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In this work, different concentrations of coal-water slurry and coal-oil-water slurry were prepared and pyrolyzed at various temperatures of 800–1000 °C. The chemical characteristics and combustion reactivities of chars and the formation mechanism of main gas components of CO, CO2, CH4, and H2 were investigated. With the water content of the coal-water slurry increasing, the formation of CO and CH4 were hindered, while CO2 and H2 were promoted. For the coal-oil-water slurry, oil promoted CH4 and H2 production but inhibited CO and CO2. Moreover, the variation of the nitrogen-containing pyrolytic gas during pyrolysis was studied for various concentrations of coal-water and coal-oil-water slurries at different temperatures. The relative content of HCN and NH3 gradually increased with the increase of pyrolysis temperature and water content. For coal-oil-water slurry, the waste lubricating oil promoted the formation of HCN and NH3, with the relative content of HCN being much higher than that of NH3. To study the mechanism of nitrogen migration during pyrolysis, Lammps was used to simulate pyrolytic behavior of pyrrole and pyridine under N2 and steam atmospheres. The increase in temperature promoted the decomposition of pyrrole and pyridine, thereby promoting the production of HCN and NH3. Finally, the properties and the combustion reactivities of the chars were analyzed. The water and oil content in the coal-water slurry increased the structural ordering degree of chars but decreased the combustion reactivities.

In this work, a combined ReaxFF-MD simulation and density functional theory (DFT) study was performed to study the pyrolysis behavior of polycarbonates under nonisothermal and isothermal conditions...

In this work, NR and D-limonene were pyrolyzed using ZSM5, Zn/ZSM5, ZnO/ZSM5 and ZnS/ZSM5 catalysts on a Py-GCMS system. The effects of Zn loading (1, 3, 5 wt%) and catalyst preparation methods (impregnation method, ion-exchange method) on catalytic pyrolysis experiments were studied. The results indicated the introduction of Zn species into zeolites can form new Lewis acid (L acid) sites at the expense of Bronsted acid (B acid) sites. For Zn/ZSM5 catalysts prepared by impregnation method, Zn species mainly existed in the form of the divalent zinc cation at the exchange sites and ZnO, and the proportion of ZnO increased with the Zn loading increasing. For Zn/ZSM5 catalyst prepared by ion-exchange method, most Zn2+ were tightly interacted with zeolite framework. For ZnO/ZSM5 and ZnS/ZSM5 catalysts, the Zn species primarily existed in the form of ZnO and ZnS, respectively. Py-GC/MS experimental results showed that proper Zn loading helped to improve the selectivity of aromatic hydrocarbons in NR pyrolysis products, especially BTEX (Benzene, Toluene, Ethylbenzene, Xylene), but excessive Zn loading had a negative effect. Compared with impregnation method, Zn/ZSM5 catalyst prepared by ion-exchange method showed higher selectivity towards BTEX due to more Zn species existed in the form of divalent zinc ions.

In this study, power parameters (power, frequency, and voltage), initial Hg0 concentration, and residence time are investigated for the removal of the increased Hg0 concentration via surface dielectric barrier discharge (SDBD). The synergistic effect of a Mn/Ce/Ti catalyst with SDBD is verified with a mixture of flue gas (Hg0, NO, and SO2). Results show that Hg0 oxidation efficiency has an optimal frequency, which declines as the input voltage increases. The amplification of the Hg0 removal efficiency decreases as voltage increases. The effect of the initial Hg0 concentration gradually decreases as the peak voltage increases. The residence time slightly affects the Hg0 removal efficiency at a high peak voltage. The cooling water temperature behaves differently on Hg0 oxidation under high and low voltages. X-ray photoelectron spectroscopy (XPS) reveals the relative atomic concentrations of Mn2+ and Mn3+ in the Mn-TiO2 and Mn-Ce-TiO2 catalysts are 66.84% and 65.80%, respectively, which indicate that Ce addition will not affect surface Mn. Mn has a limited catalytic action on the removal of flue gas with and without SDBD. Nevertheless, SDBD can stimulate the oxygen storage capacity of Mn to increase the NO2 conversion rate. Mn-Ce-TiO2 greatly improves the removal efficiencies of NO and SO2 because of the existence of the redox pairs of Mn4+/Mn3+, Ce4+/Ce3+, and Ti4+/Ti3+. However, the three catalysts slightly differ on Hg0 removal when combined with SDBD, indicating that the effect of the catalyst was weakened after SDBD was added.

