Olefin Content Research Articles

Kinetics study on supercritical water conversion of low-maturity shale for hydrogen-rich hydrocarbon gas generation

Supercritical water (SCW) has gained substantial interest for shale exploitation due to its high conversion efficiency. To quantify the generated gases and the mutual conversion of gases on reaction of shale in SCW, experiments were carried out in batch reactor at 400–600°C and residence time up to 480 min. The products are classified as residual solids, liquid intermediates and gases. Experimental results show that the generated gases are mainly C1, C2, C3 alkanes, H2 and CO2. The concentrations of C1 and C2 alkanes decrease with temperature and residence time but the other three are the opposite. A kinetic model of shale-intermediates-gases reaction is developed. This model can characterize the gas generation features of shale and SCW resulting from chemical reactions, and can quantitatively describe the mutual conversion between gases. The calculated results demonstrate well applicative for predicting gas concentration at various residence time within an acceptable deviation. The reaction process can be divided into three stages: pyrolysis of organic matter to generate intermediates, hydrolysis reaction and alkyl thermal cracking of intermediates to generate gases, mutual conversion between the generated gases. Reactions among gases involve methanation reaction, water-gas shift reaction and hydrocarbon gas decomposition. This study provides a potential kinetic model for the gas generation characteristics of reaction with shale and supercritical water.

Integrated physiological, biochemical, and transcriptomic analyses of Bruguiera gymnorhiza leaves under long-term copper stress: Stomatal size, wax crystals and composition

Copper (Cu) is a necessary mineral nutrient for plant growth and development and is involved in several morphological, physiological, and biochemical processes; however, high concentrations of Cu can negatively impact these processes. The role of stomata in responding to various biotic and abiotic stimuli has not been studied in Bruguiera gymnorhiza, particularly in terms of their coordinated interactions at the molecular, physiological, and biochemical levels. Moreover, numerous plants employ strategies such as the presence of thick waxy cuticles on their leaf epidermis and the closing of stomata to reduce water loss. Thus, this study investigates the accumulation of Cu in B. gymnorhiza and its effect on leaf morphology and the molecular response under different Cu treatments (0, 200, and 400 mg L⁻¹, Cu0, Cu200, and Cu400, respectively) during a two years stress period. The results show that Cu stress affected accumulation and transport, increased the activities of peroxidase and ascorbate peroxidase, concentrations of soluble sugar, proline, and H2O2, and decreased the activity of catalase and content of malondialdehyde. Also, Cu-induced stress decreased the uptake of phosphorus and nitrogen and inhibited plant photosynthesis, which consequently led to reduced plant growth. Scanning electron microscopy combined with gas chromatography-mass spectrometry showed that B. gymnorhiza leaves had higher wax crystals and compositions under increased Cu stress, which forced the leaf’s stomata to be closed. Also, the contents of alkanes, alcohols, primary alcohol levels (C26:0, C28:0, C30:0, and C32:0), n-Alkanes (C29 and C30), and other wax loads were significantly higher, while fatty acid (C12, C16, and C18) was lower in Cu200 and Cu400 compared to Cu0. Furthermore, the transcriptomic analyses revealed 1240 (771 up- and 469 downregulated), 1000 (723 up- and 277 down-regulated), and 1476 (808 up- and 668 downregulated) differentially expressed genes in Cu0 vs Cu200, Cu0 vs Cu400, and Cu200 vs Cu400, respectively. RNA-seq analyses showed that Cu mainly affected eight pathways, including photosynthesis, cutin, suberin, and wax biosynthesis. This study provides a reference for understanding mangrove response to heavy metal stress and developing novel management practices.

Walnut shell oil-bath torrefaction coupled with fast pyrolysis: Effect of torrefaction heating modes

Lignocellulosic biomass, renewable with short growth cycle and diverse sources, can be substituted fossil fuel. However, low effective hydrogen-to-carbon ratio (H/Ceff) limits its applications. Torrefaction and co-pyrolysis with high H/Ceff feedstocks are promising technology. This paper investigated the effect of heating modes on oil-bath torrefaction of walnut shells, followed by fast co-pyrolysis. Six heating modes during oil-bath torrefaction were evaluated. Com1 (Microwave 67 %, Lightwave 33 %) yielded the lowest residual yield 84 wt%, while the highest gas production 495.47 mL/g which mainly composed of CO and CO2. Torrefied feedstock under Com1 had the highest H/Ceff. Decarboxylation and decarbonylation reactions dominated among oil-bath torrefaction. Com1 produced the most hydrocarbons and least oxygen-containing compounds. As microwave ratio decreased, the content of olefins, acids and phenols decreased, monocyclic aromatic hydrocarbons and alcohols was showed opposite tend. This study offers new ideas for microwave and lightwave torrefaction and promoting hydrocarbon production from lignocellulosic biomass.

