The removal of sulfur dioxide from flue gas is an important process for the mitigation of acid rain. Activated carbons have a low affinity for water and a high affinity for polarizable molecules, such as sulfur dioxide, making them good candidates for selective adsorbents for flue gases. This work presents results on the multicomponent adsorption of N2/CO2/SO2 and N2/CO2/SO2/H2O flue gas mixtures on four activated carbons prepared from petroleum coke, and one carbon black. Multicomponent adsorption was measured at T = 30, 60, 90 °C. All five activated carbons had a high affinity and selectivity for SO2 in both the presence and absence of water. The activated carbons prepared with KOH (P_K) and NaOH (P_Na) showed the highest capacity for SO2 under wet conditions with thermal swing regeneration (P_K: nadsSO₂ = 0.148 ± 0.002 mmol g−1, P_Na: nadsSO₂ = 0.13 ± 0.01 mmol g−1). In pressure swing experiments of the wet flue gas mixture, the activated carbon prepared with a K2CO3 and KOH (P_CK) (nadsSO₂ = 0.077 ± 0.002 mmol g−1) and P_K (nadsSO₂ = 0.064 ± 0.005 mmol g−1) activated carbons had the highest SO2 capacities. Of the activated carbon, P_K had the greatest SO2/H2O selectivity for the thermal swing adsorption (T = 30 °C, SSO₂/H₂O = 3.0 ± 0.2) and pressure swing adsorption (T = 90 °C, SSO₂/H₂O = 3.9 ± 0.6) experiments. It was observed that activated carbons with higher carbon fraction were less likely to have a difference in SO2 adsorption from dry versus wet conditions. After the wet SO2 multicomponent adsorption, no change in the adsorption performance of any activated carbons was observed after 10 cycles.

To reduce the corrosion failure frequency of oil and gas pipelines, corrosion monitoring coupons are often used to evaluate the internal corrosion status of pipelines. However, the local flow field varies after the installation of the coupons, so the monitoring corrosion rate is different from that of the pipe wall. To evaluate the effectiveness of corrosion coupons monitoring, a lab-scale flow loop system was used to carry out flow corrosion experiments to obtain the local corrosion rates of corrosion monitoring coupons and pipe wall, respectively. Combined with the characterization of corrosion products and multiphase flow, a mechanism model of corrosion monitoring effectiveness was established. It was clear that the deviation of corrosion monitoring rate was related to the flow rate, shear force and turbulent kinetic energy. The accumulation of corrosion media and the detachment of corrosion product films resulted in variation in the morphology and the monitoring effectiveness.

Herein, as an alternative to heavy fuel oil (HFO), a multi-component surrogate fuel was developed, consisting n-tetradecane (6.36 %), n-hexadecane (4.25 %), i-hexadecane (20 %), n-eicosane (15 %), decalin (17 %), toluene (4.45 %), naphthalene (13 %), and phenanthrene (19.94 %). The proportions of the components of the surrogate fuel were determined by studying the chemical and physical characteristics of HFO. The surrogate fuel was optimized by matching the cetane number (CN), density at 20 °C, lower heating value (LHV), and hydrogen-carbon (H/C) ratio. The developed skeletal surrogate mechanism constituted 128 species and 375 reactions. It was extensively validated using various fundamental experiments based on its single components and HFO performance under relevant engine conditions. The predicted ignition delay time in shock tubes and the concentrations of primary species in jet stirred reactors and flow reactors were in good agreement with the previously measured values. The predicted laminar flame speed in counterflow configuration was close to the experimental data. The flame spray and combustion characteristics were found to be well produced by the proposed mechanism in a fuel ignition analyzer and a two-stroke marine diesel engine. The proposed skeletal mechanism exhibited reliable overall performance for combustion behavior, indicating that it can be used for modeling HFO in realistic engine applications.