Particle emission is one of the major problems during municipal solid waste (MSW) combustion. This study investigated the particle emission distribution in flue gas and the effect of three types of...

The behavior of ash fusion at high temperatures plays a key role in the stable operation of gasifiers. This study investigated the effect of synthetic mineral compounds on the transformation and as...

Novel hydroxylated UIO-66 for gaseous elemental mercury (Hg0) removal has been considered to be an emerging method because of its economical and reusable property. Density functional theory studies were investigated to reveal the enhanced heterogeneous interaction mechanisms between mercury and hydroxylated UIO-66 with and without the presence of H2O2 vapor. The adsorption and dissociation of H2O2 and the generation mechanism of surface hydroxyls on UIO-66 were investigated. Results indicated that H2O2 preferred to disconnect the O–O bond followed by the generation of two hydroxyls in the presence of H2O2. The hydroxyl adsorbed on UIO-66 and formed the UIO-66 hydroxylation product. The interaction performances between Hg0, H2O2, and UIO-66 as well as the interaction performances between Hg0 and hydroxylated UIO-66 systems were both evaluated through binding energy and the Mulliken charge analysis. Interacted energies indicated thermodynamically favorable processes of Hg–OH formation on hydroxylated UIO-66. The Mulliken charge changes revealed an oxidative process of mercury.

Simultaneous removal of NOx and SO2 is carried out by an oxidation-absorption process, which NO oxidized by active hydroxyl radicals (·OH) derived from catalytic decomposition of vaporized H2O2 over Fe3O4/TiO2 and then adsorbed by NaOH solution along with SO2. Fe3O4/TiO2 synthesized by wet impregnation method with an additional reduction under H2 atmosphere was characterized by XRD, FTIR, BET, XPS, and VSM analysis. Effects of H2O2 concentration, H2O2 injection rate, reaction temperature, gas flow rate, and flue gas component on simultaneous removal were investigated. The experimental results show that NO can be effectively oxidized by highly reactive ·OH radicals generated from H2O2 decomposition over Fe3O4/TiO2 catalyst, and removal efficiencies of 93.31% for NO, 85.90% for NOx, and 100% for SO2 were obtained. The surface zero-valent iron (Fe0) and divalent iron (Fe2+) are the key factors of the catalytic oxidation with hydroxyl radical. H2O2 adsorption and dissociation mechanism on catalyst surface was studied using DFT calculation. The calculation results demonstrate that H2O2 prefers to dissociate on iron containing surface, and ·OH radicals generation follow by Haber-Weiss (H-W) mechanism. The stable oxidative product of HNO2 and HNO3 were generated through NO/NO2 and H2O2 co-adsorption on the FeO/TiO2 (0 0 1) surface.

In this work, ReaxFF molecular simulations were performed to study the pyrolysis behavior of chemical cross-linked natural rubber (NR) under non-isothermal and isothermal conditions. Three different sulfur vulcanized NR models were established and simulated to study the effect of inner sulfur structure on NR decomposition behavior and sulfur evolution in comparison with carbon cross-linked structure. To understand the NR decomposition with temperatures, the non-isothermal simulations were performed between 300 and 3800 K at a 50 K ps

Oily sludge is a hazardous waste due to the enrichment of nitrogen, sulfur, PAHs, and heavy metals. In this work, an oily sludge from oil refining factory was pyrolyzed at various temperatures of 250–850 °C in a fixed bed reactor focusing on product distribution and migration of hazardous compounds of PAHs, sulfur, nitrogen-containing compounds, and heavy metals. The mechanism of PAHs formation and migration of nitrogen, sulfur, heavy metals were elucidated by comprehensive analysis of the solid, liquid, and gas products. The distribution and risk analysis of heavy metals were also conducted. The pyrolytic products distribution was markedly affected by pyrolysis temperatures. A maximum oil yield was observed at 500 °C, which can further crack into gas due to secondary reaction. The pyrolytic gas was enriched in the order of CO2 > CO > CH4 > H2. At lower temperatures, CO2 was largely generated due to the elimination of oxygen-containing functional groups, while H2 was mainly formed above 450 °C due to the recombination reaction. Higher temperatures promoted more N-/S-containing compounds into tar and gas phases. The N-/S-containing compounds mainly included NH3, HCN, H2S, SO2, COS in the gas phase and amines, indoles, pyridines, nitriles, thiophenes in liquid phase. PAHs with 2-ring to 5-ring were mainly generated due to the secondary reaction at higher temperatures. Moreover, Pyrolysis caused the accumulation of heavy metals in chars. Cd presented a high potential risk while the other heavy metals in chars presented a low risk.

