Coal Chemical Industry Research Articles

Synthesis of Fe–N doped porous carbon/silicate composites regulated by minerals in coal gasification fine slag for synergistic electrocatalytic treatment of phenolic wastewater

Coal gasification fine slag (CGFS), as a difficult-to-dispose solid waste in the coal chemical industry, consists of minerals and residual carbon. Due to the aggregate structure of minerals blocking pores and encapsulating active substances, the high-value utilization of CGFS still remains a challenge. Based on the intrinsic characteristics of CGFS, this study synthesized Fe–N doped porous carbon/silicate composites (Fe-NC) by alkali activation and pyrolysis for electrocatalytic degradation of phenolic wastewater. Meanwhile, minerals were utilized to regulate the surface chemical and pore structure, turning their disadvantages into advantages, which caused a sharp increase in m-cresol mineralization. The positive effect of minerals on composite properties was investigated by characterization techniques, electrochemical analyses and density functional theory (DFT) calculations. It was found that the mesoporous structure of the mineral-regulated composites was further developed, with more carbon defects and reactive substances on its surface. Most importantly, silicate mediated iron conversion through strong interaction with H2O2, high work function gradient with electroactive iron, and excellent superoxide radical (•O2−) production capacity. It effectively improved the reversibility and kinetics of the entire electrocatalytic reaction. Within the Fe-NC311 electrocatalytic system, the m-cresol removal rate reached 99.55 ± 1.24%, surpassing most reported Fe–N-doped electrocatalysts. In addition, the adsorption and electrooxidation experiment confirmed that the synergistic effect of Fe–N doped porous carbon and silicate simultaneously promoted the capture of pollutants and the transformation of electroactive molecules, and hence effectively shortened the diffusion path of short-lived radicals, which was further supported by molecular dynamics simulation. Therefore, this research provides new insights into the problem of mineral limitations and opens an innovative approach for CGFS recycling and environmental remediation.

Advances Treatment Technologies in Chemical Industry Wastewater

The main treatment methods of chemical wastewater were reviewed. Physical, chemical, and biochemical treatment technologies effective for removing those pollutants were presented with their applicability, effectiveness and advantages. The problems facing the wastewater treatment in the petroleum chemical industry and coal chemical industry were introduced. In the end, the new progress and trend of the processes were overviewed.

Techno-economic analysis of green hydrogen production using a 100 MW photovoltaic power generation system for five cities in North and Northwest China

In recent years, photovoltaic power generation technology has developed rapidly, but due to its impact on the stability and security of the power grid, some areas in North and Northwest China have a certain degree of photovoltaic power curtailment phenomenon. Hydrogen is considered a good medium for energy storage, and the photovoltaic power generation system based on hydrogen energy storage has been the focus of research. Therefore, this work established simulation models of a photovoltaic power generation with a rated capacity of 100 MW coupling with hydrogen production system using MATLAB software and performs real-time simulation. Techno-economic performance of the integration system in five cities of Hami, Ordos, Datong, Yinchuan, and Yulin was analyzed. The results show that the coupling system can generate 158484–175675 MWh of electricity annually, which can drive the electrolyzer to produce 2524–2761 tonnes of hydrogen. The energy efficiency of the overall system and levelized cost of hydrogen are 9.03–9.31 % and 25.95/22.54–28.38/24.97 CNY/kg. The total CO2 emissions reduction and carbon credits earned by the established system over a lifetime of 20 years can reach 1.81–2.00 million tonnes and 92.19–102.19 million CNY. This paper will provide economic and energy efficiency reference for studying the coupling of green hydrogen production systems with the coal chemical industry in the above regions.

Wulff Constructions for an Equilibrium MFI-Type Zeolite Shape Modelling under Different Conditions

As an MFI-type zeolite, ZSM-5 zeolite has wide applications in industry, such as in the fine chemical, petrochemical, and coal chemical industries. However, shape control of ZSM-5 nanocrystals constitutes one of the major challenges of current nanotechnology. Here, the MFI framework structure was used as the theoretical model of pure silicon ZSM-5 to investigate the surface energy and Wulff shape. The models with different crystal surfaces were simulated by molecular dynamics (MD) with the assistance of machine learning potentials (MLPs). The factors influencing the crystal surface energy, such as temperature, pH, and ionic concentration, have been studied in detail. Depending on the calculated surface energies, the crystal surface morphology and its ratio were obtained by means of the Wulff theorem. The results show that the area in the equilibrium shape of the (110) surface is usually the largest, and its proportion varies with external conditions. A high temperature and high concentration of the aluminum source promoted the growth of the (110) crystal surface, and the theoretical value of the crystal surface ratio was as high as 90%. This study provides theoretical insight into the synthesis of zeolites with different morphologies of all-silicon or low-aluminum.