Valorization of lignite to arene-rich compounds via two-stage selective cleavage of C-O bridged bonds over Co-MoS2

Directly converting lignite into arenes as commodity chemicals and drop-in fuels is a highly desirable target for researchers. However, this is severely limited by the presence of stable inter unit C-O linkages in lignite. Herein, a highly active catalyst, Co-MoS2, has been designed and prepared to be used for the selective catalytic cleavage of inter unit C-O bridged bonds (BBs) in the conversion of Naomaohu (NMH), a lignite, to yield arenes. Both catalytic hydrogenation conversion (CHC) and thermal dissolution (a non-catalytic process, named NCHC) of NMH were conducted using n-hexane as the solvent. The soluble fractions from the first stage of NCHC (SFNCHC-1) and CHC (SFCHC-1), as well as the second stage of NCHC (SFNCHC-2) and CHC (SFCHC-2) were obtained using the same solvent. After the first-stage catalytic treatment, the relative contents of arenes and alkanes in SFCHC-1 increased by 16.7 % and 9.3 %, respectively, compared to those in SFNCHC-1, and the relative content of oxygen-containing compounds (OCCs), such as alcohols, phenols, esters, ketones, acids, and furans, decreased by 13.2 %. For the second-stage conversion, the relative contents of arenes and alkanes in SFCHC-2 were 53.5 % and 15.5 % higher than those in SFNCHC-2, and the relative contents of OCCs was only 6.6 % in SFCHC-2. The catalytic mechanisms of cleavage of C-O BBs and deoxygenation were proposed based on the CHC of model compounds and density functional theory (DFT) calculation. The adsorption of OCCs and the activation of released hydrogen radical (H·) by Co-MoS2, followed by H· addition to the carbon atom connected to oxygen in C-O BBs and oxygen-containing functional groups, are crucial for the cleavage of C-O BBs and formation of deoxygenated compounds, particularly arenes.

CONVERSİON OF n-HEXANE OVER CATALYSTS BASED ON SULFATED ZIRCONIUM DIOXIDE

The isomerization process is becoming increasingly important in the modern petroleum refining context due to the limitations on the content of benzene, aromatic compounds, and olefins in gasoline. Isomerization is an effective and profitable process for octane enhancement of gasoline unlike other octane increasing processes. Due to the low sulfur and benzene content, the isomerate can be used as an ideal blending gasoline component. Therefore, the isomerization process has a great importance in petroleum refineries to increase the fuel octane number. This article aimed to study the conversion process of normal hexane over palladium and platinum containing catalysts on the base of sulfated zirconium dioxide. It has been determined that due to their high-performance characteristics, catalytic systems based on sulfated zirconium dioxide can be considered the most promising for isomerization of normal alkanes. Moreover, comparison of palladium-containing catalysts based on sulfated zirconium dioxide with platinum-containing catalysts based on sulfated zirconium dioxide showed that palladium sulfated zirconia catalysts have high catalytic performance in the isomerization of normal hexane. Keywords: alkanes, catalyst, platinum, palladium, isomerization, temperature, sulfated zirconium dioxide. .