With the wide application of selective catalytic reduction (SCR) systems in power plants for the control of NOx emission in China, a serious problem of catalyst deactivation due to the channel bloc...

The evolution of Ni and V species during CO2/H2O/H2O+O2 gasification is investigated at 600 °C–1500 °C. The high S content inhibits the conversion of Ni3S2 into Ni and facilitates the formation of FeS, thus inhibiting the formation of FeV2O4(s). During CO2 gasification, Ni exists in Ni3S2 and converts into Ni at above 1200 °C. The V compound undergoes a mutual conversion between V2O3 and FeV2O4. Ni in Handan petcoke converts into AlNi2O4 and FeNi2O4 during H2O gasification given the high content of Fe and Al. The O2 promotes the decomposition of spinel (FeAl2O4 and FeNi2O4), thereby reserving the Fe in slag-phase FeS. The difference in the mineral transformation between samples increases with the oxidizability of the gasifying agent.

Single step and two-step pyrolysis of waste computer casing plastic were conducted to optimize both the product distribution and characteristics of liquid products. The single step pyrolysis was performed under various final temperatures ranging from 350 to 600 °C. The two-step pyrolysis was undertaken by initially increasing the temperatures to 350–380 °C and holding for 15 min, followed by a further increase to a peak temperature of 500 °C. The pyrolysis kinetic studies showed the activation energy of the two stages against conversion and revealed the synergistic reactions between BFR additives and plastic matrix. In the single step pyrolysis, fixed bed experiments showed that the final pyrolysis temperature had a significant influence on the product yield. The highest yield of 45.3 wt% oil was produced at 500 °C. The oil products mainly consisted of aromatic compounds, phenolic compounds, nitrogen-containing compounds, and approximately 11.3–15.9 wt% of toxic bromine. For the two-step pyrolysis, the impurities of O-, N- and Br-containing compounds were mainly enriched in the pyrolytic oils from the first step. Comparatively, more than 57% of single aromatic compounds was obtained in the pyrolytic oils from the second step, with less than 2.0 wt% of bromine. Meanwhile, the depolymerization of the plastic for the formation of styrene was promoted at the second step. The results suggested that in the two stage pyrolysis, bromine can be transferred into the liquid phase in the first stage, thus producing bromine containing compounds deficient oil in the second stage.

A spiral Surface Dielectric Barrier Discharge reactor was employed to remove both NO and Hg from the flue gas. The effects of O2 and peak voltage were extensively studied. Only NO, NO2 and N2O were observed using FTIR at the outlet of the reactor in the atmosphere of NO/O2/N2. A desired NO conversion efficiency of 99.2% at 7 kV was obtained in the absence of O2 with low energy cost. The presence of O2 can suppress the reduction reaction while accelerating the oxidization of NO, consequently restraining the NO reduction to N2 and promoting the NO2 generation. O2 is necessary for the oxidation of Hg. At peak voltage of 7.0 kV, the Hg conversion reached above 94% at O2 concentration higher than 4%. It decreased to lower than 55% at 3.5 kV. Different concentrations of CO2, C2H4, SO2, HCl and H2O were also introduced to study their effect on NO and Hg conversions. When the CO2 concentration was increased from 0% to 5 and 10%, the NO conversion decreased from 81.0% to 74.1% and 73.6% respectively. At peak voltage of 7 kV and 500 ppm and 1000 ppm of C2H4 were introduced, the NO conversion increased from 78.7% to 85.4% and 93.8% accordingly, while Hg removal efficiency declined. With HCl concentration increasing to 30 and 60 ppm, the Hg oxidation rate increased significantly to above 90% at peak voltage of 9 kV. A strong inhibition effect of SO2 and H2O on NO and Hg conversion were observed.