Erosion Characteristics and Flashing Flow of High-differential-pressure Control Valves: A Numerical Study using an Erosion-Coupled Dynamic Mesh

To address the issue of erosion in the control valves of blackwater flash systems in the coal chemical industry, this study investigates the dynamic erosion characteristics of one such control valve. Computational fluid dynamics is employed to compare the results obtained with a static mesh and an erosion-coupled dynamic mesh, and the valve erosion is investigated by analyzing the erosion rate, the particle impact velocity, trajectories and angle. Moreover, the relationship between the deformation caused by erosion and the dispersion of the flash vapor phase in the valve is studied, focusing on the flow resistance coefficient. The results indicate that over a period of 9 × 106 s, the impact velocity and subsequent collisions of particles reduce, and the impact angle decreases with the accumulated deformation of the valve core. Notably, the valve core is influenced primarily by the cutting that results from low impact angles, leading to a substantial decrease in the overall erosion rate of the valve, amounting to a reduction of 56.4%. The region facing the flow is at significant risk of erosion, and as the opening decreases, the erosion zone extends gradually to the annular region of the valve core and valve head, leading to increased erosion deformation. Furthermore, as the flow resistance coefficient decreases, so does the vapor volume fraction inside the valve. This study provides a theoretical basis for predicting faults and developing online monitoring solutions for high-differential-pressure control valves in blackwater flashing systems.

Pilot-scale evaluation of the sustainability of membrane desalination systems for the concentrate volume minimization of coal chemical wastewater

5 stars represents the best technical performance/highest cost.

Analysis on application status of CCUS technology in emission reduction of modern coal chemical project in chemical industry

To gain a deeper understanding of the current application status of carbon capture, utilization, and storage (CCUS) technology in modern coal chemical projects aimed at reducing emissions in the chemical industry, a study on the application of CCUS technology in emission reduction in the chemical industry was proposed. This article provides a detailed summary of the application status of CCUS technology in the global chemical industry, comprehensively sorts out its technical classification and characteristics, and deeply analyzes the carbon emission characteristics of modern coal chemical industry. On this basis, a comprehensive analysis was conducted on the main technical, economic, and policy issues faced by the modern coal chemical industry in promoting the application of CCUS technology. Through the analysis and research of these issues, some suggestions have been made, including strengthening top-level planning, focusing on solving CCUS technology challenges, enhancing policy support, etc., to promote better progress in the modern coal chemical industry in carbon capture technology engineering demonstration and low-carbon development.

Coal gasification crude slag based complex flocculants by two-step acid leaching process: synthesis, flocculation and mechanisms.

Coal gasification crude slag (CGCS) is the side-product of the coal gasification process, and its effective utilization has attracted great attention. A novel flocculant of poly-aluminum-ferric-acetate-chloride (PAFAC) was synthesized based on the recovery of CGCS by a two-step acid leaching process, namely HCl-acid leaching and HAc-acid leaching, which was optimized by an acid leaching liquor volume ratio of HCl to HAc of 3 : 2, polymerization pH of 3.5, and reaction temperature and time of 70 °C and 3.0 h, respectively. The performance of PAFAC was further evaluated by kaolin simulated wastewater, domestic sewage, river water, and aquaculture wastewater. The results revealed that PAFAC was feasible for the removal of turbidity, chemical oxygen demand (COD) and total phosphorus (TP). Moreover, PAFAC was characterized by X-ray Diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray fluorescence spectrometry (XRF) and scanning electron microscopy (SEM), which proved that PAFAC was a kind of amorphous polyionic composite. Additionally, the acid leaching kinetics and flocculation mechanisms were further investigated. It was found that the acid leaching process was followed by the unreacted shrinkage core model, and the flocculation process was dominated by charge neutralization, adsorption bridging and precipitation net trapping. The work is expected to develop a new method for the safe disposal of CGCS and provide a novel way for the preparation of Fe-Al composite flocculants, especially, offering a potential strategy for the promotion of the additional value of the coal chemical industry.