Partial upgrading of bitumen with supercritical water— liquid products characteristics, gas composition and coke morphology

The study aimed to investigate the partial upgrading of bitumen in the absence of water (non-water) and the presence of supercritical water (SCW). Partial upgrading experiments were conducted at the target temperature of 420 °C, with the reaction time varying from zero to 60 min in a batch reactor. The liquid products were analyzed for density, viscosity, composition, total acid number (TAN), olefin content, and elemental analysis. The gas composition and morphology of solid products were also studied. The experimental results revealed that while partial upgrading of bitumen with SCW could accelerate improvement in oil quality, particularly in terms of API and viscosity, it concurrently led to elevated gas and coke formation levels. Moreover, the difference in the distribution of oil fractions between the two environments (absence and presence of SCW) tends to diminish with an extended residence time. Additionally, as the residence time increases, the efficiency of TAN reduction under SCW conditions is less pronounced compared to the non-water conditions. Liquid products obtained in an SCW environment exhibited higher olefin content (between 3 and 4 wt %) compared to non-water conditions (between 1.8 and 2.7 wt %). In both environments, the olefin content was initially increased up to a residence time of 20 min and then decreased. Regarding heteroatoms, the sulphur (S) and nitrogen (N) contents decreased up to 36 % and 72 %, respectively, while a greater reduction was observed in the presence of SCW. More non-hydrocarbon gases (H2S, CO2 and CO) were produced in the presence of SCW. SEM images showed that an extended residence time led to a shift in coke morphology towards a more uniform and compact structure, regardless of the upgrading environment. However, the porous structures of coke samples obtained under SCW are distinguished from those formed without water, which is attributed to the phase inversion of precursors. The findings of this study confirm that SCW plays a beneficial role as a solvent in the partial upgrading of bitumen, expediting the process. However, the increased level of coke formation and olefin contents suggest that it may not function effectively as a hydrogen donor in the process.

FEATURES OF RECEIVING THE GASOLINE FRACTION BY THERMAL PYROLYSIS OF POLYOLEFIN RAW MATERIALS

The article examines the peculiarities of the process of thermal pyrolysis of secondary polymer raw materials, aimed at obtaining a gasoline fraction - the basis for obtaining mixed or synthetic automobile gasoline. Based on the global experience of polymer processing, polyolefins represented by high-density polyethylene (HDLP) and polypropylene (PP) were chosen for the study. Thermal pyrolysis was carried out at atmospheric pressure (0.10-0.12 MPa) on a reactor-type laboratory installation with subsequent removal of the gasoline fraction (30-210 °C) from liquid pyrolysis products according to the ASTM D 86 method. It has been established that the temperature interval in which pyrolysis of polyolefin raw materials must be carried out is for HDLP - 400-430 °С (the maximum output of the gasoline fraction at 420 °С); for PP - 350-370 °C (maximum yield of gasoline fraction at 365 °C). By controlling the duration of thermal pyrolysis, it is possible to increase the yield of the gasoline fraction by an average of 15-17%, which must be taken into account during the industrial implementation and further operation of pyrolysis plants for polymer raw materials. Increasing the temperature of the end of boiling of the gasoline fraction from 150 °С to 210 °С allows to increase its output by 9% (for HDLP) and by 12% (for PP). But at the same time, there is also an increase in the content of olefins in it (by 13-14%), which is a positive point from the point of view of resistance to detonation of the gasoline fraction, and a negative point - in view of its low chemical stability. The conducted studies showed that secondary polyolefin raw materials should be considered as an alternative to classic raw materials (oil and gas condensate), and the pyrolysis process as the main technological process for obtaining the gasoline fraction - the basis for obtaining commercial automobile gasoline. Prospective places for the implementation of this technology are both production sites of oil refineries and sites located in close proximity to places of accumulation of raw materials - ports, city landfills, special landfills.

Influence mechanism of original components on mechanical properties and transformation behaviors of natural bitumen

Natural bitumen is an important component with high-purity organic matter in fossil energy and energy engineering scenarios. However, the production and application of natural bitumen could be severely hindered by the lacking of understanding the effects and influencing mechanisms of original components on physical properties of natural bitumen. Therefore, the main purpose of this work is to illustrate the influence mechanisms of original components (saturated hydrocarbon, aromatic hydrocarbon, resin and asphaltene) on mechanical properties of natural bitumen by the combination of nanoindentation technology and molecular structure analysis. The effects of each original component on the mechanical properties were carried out for Wuerhe natural bitumen which collected from Junggar Basin of China, and the influencing mechanisms were further revealed based on nanoindentation and X-ray diffraction (XRD) results. The occurrence units of each component in the chemical structural stacking of bitumen were established for the first time. It was found that hydrocarbons and resins can disintegrate the chemical structural stacking, thereby reducing the mechanical strength of natural bitumen. According to our micro-scale analysis results, the plastic and elastic deformation of natural bitumen were controlled by the structural units of amorphous carbon and aromatic carbon microcrystalline, as determined by saturated and aromatic hydrocarbons, respectively. And the schematic diagram of occurrence of each component in solid bitumen for the first time. Hence, the mechanical strength of natural bitumen can be effectively reduced by retaining or increasing the content of alkanes during exploitation, transportation and processing of natural bitumen. This research provided a new understanding for the stacking structure and physical property change mechanism of natural bitumen.