In this paper, a 600 MWe Babcock & Wilcox boiler is selected as the research object. Numerical simulation and field experiments have been applied to this study under original and new combustion systems. The new approach mainly involves changing the operation mode of swirl burner, rearranging secondary air, and employing separated over-fire air. Numerical results showed that NOx emissions and the unburned combustible in flue dust decrease with the arrangement of the swirl burner changing from co-rotating mode to counter-rotating one. Consequently, counter-rotating mode of adjacent burners was chosen as the optimized arrangement. The introduction of separated over-fire air resulted in a remarkably reduction of the NOx emissions, which reduced from 1085 mg/m3 to 547 mg/m3. With increase of the distance between separated over-fire air and arch from 0.5 m to 3.0 m, NOx emissions changed slightly and the unburned combustible in flue dust were not greatly affected. When the distance continued increase to 6.0 m, NOx generation was suppressed and boiler efficiency declined. Considering the economic efficiency and NOx emissions reduction, the optimal sofa position is 3.0 m above the arch. In situ measurement results are consistent with the modelling predictions This work provides a feasible and economic approach for Babcock & Wilcox down-fired boilers to achieve high efficiency and low pollutant emissions.

The fate of antibiotics in activated sludge has attracted increasing interests. However, the focus needs to shift from concerning removal efficiencies to understanding mechanisms and sludge responding to antibiotic toxicity. Herein, we operated two anaerobic sequencing batch reactors (ASBRs) for 200 days with sulfadiazine (SDZ) and sulfamethoxazole (SMX) added. The removal efficiency of SMX was higher than that of SDZ. SDZ was removed via adsorption (9.91-21.18%) and biodegradation (10.20-16.00%), while biodegradation (65.44-86.26%) was dominant for SMX removal. The mechanisms involved in adsorption and biodegradation were investigated, including adsorption strength, adsorption sites and the roles of enzymes. Protein-like substance (tryptophan) functioned vitally in adsorption by forming complexes with sulfonamides. P450 enzymes may catalyze sulfonamides degradation via hydroxylation and desulfurization. Activated sludge showed distinct responses to different sulfonamides, reflected in the changes of microbial communities and functions. These responses were related to sulfonamides removal, corresponding to the stronger adsorption capacity of activated sludge in ASBR-SDZ and degradation capacity in ASBR-SMX. Furthermore, the reasons for different removal efficiencies of sulfonamides were analyzed according to steric and electronic effects. These findings propose insights into antibiotic removal and broaden the knowledge for self-protection mechanisms of activated sludge under chronic toxicities of antibiotics.

In this work, the pyrolysis of natural rubber (NR) under N

In this study, power parameters (power, frequency, and voltage), initial Hg

This paper presents an information on size distribution, inorganic composition and formation mechanism of submicron particles generated from MSW combustion. The XRD and CCSEM analysis results clearly showed that NaCl, KCl, K3Na(SO4)2, and SiO2 are the major inorganic mineral components in submicron particles. Submicron particles are mainly composed of organic components, alkali chlorides, alkali sulfates, and refractory inorganic minerals, but they account for different proportions in PM0.2 and PM0.2-1. There are five formation modes of submicron particles in MSW combustion: “condensation”, “nucleation”, “accumulation”, “crystallization” and “fragmentation”. The “condensation” mechanism mainly seen in PM0.2 composed of gas components, the “crystallization” and “fragmentation” modes formed by alkali salts and char particles are mainly present in PM0.2-1, the “nucleation” and “accumulation” modes coexist in PM0.2 and PM0.2-1. As the combustion temperature increased, the alkali chlorides and sulfates in the “crystallization” form decreased, and the inorganic mineral components in the “nucleation” form increased, which results in the variation of size distribution of submicron particles. In addition, volatile alkali salt nucleation experiments show that when alkali chloride and sulfate coexist in high-temperature flue gas, heterogeneous nucleation and agglomeration can significantly enhance the accumulation of particles in the range of 0.2–0.5 μm.

A research on the fate of active groups from three typical petroleum cokes (petcokes) during gasification in a drop tube furnace have been presented. The results showed that the relative reduction (R) index can be used to assess the gasification reactivity of petcoke. The decomposition of side chain reaction of dealkylation is easier to proceed. Petcoke with a relative ordered degree of char structure has an energy barrier resulting in the transformation from the ordered graphitic carbon structure to amorphous carbon structure occurred only after the temperature reaches 1200 °C. It is recommended to control the petcoke gasification temperature above 1200 °C. A high temperature is beneficial for the conversion of oxygen-containing functional groups to hydroxyl groups. Petcoke with high ash content promotes the decomposition of functional groups to form active radicals, which favors the formation of amorphous carbon and, consequently, more active sites resulting in the high gasification reactivity. The high temperature gasification can make the stable active radicals (aromatic hydrocarbons groups) to break up the thermal barrier and convert to active radicals (aliphatic hydrocarbons and side chains on aromatic structure, oxygen functional groups and hydroxyl groups). The active radicals react with oxygen adsorbed on the carbon surface to generate CO, H2, CH4, etc.

