Aromatization Process Research Articles

The influence of tectonic action on the characteristics of microcrystalline and pore structure of anthracite in Qianbei Coalfield

Tectonic action strongly impacts the coal's microcrystalline and pore structural features. X-ray diffraction (XRD) was employed to analyze the impact of tectonic action on the microcrystalline structure of coal. The pore structure of anthracite was investigated through electron microscope image, mercury intrusion porosimetry and low pressure N2/CO2 adsorption, with a focus on exploring the relationship between the microcrystalline structure of coal and its micropore structure. The results show that under tectonic action, interlayer spacing of the aromatic layer d002 decreases from 0.345 to 0.342 nm, the stacking height Lc decreases from 2.73 to 2.23 nm, the average number of the effective aromatic layer Nave slightly decreases from 6.61 to 6.51, and the crystallite diameter La increases by 0.13 nm, which indicates that tectonic action changes the microcrystalline structure of anthracite. The microcrystalline structure changes from "short and thick" to "long and thin", thus schematic diagram of the anthracite basic structural unit (BSU) under tectonic action was established. The fa of tectonic coal increased by 16.92% compared with that of original coal, and the g increased from 0.85 (original) to 0.89 (tectonic), indicating that the process of aromatization and graphitization of coal was accelerated by tectonic action. Tectonic action plays an important role in promoting pore development, which makes the pore surface of anthracite more rough, the lattice fringe more dense and clear, and increases the pore volume and specific surface area of anthracite by 1.21 and 1.08 times, respectively. Tectonic action can change the BSU of coal, thus producing more nanoscale space. This study holds important implications for comprehending how tectonic action affect the microcrystalline structure of coal as well as its relationship with nanopore structures in tectonic coal.

Production of synthetic high-octane gasoline from associated petroleum gas

The article proposes a method for producing high-octane gasoline from associated petroleum gas (APG), which consists of a combination of the processes of direct aromatization of APG and Fischer-Tropsch synthesis (FT). The APG aromatization process was experimentally studied in a flow-through installation at a pressure of 0,1 MPa and a temperature of 450-600 °C on a ZnO/ZSM-5/Al2O3 catalyst. It has been shown that at a temperature of 600 °C the degree of conversion of C3+ hydrocarbons is 27,8%, and the yield of aromatic hydrocarbons is 10,9 %. The synthesis of FT was studied on a hybrid Co-Al2O3/SiO2/ZSM-5/Al2O3 catalyst at a temperature of 250 °C, pressure 1,0 MPa, GHSV 1000 h-1. A pilot batch of synthetic gasoline fraction with a volume of 1 liter was produced at a pilot plant, and its main physicochemical and operational properties were analyzed. It has been shown that compounding the gasoline fraction of the FT synthesis and direct aromatization products of APG makes it possible to increase the octane number from 78,5 to 92,8 units, while the density increases from 710 to 778 kg/m3. The proposed technological solutions can be used for processing APG into high-octane synthetic gasoline using GTL modular units.

Robust Catalytic SEAr H/D Exchange of Arenes with D2O: Metal‐Free Deuteration of Natural Complexes and Drugs

AbstractA catalytic metal‐free approach for the H/D exchange in aromatic compounds using D2O as the terminal deuterating reagent has been developed. This metal‐free protocol employs a triaryl carbenium as the mediator and showcases a wide applicability in the late‐stage deuteration of various natural products and small‐molecule drugs. Gram‐scale deuteration was successfully demonstrated with β‐Estradiol, highlighting the method‘s practicability. Detailed mechanistic insights, supported by DFT calculations, unveiled the essential role of in situ generated acidic species in this electrophilic aromatic substitution process. This newly developed method offers a sustainable and versatile alternative to traditional metal‐catalyzed H/D exchange techniques, addressing challenges such as the use of expensive metals, impurity formation, and the necessity for residual metal removal from the final products.

Robust Catalytic SEAr H/D Exchange of Arenes with D2O: Metal-Free Deuteration of Natural Complexes and Drugs.

A catalytic metal-free approach for the H/D exchange in aromatic compounds using D2O as the terminal deuterating reagent has been developed. This metal-free protocol employs a triaryl carbenium as the mediator and showcases a wide applicability in the late-stage deuteration of various natural products and small-molecule drugs. Gram-scale deuteration was successfully demonstrated with β-Estradiol, highlighting the method's practicability. Detailed mechanistic insights, supported by DFT calculations, unveiled the essential role of in situ generated acidic species in this electrophilic aromatic substitution process. This newly developed method offers a sustainable and versatile alternative to traditional metal-catalyzed H/D exchange techniques, addressing challenges such as the use of expensive metals, impurity formation, and the necessity for residual metal removal from the final products.