The use of lignocellulosic biomass pyrolysis to produce renewable fuels and high value-added chemicals can help alleviate the energy and resource crisis facing the world today. However, the direct pyrolysis of lignocellulosic biomass encountered some problems. For example, the bio-oil obtained from lignocellulosic biomass pyrolysis has the disadvantages of lower heating value with strong acidity due to the high oxygen contents of biomass. The use of biomass and other types of waste for co-pyrolysis can effectively solve these problems. Among them, the co-pyrolysis of lignocellulosic biomass and plastics has been extensively studied, the co-pyrolysis can not only improve the composition and quality of lignocellulosic biomass pyrolysis liquid products but also realize the reduction and resource utilization of waste plastic waste. This article summarizes the current research status of lignocellulosic biomass and plastic co-pyrolysis technology in recent years, focusing on the synergistic effect of lignocellulosic biomass pyrolysis and plastic pyrolysis, and prospects the development of biomass co-pyrolysis technology. In addition, the article also summarizes the catalysts used in the catalytic co-pyrolysis system of lignocellulosic biomass and plastics and the catalytic mechanisms involved. A comprehensive discussion on the CO2 emission of co-pyrolysis is presented. This review reveals the application prospects of pyrolysis technology in the pyrolysis of lignocellulose to produce fuels and chemicals, and also proposes future research directions in pyrolysis technology optimization and catalyst development.

The significant variation in production in different blocks has seriously restricted the large-scale breakthrough of China’s low-rank coalbed methane industry for a long time. This study describes in detail the effects of lignite composition on reservoir structure, gas-bearing characteristics, and methane enrichment in the Erlian Basin, thus providing a theoretical basis for accurate exploration of lignite methane. Homogenization of huminite-rich lignite results in the disappearance of cellular structure, closure of cell cavity, small pore size, and low proportion of macropore. The cell wall of inertinite-rich lignite is thin, the cell structure is well preserved, and many cellular pores are developed, providing abundant macropore space. The inertinite-rich lignite contains larger pores and throats, and the content of high coordination number pores is also more abundant. Reservoir characteristics further control the occurrence, migration, and preservation of methane. The inertinite bands provide good seepage space and channels for lignite. The inertinite-rich lignite has high permeability and a low proportion of adsorbed methane, so methane has high mobility in it. The huminite-rich lignite has an excellent “self-sealing” effect on the gas. Overall, huminite-rich lignite in the stagnant area and inertinite-rich lignite in the regional structural culmination are potential favorable positions for the enrichment of lignite methane. Moreover, the interbedded thick coal seam of huminite-rich lignite and inertinite-rich lignite can provide advantageous conditions for water infiltration and gas preservation, thus forming a complete combination of “source, reservoir, and cap rock” in the thick lignite itself.

The core issue of photocatalytic H2 generation from water decomposition is to explore high activity, ultra stability and environment-friendly photocatalytic materials. Graphitic carbon nitride (g-C3N4, GCN) is preferred by global scientists for the diversified superiorities, such as the characteristic of flake graphite-phase fabric, competitive cost, non-poisonous, ideal bandgap (∼2.7 eV) and decent stability. Nevertheless, by reason of the deficiencies in small specific surface area and rapid photo-excited charge pairs recombination, photocatalytic hydrogen evolution activity of g-C3N4 is undesirable and it cannot be put into large-scale industrial production for these reasons. Construction of heterojunctions to boost electrons/holes (e-/h+) segregation efficiency is identified as a resultful tactic to promote the activity of g-C3N4. In current work, CuO/g-C3N4 with disparate CuO/g-C3N4 mole ratio (0.5%, 1%, 1.5%, 2%) were prepared through an impregnating strategy and investigated via various methods. Photocatalytic properties of CuO/g-C3N4 (CuO/CN) photocatalysts exert superior H2 evolution rate and consistency under solar light illumination. The optimal H2 evolution activity with non-cocatalyst is 130.1 µmol·g−1·h−1 upon the 1.5% CuO/CN, realizing 46.1 folds as fast as that of GCN (2.8 µmol·g−1·h−1). Coupling with CuO is confirmed to narrow bandgap of the samples, thus enhancing the light absorptivity and utilization. Besides, photo-stimulated e-/h+ pairs have acquired more efficient separation after formation of CuO/g-C3N4 heterojunctions. The method for preparation of S-scheme CuO/g-C3N4 heterojunction catalysts furnishes a perception of boosting the photocatalytic H2 generation rate through coupling with transition metal oxides.