Magnetite is considered a promising catalyst for catalytic oxidation of nitrogen oxide (NOx) by vaporized H2O2. The NO oxidation mechanisms on original and Ti-doped Fe3O4 (1 1 1) catalyst surfaces were analyzed by density functional theory, and the individual and combined adsorption characteristics of H2O2 and NO on the original and Ti-doped surfaces were investigated. Results revealed that H2O2 disassociates on the original and Ti-doped surfaces with large adsorption energies. Ti doping significantly augmented the adsorption intensity of H2O2 and promoted the decomposition of H2O2 on the catalyst surface. NO was adsorbed on the original and Ti-doped surfaces in molecular form. The adsorption intensity of H2O2 was greater than that of NO. HNO2 was generated on the original and Ti-doped surfaces through NO and H2O2 co-adsorption, thereby confirming that NO was oxidized. Analysis of electronic structures demonstrated that H2O2 was decomposed according to the Haber-Weiss mechanism. The oxidation of NO by surface oxygen atoms over the original and Ti-doped surfaces was also calculated, and the low energy barrier obtained suggests that NO is easily oxidized by active O over catalyst surfaces.

The catalytic upgrading of the vapor intermediates from the pyrolysis of brominated acrylonitrile-butadiene-styrene (Br-ABS) was investigated over the Fe/ZSM-5 catalysts in a two-stage fixed bed reactor. Results showed that HZSM-5 and Fe/ZSM-5 catalysts exhibited high catalytic cracking activities, resulting in the increased yield of oil from 62.8 wt% to 64.3 wt% and 66.7 wt%, respectively. When the higher amounts of Fe/ZSM-5 catalysts were applied, the oil yield decreased to 59–61.6 wt%, whereas high amounts of coke were deposited on the catalysts. On the other hand, the higher percentages of the single ring and 2 ring aromatic compounds in the oils was obtained by the Fe/ZSM-5 catalysts, compared to the thermal pyrolysis and the catalytic upgrading by the parent HZSM-5 catalyst. The Fe/ZSM-5 catalysts significantly promoted the formation of styrene monomer and dimer derivatives. It could be proposed that the Fe based materials was in favor of the depolymerization of the polymer matrix, providing the styrene sources for the secondary oligomerization over the parent HZSM-5 catalyst. In addition, the Fe/ZSM-5 catalyst exhibited effective debromination performance, by means of cracking the organobromine compounds and capturing the inorganic bromine in the catalyst. The possible catalytic cracking mechanism over the Fe/ZSM-5 catalyst was discussed.

The gasification of petroleum coke (petcoke) can cause fouling and erosion problems. In this study, the evolution of Ni and V during steam gasification is investigated in a fluidized bed from 800 to 1100 °C. The occurrence modes determined by the sequential extraction show that raw petcoke contains diversified Ni forms, whereas V is dominated by organic matter and residual form. The organic matter is rapidly converted to residual form. The Ni in residual form is partially released, whereas the V in residual form is considerably converted to other forms. The volatilization of Ni is positively correlated with the temperature and sulfur content, whereas V has a positive correlation with the exchangeable form. The exchangeable form of V is conducive to forming a well-developed pore structure, whereas carbonates play the opposite role. Under the practical fluidized bed gasification, Ni tends to cause erosion, especially for continental petcoke, whereas V is inclined to cause slagging and fouling.