Occurrence characteristics, environmental trend, and source analysis of polycyclic aromatic hydrocarbons in the water environment of industrial zones

The middle reaches of the Yellow River are rich in energy resources, with the Kuye River, a first-class river in this region, serving as a vital hub for the coal chemical industry within China. This study investigated the occurrence patterns, environmental trends, and ecological risks associated with polycyclic aromatic hydrocarbons (PAHs) in the Kuye River Basin, offering insights into the environmental dynamics of regions. The findings indicated that the river sediments primarily contained PAHs with medium to high-molecular weights, exhibiting levels ranging from 402.92 ng/g dw to 16,783.72 ng/g dw, while water bodies predominantly featured PAHs with low to medium molecular weights, ranging from 299.34 ng/L to 10,930.9 ng/L. The source analysis of PAHs indicated that industrial and traffic exhaust emissions were the primary contributors to PAHs in the Kuye basin, with sediments serving as a secondary release source based on fugacity fraction. The content of PAHs in sediment correlated closely with the environmental factors, and the PAHs inventory of the basin was 19.97 tons. The increased overall PAH concentration in the basin posed significant ecological and public health concerns, necessitating urgent attention.

Study on material structure design, selective adsorption mechanism, and application for adsorption recovery of oil substances in coal chemical wastewater

In response to the problem of high emulsified and dissolved oils being difficult to recovery from coal chemical wastewater (CCW), this study specifically constructed a non-polar, macropore, and hydrophobic adsorption material (pSt-X) based on the main components of these two oils (aromatics and phenols) for selective recovery. The results revealed that pSt-X had an adsorption capacity of 215.52 mg/g, which had remained stable for multiple recycling sessions, with an adsorption capacity constantly above 95 %. The pSt-X has significantly larger particle size (0.7 mm–1.2 mm), which simplifies the process of adsorption regeneration and effectively prevents the loss of the adsorbent powder problem. The pSt-X adsorbent demonstrated remarkable selectivity towards dissolved and emulsified oils, exhibiting removal rates of 90.2 % and 81.7 %, respectively. Moreover, pSt-X proved remarkable selectivity in removing aromatic hydrocarbons (AHs) and phenols, with impressive removal rates of 77.8 % and 85.9 %, respectively. The selective separation mechanism of pSt-X for oil substances was further analyzed, indicating that its selective adsorption of oils was primarily driven by hydrophobic, π-π, and hydrogen bonding interactions owing to its non-polar and macropore structure and hydrophobic properties. The results of this study provide solid theoretical support for green and low-carbon recovery of oil substances in CCW and are of positive practical importance for clean production in the coal chemical industry.

The influence factors of dielectric barrier discharge plasma to production of syngas derived from H2S-CO2 acid gas

H2S and CO2, two harmful acid waste gases, often co-exist in important chemical production such as coal-chemical industry, natural gas chemical industry and petrochemical industry, causing corrosion of industrial equipment and pipelines, and must be treated innocuously. Co-conversion of H2S-CO2 mixed acid gas to syngas has been carried out using dielectric barrier discharge (DBD) plasma-catalysis, which renders the highly corrosive and toxic H2S and greenhouse gas CO2 harmless, and produces syngas. The effects of various parameters of the DBD plasma on the reaction of one-step conversion of H2S-CO2 to syngas were studied. Moreover, a comparative study of the different parameters of DBD plasma was carried out. The intrinsic correlation between the reaction performance of syngas production via H2S-CO2 conversion and these parameters, including specific energy input (SEI), discharge shape, discharge frequency, discharge gap and discharge length, was investigated and revealed. On this basis, a multi-tube parallel DBD plasma reaction system was designed and constructed.