The adsorption-desorption behavior of chlorothalonil in the cuticles of apple and red jujube

The distribution fate of chlorothalonil (CHT) in the environment (soil and water) and fruits is controlled by the capacity of cuticles to adsorb and desorb CHT, which directly affects the safety of both the environment and fruits. Batch experiments were conducted to reveal the adsorption-desorption behaviors of CHT in the cuticles of apple and red jujube. The adsorption kinetics showed that both physisorption and chemisorption occurred during the adsorption process. Furthermore, the isothermal adsorption of CHT in the fruit cuticles followed the Freundlich model. The thermodynamic parameters (ΔG ≤ −26.16 kJ/mol, ΔH ≥ 31.05 kJ/mol, ΔS ≥ 0.20 kJ/(mol K) showed that the whole CHT adsorption process was spontaneous, and the hydrophobic interaction was predominant. The CHT adsorption capacity of the apple cuticle was higher than that of the red jujube cuticle, potentially due to the significantly higher alkanes content of apples than that of red jujubes. An appropriate ionic strength (0.01 moL/L) could induce a higher adsorption capacity. In addition, the desorption kinetics were shown to conform to a Quasi-first-order model, meaning that not all the adsorbed CHT could be easily desorbed. The desorption ratios in apple and red jujube cuticles were 41.38% and 35.64%, respectively. The results of Fourier-transformed infrared spectroscopy and X-ray photoelectron spectroscopy further confirmed that CHT could be adsorbed and retained in the fruit cuticles. Investigating the adsorption-desorption behavior of CHT in the apple and red jujube cuticles allowed to determine the ratio of its final distribution in the fruits and environment, providing a theoretical basis to evaluate the risk of residue pesticide.

Atmospheric Oxidation Capacity Elevated during 2020 Spring Lockdown in Chengdu, China: Lessons for Future Secondary Pollution Control.

This study presents the measurement of photochemical precursors during the lockdown period from January 23, 2020, to March 14, 2020, in Chengdu in response to the coronavirus (COVID-19) pandemic. To derive the lockdown impact on air quality, the observations are compared to the equivalent periods in the last 2 years. An observation-based model is used to investigate the atmospheric oxidation capacity change during lockdown. OH, HO2, and RO2 concentrations are simulated, which are elevated by 42, 220, and 277%, respectively, during the lockdown period, mainly due to the reduction in nitrogen oxides (NOx). However, the radical turnover rates, i.e., OH oxidation rate L(OH) and local ozone production rate P(O3), which determine the secondary intermediates formation and O3 formation, only increase by 24 and 48%, respectively. Therefore, the oxidation capacity increases slightly during lockdown, which is partly attributed to unchanged alkene concentrations. During the lockdown, alkene ozonolysis seems to be a significant radical primary source due to the elevated O3 concentrations. This unique data set during the lockdown period highlights the importance of controlling alkene emission to mitigate secondary pollution formation in Chengdu and may also be applicable in other regions of China given an expected NOx reduction due to the rapid transformation to electrified fleets in the future.

Dynamics and Internal Structure Evolution during the Glass Transition of the Ethylene-Cyclic Olefin Copolymers: A Molecular Dynamics Simulation.