Kinetic studies and the effect of the vulcanization process on the pyrolysis of natural rubber (NR), butadiene rubber (BR) and styrene-butadiene rubber (SBR) were investigated in this work. A comprehensive kinetic study using a model-based method, a model-free method and the distribution activation energy model (DAEM) was applied and a comparison between the different models was drawn. The DAEM showed a better fitting of the experimental results than the model-based method. The activation energy distribution of the DAEM verified by the model-free method indicated that the main decomposition of rubbers followed a chain reaction mechanism. Pyrolysis of raw rubbers and their corresponding vulcanized rubbers were conducted in a fixed-bed reactor. The sulfur content and product yields were quantified. Pyrolysis oils were characterized and compared. The oil yields reached a maximum at 430 °C for NR (90.82%), 470 °C for both BR (90.61%) and SBR (92.80%). Pyrolytic oils of raw rubbers were mainly composed of their corresponding monomer or dimer, trimer compounds. However, the results of vulcanized rubbers pyrolysis were significantly different. Sulfur in the vulcanized rubbers was released at low temperatures due to the lower bond energy. Higher temperatures led to the conversion of sulfur-containing oils to gaseous compounds. Vulcanization promoted the decomposition of rubbers at low temperatures but had an insignificant influence on pyrolysis products distribution at high temperature. Pyrolysis oils of vulcanized rubbers were more complex, constituting various aromatic hydrocarbons and thiophenes.

Elemental mercury (Hg0) emitted from coal-fired power plants and municipal solid waste (MSW) incinerators has caused great harm to the environment and human beings. The strong oxidized •OH radicals produced by UV/H2O2 advanced oxidation processes were studied to investigate the performance of Hg0 removal from simulated flue gases. The results showed that when H2O2 concentration was 1.0 mol/L and the solution pH value was 4.1, the UV/H2O2 system had the highest Hg0 removal efficiency. The optimal reaction temperature was approximately 50 °C and Hg0 removal was inhibited when the temperature was higher or lower. The yield of •OH radicals during UV/H2O2 reaction was studied by electron paramagnetic resonance (EPR) analysis. UV radiation was the determining factor to remove Hg0 in UV/H2O2 system due to •OH generation during H2O2 decomposition. SO2 had little influence on Hg0 removal whereas NO had an inhibitory effect on Hg0 removal. The detailed findings for Hg0 removal reactions over UV/H2O2 make it an attractive method for mercury control from flue gases.

The gaseous oxidation process for Hg0 oxidation is regarded as an efficient and low-cost option for mercury control in solid fuel combustion devices. The heterogeneous Hg0 oxidation by gaseous H2O2 over Fe3O4 (0 0 1) surface was calculated using periodic density functional theory (DFT) method to gain a fundamental understanding of Hg0 oxidation mechanism on H2O2/Fe3O4 (0 0 1) surface. The results showed that on the Fe3O4 (0 0 1) surface, the Fetet site (A layer) is more active than the Feoct site (B layer). H2O2 can easily undergo dissociation process to form two OH radicals, which have highly active in Hg0 oxidation over the A layer. The Mulliken charge population analysis showed that a large amount of electron transfer occurred from Hg0 to the produced OH. The calculated reaction energy barriers suggested that the interaction between OH and Hg0 is exothermic and Hg0 oxidation processes by OH produced from H2O2 are thermodynamically and kinetically favorable. In addition, Hg0 oxidation processes on the H2O2/Fe3O4 (0 0 1) surface may simultaneously undergo through three different pathways. The possible Hg-OH product will easily desorbs from the surface, whereas the Hg(OH)2 is stable on the surface and belongs to chemisorption. The detailed mechanism for the oxidation reaction over Fe3O4 makes it an attractive method for Hg control from flue gases.

The paper takes Wuhan Iron and Steel Co., Ltd. (hereinafter referred to as “ WISCO “) energy consumption and carbon emissions as the research object, and analyzes WISCO’s carbon emissions. Through the construction of WISCO’s Long range Energy Alternatives Planning system (hereinafter referred to as LEAP) prediction model for energy consumption and carbon emissions, three scenarios have been set up: a baseline scenario, an energy efficiency improvement scenario, and an energy structure change scenario to measure WISCO’s carbon emissions. Based on the results of the LEAP model, this article puts forward the following recommendations for WISCO’s low-carbon transformation. WISCO must strictly control steel output.WISCO should introduce electric furnaces to increase the proportion of electric furnace steel. While ensuring the supply of scrap steel resources, WISCO ought to use scrap steel efficiently. In addition, introduction of hydrogen direct reduction iron technology is also crucial to WISCO in a planned way.

This study aimed to evaluate the environmental impacts of the biochar production process through low-temperature pyrolysis of Chinese medicine residue via life cycle assessment (LCA). An LCA model consisting of biomass pretreatment, pyrolysis, separation and cooling was developed. The results indicated that the low-temperature pyrolysis process has the highest environmental impact on AP and GWP. The consumption and direct emission of pyrolysis process were the primary sources of environmental impact. In addition, by comparing to the traditional landfill process of Chinese medicine residue, it turns out that the low-temperature pyrolysis process has improved environmental protection performance.

