon-supported iron catalysts on tar removal efficiency and syngas yield during catalytic biomass gasification

Raw biomass, biochar, and activated carbon (AC) were used to produce carbon supported iron catalysts for catalytic biomass gasification. K2CO3 was used to activate the biochar and provide the K promoter of the catalysts. The results showed that the catalyst prepared by co-impregnating and calcining Fe and K on the raw biomass (B-Fe-K) could remove 80.23 % tar, which was much higher than 73.73 % for the catalyst of B-Fe without the K promoter, and 76.25 % for the catalyst by co-impregnating and calcining Fe and K on the biochar (C-Fe-K). The supports of AC and biochar themselves could also remove 63.16 % and 37.23 % tar, respectively. The use of B-Fe-K almost doubled the syngas yield to 473.79 ml/g (including 243.56 ml/g CO, 198.25 ml/g H2, and 31.98 ml/g CO2), compared to 241.37 ml/g syngas (including 108.98 ml/g CO, 66.41 ml/g H2, and 65.987 ml/g CO2) produced by the pyrolysis of biomass without a catalyst. The addition of biochar during the pyrolysis slightly increased the syngas yield to 248.96 ml/g (117.36 ml/g CO, 74.22 ml/g H2, and 57.38 ml/g CO2) while the use of AC could significantly increase the syngas yield to 347.60 ml/g (179.39 ml/g CO, 124.22 ml/g H2, and 43.99 ml/g CO2). It was found that the porosity, dispersion of active sites and the oxidation state of iron oxide are substantial factors determining the performance of catalysts in tar removal efficiency. The addition of potassium and enhancing the porosity of the catalysts enhanced the reducibility of iron resulted in increasing the tar removal efficiency and gas yield.

IMPLEMENTATION OF THE K-EPSILON (K–Ε) MODEL FOR THE SIMULATION OF COAL GASIFIER /REACTOR

The objective of the present research is to use the standard turbulent kinetic energy and turbulent dissipation (k-e) model to do a numerical modelling and simulation of the gasification chamber or reactor which was used to gasifier Lafia-Obi bituminous coal. The numerical modelling and simulation were implemented with the aid of AutoCAD and Ansys softwares. The gasifier/reactor geometry was modelled using AutoCAD and then imported to Ansys workbench for simulation. Results show the modelled reactor geometry comprising a height of 0.9m, diameter of 0.5m and volume of 0.177m 3. Simulation results show mass fraction of producer gas components comprising of 16% carbon monoxide, 14% hydrogen, 2.7% methane and 18% carbon dioxide. The producer gas yield is in conformity with standard producer gas yield. Temperature profile around the modelled gasifier/reactor was displayed with a maximum of 960K.

Optimal design and off-design performance improvement for power-to-methane system integrating solid oxide electrolysis cell with methanation reactor

Power-to-methane (PtM) is a prospective solution to the mismatching between the supply and consumption of renewable energy resources (RES) by converting renewable power into methane. However, the continuous fluctuation of RES causes the PtM system to deviate from the design condition in the vast majority of cases, and thus it is significantly vital to study the operating characteristics of the PtM system under off-design conditions. This paper proposes a comprehensive investigation framework from design to off-design steps for the performance improvement of a PtM system combining solid oxide electrolysis cell with methanation reactor, and solar energy is selected as renewable energy input. Firstly, the system with the total exergy efficiency (ηEX,tot) of 11.83% and levelized cost of exergy (LCOE) of 150.76 $/MWh is selected as the optimal design condition based on the homogeneous assessment from both thermodynamic and economic aspects, by means of Non-dominated sorting genetic algorithm-II. Then, based on the optimal design point, the off-design performances are quantitatively investigated under varying solar radiation and key operating parameters, in terms of synthetic natural gas (SNG) yield and ηEX,tot. The results indicate that with the increment in solar radiation, the SNG yield rises, while the ηEX,tot increases first and then decreases. Finally, the multi-objective optimization based on the Artificial Neural Network models is implemented for the system under off-design conditions to acquire the best trade-off between hourly SNG yield and ηEX,tot. The off-design optimization solutions reveal that the hourly optimal SNG yield is located in the range of 275.06–946.53 kW, achieving a total annual SNG yield of 1697 MWh/y, and the hourly optimal ηEX,tot mainly varies in the range of 10.40–11.40%.

