Fringe Separation Research Articles

Effect of oxygen contents on morphology, nanostructure, and its formation of soot in laminar coflow ethylene-ammonia diffusion flames

Oxygen content plays a crucial role in influencing the characteristics and formation processes of soot particles. This study explores the effects of varying oxygen levels on the morphology, nanostructure, and formation of soot particles in laminar coflow ethylene-ammonia diffusion flames using a combination of experimental analysis, model development, and numerical simulation. Initially, the impact of oxygen concentration on morphology and nanostructure of particles is examined experimentally. Subsequently, a novel C2H4-NH3-PAHs kinetic model, incorporating cross-reactions between C3\\A1-A3 and HCN, is developed and validated through parameters such as ignition delay, laminar flame speed, and species concentrations. The new model is then used to analyze the effects of different oxygen concentrations on soot formation and nitrogen-containing PAHs in ethylene-ammonia flames. The findings show that a decrease in oxygen concentration results in an increase in the average diameter of primary particles, a reduction in fringe separation distance and fringe length, and an increase in fringe tortuosity. Additionally, lower oxygen concentrations are found to slightly reduce PAH formation and significantly decrease the surface growth rate via the HACA mechanism, leading to reduced soot formation. Furthermore, the primary nitrogen-containing PAHs identified are 2-benzonitrile and 2-naphthonitrile, followed by pyrrolyl and cyanophenanthrene, with lower oxygen concentrations diminishing the formation of these nitrogen-containing PAHs.

Investigation on nanostructure, surface functional groups, and oxidation activity of particulate along the exhaust after-treatment of a diesel engine fueled with waste cooking oil biodiesel blends.

In this study, the nanostructure, surface functional groups, and oxidation activity of soot particulate along the exhaust after-treatment system of a heavy-duty diesel engine fueled with waste cooking oil (WCO) biodiesel blends are investigated by TEM, XPS, and TGA respectively. The main findings are as follows: Along the exhaust after-treatment system, fringe length of primary particles of soot particulate emitted from tested heavy-duty diesel engine fueled with B0, B10, B20, and B100, i.e., 0%, 10%, 20%, and 100% ratio of WCO biodiesel blended into petroleum diesel in volume respectively increases, while fringe tortuosity and separation distance of primary particles reduces. The fringe length of B10, B20, and B100 is smaller, but the fringe tortuosity and separation distance are larger than that of B0. The O/C ratio of soot particulate tends to increase firstly and then decrease as the exhaust passes through DOC+cDPF and SCR+ASC in sequence. The O/C ratio of B10, B20, and B100 are also higher than that of B0. Soot particulate at cDPF outlet contains carborundum and biuret is found at SCR+ASC outlet. The sp3/sp2 ratio decreases along the exhaust after-treatment system, and B10, B20, and B100 tend to get higher sp3/sp2 ratio than B0. The C-OH and C=O content of soot particulate from different WCO biodiesel blends show generally similar trends along the exhaust after-treatment system, while the activation energy of soot particulate keeps increasing along the exhaust after-treatment system, but decreases with the increasing of blend ratio. These findings can provide useful references for optimizing the after-treatment system for WCO biodiesel blends.

Research on Particle Emissions of Light-duty Hybrid Electric Vehicles in Real Driving

Real driving emission (RDE) assessments were conducted on light-duty hybrid electric vehicles (HEVs) compliant with China-VI standards across various altitudes, including Kaiyuan, Jianshui, and Kunming. Portable Emission Measurement Systems (PEMS) were utilized to analyze instantaneous particulate number (PN) emissions. At the same time, a particle trap was used to collect primary particulate matter (PM). High-resolution Transmission Electron Microscopy (TEM) was employed to capture the micro-morphology and nano-structure of PM. The findings revealed a positive correlation between PN emission factors and altitude, suggesting more stringent regulations are necessary in high-altitude regions. Cold-start conditions exhibited heightened PN emissions, surpassing regulatory thresholds (primarily when the coolant temperature is below 30°C). Notably, the PN emission rate increases when the vehicle is under light acceleration (0 ≤ a ≤ 0.5 m/s2) and the coolant temperature is within the range of 20∼30°C. The PM emitted by HEVs exhibited an unimodal distribution across different driving conditions, with cold-start yielding finer particles. In contrast, urban and rural driving conditions showed enhanced PM aggregation due to more complete fuel combustion. Urban driving conditions, characterized by coolant temperatures exceeding 70°C and speeds below 60 km/h, produced PM with the largest average particle size (32.68 nm) and the broadest size distribution range (8.99 nm to 77.60 nm). Furthermore, increased engine speed and load resulted in elevated average outer shell fringe lengths of primary nanoparticles. The average inner core fringe lengths initially increased, peaked in urban environments (1.04 nm), and then decreased. Fringe separation distances gradually increased, predominantly between 0.2 nm and 0.8 nm. The increase in engine load is the primary factor influencing the growth of microcrystal tortuosity. The study underscores the significance of HEVs in PM emissions, which pose potential risks to both human health and environmental sustainability, emphasizing the need for effective mitigation strategies.