Feasibility and challenges of multi-source coal-based solid waste (CSW) for underground backfilling − A case study

The multi-source CSW produced in coal mining, power generation and coal chemical industry has become a bottleneck that restricts the green, low-carbon and high-quality development of coal power and coal chemical bases (CPCCBs) in China due to its large stock, many increments and low utilization rate. Underground backfilling has opened up a new way for CPCCBs to dispose of multi-source CSW, and it is also the most practical way, which is conducive to solve the surface accumulation of CSW and reducing the environmental pollution risk. Based on the physicochemical properties and pollution, the feasibility of underground backfilling with multi-source CSW was systematically analyzed from four aspects: environment, technology, economy and policy. Most CSWs can be directly for underground backfilling; the high potential pollution risks of individual CSWs can reduce through technical measures such as heavy metal adsorption and complex passivation, then safely for underground backfilling. Although underground backfilling with multi-source CSWs is feasible, there are still some challenges before achieving large-scale engineering applications, such as potential risks of CGS, technical maturity, economic investment and administration. It requires the joint efforts and cooperation of research institutions, enterprises and governments to realize the harmless and large-scale underground backfilling with multi-source CSW.

Spatialized carbon-energy-water footprint of emerging coal chemical industry in China

Concerns about energy security have driven the launch of the emerging coal chemical industry (ECCI) across China. However, the resulting spatially explicit carbon–energy–water footprint remains unclear. This study aims to comprehensively identify the spatial heterogeneity, distribution, and transfer characteristics of the carbon–energy–water footprint of the ECCI in China. An original spatialized accounting method based on a multi-flow multi-node model is developed to address the difficulty that spatially integrating large amounts of spatial data for ECCI projects and their upstream coal mines and power plants. The results indicate that the provincial intensities of the carbon footprint, energy footprint, and water footprint varied by −13.4–43.6 %, −7.2–1.8 %, and −22.6–59.5 % relative to the national averages, respectively. The three intensity types have quite different spatial heterogeneities, always showing an impossible trinity of carbon reduction, energy saving, and water conservation at the provincial level. The total national carbon footprint, energy footprint, and water footprint reached 280.20 Mt CO2-eq, 5.35 EJ, and 1155.18 Mt, respectively, of which more than 90 % were centrally distributed in North China, Northwest China, and East China. Interprovincial coal transport and electricity transmission driven by the spatial mismatch between the upstream and downstream processes together led to the transfer of 10.35 Mt CO2-eq of carbon footprint, 68.72 PJ of energy footprint, and 100.92 Mt of water footprint, whereas their respective contributions significantly varied by footprint type. These results provide spatial-specific knowledge and insights for layout optimization and sustainability enhancement for the ECCI across the country.

Emission characteristics, environmental impacts and health risk assessment of volatile organic compounds from the typical chemical industry in China

To study the volatile organic compounds (VOCs) emission characteristics of industrial enterprises in China, 6 typical chemical industries in Yuncheng City were selected as research objects, including the modern coal chemical industry (MCC), pharmaceutical industry (PM), pesticide industry (PE), coking industry (CO) and organic chemical industry (OC). The chemical composition of 91 VOCs was quantitatively analyzed. The results showed that the emission concentration of VOCs in the chemical industry ranged from 1.16 to 155.59 mg/m3. Alkanes were the main emission components of MCC (62.0%), PE (55.1%), and OC (58.5%). Alkenes (46.5%) were important components of PM, followed by alkanes (23.8%) and oxygenated volatile organic compounds (OVOCs) (21.2%). Halocarbons (8.6%-71.1%), OVOCs (9.7%-37.6%) and alkanes (11.2%-27.0%) were characteristic components of CO. The largest contributor to OFP was alkenes (0.6%-81.7%), followed by alkanes (9.3%-45.9%), and the lowest one was alkyne (0%-0.5%). Aromatics (66.9%-85.4%) were the largest contributing components to SOA generation, followed by alkanes (2.6%-28.5%), and the lowest one was alkenes (0%-4.1%). Ethylene and BTEX were the key active species in various chemical industries. The human health risk assessment showed workers long-term exposed to the air in the chemical industrial zone had a high cancer and non-cancer risk during work, and BTEX and dichloromethane were the largest contributors.

Pore characteristics of sulfate-activated coal gasification slag cement paste backfill for mining.