Intensification of two-stage biomass gasification for hydrogen production

Hydrogen production from wood pellets was investigated using a modulus two-stage gasification. The results showed that up to 88 mg H2/g wood pellets, which is 1.3 times higher than the theoretical hydrogen from feedstock (around 65 mg/g), was obtained at temperatures below 1000 °C. Combining CO2 and steam as gasifying agents resulted in a 6% increase in the gas yield and up to 93% reduction in tar content (0.03g/Nm3) compared to steam gasification (0.5–0.7 g/Nm3). Although the hydrogen content in the gas stream was similar in both cases of steam and CO2-steam gasification (88 mg/g pellets), the CO2 content in the gas stream from CO2-steam gasification was reduced by 12%–17% compared with steam gasification. The H2/CO ratio in the gas stream was between 3.2 and 3.8 for steam gasification and 1.6–2.3 for CO2-steam gasification. The cold gas efficiency (a ratio of calorific value of products to that of wood pellets) of CO2-steam gasification was up to 14–16% higher than that of steam-gasification due to higher CO content in the gas. It can be concluded that using CO2- steam two-stage gasification increases the process efficiency and sustainability by utilising carbon source in CO2 emission.

Gases production from microwave-assisted pyrolysis of polypropylene plastic

Polypropylene (PP) is widely used around the world, but PP waste has caused environmental problems after being abandoned. To deal with this massive PP waste, pyrolysis is one of the potential technologies appropriate for PP final utilization. Microwave assisted heating was adopted in this study to investigate the effects of pyrolysis temperatures from: 700, 750, 800, 850 and 900 ℃; microwave power set at: 600, 700, 800, 900 and 1000 Watts; and SiC/PP mass ratios of: 60:5, 60:10, 60:15, 60:20 and 60:25. Results for the above range of operating conditions were recorded for: product gas yields, pyrolytic gas transient compositions, and product gas heating values (HHVs). The transient product gases included C3H6, CH4 and H2 with stable concentrations ranging from 7.5 to 22.1 vol%, 5.1–20.2 vol% and 5.4–21.1 vol%, respectively. The optimal gas yield of 70.7 wt% was obtained when the pyrolysis temperature, microwave power, and mass ratio were 900 ℃, 1000 Watts, and 60:15, respectively. Based on the gas components, the corresponding HHVs ranged from 13.9 to 34.4 MJ/Nm3.

Model development for biogas generation, purification and hydrogen production via steam methane reforming

Biogas, a renewable energy source produced by the anaerobic digestion of organic matter, can reduce greenhouse gas emissions. The purification and hydrogen conversion of biogas enhance its versatility as an energy carrier and reduce dependency on fossil fuels. This sustainable process fosters a cleaner future. In this study, simulation models were used to optimize the process conditions and assess the technical feasibility of the biogas-to-hydrogen production. In addition to the anaerobic digestion process, simulation models were also developed for biogas purification via water scrubbing and hydrogen production via steam methane reforming (SMR) using Aspen Plus simulation software. Simulation results demonstrated that the maximum methane yield of 520 mL/gVS was achieved at an organic loading rate of 20 g/L, while the minimum yield of 230 mL/gVS was observed below 10 g/L. Optimal anaerobic digestion temperature for maximum gas yield (548 mL/gVS) was found to be 30 °C, with a decrease in biogas production above 40 °C. In the water scrubbing model, maximum CO2 absorption occurred at 15 bar pressure, whereas reducing the pressure to 5 bar significantly lowered the absorption rate. The SMR model yielded the highest hydrogen production rate of 10.15 kg/h using purified methane (99%) as feed, but the methane content was affected by the biogas composition.

