Coal conversion in co-processing with heavy petroleum residues (2023)

Eleven low rank coals from North Bohemian mines were comprehensively characterized by using a number of analytical methods. Along with common proximate and ultimate analysis, spectroscopic techniques, porosity measurement, extractability and swelling in organic solvents were used. Although coals were of similar geological origin, some of their characteristics largely differed from one coal to another. Coals were coprocessed with petroleum vacuum residue at 440°C for 1 h and yields of reaction products and coal conversions were determined. Despite the differences in composition and properties, the coals provided similar conversions and yields of distillable reaction products. A small positive effect on coal conversion was found for ash content and microporosity of coals. However, a small negative effect was found for carbon content, optical reflectance and solvent extractability of coals.

The catalytic coprocessing of two Spanish lignites with a vacuum residue of petroleum has been studied. Two catalysts supported on γ-Al₂O₃, with loadings of 25% Fe₂O₃ and 25% Fe₂O₃/10% MoO₃, have been tested at temperatures from 400 to 425°C with an initial hydrogen pressure of 8 MPa. Results show that both catalysts improve the conversion of coal and upgrade the liquid product distribution. When a high ash lignite is used the catalytic effect of the own mineral matter overcomes the effect of added catalysts. The FeMo catalyst yields the highest coal conversion, oil production and desulphuration within the range of temperatures studied.

This work studies the influence of temperature and hydrogen availability on the coprocessing of two high sulphur content Spanish lignites, with a petroleum vacuum residue. The experimental results show that temperature and partial pressure of hydrogen have a great influence on the conversion of coal and on the quality of oils formed. The conversion increases with temperature of reaction until a maximum is achieved. This maximum is between 400 and 420 °C depending on the reaction conditions. Beyond this maximum the conversion drops quickly, even producing negative results, due to recombination reactions. A higher hydrogen partial pressure induces a larger coal conversion but the maximum is achieved at lower temperatures. On the basis of these results, hydrogen transfer through aromatic compounds is proposed as the reaction mechanism of coprocessing.

¹³C n.m.r. spectral editing techniques have been used to determine the concentrations of aliphatic CH, CH₂ and CH₃ groups directly in aromatic fractions from a North Sea waxy heavy distillate (vacuum gas oil) and a hydrotreated sample of this distillate. To help resolve effective and poor hydrogen-donor naphthenic groups, these fractions were catalytically dehydrogenated and re-examined by ¹³C n.m.r.. The results indicate that naphthenic groups in the initial aromatic fraction account for a maximum of 40% of the total carbon but only 10% of the carbon is present in effective hydrogen donors and that, in contrast to earlier structural models for heavy petroleum fractions, the naphthenic groups are relatively small comprising no more than two rings on average.

Chemosphere, Volume 305, 2022, Article 135490

This study employs ISORROPIA-II for the evaluation of aerosol acidity and quantification of contributions from chemical species and meteorological parameters to acidity variation in the Indian context. PM_2.5 samples collected during summer (April–July 2018), post-monsoon (September–November 2018), and winter (December 2018–January 2019) from a rural receptor location in the eastern Indo-Gangetic Plain (IGP) were analyzed for ionic species, water-soluble organic carbon (WSOC), and organic and elemental carbon (OC, EC) fractions. This was followed by estimation of the in situ aerosol pH and liquid water content (LWC) using the forward mode of ISORROPIA-II, which is less sensitive to measurement uncertainty compared to the reverse mode, for a K⁺-Ca²⁺-Mg²⁺-NH₄⁺-Na⁺-SO₄^2--NO₃^--Cl^--H₂O system. Aerosol pH was moderately acidic (summer: 2.93±0.67; post-monsoon: 2.67±0.23; winter: 3.15±0.34) and was most sensitive to SO₄²⁻ and total ammonium (TNH₃) variation. The LWC of aerosol showed an increasing trend from summer (16.6±13.6μgm⁻³) through winter (32.9±10.4μgm⁻³). With summer as the baseline, the largest changes in aerosol pH during the other seasons was driven by SO₄²⁻ (ΔpH: −0.70 to −0.82 units), followed by TNH₃ (ΔpH: +0.25 to +0.38 units) with K⁺ and temperature being significant only during winter (ΔpH: +0.51 and+0.46 units, respectively). The prevalent acidity regime provided three major insights: i) positive summertime Cl⁻ depletion (49±20%) as a consequence of SO₄²⁻ substitution increased aerosol pH by 0.03±0.20 units and decreased LWC by 2.4±5.9μgm⁻³; ii) the rate of strong acidity (H⁺ _str) neutralization and the [H⁺ _str]/[SO₄²⁻] molar ratio suggested the existence of bounded acidity in ammonium-rich (winter) conditions; and iii) significant correlations between LWC, WSOC, and secondary organics during post-monsoon and winter pointed towards a possible indirect role of WSOC in enhancing LWC of aerosol, thereby increasing pH. Given the inability of proxies such as H⁺ _str and charge ratios to accurately represent aerosol pH as demonstrated here, this study emphasizes the need for rigorous thermodynamic model-based evaluation of aerosol acidity in the Indian scenario.