Most of oilfields have entered the development stage of high water-cut and low recovery factors, and stabilizing oil production and controlling water production are the key to enhancing subsequent oil recovery. Adopting the 1/4 five-point injection-production well pattern, the chemical flooding experiments were conducted using a three-dimensional (3D) visualization sand-pack model with liquid drain orifices. A real-time image acquisition and dynamic observation device for detecting droplet textures as fluid flowing was developed with experimental system. In heterogeneous reservoirs with a high permeability contrast, the effects of oil-displacement agents on production dynamics, sweep morphology, and emulsifying characteristics of remaining oil at different locations were investigated to reveal the synergistic mechanism of compound flooding for enhanced oil recovery. The results showed that, in the main streamline region, the mean droplet diameter decreased, the distribution density increased first and then decreased, and the maldistribution decreased first and then increased with an increase in injection volume of the compound system. In the vertical region with the main streamline, the mean diameter and maldistribution reduced, and the distribution density increased owing to the synergistic mechanism. The viscosity reducer can increase sweep efficiency by 8.34% and recovery factor by 5.95% due to the viscous crossflow in the high permeability channel. The compound system can increase sweep efficiency by 15.92% and recovery factor by 12.67% due to the synergistic effect of emulsifying-tapping, emulsion plugging conversion, and profile control. Therefore, chemical compound flooding has great potential of enhancing heavy oil recovery in heterogeneous reservoirs due to the synergistic effect of the compound system.

Weighted fracturing fluid was considered to be one of the key technologies to deal with the challenge of abnormally high pressure and ultra-high temperature reservoir stimulation in the case of existing fracturing equipment. In this work, a thickener polymer Pt-Fb that meets the requirements of fracturing fluid weighting by HCOONa was synthesized. And HCOONa- weighted fracturing fluid with delayed crosslinking characteristics and good friction reduction performance was developed based on the polymer Pt-Fb. It is much cheaper than CHKO2-weighted guar gum fracturing fluid. The density of HCOONa-weighted fracturing fluid was up to 1.3 g/cm3. The fracturing fluid proposed in this study meets the temperature resistance and shear resistance requirements of 170 °C and 170 s−1. Besides, a complete gel breaking was obtained by using NaBrO3, and the internal mechanism was investigated from both experimental and theoretical aspects. It was revealed that a mild multi-step oxidation reaction enables NaBrO3 to break the HCOONa-weighted fracturing fluid.

Magnetic copper ferrite (CuFe2O4) was prepared by hydrothermal synthesis method and used for the catalytic hydroconversion (CHC) of Hanglaiwan long flame coal (HLFC) in cyclohexane under 1 MPa of initial hydrogen pressure (IHP) at 300 °C for 4 h. The total yield of soluble portion (SP) from the CHC is 33.7 wt%, significantly being higher than that (10.5 wt%) from the non-CHC (NCHC) under the same conditions. The main compounds detected in SPCHC (for CHC) are arenes and oxygen-containing organic compounds (OCOCs). Benzyloxybenzene (BOB), 2-(benzyloxy)naphthalene (BON), oxybis(methylene)dibenzene (OBMDB), oxydibenzene (ODB), and 2,2′-oxydinaphthalene (ODN) were used as HLFC-related model compounds to investigate the catalytic activity of CuFe2O4 and understand the CHC mechanism of HLFC. According to the model reactions, CuFe2O4 activates H2 to biatomic active hydrogen (H…H) and splits H…H to mobile H+ and immobile H-. H+ addition to oxygen atoms (OAs) in >C-O- bridged bonds (BBs) cleaves the BBs and releases SP during the CHC of HLFC.