Recognition and separation of fringe patterns in deflectometric measurement of transparent elements based on empirical curvelet transform

In the deflectometric measurement of transparent elements, it is critical to separate the superposed fringes reflected from the front and rear surfaces to establish the pixel correspondences between the camera and screen pixels. But it is a challenging task due to the low reflectivity and uneven background of transparent elements. A reliable fringe separation method is proposed based on the empirical curvelet transform. The captured fringe images are decomposed into different modes according to their directions, periods, curvatures or modulation coefficients, and then a weighted-permutation-entropy-based fusing algorithm is developed to automatically aggregate those over-separated patterns. By employing the proposed method, the measurement accuracy is significantly improved, the number of demanded images is effectively reduced, and high-precision, automatic, and rapid measurement is thereby achieved. The measurement accuracy of spherical and cylindrical lenses can achieve 73 nm and 332 nm Root-of-Mean-Squares-Error, respectively.

Impacts of Fuel Stage Ratio on the Morphological and Nanostructural Characteristics of Soot Emissions from a Twin Annular Premixing Swirler Combustor.

Soot particles emitted from aircraft engines constitute a major anthropogenic source of pollution in the vicinity of airports and at cruising altitudes. This emission poses a significant threat to human health and may alter the global climate. Understanding the characteristics of soot particles, particularly those generated from Twin Annular Premixing Swirler (TAPS) combustors, a mainstream combustor in civil aviation engines, is crucial for aviation environmental protection. In this study, a comprehensive characterization of soot particles emitted from TAPS combustors was conducted using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy. The morphology and nanostructure of soot particles were examined across three distinct fuel stage ratios (FSR), at 10%, 15%, and 20%. The SEM analysis of soot particle morphology revealed that coated particles constitute over 90% of the total particle sample, with coating content increasing proportionally to the fuel stage ratio. The results obtained from HRTEM indicated that average primary particle sizes increase with the fuel stage ratio. The results of HRTEM and Raman spectroscopy suggest that the nanostructure of soot particles becomes more ordered and graphitized with an increasing fuel stage ratio, resulting in lower oxidation activity. Specifically, soot fringe length increased with the fuel stage ratio, while soot fringe tortuosity and separation distance decreased. In addition, there is a prevalent occurrence of defects in the graphitic lattice structure of soot particles, suggesting a high degree of elemental carbon disorder.

Effect of nano-graphene lubricating oil on particulate matter of a diesel engine

Nano-graphene lubricating oil with appropriate concentration shows excellent performance in reducing friction and wear under different working conditions of diesel engines, and has been widely concerned. Lubricating oil has a significant impact on particulate matter (PM) emissions. At present, there are few studies on the impact of nano-graphene lubricating oil on the physicochemical properties of PM. In order to comprehensively evaluate the impact of nano-graphene lubricating oil on diesel engines, this paper mainly focused on the effects of lubricating oil nano-graphene additives on the particle size distribution and physicochemical properties of PM. The results show that, compared with pure lubricating oil, the total number of nuclear PM and accumulated PM of nano-graphene lubricating oil is significantly increased. The fractal dimension of PM of nano-graphene lubricating oil increases and its structure becomes more compact. The average fringe separation distance of basic carbon particles decreases, the average fringe length increases. The degree of ordering and graphitization of basic carbon particles are higher. The fringe tortuosity of basic carbon particles decreases, and the fluctuation of carbon layer structure of basic carbon particles decreases. Aliphatic substances in PM are basically unchanged, aromatic components and oxygen functional groups increase. The initial PM oxidation temperature and burnout temperature increase, the maximum oxidation rate temperature and combustion characteristic index decrease, and the activation energy increases, making it more difficult to oxidize. This was mainly caused by the higher graphitization degree of PM of nano-graphene lubricating oil and the increased content of aromatic substances.