Process Safety and Environmental Protection, Volume 159, 2022, pp. 992-995

This special issue aims to provide innovative research work that has recently been carried out in air pollution prevention and pollution source identification of chemical industrial parks, including both theoretical developments, experimental and/or application research. Chemical industrial parks have become a critical production space and brought enormous economic benefits to the regions. Consequently, they have caused tremendous pressure on the surrounding and regional environment. This preface firstly introduces the features of chemical industrial parks, then presents the five challenges on air pollution prevention, pollution source identification and source term estimation, and finally summaries the thirteen papers included in the special issue.

Journal of Molecular Liquids, Volume 338, 2021, Article 117021

Solvent plays an important role as a green chemistry. The solvents must meet certain criteria such as biodegradable, recyclability, low cost, availability and non-toxic to be qualified as a green medium. To date, solvents which are labelled as green medium are very limited. The new family of ionic fluids, called deep eutectic solvents (DESs) are now rapidly developing in terms of green research. A DES is a fluid that typically consists of two or three components that are secure and cost-friendly, able to associate frequently by itself through interactions of the hydrogen bond, creating a eutectic mixture with a melting point lower than that of each component. The DESs tend to be liquid at temperatures below 373.15K. Most of the DESs exhibits similar physico-chemical properties to the traditionally used ionic liquids, adding in the advantage that it is much cheaper and environmentally friendlier. Thus, DESs are increasingly involved in many research areas, this is because of the advantage that it carries compared to ionic liquids itself especially in sulfur dioxide gas separation process. The main aim of this review is to determine and summarize the recent research and the major contributions of DESs especially in sulfur dioxide extraction and absorption.

Science of The Total Environment, Volume 851, Part 2, 2022, Article 158206

PM_2.5 affects air quality, therefore, chemical evolution, formation mechanism and source identification of PM_2.5 are essential to help figure out mitigation measures. PM_2.5 and its constituents were comprehensively characterized with highly time-resolved measurements from 2019 to 2020 in north Zhejiang Province (Shanxi, SX) for the first time, with an emphasis on the contribution of secondary formation and vehicle emission to PM_2.5. Secondary inorganic ions (sulfate: 3.86 μg/m³, nitrate: 7.82 μg/m³ and ammonium: 4.59 μg/m³, SNA) were found to be the major components (54%) in PM_2.5 (29.70 μg/m³). The highly consistence of nitrate, sulfate and secondary organic compounds (SOC) with Ox (NO₂ + O₃) or RH indicated the importance of photochemical oxidation and heterogeneous reaction in different scenarios. Higher atmospheric oxidative potential facilitated the SOC formation in spring. The PM_2.5 mass was apportioned to eight sources resolved by positive matrix factorization (PMF): secondary nitrate (9.63 μg/m³), secondary sulfate (5.14 μg/m³), vehicle emission (7.26 μg/m³), coal combustion (2.39 μg/m³), biomass burning (1.38 μg/m³), soil dust (0.86 μg/m³), industry emission (0.50 μg/m³), and ship emission (0.32 μg/m³). Secondary nitrate (35%) and sulfate (19%) formation and vehicle emission (26%) were the main factors contributing to the PM_2.5. Furthermore, the contribution of secondary nitrate formation increased with elevating PM_2.5 concentration. Regional transport was synthetically studied by chemical and backward trajectory analysis, reflecting that secondary nitrate contributed severely to the air quality at SX, while vehicle emission contribution enhanced when atmosphere was stagnant. This study first provides long-term comprehensive chemical characterization and source apportionments of PM_2.5 pollution in north Zhejiang, which may provide some guidance for the air pollution control.

Electrochemistry Communications, Volume 68, 2016, pp. 10-14

Four kinds of iron hydroxide (FeOOH) structures with the morphologies of bulk, nano-sheet, nano-sphere, and nano-rod were synthesized using solvothermal processes. During synthesis different reagents were added to tune the morphology of FeOOH structures. These structures were characterized using TEM and SEM as well as from their Raman and XPS spectra. Voltammetric response of these structures as well as redox probes and endocrine disrupting compounds (EDCs) on these structures based electrodes was investigated. The morphology-dependent electrochemistry of these FeOOH structures was found. The highest redox activity of FeOOH was achieved on the FeOOH nano-rod structure based electrode, which was the best interface as well for the electrochemistry of both redox probes and EDCs. On such an interface, the highest magnitudes of both diethylstilbestrol (DES) and bisphenol A (BPA) were obtained.

Materials Today, Volume 20, Issue 10, 2017, pp. 592-610

The molecular design of porous solids from predefined building blocks, in particular metal-organic and covalent frameworks, has been a tremendous success in the past two decades approaching record porosities and more importantly was an enabler for integrating predefined molecular functionality (enantioselectivity, optical and catalytic properties) into pore walls. Recent efforts indicate that this concept could also be applicable to rationally design porous and nanostructured carbonaceous materials, a class of materials hitherto and especially in the past often considered as “black magic” in terms of pore-wall structure definition and surface functionality. Carbon precursors with structural and compositional information in their molecular backbone, pre-formed covalent bonds, or integrated functional groups enable the design of carbon materials that can be tailored for certain applications. We review this exciting field of synthetic approaches based on molecular building blocks such as ionic liquids, bio molecules, or organic precursor monomers enabling the design of advanced carbonaceous architectures such as porous carbons, porous carbon-rich polymers or graphene nanoribbons. Moreover, our review includes approaches using the reactive and thermal transformation of periodic crystalline structures such as metal-organic frameworks, or carbides into equally defined carbon material. Such molecularly designed carbons are not only ideal model materials for fundamental science but also emerge in applications with until now unattained functionality.