Water gas shift reaction (WGSR) is urgently calling for an alternative to the Fe-Cr catalyst. Ni-based catalysts are taken into consideration but remain challenging because of their high methanation activity. Here we report a highly active and selective NiCx/Ni-foam catalyst with clearly detectable Ni3C phase, facilely obtainable by endogenous growth of NiC2O4 onto a Ni-foam and subsequent H2-reduction treatment. The preferred catalyst with high content of NiCx is capable of converting 63.6% or 94.3% CO at 350 °C or 400 °C with trace or < 0.8% CH4 formation for a feed gas with H2O/CO/Ar molar ratio of 4/1/9, and is stable for at least 110 h. It is experimentally and theoretically unveiled that the Ni3C facilitates the dissociative activation of H2O and favors CO to form carboxylate species (favorable for CO2 formation) rather than active Ni(CO)n intermediates for CH4 formation thereby enabling the catalyst with high WGSR activity and selectivity.

Combustion characteristics of premixed H2/CH4/Air in a combustor with dual-inlet are investigated under various operating conditions. Effects of reactants ratio in the two inlets, dual-inlet setting and flow rates on the combustion characteristics and heat transmission are compared and analyzed. Results demonstrate that the setting of dual-inlet strongly affects burning such as OH generation and consumption, and the weak flame is formed in the second-inlet, modifying the species distribution and gas temperature. For the seven conditions with 28 cases under a kept H2/CH4 blended ratio mCH4 = 5%, the case of 20% H2/CH4/Air imported via the second-inlet achieves a better thermal performance, where reactions around the second-inlet contribute to the sufficient burning, heat release, heat transfer of gas-wall and gases. It also reduces the heat loss through exhaust gases, resulting in a higher burner radiation temperature, and the mean radiation temperature of case 19 is 55 K higher than that of case 21. Moreover, the radiation power of the combustor can be further improved by optimizing the second-inlet setting. The combustor with the distance of the two inlets L = 14 mm obtains a higher thermal performance, where the Tm reaches 1254 K and is 16 K higher than the stepped tube and the radiation power reaches 44.1 W under condition of mf = 3.339 × 10-5kg/s andmCH4 = 5%.

The effect of acidity and alkalinity of mine water on the ability of surfactants to wet coal was studied with contact angle measurements to determine the optimal aqueous surfactant concentration, quantitative osmosis experiments to characterize the wettability of coal, and atomic force microscopy to analyze the surface microstructure of the coal. The contact angle measurements showed that the optimum concentrations of both selected surfactants, sodium dodecyl sulfate (SDS) and coconut oil diethanolamide (CDEA), were 1.0 wt%, with contact angles on the coal samples of 25.8° and 36.1°, respectively, which were lower than from other concentrations of the surfactants. The use of quantitative osmosis experiments revealed that the acid-base environment of the surfactant solutions impacted the effect of the surfactants to different extents depending on the type of surfactant. SDS at pH = 9 had the best wetting performance and its osmosis height was 17.2 × greater than the treatment with water at pH = 7. Analyses with atomic force microscopy determined the effect of the wetting mechanism of the surfactant in different acid-base environments on the microstructural characteristics of the coal. The experiments showed that the surface morphology and pore structure of the coal changed after surfactant treatment in different acid-base environments, with more pore structures appearing on the surface of the coal samples. Both acidic and alkaline conditions could enhance the surface roughness of coal. Coal treated with SDS at a pH of 9 had the highest surface porosity of 13.8%. These studies clarify the microscopic wetting mechanism of the surfactants SDS and CDEA at different pH levels of mine water in terms of the microscopic surface morphology and pore structure of the coal, and provide an experimental basis for improving the wetting of coal and the water injection process of a coal seam.