Quantitative Analysis of the Impacts of Ash from Lubricating Oil on the Nanostructure of Diesel Particulate Matter

Microscopic analyses of the effects of ash on particulate matter oxidation are rather scarce. In this study, three different lubricating oils with varying ash contents were used to investigate their effects on the nanostructure of diesel particulate matter. The nanostructure and nanostructure parameters, including fringe length, fringe separation distance, and fringe tortuosity, were studied using high-resolution transmission electron microscopy. The results show that all samples obtained from blending with different lubricant oil present typical core–shell structures. The inner cores remain relatively unchanged, whereas the thickness of the outer shells increases with the increasing ash content in the lubricant oil under the same working conditions. The fringe length increases and the fringe separation distance decreases with the rising ash content in the lubricant oil operating in the same working conditions. The fringe tortuosity decreases when the ash content in the lubricant oil increases from 0.92% to 1.21%, but shows little change when the ash content in the lubricant oil increases from 1.21% to 1.92%. Based on the effects of ash on the nanostructure parameters, it can be inferred that the oxidation activity of particles decreases with increasing ash content in the lubricant oil.

Particulate emissions and soot characterisation of diesel engine exhaust for steady-state operating condition using dioctyl phthalate blends with diesel

The study investigates the particulate emission and soot characterisation of particles originating from a six-cylinder common-rail direct injection (CRDI), turbocharged diesel engine. The experiments were conducted using steady-state operating conditions, a constant rpm of 1500 and four different engine loads (25, 50, 75, and 100%). Three different fuels were tested: neat diesel and two dioctyl phthalate (DOP) blends with diesel (DOP10 and DOP20). Particulate emissions were measured using DMS500 and collected on transmission electron microscope (TEM) grids for further analysis of the morphology and nanostructure of the soot structure. The particle number and mass concentrations for neat diesel were found to be lower than DOP fuel blends for all four loads. The primary particle diameter increases with increase in the engine load and decreases with an increase in DOP fuel content in the blend. A compact structure of soot aggregate was observed for DOP fuel blends compared to that of diesel and it increased with an increase in the engine load. Short and curved fringes were observed for DOP fuel blends. Also, an increase in fringe length and a reduction in fringe tortuosity was observed with an increase in engine load. The fringe separation distance results show an opposite trend with respect to fringe length and fringe tortuosity for DOP fuel blends i.e. less inter-planar spacing was observed for DOP fuel blends compared to that of diesel. This would result in an overall decrease in the oxidation reactivity of soot particles.

Effect of Potassium Chloride on the Nanostructure and Reactivity of Soot Particles from Combustion of Municipal Solid Waste

This work studied the effect of potassium chloride (KCl) on soot formation during the combustion of municipal solid waste (MSW). The nanostructural and oxidative properties of soot particles were characterized by high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) spectroscopy, Raman spectroscopy (RS), and thermogravimetric analysis (TGA). HRTEM images showed that, under the same combustion environment, the KCl-loaded fuel samples generated soot particles with smaller particle sizes and more compact morphologies. Quantification of the nanostructure further indicated that, with increasing potassium concentrations from 1 to 5%, the fringe separation distance and fringe tortuosity of soot particles slightly increased, yet no clear trend was observed in the fringe length. Raman spectral analysis verified the fringe analysis, suggesting that the addition of KCl made the soot nanostructure more disordered with a larger separation distance and higher fringe tortuosity. In addition, oxidation profiles determined that the reactivity of K-doped soot was enhanced because of a decrease in the apparent activation energy (Ea) from 167 to 124 kJ/mol. Moreover, Ea showed strong linearity with the fringe tortuosity and fringe separation distance, with R2 values of 0.91 and 0.97, respectively. On the basis of the experimental data, a schematic of four K–soot interaction routes is proposed to better understand the soot formation during the combustion of solid wastes.