Presently, the characteristic of hazardous polycyclic aromatic hydrocarbons (PAHs) emission from used mineral oil (UMO) combustion in the industrial scenario is poorly explored and elucidated. In this work, the emission characteristic and source identification of 16 PAHs emitted from atomization combustion of five kinds of UMO and two types of base oil were investigated. The influence of temperature (600–1000 °C) and excess air ratio (0.8–1.4) on PAHs emission were assessed. Regarding emission factor (EF) and distribution of specific PAHs, high similarities were observed for combustion of different UMOs. EFs of PAHs were within the range between 61.58 µg g−1 and 105.03 µg g−1 (800 °C, stoichiometric air). The 2- and 3-ring PAHs made up more than 70% of the total PAHs in the flue gas, with the naphthalene accounting for 30.7%–48.1%. Over 80% of the emitted PAHs was partitioned into gas phase. The EFs of PAHs showed a parabolic trend with temperature and peaked at 800 °C. Higher temperature can decrease the total PAHs emission but lead to the enrichment of high-ring PAHs. Adequate air supply can efficiently reduce PAHs formation, especially at high temperatures. More than 95% of the total PAHs was eliminated when the excess air ratio was increased from 0.8 to 1.4 at 900 °C. Temperature influence on PAHs emission can be greatly weakened in high excess air level. The PAHs emitted from UMO combustion were randomly irrelevant to the original PAHs in UMO.

Formaldehyde and benzene adsorption on UIO-66 in coordination with gaseous H2O2 is an efficient and recyclable method for removing formaldehyde and benzene. In this study, the interaction mechanism of formaldehyde and benzene coordinated with UIO-66 under the existence of H2O2 was studied using density functional theory. The results showed that the decomposition of H2O2 by UIO-66 was promoted to produce highly oxidizing hydroxyl groups. The structure of formaldehyde obviously changed in H2O2/UIO-66 system after equilibrium. The C H bond of HCHO molecule was easy to break at different adsorption sites of UIO-66. Comparatively, benzene with distorted ring structure tended to chemically bound to the carbon site of UIO-66, but the decomposition of benzene was difficult. Density of states analysis showed that the adsorption between C6H6 and UIO-66 was chemisorption. The study is of great significance for providing theoretical guidance to the removal of organic pollutants from exhaust gas by UIO-66.

In this work, the pyrolysis of natural rubber (NR) under N2 and H2S atmosphere was performed to illustrate the possible effect of H2S on NR decomposition with and without catalysts. A molecular dynamics simulation based on reactive force field (ReaxFF) was also conducted to understand the interaction mechanism between H2S and intermediates from NR decomposition. Furthermore, the catalytic decomposition of NR under H2S atmosphere and the adsorption characteristics of H2S by zeolites alone were also carried out to investigate the effect of catalysts on sulfur behavior and the reversed effect of H2S on catalyst activity. This work revealed that the introduction of H2S can influence the yields of pyrolytic oil and gas, as well as composition of the oil. Combining experimental and simulation studies, H2S can interact with intermediates from NR decomposition forming sulfur-containing substances in pyrolytic oil. The H2S adsorption experiments by various catalysts revealed that catalysts can chemically adsorb H2S. The introduction of Zn can promote the adsorption ability by reacting with sulfur-containing substances to generate ZnS, with the desulfurization effect following the order of 3Zn/ZSM5 > ZSM5 > 3ZnO/ZSM5.

The Fe3O4 catalytic oxidation of gaseous elemental mercury (Hg0) has been regarded as a promising method to control mercury from flue gases given its high efficiency, magnetic separation, and recyclable properties. Density functional theory (DFT) calculations were performed to study the heterogeneous reaction mechanism between Hg0 and H2O2 over Fe3O4 (1 1 0) surface. The generation mechanism of surface hydroxyl on two Fe3O4 (1 1 0) layers was investigated. Binding energies, geometric parameters, and the Mulliken charge population of the possible configurations for Hg0 interaction were studied. Results provided evidences that the H2O2 prefers to break the O O bond and produces two OH groups, which combine with Hg0 on Fe3O4 (1 1 0) A layer. The calculated binding energies suggested that the process of OH Hg OH and Hg OH generation are exothermic on Fe3O4 (1 1 0) surface with H2O2. The Mulliken charge population revealed Hg oxidation when systems were in equilibrium because a large number of electrons transfer from Hg0 to the surface hydroxyl. The reaction of Hg0 oxidation followed the processes of Hg + OH → Hg OH, Hg OH + OH → HO Hg OH, and OH Hg OH desorption from the Fe3O4 (1 1 0) surface.