With the mass production of coal-based solid waste, coal mine filling can effectively consume it. The coal gasification slag is modified and prepared as coal mine filling material to meet the relevant technical requirements, which can realize the recycling of coal mine → coal chemical industry → coal mine. In this paper, in order to explore the evolution law of the mechanical properties and pore structure characteristics of the modified coal gasification slag-cement cemented paste backfill (MCGS-CPB) prepared by sodium sulfate excitation coal gasification slag, a combined macro-meso-micro testing method is used. MCGS-CPB with different sodium sulfate contents (1~5%) were prepared and tested for uniaxial compressive strength (UCS), mercury intrusion (MIP) and microscopic tests. The results show that sodium sulfate has a significant effect on the UCS and pore structure characteristics of MCGS-CPB. The mechanical properties and pore structure characteristics of MCGS-CPB were best when sodium sulfate was doped at 3%; the mechanical properties and pore structure characteristics of MCGS-CPB were deteriorated when the addition of sodium sulfate is higher than 3%. On the meso-scale, when sodium sulfate was doped with 3%, the more harmful pores of MCGS-CPB gradually changed into harmless, less harmful, and harmful pores, and the macroscopic mechanical properties were gradually improved; when the addition of sodium sulfate is higher than 3%, the harmless, less harmful, and harmful pores of MCGS-CPB gradually changed into more harmful pores, and the macroscopic mechanical properties were deteriorated. On a microscopic scale, sodium sulfate can cause MCGS-CPB to form hydration products with expansion properties. The presence of a reasonable amount of sodium sulfate in the pores of MCGS-CPB is beneficial to the development of mechanical properties. However, excessive presence will lead to the formation of expansion stress, gradual formation of micro-expansion cracks, and deteriorate the macroscopic mechanical properties. Hence, the volcanic ash activity of coal gasification slag excited by external addition of sodium sulfate should not exceed 3%. This study provides a reference value for application ratio of sodium sulfate-stimulated MCGS-CPB used in coal mine filling design.

Bioaugmentation treatment of coal chemical reverse osmosis concentrate in biological contact oxidation system coupled with ozone pretreatment

With the zero discharge requirements of coal chemical industry in China, reverse osmosis technology and fractional crystallization technology have been applied to recover water and valuable salts. Organic matter significantly inhibits salt crystallization, therefore it is urgent to remove organic matter from coal chemical reverse osmosis concentrate (CCROC) efficiently and economically. Common biological systems have the bottlenecks of long start-up period and poor pollutants removal efficiency due to the inhibition of toxic compounds and high salinity to the microorganisms. In this work, a self-prepared halotolerant bacteria preparation (HBP, mixture of screened Bacillus, Pseudomonas, and Halomonas with strong degrading capacity of CCROC) was inoculated into different biochemical systems (activated sludge and biological contact oxidation in sequencing batch reactor) to try to enhance the pollutants removal of extremely refractory CCROC (BOD5/COD of 0.05). The results showed that HBP increased the total organic carbon (TOC) removal efficiency from 8% to 15% in activated sludge system. In addition, biological contact oxidation reactor (BCOR) could better retain the HBP, leading to a higher TOC removal efficiency (20%). Typically, the inoculation of HBP without activated sludge in BCOR contributed to the highest TOC removal (28%). The class Bacilli (genus Bacillus) was dominant during the start-up and stable period of this bioaugmented treatment process. To further increase the pollutants removal, ozone oxidation pretreatment was conducted prior to biological treatment to break the ring structures. The total TOC removal increased to 42% under the combined treatment, while the dominant classes in biofilms shifted to Actinobacteria, Gammaproteobacteria, Alphaproteobacteria, and Bacteroidia. This study provided an effective approach for CCROC treatment with industrial application potentials.

Novel membrane contactor-like bioreactor for selective separation and biodegradation of phenol and ammonium from coal chemical wastewater

The development of coal chemical industry usually generates high-concentrated wastewater containing phenol and ammonium, which requires deep treatment before disposal. Herein, a novel combined process of membrane contactor and bioreactor (MCBR) was established for the efficient treatment of phenol-ammonium wastewater for the first time. When pH was in the range of 8–13, the increase of pH weakened the transmembrane mass transfer of phenol and enhanced the mass transfer of ammonia, owing to their different existing forms at different pH values. At a temperature of 20–30 ℃, the transmembrane mass transfer of phenol and ammonia both increased with temperature increasing. Meanwhile, the established transmembrane mass transfer model reflected the same tendencies of phenol and ammonium recovery rates between experiment and theory. The precise control of concentrations of phenol and ammonium by membrane contactor ensured the safety and effectiveness of subsequent biodegradation process. After biodegradation, the concentrations of phenol and ammonium reduced from 120.1 and 78.9 mg/L to 7.8 and 2.5 mg/L, respectively. The volatile solid content of activated sludge remained relatively constant, while the settling ratio decreased from 39 % to 29 %. Overall, this study established a novel MCBR system for green and cost-effective treatment of high-concentrated coal chemistry wastewater.