Natural dried Vanilla Beans powder (VBP) mediated CuO nanoparticles catalysis: Aerobic oxidation of hydroxylamines from industrial waste water using ecofriendly method

In an industrial waste water treatment plant, a novel efficient approach is employed to achieve quantitation of hydroxylamines. For aerobic alcohol oxidation, Vanilla Beans Powder (VBP) mediated Copper oxide nanoparticles were created. Over the CuO NPs, various Hydroxylamines alcohol substrates were converted to the appropriate aldehyde in excellent yield. XRD, XPR, FTIR, UV, TEM, EDX, TGA, and DTA were all used to characterise CuO NPs. Metal nanoparticle stabilisation and oxidation state management are crucial features of nanocatalysis. The CuO NPs was validated by XRD peaks are linked to copper's cubic crystalline structures (002), (111), (202), (202), and (113), and the HR TEM research 20 nm image of a small segment displayed clear lattice fringe separations between 0.250 nm and 0.226 nm, which correspond to CuO (002)'s fcc (face-centered cubic). The XPS analysis of Cu O NPs survey scan of CuO-Nps revealed the presence of Cu, O, and C without any other impurity in the nanoparticles, Cu 2p3/2 and Cu 2p1/2, with binding energies of 931.26 and 950.97 eV and a spin-orbit splitting of 19.71 eV, respectively, were identified in the XP spectra of the Cu 2p electrons. Catalytic activity of CuONPs were used various concentration for conversion of hydroxylamines, for example 2-((2-amino ethyl) amino)ethanol (1a) is converted to 2-((2-aminoethyl)amino)acetaldehyde. CuO NPs (6%) of catalyst was performed well, it is 98% recovery and 100% conversation of product with 4 mints compared with Vanilla Beans powder (VBP) and vaniline. In addition to (FT-IR, 1 H, 13 C NMR, GC-MS) and elemental analysis was performed on the isolated product. The new volatile compounds was analyzed by GC-MS and also fragmentation studies discussed in this work. These stabilization and frequentation were well described. • Vanilla Beans powder mediated Cupper oxide nanoparticles were used to obtain heterogeneous catalysts. • Removal of Industrial wastewaters contamination of β -Hydroxylamines • Efficient procedure for the Aerobic oxidation of oxidation of β -Hydroxylamines in the presence of CuO NPs catalyst. • Efficient recyclability of the catalyst.

An analysis of the in-cylinder soots generated from the main- and post-injection combustion in diesel engines

In modern diesel engines, the exhaust soot primarily comes from the main-injection combustion and post-injection combustion. Therefore, to reduce the diesel soot emissions, it is essential to better understand the soots generated from the main-injection combustion (main-soot) and from the post-injection combustion (post-soot). This work focused on the properties of the main-soot and post-soot during the combustion process, including the primary particle size, nanostructure and soot mass. The in-cylinder soot samples were obtained using a self-developed total cylinder sampling system, and the primary particle size and nanostructure were determined using high-resolution transmission electron microscopy. The isolation of the post-soot was achieved by adding dimethyl ether to the intake gas instead of the real main-injection to create a simulated main-injection combustion environment for post-soot formation. Combustion analysis and numerical simulation results showed that the simulated combustion environment for post-soot formation generated by the DME combustion was very similar to that generated by the real main-injection combustion. During the combustion process, although the main-soot and post-soot exhibit similar variations in the primary particle size, the maximum primary particle size of the post-soot is smaller than that of the main-soot (23.38 nm for the main-soot and 20.51 nm for the post-soot). The main-soot and post-soot show almost the same trends in the nanostructure, as characterized by the fringe length, separation and tortuosity, throughout the combustion process. The introduction of the post-injection accelerates the reduction of the primary particle size of the main-soot and the increase in the structural order of the main-soot. Because a large number of the main-soot particles are oxidized during the post-injection combustion, the post-soot accounts for a considerable proportion in the engine-out soot (i.e., 42%).