Amorphous ethylene-cyclic olefin copolymers (COCs) which can be used in cell phone lenses and prefilled syringes have attracted increasing attention due to their excellent and tunable thermal properties. In order to better explain the influence of COC microstructure (cyclic olefin types and content) on the glass transition mechanism, we used molecular dynamics (MD) simulations to track the evolution of free volume, diffusion coefficients, atomic mobility, trans conformation probabilities, and characteristic parameters of α-relaxation kinetics during the quenching process. MD results show that for the classic COC E-co-NB (ethylene-norbornene copolymer), an increase in cyclic olefin content from 25 to 50 mol % reduces atomic mobility, limiting the molecular chain movement at higher temperatures and improving Tg. Compared to NB, the more rigid rings in tricyclopentadiene (TCPD) and exo-1,4,4a,9,9a,10-hexahydro-9,10(1',2')-bridged phenylidene-1,4-bridged methylideneanthracene (HBM) have the following effects: (1) reducing the thermal expansion coefficient and overall chain mobility; (2) enhancing the diffusion energy barrier; (3) promoting the formation of local ordered structures; (4) accelerating α-relaxation dynamics at high temperatures and improving the dynamic fragility m. These lead to an upward shift in the temperature region where chain movement is limited and thus improve Tg and high-temperature dimensional stability. In this simulation, the correlation equation between Tg, m, and the microstructural parameters of COCs is established, which is of great significance for the development of COCs with high performance.

Biodegradations of three different rank coals by a newly isolated bacterium Bacillus sp. XK1

Biodegradation of coal was closely related to coal rank. In this study, three kinds of coals whose coal ranks from high to low were Zhundong coal (ZDC), Hongshaquan coal (HSQC) and Heishan coal (HSC) were degraded by Bacillus sp. XK1 isolated from mine water. The degradation experiment results indicated that the degradation rate increased with the decrease of coal rank, and the highest degradation rate of HSC (low-rank coal) was 78.2 %, which was three times higher than that of ZDC (high-rank coal). The enzyme activity experiment showed that the alkaline protease and lignin peroxidase secreted by Bacillus sp. XK1 were key substances for coal biodegradation, and the alkaline protease activity and lignin peroxidase activity were all the highest in the presence of HSC, which were beneficial for coal biodegradation. The adsorption experiment found that HSC was more favorable to contact with Bacillus sp. XK1 than ZDC and HSQC. Furthermore, biodegradation products analysis suggested that with the decrease of coal rank, the contents of long chain alkanes in liquid products increased, among which the highest content of long chain alkane in liquid product of HSC was 86.98 %. The above experimental results demonstrated that biodegradation of low rank coal was an effective pathway.

Porous hollow nanospheres nickel phosphide and its high catalytic hydrogenation performance on naomaohu coal soluble portion and model compounds

The catalytic conversion of oxygen-containing aromatic ring in lignite under mild conditions is crucial to obtain clean liquid fuel. Here, hollow nanosphere Ni3P-500–24 catalysts were prepared at a calcination temperature of 500 °C and acid-etching time of 24 h. The porous hollow nanospheres structure could expose more catalytic sites, and the electron-rich nickel exhibited a good catalytic activity. The conversion rate of benzyl phenyl ether (BPE) was 100 % (140 ℃, 1 MPa H2, 2 h), and the main products were methylcyclohexane and cyclohexanol, indicating that the catalyst had good catalytic hydrocracking performance. In addition, the catalyst exhibited certain deoxygenation activity and high product selectivity for other oxygen-containing model compounds. For the catalytic hydrogenation of Naomaohu coal (NMHC) soluble portion, the content of alkanes increased from 19 % to 47 %, while the content of oxygen-containing compounds decreased from 56 % to 21 %, which further demonstrate that the catalyst have good catalytic hydrogenation and deoxygenation performance. Density Functional Theory (DFT) calculations showed that the properties of the Ni3P-500–24 catalyst was similar to noble metal, which could activate H2 to produce two kind of active hydrogen: H radical and diatomic hydrogen. The synergistic pathways for the transfer of active hydrogen during the catalytic hydroconversion (CHC) process were analyzed. Above results could provide theoretical guidance for the conversion of lignite into high-quality clean liquid fuels.