Low energy storage density, intermittent phase changes, and heat transfer barriers have posed significant challenges in the implementation of hydrate energy storage systems. Based on the heterogeneous nucleation mechanism for tetrabutylammonium bromide (TBAB) hydrate phase change energy storage, a novel cold storage system with internally circulating gas disturbance was constructed for energy evaluation and thermodynamic evolution. The hydrate cold storage efficiency, response time, dynamic driving force, unique force pattern of the coils and guest molecule diffusion were analyzed for the first time. The bubbles generated by gas internal circulation provided numerous nucleation sites for hydrate formation, efficiently promoting the energy storage process. The disturbances caused by the bubbles also rapidly transmitted the energy generated by the phase change. A hydrate storage density of 57.4 kWh/m3 for this system was the maximum among known hydrate storage systems. Notably, a change in solution concentration (from 10 wt% to 40 wt%) resulted in a 2–3-fold increase in the cold charge capacity. Rapid dilution of local solutions and rapid release of cold were the ways to promote the cold discharge. Less damage to the stress structure of the coil was due to the loose accumulation of hydrate particles under gas disturbance. The microbubbles generated by the gas disturbance enabled heterogeneous nucleation and heat-mass transfer in the hydrate cold storage. The gas disturbance-based hydrate energy storage process holds significant guiding value for various applications such as refrigerated transport, building cooling systems, and grid peak shaving.

In order to investigate the effect of sodium in coal spontaneous combustion, different types of inorganic and organic sodium were added to the raw coal to analyze the changes of spontaneous combustion characteristics of coal samples. The combustion characteristics parameters of each group of coal samples were calculated by simulating the spontaneous combustion reaction process of coal through programmed warming thermogravimetric experiments, and the results showed that the combustibility index of coal samples loaded with various types of sodium-containing reagents increased by 8.32 %–45.37 %, and the combustion characteristics index decreased by 13.82 %–39.15 %. It indicates that inorganic sodium salts and organic sodium salts promote the combustion of coal in the low temperature stage and inhibit it in the high temperature stage. Subsequently, the changes of characteristic functional groups in coal during combustion after loading sodium were analyzed by using in-situ infrared spectroscopy experiments, and it was concluded that sodium in organic salts would combine with peroxyl radicals and thus inhibit the oxidation process of oxygen-containing functional groups in coal; sodium in inorganic salts would replace hydrogen in carboxyl and hydroxyl groups and thus promote the oxidation reaction of coal. The results of the study can provide some theoretical basis for the development of new coal spontaneous combustion inhibitors with specific functions.

This study aimed to simulate the thermodynamics of ammonia addition to iron oxide reduction and to use the results of the thermodynamic analysis to develop a neural network that predicts iron oxide reduction performance from input parameters. The results showed that ammonia addition can increase iron (Fe) reduction when carbon and air are proportionally subtracted. However, iron oxide reduction assisted by ammonia is more endothermic, indicating ammonia may have insufficient exothermic activity to maintain the endothermic reduction of iron oxides. Additionally, the simulation suggests ammonia addition can limit the carbon dioxide (CO2) produced by conventional iron oxide reduction using coke. Further, ammonia addition can reduce oxides of nitrogen (NOX) and nitrous oxide (N2O) emissions, depending on the addition method. A neural network was developed using one hidden layer with 10 neurons to predict the system enthalpy, the extent of iron oxide reduction, carbon dioxide production, NOX concentration, and CO concentration from the temperature, ammonia addition percent, and method of ammonia addition. After training for 43 epochs, the neural network achieved an R2 value of 0.9985. Although there are some limitations to the Gibbs minimization method employed in this study, the results indicate ammonia has the potential to supplement coke in ironmaking. More research is required to determine the extent ammonia could be employed to reduce greenhouse gas emissions from ironmaking processes.

Abstract not available

A series of hydraulic fracturing experiments were conducted using Lushan shale cores (50 mm in diameter and 100 mm in length) to unravel the formation mechanism of fracture networks under the combined effects of wellbore type (vertical or horizontal well), wellbore orientations relative to the bedding plane (0°, 30°,45°, 60°, and 90°), bedding inclinations (0°, 30°,45°, 60°, and 90°), and injection rates (0.03, 0.3, 3, and 30 mL/min). We monitored acoustic emission and surface displacements during the test and conducted post failure inspection via a fluorescent tracer and a 3D laser scanner. We show that adjusting the maximum principal stress perpendicular to the wellbore is beneficial for reducing the breakdown pressure. Inclined bedding tends to initiate along the bedding plane with relatively low fracture initiation pressure and breakdown pressure. Deploying the wellbore inclined to bedding inclination and/or adopting a low injection rate is beneficial to reduce the shale breakdown strength and create a complex fracture network. However, this will correspondingly increase the fracture surface roughness, which may impede the effective transportation of proppant. These findings can provide an important reference for field hydraulic fracturing.