Physicochemical analysis of the exhaust soot from a gasoline direct injection (GDI) engine and the carbon black

The purpose of the present study is to understand the physicochemical properties of the GDI soot and determine a GDI soot surrogate for the oxidation investigations. The high-resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and thermogravimetric analyzer were used to characterize the soot properties, including the morphology, nanostructure, chemical composition, carbon chemical state and oxidation reactivity. The GDI soot sample was harvested from the gasoline particulate filter equipped on a modern China VI passenger vehicle operated over the Worldwide harmonized Light-duty Test Cycle. The obtained GDI soot comprises large numbers of near-spherical primary particles that cluster together to form aggregates with a mean gyration radius of 123.79 nm, and the mean diameter of primary particles is 27.63 nm. The primary particle exhibits a typical core–shell structure, and the mean values of fringe length, separation distance and tortuosity are 0.836 nm, 0.362 nm and 1.263, respectively. In addition to the carbon element, the oxygen element is another important component of soot particles, accounting for 6.28% of the total number of atoms. The carbon component is mainly composed of sp2 hybridized graphitic carbon and sp3 hybridized aliphatic carbon, and the ratio of sp2/sp3 is 2.02. Moreover, the apparent activation energy of soot sample is determined to be 141.7 kJ/mol. The Special Black 4 (SB4) was assessed as a potential surrogate for the GDI soot. The comparison of physicochemical properties shows that the SB4 and GDI soot have almost the same fractal dimension, gyration radius, primary particle size, fringe length, separation distance, tortuosity, sp2/sp3 ratio and apparent activation energy. The great similarities in physicochemical properties highlight that the SB4 can serve as a good GDI soot surrogate for the soot oxidation investigations.

Morphology and nanostructure of flame-formed soot particles from combustion of typical municipal solid waste

The structural property of soot particles released during the pellet combustion of different municipal solid waste (MSW) was comparatively investigated through high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and X-Ray diffraction (XRD). The results showed under the same combustion condition, soot particles generated from different waste components have the same typical core-shell shape. But soot mass and aggregate morphology were strongly dependent on waste component material. When plastic (textiles) waste was burned, the soot obtained featured a much higher mass and more compact morphology with larger particle size compared to that from burning biomass and kitchen waste. Nanostructural characterization results revealed that paper and kitchen waste possessed the highest graphitization degree in soot, followed by wood waste, textiles, and plastic. Additionally, with the increasing addition of plastic in the mixed waste, the flame temperature was slightly reduced. And the soot was formed a lot and became more disordered in the nanostructure with shorter, more tortuous fringes and larger separation distances, which suggested a higher oxidation tendency. The AD1/AG ratio had a linear relationship with the fringe separation distance and fringe tortuosity, with R2 values of 0.824 and 0.847, respectively.

Waste cooking oil biodiesel and petroleum diesel soot from diesel bus: A comparison of morphology, nanostructure, functional group composition and oxidation reactivity

Biodiesel is one of carbon neutral fuels for diesel engine and waste cooking oil (WCO) would be the most viable source for biodiesel production in China. This paper studied the micromorphology, nanostructure, surface functional group composition, and oxidation activity characteristics of particles emitted from a China V bus fueled by pure WCO biodiesel and petroleum diesel, respectively. Compared with petroleum diesel, the results showed that particle mass (PM) and particle number (PN) of WCO biodiesel decreased by 38.66% and 38.12%, respectively, while the proportion of nucleation mode particles increased by about 10%. The soot particles of WCO biodiesel have higher disordered nanostructure, smaller primary particle size and fringe length, larger fringe separation distance and tortuosity, and lower graphitization degree than those of petroleum diesel. Moreover, the oxygen-containing surface functional groups content and carbon atom hybrid ratio of soot particles of WCO biodiesel were higher than those of petroleum diesel under the same oxidation temperature. And then the activation energy of soot particles from WCO biodiesel which contained more lattice defect structures was 38.43 kJ/mol, 37.8% lower than petroleum diesel, which is easier to be oxidized.

An experimental investigation into the soot particle emissions at early injection timings in a single-cylinder research diesel engine

Engine experiments were performed to examine the effect of early-injection on smoke emissions and engine performance under typical low temperature combustion (LTC) and reactivity controlled compression ignition (RCCI) operating conditions. On that basis, the influence of exhaust gas recirculation (EGR), intake pressure, fuel properties and fuel injection strategy on the engine-out soot emissions at early injection timings was also assessed. At last, the morphology, nanostructure characteristics of exhaust soot particles were analyzed. The test results showed when the injection timing was advanced before −30° crank angle after top dead center (CA ATDC) and earlier, the fuel spray impinged onto the piston crown surface, and a part of fuel entered into the squish zone and expanded to reach the cylinder liner wall and entered into the crevice volume, leading to a continuous increase in soot emissions, the peak smoke emission was found to occur at −55° CA ATDC. By adopting fuels with high volatilities and a RCCI fuel delivery strategy, soot emissions can be effectively reduced at early timings. Most of the high-resolution transmission electron microscopy (HRTEM) images of the sampled soot particles showed small spherical particles with a wide range of size distribution connected, and “onion-like” fringe arrangement was found in most of the images. As the fuel injection timing was retarded from −55° to −35° CA ATDC, the samples exhibited more highly organized carbon nanostructures; the fringe tortuosity and separation distance increased, while the fringe length decreased. The formation of more ordered arrangement of graphene layers led to significant resistance to oxidation.