Construction of 2-Substituted-3-aryl Benzofurans and Indoles through an Acid-Catalyzed Cascade Intramolecular Friedel-Crafts Reaction/Rearrangement/Aromatization Process.

We present here a new method for the synthesis of 2-substituted-3-aryl benzoheterocycles through a more challenging constrained [1,5]-type Friedel-Crafts reaction/rearrangement and aromatization process. By using the readily available 2-aryoxy-1,3-indandiones and 2-arylamino-1,3-indandiones, a range of 2-substituted-3-aryl benzofurans and indoles were prepared in good to excellent yields (yields up to 86%) under the catalysis of CF3SO3H or Sm(OTf)3. Compared with previous methods for constructing similar structures, this approach offers several advantages, including the use of easily accessible starting materials, mild reaction conditions, high yield, excellent regio- and diastereoselectivity, and a broad substrate scope.

The effect of using two stabilization temperatures and fixation process on preparation of carbon nanofibers

Carbon nanofibers (CNFs) are prepared from electrospun polyacrylonitrile (PAN) because of their high carbon content. Heat treatment (oxidative stabilization and carbonization) is necessary to convert PAN nanofibers into CNFs. The fixation of fibrous structure of polymer precursor during heat treatment is always considered as a problem. The aim of this work is to study the effects of two different stabilization temperatures and fixation on CNFs prepared from electrospun PAN nanofibers. In this study, we use two different stabilization temperatures (275 and 300 °C) to investigate the effect of temperature on the oxidation, cyclization, crosslinking, aromatization, and dehydrogenation processes that occur during the stabilization heat treatment. Further, we study the effect of electrospun sheet fixation during heat treatment on the fibrous structure of electrospun fibers and methods to prevent shrinkage and folding of the electrospun sheet. Fourier transform infrared spectroscopy revealed the effectiveness of stabilization at 300 °C when transforming PAN elctrospun nanofibers to CNFs. Raman spectroscopy showed that carbonization at 800 °C after stabilization at 300 °C lowers the R-value (ID/IG ratio) comparing with that stabilized at 275 °C which indicates increasing the amount of structurally ordered graphite crystallites relative to the disordered structure. Scanning electron microscopy (SEM) revealed that fixation process maintained a uniform fibrous structure for the stabilized sheets without shrinkage, whereas carbonization at 800 °C without fixation resulted in deformed and folded carbonized PAN with loss in the fibrous structure.

Evaluation of the Shelf Life of Myristica-fragrans Powder-Flavored Oils Obtained through the Application of Two Processes: Infusion and Co-Pressing Technology.

This work aimed to evaluate the impact of enrichment processing on the quality parameters, bioactivity and sensorial aspects of Myristica fragrans (mace)-flavored olive oil storage for one year. The mace powder was added to extra virgin olive oil through two different processes: immediately after crushing the olives by mixing mace (1% weight/weight (w/w)) with the olive paste (MAVOO-M) and by adding mace to extra virgin olive oil (C) (2% w/w) (MAVOO-I). A multi-analytical approach was applied to measure the main qualitative indexes, such as the free acidity, peroxide value and ultraviolet parameters. The total phenolic and carotenoid contents (TPC and TCC, respectively) and α-tocopherol were also evaluated, as well as the sensory attributes. The radical scavenging potential was estimated by using two different in vitro tests, namely, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH). A significant increase in the free acidity parameter was found in all the flavored oils, and particularly in the MAVOO-M (1.27% oleic acid); at the same time, this oil was the sample with the lowest peroxide value (i.e., 9.68 meqO2/kg) after 360 days of storage. At the end of the storage, an increase in L* values was found in both the MAVOO-M and -I vs. the C (43.88 and 43.02, respectively, vs. 42.62). The TCC was strongly influenced by the addition of mace, especially when the infusion process was used. In fact, after one year of storage, the TCC in the MAVOO-I resulted in ~34.7% more than the MAVOO-M. A promising DPPH radical scavenging activity was observed independently by the applied aromatization process, with IC50 values of 19.77 and 17.80 μg/mL for the MAVOO-M and MAVOO-I, respectively. However, this activity decreased during storage, and a similar trend was observed using the ABTS test. In conclusion the infusion as enrichment methodology led to more promising results in terms of functionality compared with the co-mixing one.