Alkali and alkaline earth metals catalytic steam gasification of ashless lignin: Influence of the catalyst type and loading amount

This work studies the effects of alkali and alkaline earth metallic species (AAEMs) (Na2CO3, K2CO3, and CaCO3), Na+ impregnation amount (2, 5, and 7 mmol) and sodium salts (NaHCO3, Na2SO4, and NaAlO2) on the gasification characteristics and product distribution of G-type lignin in a fixed-bed system for continuous gasification. The results showed that six catalysts all could improve lignin gasification performance by increasing total gas yields, syngas yields, H2/CO ratios, and carbon conversion rates. Na2CO3 had the strongest catalytic ability, followed by NaHCO3 and K2CO3, while CaCO3, Na2SO4 and NaAlO2 had poor catalytic abilities. Gaseous AAEMs, especially NaOH and KOH, could enhance tar cracking, volatiles reforming, coke gasification, the water-gas shift reaction, and methane steam reforming. The high melting points of CaO and NaAlO2 greatly reduced the catalytic capacities of CaCO3 and NaAlO2. AAEMs could combine with the carbon matrices to form carboxylate structures or phenol/aldehyde structures which might volatilize to catalyze homogeneous reactions. Moderately increasing Na+ impregnation amount to 5 mmol was beneficial to lignin gasification, but excessive impregnation reduced the gasification parameters. In addition, all six catalysts had effects on the tar composition, especially K2CO3 and NaAlO2, which could effectively catalyze tar cracking and reduce heavy compounds.

Metagenomic analysis of ethylene glycol contamination in anaerobic digestion

Anaerobic digestion is an established method for the biological conversion of waste feedstocks to biogas and biomethane. While anaerobic digestion is an excellent waste management technique, it can be susceptible to toxins and pollutants from contaminated feedstocks, which may have a detrimental impact on a digester’s efficiency and productivity. Ethylene glycol (EG) is readily used in the heat-transfer loops of anaerobic digestion facilities to maintain reactor temperature. Failure of the structural integrity of these heat transfer loops can cause EG to leak into the digester, potentially causing a decrease in the resultant gas yields. Batch fermentations were incubated with 0, 10, 100 and 500 ppm (parts per million) of EG, and analysis showed that the EG was completely metabolised by the digester microbiome. The concentrations of EG tested showed significant increases in gas yields, however there were no significant changes to the digester microbiome.

Catalytic steam gasification of soy hull pellets in a fluidized bed gasifier

The catalytic effects of inherent alkali-based metal catalysts present in biomass residues on biomass pellets were explored in this work. Gasification experiments were carried out in a pilot scale fluidized bed gasifier in the presence of alkali metal catalysts. By using a response surface methodology experimental design technique, soy hull biomass pellets were subjected to steam gasification within a temperature range of 750–950 °C. Additionally, the effects of steam-to-biomass (S/B) ratio and the catalyst loading on the gas and tar yields, and gaseous compositions were investigated. It was found that lower temperature resulted in the formation of more tar residue since the temperature was insufficient to crack the tar formed. Lower S/B ratio led to increased tar yield. Addition of catalyst significantly reduced the tar residue produced during the gasification experiments. An increase in the catalyst loading led to a steady decrease in the tar yield with up to 52% reduction at 950 °C. Further increasing catalyst loading beyond 5% had no significant effect on tar reduction. Gas yield increased slightly with catalytic gasification of the biomass pellets compared to the non-catalyzed reactions earlier studied. The reaction mechanism of the catalyzed reactions and effect on tar decomposition were discussed. Catalytic effects on tar composition were also investigated. The results from these experiments provide further insight into considering co-pelletization of catalysts during production of pellets for better gasification performance in terms of increased yields of the major gaseous components.