Morphological characterization of soot from a compression ignition engine fueled with diesel and an oxygenated fuel

Compression ignition (CI) engines are highly efficient and are therefore often the first choice in application of heavy machinery and heavy duty vehicles. However, diesel engines are known to emit soot and oxides of nitrogen (NOx) emission. Replacing fossil diesel fuel with renewable fuel is one possibility to reduce emissions and to meet legislative requirements. In this experimental work, an oxygenated fuel blend was investigated for soot morphology and results were compared with fossil diesel fuel without oxygenates. Soot was sampled at a medium load case in a light duty single cylinder research engine and samples were analyzed with a transmission electron microscope (TEM). Furthermore, combustion characteristics and particle number (PN) emissions were compared for both fuels. The primary particle diameter (Dp), fringe length (L), fringe separation (S), and tortuosity (T) were also discussed in terms of soot nanostructure. The particle size distribution (PSD) showed a reduction in PN over for the renewable fuel blend compared to diesel. This PN reduction was from 107 to 106 (one order magnitude lower). The maximum Dp from morphological analysis of diesel fuel and renewable fuel was 69.93 and 66.36 nm respectively. Size range of fringe separation (S) was nearly identical for both fuels. Diesel fuel has marginally higher fringe separation, fringe length, and tortuosity. This investigation is valuable for fuel industries which are continuously upgrading renewable and oxygenated fuels to meet stringent emission norms.

Physicochemical properties of exhaust soot from lower and higher alcohols: Characterizations and impact on soot oxidation behavior

Alcohol fuels can effectively reduce particle emissions of diesel engines. However, the effects of lower and higher alcohols on the microscopic physicochemical properties of the particles, such as the graphitization degree, surface aliphatic C–H functional groups, O/C ratio, and the carbon atom hybridization is still unclear. Moreover, the relationship between microscopic physicochemical properties and particle oxidation activity has not been systematically studied. Therefore, the alcohol-diesel mixtures with different carbon chain lengths and the same oxygen content were used as the fuel for commercial diesel engines in this research, such as methanol/diesel mixture (M10), n-butanol/diesel mixture (NB25), and n-octanol/diesel mixture (NO45), and the pure diesel (D100) was used as a reference. The physicochemical properties of different fuel particles under two loads were analyzed using Raman spectroscopy, Fourier Transform Infrared, and X-ray photoelectron spectroscopy. The results showed that as the load increased, the AD1/AG of the particles decreased, which meant that the graphitization degree increased. Moreover, the addition of alcohol fuel will increase the graphitization degree of the particles. In addition, the addition of alcohol fuel will reduce the aliphatic C–H functional groups and the O/C ratio on the surface of the particles. However, with the use of M10 to NO45, the aliphatic C–H functional groups continued to increase, while the O/C ratio first decreased and then increased, and the NB25 particle had the smallest O/C ratio. Through the Partial Least Square analysis, it was found that the fringe length and fringe separation distance had the most significant impact on the activation energy of the particles. Interestingly, among the characteristic parameters of Raman spectroscopy, the D1-full width at half maximum had the largest contribution to the activation energy.