Ternary system with sandwich configuration facilitates aromatic production from CO2 hydrogenation

Enhancing the selectivity of light olefin intermediates is crucial for efficiently synthesizing aromatic hydrocarbons from CO2 hydrogenation. However, due to the limitations of Anderson-Schulz-Flory law, the oriented synthesis of light olefins over Fe-based catalysts is challenging. Herein, we creatively insert Y zeolite between the Fe-based catalyst and ZSM-5 zeolite to form a sandwich configuration. The excellent cracking function of sandwich Y zeolite enables the products before the aromatization to be concentrated in the light unsaturated hydrocarbons, leading to a high aromatic selectivity during the succedent aromatization processes. With the assistance of Y zeolite, the light olefin selectivity of the K-Fe catalyst increases from 30.8 % to 40.3 %. After combining with ZSM-5 zeolite, the aromatic selectivity of the ternary system is boosted from 27.6 % to 51.5 % compared to the bifunctional catalysts without Y zeolite. Our studies offer insightful guidance for the rational utilization of multifunctional zeolites to directly synthesize target products.

In situ visualization of polycyclic aromatic hydrocarbon hydrothermal decomposition process utilizing planar induced fluorescence: A mechanistic analysis

Hydrothermal decomposition of coal or biomass for hydrogen production is a clean and efficient technology. Comprehending the hydrothermal decomposition mechanism of Polycyclic Aromatic Hydrocarbons (PAHs) is pivotal for advancing biomass or coal hydrothermal reaction technology. Traditional non-in situ measurement methods present challenges in thoroughly exploring the intricacies of PAHs’ hydrothermal reaction mechanisms. To address this issue, this study establishes an in situ visualization platform leveraging planar laser-induced fluorescence (PLIF) technology. Fluorescence signals emanating from naphthalene are meticulously measured in situ across diverse temperature conditions (450 °C-650 °C). The decomposition rate characteristics of PAH in hydrothermal process are thereby elucidated. A proportional increase in the reaction rate of naphthalene with elevated temperatures, concomitant with an augmented risk of coking. Moreover, the generation of hydroxyl radicals (OH) during the hydrothermal decomposition process was observed in the in situ visualization platform. Afterwards, to promote the generation of OH radicals and improve the conversion of PAHs, small molecule additives (formic acid, acetic acid, methanol, and ethanol) were added into the reactions. The experimental results indicate that the addition of small molecules increases the conversion rate of PAH and significantly reduces coking. These radicals effectively occupy reactive sites on naphthalene, thereby suppressing the coking proclivity of PAHs. This work provides a novel method to investigate the mechanism of hydrothermal process and offers a potential way to improve the conversion efficiency.

Anti-ageing and rheological performance of bitumen modified with polyaniline nanofibres

Asphalt pavements represent the great majority of roads worldwide. However, the bitumen physico-chemical properties change due to ageing processes during both the production and service life of the asphalt mixes. In recent years, a completely new trend has been observed in the road engineering industry oriented to extending the service life of roads, bringing direct economic, ecological and social benefits. This work presents the possibility of inhibiting ageing of road bitumen by using polyaniline nanofibers (PANI_NFs) as well as enhancing its rheological properties examined with Linear Amplitude Sweep (LAS) as well as Multiple Stress Creep and Recovery (MSCR) tests. These results show that the application of PANI_NFs maintains the primary penetration value of bitumen short-term and long-term aged road bitumen at 88 % and 52 %, respectively. Moreover, bitumen modification with PANI_NFs reduces the softening temperature increase by 33 % and 24 %, respectively, and the viscosity increase of road asphalt by 50 % and 25 %, respectively. PANI_NFs also stabilised the bitumen surface adhesion force, determined with AFM, consequently confirming the enhanced resistance to ageing processes. In addition, changes in the carbonyl index, sulphoxide index and aromaticity of bitumen demonstrated that PANI_NFs inhibit oxidation and aromatisation reactions of its components. The tests indicated a 4-fold decrease in the degree of bitumen component oxidation after short-term ageing and a 33 % decrease after long-term ageing. FTIR analysis also showed a reduction in the degree of bitumen component aromatisation process of 79 % and 76 % for short-term and long-term ageing, respectively. The LAS and MSCR test results also showed that PANI_NFs had a beneficial impact on the resistance of the bitumen to fatigue and rutting. Overall, the study results suggest that PANI_NFs consitute a promising modifier for bitumen in terms of ageing inhibition and performance characteristics.

Mechanosynthesis of Pyrrole-2-carboxylic Acids via Copper-Catalyzed Spiroannulation/Ring-Opening Aromatization of 4-Arylidene Isoxazol-5-ones with Enamino Esters.