Substances and energy metabolism of green Hydrogen-Assisted/Coal-Methanol-Olefin-Polyolefin system using ecological network methodology

It is crucial to comprehend the complex interconnections among units in coal chemical industry for its lower carbon and efficient transformation. This understanding can help identify priority nodes for optimization in the pursuit of lower carbon emissions and improved efficiency. Ecological network analysis method is employed to study the substances and energy metabolism in the coal chemical industry treating it as a superorganism comprising numerous intricate metabolic processes. Network utility analysis and network control analysis are conducted to evaluate the substances and energy metabolism of the coal-methanol-olefin-polyolefin (CMOP) system and green hydrogen-assisted CMOP (GH-CMOP) system, applying an innovative perspective and methodology. Key units for significant improvements in C/H/O and energy metabolism are disclosed. The GH-CMOP system shows better cascade utilization of C/H/O and energy, but hydrogen-carbon ratio adjustment has less impact on the overall metabolic utility relationships. Therefore, both systems need process route modifications to enhance substances and energy use.

Research on the Current Situation and Economic Development Trends of China's Energy Economy Structure: Taking Shandong Province as an Example

Shandong Province is a province with strong economic growth and high energy consumption in China. The energy consumption structure is mainly composed of coal and oil. While the regional GDP is increasing with each passing year, carbon emissions are also increasing year by year, and carbon emissions are mainly concentrated in high energy consuming industries. Coal plays a very significant part in the growth of social economy and has become a necessity for people's production and life. The coal based chemical industry is one of the six leading industries of Shandong Energy Group. The coal chemical industry is a significant component of China's energy construction, and how to improve the quality and efficient utilization of coal chemical products is currently the focus of close attention in the coal chemical industry. Promoting economic transformation and upgrading, as well as energy structure adjustment, is a necessary path for China to achieve the objective of "carbon peaking and carbon neutrality". Carbon peaking and carbon neutrality "is the main foundation and new engine for China's economic and social growth in the next 40 years, which will inevitably drive systematic changes such as low-carbon transformation, structural reshaping, and technological innovation in the energy industry. This article takes Shandong Province as an example to study the current situation of China's energy economy structure and economic development trends.

An Assessment Framework for Human Health Risk from Heavy Metals in Coal Chemical Industry Soils in Northwest China

Coal chemical industry (CCI) sites are characterized by complex environmental media, combined heavy metal pollution, and diverse exposure routes. However, existing human health risk assessment (HHRA) methods have multiple drawbacks, such as their small scope of application, limited assessment factors, and insufficient case applications. After 128 soil samples were collected, the contents of Be, V, Ni, Cu, Zn, As, Cd and Hg in the soils were analyzed based on general risk assessment guideline of China. Then, risk levels were calculated based on oral ingestion, skin contact and inhalation as the main exposure routes to compare and screen priority heavy metals. Furthermore, control values were identified through a contribution rate calculation model when CR > 10−6 or HQ > 1. As reference values, risk thresholds were proposed for heavy metals, and then a soil HHRA framework for the CCI site was constructed. Under the three exposure routes, the total CR was As > 10−6, and the total HQ was 1 > As > Cd; the HHRs related to As and V via the oral ingestion, dermal contact, and inhalation pathways were 76.67%, 13.13%, and 10.18% and 1.66%, 0, and 98.34%, respectively. The risk control value of As was 1.59 mg/kg and that of V was 25.1 mg/kg. Based on these results, the threshold values for priority heavy metals should be based on comprehensive considerations of the elemental background of a specific area, the contaminant criteria in different areas, the regional industrial development plan, and the most important control criterion, as well as the control value. Through the development of an HHRA framework and case verification, the authors of this article aim to guide CCI managers in screening priority heavy metals, formulating protection measures, developing improved operational procedures and improving the HHRA system for polluted CCI sites.