The regulation of the engineering regionally spatial framework aluminum (AlF) distribution in MFI channels has been considered as an effective way for the production of light olefins by targeted fluid catalytic cracking (TCO) technology. In this work, ZSM-5 zeolites with controlled AlF distributions are facilely synthesized by tuning the combinations of pentaerythritol (PET), tetrapropylammonium (TPA) and Na cations. The AlF atoms in the prepared HZ5-[PET + Na] and HZ5-[TPA] samples are enriched in the straight channels and intersection channels, respectively, which are favorable to the n-butane monomolecular reaction pathway, promoting the propylene production. Whereas the AlF atoms in the HZ5-[TPA + Na] sample are simultaneously distributed in both the straight and intersection channels, the n-butane molecules preferentially take place monomolecular reaction in the straight channels to generate carbonium ions (e.g., C2H5+, C3H7+ and C4H9+). Subsequently, all of them enter into the intersection channels to induce the occurrence of bimolecular reaction. Such a process is conducive to the formation of ethylene. These insights can help to clarify the catalytic behavior of regional framework acid sites in ZSM-5 channels and then provide an effective approach to design efficient TCO catalysts.

The field tests were carried out in a full-scale residence building with volume of 105 m3 to reveal the hazards and mechanism of methane-air mixture explosions. The real layout and variations of gas concentration, initial state and ignition position are considered in the explosion tests. The pressure–time histories and flame development of each test were recorded and analyzed. The concentration distribution was also measured by using the fixed concentration sensors and mobile robots. It is found that when the methane diffuses freely in the resident buildings, concentration stratification can be observed in the vertical direction and the concentration of region with height of 0.64 ∼ 2.38 m is within the explosive limit in the 9.5 vol% case. In the real scenario, the maximum overpressure of gas explosions in residence buildings is less than 10 kPa due to the effective venting of doors and windows. The concentration of 9.5 vol%, uniform gas distribution and ignition position in room 2 can bring about more intensive gas explosions and in turn result in higher overpressure loads and stronger external flame propagation. What is more, the acoustic oscillation is significantly restrained by the disturbance on the acoustic field caused by the effective venting, gas stratification and obstacle distribution in residence buildings.

In the present work, the explosion of hydrogen-propane-nitrous oxide mixtures with various equivalence ratios (ϕ=0.2-2.4), propane fractions (ωC=0-1.0) and initial pressures (P0=50-100 kPa) at ambient temperature (288 K, room temperature) was experimentally performed in a standard 3.375-L cubic vessel. The maximum explosion pressure (Pmax), maximum pressure rise rate ((dp/dt)max) and explosion time (te) were obtained in light of pressure–time curves, and the normalized maximum explosion pressure (Pmax/P0) and normalized explosion time (td/te) were analyzed as well. Moreover, the adiabatic pressure (Pad) and laminar burning velocity (SL) were also calculated for argumentation. The results indicate that with the increase of ωC, Pmax and (dp/dt)max both present three characteristic variation trends for different ϕ, while the inflections of Pmax-ϕ and (dp/dt)max-ϕ transient gradually from lean to rich mixtures. Besides, te and td/te are monotonously rising with ωC, illustrating that propane addition can remarkably decelerate the explosion process. In addition, with the increase of P0, Pmax/P0 raises monotonously and is asymptotic to Pad/P0 at ωC⩽0.2, demonstrating that heat loss decreases under higher P0. Linear dependence is also found between (dp/dt)max and P0 for any composition. Furthermore, te monotonically decreases with P0, due to the flame acceleration occurring in the combustion period. In general, the presence of nitrous oxide (N2O) with a large content makes the explosion extremely unstable, and a spot of propane can dramatically alter the explosion characteristics of H2-N2O mixtures. These results will be meaningful for the development of explosion-mitigation devices and technology in case of underlying explosion and fire hazards.