An efficient and practical tandem reaction of 4-arylidene isoxazol-5-ones with enamino esters catalyzed by an inexpensive copper salt has been established in a ball mill. This innovative approach yields a diverse array of structurally novel pyrrole-2-carboxylic acids, showing excellent tolerance toward different functional groups. By integrating spiroannulation and ring-opening aromatization processes, this protocol introduces a facile and cost-effective strategy for synthesizing highly functionalized pyrrole derivatives.

Oregano and thyme by-products of olive oil aromatization process with microwave assisted extraction as a rich source of bio-active constituents.

Processing of Medicinal Aromatic Plants (MAPs) results in the production of a significant amount of by-products, which are not commercially exploitable. Towards this direction, we studied extensively the by-products of oregano and thyme, remaining after the aromatization of olive oils with microwave assisted extraction (MAE). The purpose of the study was the exploitation of the "wastes" of these two economically significant herbs of Greece, for the potential development of innovative bioactive products. Hence, superior and inferior quality plant material from Origanum vulgare subsp. hirtum and Thymus vulgaris, were extracted with extra virgin olive oil using MAE. For the evaluation of raw plant material, beside the characterization of the essential oils (EOs), the hydroalcoholic extracts of superior and inferior plant material were afforded by ultrasound assistant extraction (UAE). In addition, the remaining plant material after the flavoring of olive oil by MAE, was extracted with c-Hex, MeOH, H2O:MeOH using UAE. All the extracts were evaluated for their DPPH free radical scavenging activity and total phenolic content (TPC) as well as their chemical profile was investigated by HPTLC. In parallel, the EOs, the olive oils and the c-Hex extracts were analyzed by GC-MS and Headspace Solid Phase Microextraction (HS-SPME)-GC-MS. The results showed that the composition of the EOs and the volatile fraction of the olive oil extracts were similar for the superior quality material whereas for the inferior the composition of the volatile fraction of olive oil extracts was not analogous to the respective EOs. GC-MS analyses of oregano and thyme by-products revealed the presence of carvacrol, thymol, γ-terpinene and p-cymene among the major constituents. Moreover, the hydroalcoholic extracts obtained from the plant material remaining after olive oil flavoring with MAE showed similar phenolic content and scavenging activity with the hydroalcoholic extracts of the corresponding raw plant materials underlying their potent use in the preparation of high-added value products such as nutraceuticals and cosmeceuticals as well as enriched animal nutrition products.

Synthesis of 2,3-Dialkyl-5-hydroxybenzofurans via a One-pot, Three-step Reaction Sequence of 2-Monosubstituted 1,3-Diketones and 1,4-Benzoquinones.

An economical one-pot, three-step reaction sequence of readily available 2-monosubstituted 1,3-diketones and 1,4-benzoquinones has been explored for the facile access of 2,3-dialkyl-5-hydroxybenzofurans. By using cheap K2CO3 and conc. HCl as the reaction promoters, the reaction occurs smoothly via sequential Michael addition, aromatization, retro-Claisen, deacylation, hemiketalization, and dehydration processes under mild conditions in a practical manner. Additionally, an interesting phenomenon was observed during the derivatization studies, where the dihydroquinoline was converted into tetrahydroquinoline and quinoline products, respectively, via a disproportionation process.

ZSM-5@Zn/ZSM-5 core@shell nanocrystals as integrated catalysts for efficient methanol conversion into aromatics

The use of ZSM-5@Zn/ZSM-5 core@shell nanocrystals as integrated catalyst for efficient aromatic production from methanol aromatization is demonstrated. By combining the attributes associated with core@shell structural and acidic features, ZSM-5@Zn/ZSM-5 exhibited synergistic and improved catalytic performance toward methanol aromatization. The effect of Zn/ZSM-5 shell thickness and the acid density of the ZSM-5 core on synergistic performance was systematically investigated. Results showed that aromatic selectivity could be increased with shell thickness and the acid density of the ZSM-5 core, while catalytic stability was subject to the optimization on both shell thickness and core acid density. The strengthening of dehydroaromatization on the shell catalyst after Zn introduction and the hydrogen transfer for aromatization with increasing core acid density was confirmed. A double boost on catalytic stability from methanol conversion along with 40.7% increase on aromatic selectivity could be achieved for core@shell catalyst with a coating ratio of 0.3 compared with that on single core catalyst. The fabrication of ZSM-5 core with low SiO2/Al2O3 ratio for Zn/ZSM-5 not only provided more acid sites to promote the aromatization, but also promoted the dealkylation of the formed aromatics, which could enhance the selectivity of light aromatics and catalytic lifetime. The findings in the work not only enrich the family of core@shell composite zeolite catalysts, but also provide the fundamental understanding on the aromatization process over core@shell structural features.