Experimental Characteristics of Hydrocarbon Generation from Scandinavian Alum Shale Carbonate Nodules: Implications for Hydrocarbon Generation from Majiagou Formation Marine Carbonates in China’s Ordos Basin

The hydrocarbon source rocks of the marine carbonates of the Ordovician Majiagou Formation in the Ordos Basin are generally in the high-overmature stage and are, therefore, not suitable for hydrocarbon thermal simulation experiments. Their hydrocarbon generation potential and hydrocarbon generation characteristics are not clearly understood. Meanwhile, Nordic Cambrian carbonates are similar in lithology, parent material type, and sedimentary age, and are in the low evolution stage, which is suitable for hydrocarbon thermal simulation experiments. Therefore, in this study, we selected the Nordic carbonates for the gold tube thermal simulation experiment to analyze the content and geochemical characteristics of the thermal simulation products. The experimental results are also compared and analyzed with the characteristics of thermal simulation products of Pingliang Formation mud shale (contemporaneous with the Majiagou Formation) and Shanxi Formation coal (in the upper part of the Majiagou Formation), which are similar to the Majiagou Formation in the Ordos Basin. The results showed that the Nordic carbonate has different hydrocarbon production characteristics from the mud shale of the Pingliang Formation of the same parent material type, and although the hydrocarbon production yields of the two are not very different, the carbonate still produces methane at 600 °C. The hydrocarbon production yield of the Nordic carbonates is almost equivalent to that of type-II2 kerogen, indicating that the hydrocarbon production yield is not related to lithology and only to the organic matter type; however, the Nordic carbonate can produce a large amount of H2S. The alkane carbon isotope changes are mainly controlled by the degree of thermal evolution, showing gradual heaviness with increasing temperature. No carbon isotope sequence reversal occurred during the thermal simulation, and its distribution range is roughly the same as that of the alkane carbon isotope composition of the mud shale of the Pingliang Formation. The ethane carbon isotope composition is as heavy as −21.2‰ at the high-temperature stage, showing similar coal-type gas characteristics. The addition of calcium sulphate (CaSO4) causes the TSR reaction to occur, which has a significant impact on the methane content under high maturity conditions, reducing its content by more than 50% at 600 °C. However, the addition of CaSO4 increases the yield of heavy hydrocarbon gases, such as ethane, and promotes the production of C6-14 hydrocarbons and C14+ hydrocarbons at high-temperature stages, and the addition of CaSO4 substantially increases the yield of H2, CO2, and H2S. The thermal simulation results have implications for the hydrocarbon formation mechanism of the early Paleozoic marine carbonate formation system in the stacked basins of the Ordos Basin and the Tarim Basin in China.

Research on co-gasification of polyethylene and cellulose via reactive molecular dynamics simulation

Co-gasification of waste plastic and biomass is an effective way for waste disposal and renewable energy utilization. In this paper, the co-gasification of polyethylene and cellulose was explored. The reaction mechanism and thermochemical characteristics of co-gasification were comprehensively analyzed. Results showed that the co-gasification reduced the initial decomposition temperature of polyethylene but delayed its later decomposition, and also delayed the decomposition of cellulose. Polyethylene acted as a hydrogen donor in co-gasification to provided free radicals conductive to hydrogen and hydrocarbon generation. Cellulose as an oxygenated compound contributed to CO production. Compared with the separate gasification of cellulose, the separate gasification of polyethylene and the co-gasification of the two produced more hydrogen and hydrocarbons but less CO. The synergistic effect of co-gasification increased the lower heating value of gas product and carbon conversion rate and reduced the activation energy, but decreased the combustible gas yield. The gas product composition of co-gasification could be regulated by adjusting the blending ratio. This work sheds lights on the co-gasification characteristics of polyethylene and biomass, which would be helpful for the application of this technology to produce high-quality syngas.