Density functional theory calculations have been carried out for H2O2 and Hg0 co-interaction on Fe3O4 (111) surface. On the Fetet1-terminated Fe3O4 (111) surface, the most favored configurations are H2O2 decomposition and produce two OH groups, which have strong interaction with Hg atom to form an OH Hg OH intermediate. The adsorbed OH Hg OH is stable and hardly detaches from the catalyst surface due to the highly endothermic process. A large amount of electron transfer has been found from Hg to the produced OH groups and has little irreversible effect on the Fe3O4 (111) surface. On the Feoct2-terminated Fe3O4 (111) surface, the Feoct2 site is more active than Fetet1 site. H2O2 decomposition and Hg0 oxidation processes are more likely to occur due to that the Feoct2 site both contains Fe2+ and Fe3+ cations. The calculations reveal that Hg0 oxidation by the OH radical produced from H2O2 is energetically favored. Additionally, Hg0 and H2O2 co-interaction mechanism on the Fe3O4 (111) interface has been investigated on the basis of partial local density of state calculation.

The pyrolysis-catalytic upgrading process of brominated high impact polystyrene (Br-HIPS) was performed using Fe and Ni modified ZSM-5 and MCM-41 catalysts in a two-stage fixed bed reactor. The characterization of catalysts, the product yield and debromination performance in relation to different catalysts were investigated. The results showed that the addition of HZSM-5 and MCM-41 reduced the yield of oil from 69.0 wt % to 64.4 wt % and 62.3 wt %, respectively. The modified catalysts of Fe/ZSM-5 and Ni/ZSM-5 exhibited prominent cracking performance, resulting in the decrease of the oil to 63.2 wt % and 61.2 wt %, respectively, corresponding with an increase of gas products from 7.7 wt % to 16.1 wt % and 20.3 wt %, respectively. However, the mesoporous catalysts of Fe/MCM-41 and Ni/MCM-41 tended to preserve the yield of oil to 65.9 wt % and 65.3 wt %, respectively. In terms of the composition of the oils, a higher yield of single ring aromatics was obtained with Fe modified catalysts, while the addition of ZSM-5 and Ni/ZSM-5 catalysts promoted increased formation of 2 ring aromatics at the expense of single ring aromatics. In addition, the modified catalysts were found to be highly effective at removing bromine from the oils. The Fe modified catalysts exhibited a better debromination performance than Ni modified catalysts, which was in favor of capturing more inorganic bromine and removing bromine from the oils.

Catalytic oxidation with H2O2 is a promising method for NOx emission control in coal-fired power plants. Hematite-based catalysts are attracting increased attention because of their surface redox reactivity. To elucidate the NO oxidation mechanism on α-Fe2O3 surfaces, density functional theory (DFT) calculations were conducted by investigating the adsorption characteristics of nitric oxide (NO) and hydrogen peroxide (H2O2) on perfect and oxygen defect α-Fe2O3 (0 0 1) surfaces. Results show that NO was molecularly adsorbed on two kinds of surfaces. H2O2 adsorption on perfect surface was also in a molecular form; however, H2O2 dissociation occurred on oxygen defect α-Fe2O3 (0 0 1) surface. The adsorption intensities of the two gas molecules in perfect α-Fe2O3 (0 0 1) surface followed the order NO > H2O2, and the opposite was true for the oxygen defect α-Fe2O3 (0 0 1). Oxygen vacancy remarkably enhanced the adsorption intensities of NO and H2O2 and promoted H2O2 decomposition on catalyst surface. As an oxidative product of NO, HNO2 was synthesized when NO and H2O2 co-adsorbed on the oxygen defect α-Fe2O3 (0 0 1) surface. Analyses of Mulliken population, electron density difference, and partial density of states showed that H2O2 decomposition followed the Haber–Weiss mechanism. The trends of equilibrium constants suggested that NO adsorption on α-Fe2O3 (0 0 1) surface was more favorable at low than at high temperatures, whereas H2O2 adsorption was favorable between 375 and 450 K. These calculations results well agreed with the experimental ones and further elucidates the reaction mechanisms.