Effect of the Coal Molecular Structure on the Micropore Volume and the Coalbed Methane Content

Coal mainly consists of complex organic macromolecular polymers. Their spatial arrangement and macromolecular structural parameters control the coal reservoir property. This study evaluated the effects of coal’s macromolecular structural evolution on the micropores and established the relation between the coal heterogeneity and the coalbed methane content in the vertical direction. Five groups of samples with a reflectivity range of 0.60–1.01% and a burial depth range of 400–1200 m were collected from the Fukang mining area, Xinjiang, China. Variations of coal’s macromolecular structural parameters, namely, the preferential development direction, fringe length, fringe separation, and fringe tortuosity, with the burial depth were experimentally determined via high-resolution transmission electron microscopy. As the burial depth increased, coal’s mean fringe length increased and the fringe separation dropped linearly, while the fringe tortuosity gradually decreased at a burial depth of approximately 800 m. In terms of the aromatic ring species, with an increase in the burial depth, the share of aromatic fringes below 2 × 2 dropped while that of aromatic fringes above 3 × 3 increased steadily. The increase in aromatic fringes above 3 × 3 was not conducive to the development of micropores. In addition, the mean fringe separation in the research area decreased linearly with the buried depth, and it decreased by 0.00295 nm per 100 m at the buried depth of 400–1200 m. The reduction in aromatic fringe spacing further reduces the intermolecular pores volume, which is illustrated in low-pressure CO2 measurements. At a burial depth exceeding 1000 m, the content of adsorbed-state methane in the reservoir dropped. Both the fringe separation and the tortuosity degree influenced the Langmuir volume and pressure parameters. The Langmuir pressure dropped with increasing fringe separation. However, it decreased rapidly at first and then slowly with increasing tortuosity degree of the aromatic fringes.

Impact of carbon chain length of alcohols on the physicochemical properties and reactivity of exhaust soot

Particle is the main pollutant in diesel engine exhaust, which seriously endangers human health and the atmospheric environment. The use of alcohol fuels in diesel engines can effectively reduce particle emissions, but alcohol fuels with different carbon chain lengths will affect the generation process of particles, which in turn changes the physicochemical properties and oxidation characteristics of the particles. Therefore, it is particularly important to study the properties of particle emitted by diesel engines fueling alcohol fuels with different carbon chain lengths. The physicochemical properties of soot emitted from commercial diesel engines were studied by thermogravimetric analyzer, HRTEM (high-resolution transmission electron microscopy), and XPS (X-ray photoelectron spectroscopy) in this paper, respectively. The diesel engine used alcohol-diesel blends of different carbon chain lengths with the same oxygen content as fuels, such as methanol/diesel blend (M10), n-butanol/diesel blend (NB25), and n-octanol/diesel blend (NO45), and pure diesel fuel was used as a reference. The results showed that the use of alcohols reduced the fractal dimension (Df) of particles, and the NB25 particles had the smallest Df. Moreover, the particles of blended fuels had smaller primary particle diameter (dp) compared to pure diesel. However, with the use of short-chain to long-chain alcohols, an increasing tendency of dp was observed. In terms of the nanostructure, as the use of short-chain to long-chain alcohols, the La (fringe length) increased, both the d (fringe separation distance) and Tf (fringe tortuosity) reduced, which was not favorable for the oxidation of the particles. In addition, in terms of oxygenated surface functional groups (SFGs), the CO group occupied a higher proportion in most working conditions relative to the groups of CO and COO. Further analysis showed that the dp and nanostructure had more influence on the oxidation behavior of soot than Df and oxygenated SFGs.

Photolithographically-patterned C-MEMS graphene by carbon diffusion through nickel

In recent years the most studied carbon allotrope has been graphene, due to the outstanding properties that this two-dimensional material exhibits; however, it turns out to be a difficult material to produce, pattern, and transfer to a device substrate without contamination. Carbon microelectromechanical systems are a versatile technology used to create nano/micro carbon devices by pyrolyzing a patterned photoresist, making them highly attractive for industrial applications. Furthermore, recent works have reported that pyrolytic carbon material can be graphitized by the diffusion of carbon atoms through a transition metal layer. In this work we take advantage of the latter two methods in order to produce multilayer graphene by improving the molecular ordering of photolithographically-defined pyrolytic carbon microstructures, through the diffusion (annealing) of carbon atoms through nickel, and also to eliminate any further transfer process to a device substrate. The allotropic nature of the final carbon microstructures was inspected by Raman spectroscopy (Average I D/I G of 0.2348 ± 0.0314) and TEM clearly shows well-aligned lattice planes of 3.34 Å fringe separation. These results were compared to measurements made on pyrolytic carbon (Average I D/I G of 0.9848 ± 0.0235) to confirm that our method is capable of producing a patterned multilayer graphene material directly on a silicon substrate.