Improving the bacterial community, flavor, and safety properties of northeastern sauerkraut by inoculating autochthonous Levilactobacillus brevis

The effect of Levilactobacillus brevis as a starter in northeastern sauerkraut fermentation is still unknown, and further evaluation is worthwhile. Hence, this study aimed to evaluate the effect of autochthonous L. brevis inoculation on the bacterial community succession and formation of flavor and harmful substances in sauerkrauts. Inoculation with L. brevis lowered the pH and increased the total acid content of sauerkrauts (P < 0.05). The nitrite content of the inoculated sauerkraut was significantly lower than that of control (P < 0.05). Moreover, the spoilage bacteria of the inoculated sauerkraut were decreased and nitrogen metabolism was improved. The contents of aldehydes, alcohols, esters, acids, and alkanes increased significantly (P < 0.05), and the sensory attributes such as aroma, sourness, and gloss were also improved. L. brevis was positively and negatively correlated with flavor metabolites and nitrite, respectively, which proved to be a potential starter culture to manufacture sauerkraut.

H2 production from coal by enriching sugar fermentation and alkane oxidation with hyperthermophilic resistance microbes in municipal wastewater

Anaerobic hydrogen production from coal provides an alternative to achieve clean energy and zero greenhouse gas emissions. However, the recalcitrant structure of coal is the barrier for microorganisms to access, leading to inefficient hydrogen production. Municipal wastewater contains rich microbial resources with high degradability and a broad tolerance range to temperature, which was herein used to drive hydrogen production from coal at 35, 55 and 65 °C. The result showed the total hydrogen production (1.02 mL/g TS) at 65 °C was 34.0 and 51.0 times the 35 °C and 55 °C, respectively. For 65 °C, the decomposability of C-H linkage and aromatic ring structures in coal was the best; sugar fermentation and alkane oxidation pathways were effectively enriched, leading to the highest concentration of volatile fatty acids and alkanes. Which resulted in a shift of dominant bacteria from the lactate- and hydrogen-producing bacterium Bacillus at 35 °C and 55 °C to the hydrogen-producing bacterium Thermoanaerobacterium at 65 °C. Moreover, a gradient temperature cultivation from 35 to 65 °C (gradient increase temperature, GIT) based on the domestication concept was conducted. It is surprising that the GIT group displayed significantly lower hydrogen production (0.14 mL/g TS) compared to 65 °C group, because bacteria can adapt from mesophilic to hyperthermophilic temperatures, including Bacillus, Fonticella, Lysinibacillus, Ureibacillus, Microbacterium, and Geobacillus, inhibiting the Thermoanaerobacterium in the GIT group by producing lactic acid and competing for living space. This study proposes an alternative for efficient hydrogen production from coal. In the future, hydrogen production can be further enhanced through both substrate pretreatment and inoculum domestication, the related core mechanism will also be focus on.

Suppressing Metal Leaching and Sintering in Hydroformylation Reaction by Modulating the Coordination of Rh Single Atoms with Reactants.

Hydroformylation reaction is one of the largest homogeneously catalyzed industrial processes yet suffers from difficulty and high cost in catalyst separation and recovery. Heterogeneous single-atom catalysts (SACs), on the other hand, have emerged as a promising alternative due to their high initial activity and reasonable regioselectivity. Nevertheless, the stability of SACs against metal aggregation and leaching during the reaction has rarely been addressed. Herein, we elucidate the mechanism of Rh aggregation and leaching by investigating the structural evolution of Rh1@silicalite-1 SAC in response to different adsorbates (CO, H2, alkene, and aldehydes) by using diffuse reflectance infrared Fourier transform spectroscopy, X-ray adsorption fine structure, and scanning transmission electron microscopy techniques and kinetic studies. It is discovered that the aggregation and leaching of Rh are induced by the strong adsorption of CO and aldehydes on Rh, as well as the reduction of Rh3+ by CO/H2 which weakens the binding of Rh with support. In contrast, alkene effectively counteracts this effect by the competitive adsorption on Rh atoms with CO/aldehyde, and the disintegration of Rh clusters. Based on these results, we propose a strategy to conduct the reaction under conditions of high alkene concentration, which proves to be able to stabilize Rh single atom against aggregation and/or leaching for more than 100 h time-on-stream.