Development of a portable electronic nose for the classification of tea quality based on tea dregs aroma

Abstract The current assessment of tea quality is considered subjective. This study aims to develop a portable electronic nose to assess the aroma of tea dregs objectively by relying on the aromatic capture process through sensors and using multilayer perceptron (MLP). A MLP with some hyperparameter variations is used and compared with five machine-learning classifiers. The classification using MLP model with ReLU activation function and 3 hidden layers with 100 hidden nodes resulted in the highest accuracy of 0.8750 ± 0.0241. The MLP model using ReLU activation function is better than Sigmoid while increasing the number of hidden layers and hidden nodes does not necessarily enhance its performance. In the future, this research can be improved by adding sensors to the portable electronic nose, increasing the number of datasets used, and using ensemble learning or deep learning models.

Phase‐Transfer Catalysis for Electrochemical Chlorination and Nitration of Arenes

AbstractA biphasic anodic oxidation method for aromatic halogenation process was developed, where aqueous metal salts were directly used as halogen source. Ammonium salts serve as both electrolytes and phase transfer catalysis to facilitate anion transport and oxidative transformation. This design allows for chlorination or nitration of multiple types of arenes using NaCl or KNO2.

Phase-Transfer Catalysis for Electrochemical Chlorination and Nitration of Arenes.

A biphasic anodic oxidation method for aromatic halogenation process was developed, where aqueous metal salts were directly used as halogen source. Ammonium salts serve as both electrolytes and phase transfer catalysis to facilitate anion transport and oxidative transformation. This design allows for chlorination or nitration of multiple types of arenes using NaCl or KNO2.

Catalytic Intermolecular Deoxygenative Coupling of Carbonyl Compounds with Alkynes by a Cp*Mo(II)-Catalyst.

Carbonyl is highly accessible and acts as an essential functional group in chemical synthesis. However, the direct catalytic deoxygenative functionalization of carbonyl compounds via a putative metal carbene intermediate is a formidable challenge due to the requirement of a high activation energy for the cleavage of strong C═O double bonds. Here, we report a class of bench stable and readily available Cp*Mo(II)-complexes as efficient deoxygenation catalysts that could catalyze the direct intermolecular deoxygenative coupling of carbonyl compounds with alkynes. Enabled by this powerful Cp*Mo(II)-catalyst, various valuable heteroarenes (10 different classes) were obtained in generally good yields and remarkable chemo- and regioselectivities. Mechanistic studies suggested that this reaction might proceed via a sequence of C═O double bonds cleavage, carbene-alkyne metathesis, cyclization, and aromatization processes. This strategy not only provided a general catalytic platform for the rapid preparation of heteroarenes but also opened a new window for the applications of Cp*Mo(II)-catalysts in organic synthesis.

Socialization and Training of Aromatic Candle Processing from Used Cooking Oil for Urban Residents

This article highlights a community initiative aimed at promoting sustainable household liquid waste management in Kediri City, Indonesia. The problem identified was the insufficient attention given to liquid waste, particularly used cooking oil, which often leads to environmental pollution and infrastructure damage. The objective of the activity was to raise awareness among residents about the proper disposal and recycling of used cooking oil. The proposed approach involved conducting workshops, training sessions, and awareness campaigns to educate community members about the environmental impacts of improper disposal and the benefits of recycling used cooking oil into aromatic candles. Major findings revealed that through collaborative efforts with local officials and community organizations, the initiative successfully engaged community members and fostered a sense of responsibility towards waste management. The training programs empowered participants with practical skills to convert used cooking oil into aromatic candles, promoting the repurposing of waste while creating a pleasant atmosphere. The conclusion emphasizes the importance of community participation and public awareness in ensuring sustainable liquid waste management. The initiative showcased the feasibility of recycling used cooking oil and highlighted the potential for broader adoption of similar practices in other regions. Overall, the activity underscored the significance of individual actions in collectively addressing environmental challenges and encouraged the adoption of responsible waste management practices at the household level.

Synthesis of Benzoxazines by Heterogeneous Multicomponent Biochemo Multienzymes Cascade Reaction.

This work describes the possibility to combine multicomponent chemistry and multienzymes cascade transformations in a unique reactive framework to yield highly functionalized 1,4-benzoxazines under favorable heterogeneous conditions. The synthetic scheme involved the generation in situ of electrophilic reactive quinone intermediates of tyrosol esters catalyzed by lipase M and tyrosinase followed by nucleophilic 1,6-Michael addition of selected α-amino acid methyl esters, and successive intramolecular lactonization and aromatization processes. The immobilization of the multienzymes cascade on electroactive lignin nanoparticles improved the sustainability and recyclability of the overall system.