Degradation mechanism of cuticular wax composition and surface properties of bamboo culm during storage

Cuticular wax on bamboo culm forms a kind of protective biointerface during growing and degrades after harvesting leading to the deterioration of surface quality and protection function during storage. The degradation mechanism of the cuticular wax and surface property of harvested bamboo culm during storage is still unclear. To understand it, the microstructure of cuticular wax on the harvested bamboo culm was characterized and composition content was analyzed by GC-MS as well as the contact angle and color of bamboo culm surface were tested after the bamboo culm was stored in four simulated seasons: spring, summer, autumn and winter. The results showed that the more wax deposited on bamboo culm surface during storage, and the thickness of cuticular wax increased. During storage, the content of alkanes, alcohols and total ketone in bamboo culm cuticular wax decreased as well as the contents of terpenoids and esters increased. This suggested that the degradation of cuticular wax on bamboo culm should be due to the hydrolysis of alkane into fatty acids and terpenoids.The surface contact angle of stored bamboo culm decreased and the color of bamboo culm changed. The contact angle of the stored bamboo culm surface reduced 12.24%, 25.53%, 9.76%, 1.85% compared with the fresh bamboo culm. The surface color of bamboo culm was related to the content of cuticular wax and weight loss of bamboo culm and was the joint function of weight loss and wax content change.

Visible-Light-Triggered Difluoroacetylation/Cyclization of Chromone-Tethered Alkenes Enabling Synthesis of Tetrahydroxanthones.

Hydroxanthones have attracted considerable attention due to their significance in organic and biological chemistry, yet their synthesis remains a great challenge. In this study, a series of chromone-tethered alkenes are designed, and a radical cyclization reaction of these chromone derivatives has been achieved under photoredox conditions. The reaction uses bromodifluoroacetamides or bromodifluoroacetates as coupling partners, affording a broad range of functionalized tetrahydroxanthone products with up to 85% yields. The reaction is triggered via the generation of difluoroacetate radicals or alkene radical cations with fac-Ir(ppy)3 or 2,3,5,6-tetrakis(carbazol-9-yl)-1,4-dicyanobenzene as a photocatalyst. This approach offers access to various tetrahydroxanthone derivatives from readily available starting materials and enriches the research content of heteroarene-tethered alkenes.

Qualitative assessment of regular and premium gasoline available in Bangladesh markets

Assessing the quality of fuel is essential to comprehend its impact on the environment and human health. In this study, the evaluation of fuel quality standards at the consumer level was conducted by analyzing the motor fuels in Khulna, Bangladesh. A total of 32 samples of petrol (regular gasoline), and octane (premium gasoline) were collected from the fuel stations in the Khulna City Corporation area and analyzed with an FTIR-Fuel Analyzer. Fuel properties, such as research octane number (RON), motor octane number (MON), ethanol content, olefins content, and oxygen content were analyzed. For petrol, the average RON, MON, olefins, and oxygen content were 95.34, 85.70, 8.23 %v/v, and 0.78 %m/m, respectively, and for octane, they were 96.96, 85.39, 1.25 %v/v, and 0.09 %m/m, respectively. Almost all of these parameters complied with both Bangladesh standard and Euro 5 fuel specifications, and those that did not comply were very close to their standard values. However, benzene concentration, which was not specified in Bangladesh Standard, was the most alarming metric for octane since none of the samples matched the Euro 5 fuel specifications of the maximum concentration of 1 %v/v benzene; on average it was 3.70 %v/v. Although petrol benzene content (average 1.50 %v/v) was not as bad as it was for octane, it was still nowhere near good enough, with only 25% of the samples within the recommended level among the studied sample. This information holds significance in establishing the fuel profile and facilitating the identification of distinct samples linked to adulteration. Therefore, the analysis of motor fuel qualities is essential for maintaining the environment, human health, and the economy of a country.

Application of a property prediction model based on the structure oriented lumping method in the fluid catalytic cracking process

Based on the Structure Oriented Lumping (SOL) method and the Artificial Neural Network (ANN) algorithm, a SOL-ANN property prediction model was constructed to predict the properties of molecules and products in the fluid catalytic cracking (FCC) process. The properties of each structural vector in the molecular composition matrices of gasoline and diesel were calculated. The influences of reaction temperature on the properties of gasoline and diesel were investigated from the perspective of molecular composition. When the reaction temperature increased from 490 °C to 510 °C, the content of aromatics and olefins in gasoline and the content of aromatics in diesel increased, resulting in the research octane number (RON) of gasoline increasing by 2.96 units and the cetane number (CN) of diesel decreasing by 1.37 units. Using the molecular composition information of products to calculate the properties of molecules and products could guide the product quality evaluation and process optimization.