查看更多>>摘要：Excessive emissions of nitrogen oxides from flue gas have imposed various detrimental impacts on environment,and the development of deNOx catalysts with low-cost and high performance is an urgent requirement.Iron oxide-based material has been explored for promising deNOx catalysts.However,the unsatisfactory low-temperature activity limits their practi-cal applications.In this study,a series of excellent low-temperature denitrification catalysts(Ha-FeOx/yZS)were prepared by acid treatment of zinc slag,and the mass ratios of Fe to impure ions was regulated by adjusting the acid concentra-tions.Ha-FeOx/yZS showed high denitrification performance(＞90％)in the range of 180-300 ℃,and the optimal NO conversion and N2 selectivity were higher than 95％at 250 ℃.Among them,the Ha-FeOx/2ZS synthesized with 2 mol/L HNO3 exhibited the widest temperature window(175-350 ℃).The excellent denitrification performance of Ha-FeOx/yZS was mainly attributed to the strong interaction between Fe and impurity ions to inhibit the growth of crystals,making Ha-FeOJyZS with amorphous structure,nice fine particles,large specific surface area,more surface acid sites and high chemisorbed oxygen.The in-situ DRIFT experiments confirmed that the SCR reaction on the Ha-FeOx/yZS followed both Langmuir-Hinshelwood(L-H)mechanism and Eley-Rideal(E-R)mechanism.The present work proposed a high value-added method for the preparation of cost-effective catalysts from zinc slag,which showed a promising application prospect in NOx removal by selective catalytic reduction with ammonia.
查看更多>>摘要：Recent studies have indicated that the injection of carbon dioxide(CO2)can lead to increased oil recovery in fractured shale reservoirs following natural depletion.Despite advancements in understanding mass exchange processes in subsurface forma-tions,there remains a knowledge gap concerning the disparities in these processes between the matrix and fractures at the pore scale in formations with varying permeability.This study aims to experimentally investigate the CO2 diffusion behaviors and in situ oil recovery through a CO2 huff'n'puff process in the Jimsar shale oil reservoir.To achieve this,we designed three matrix-fracture models with different permeabilities(0.074 mD,0.170 mD,and 0.466 mD)and experimented at 30 MPa and 91 ℃.The oil concentration in both the matrix and fracture was monitored using a low-field nuclear magnetic resonance(LF-NMR)technique to quantify in situ oil recovery and elucidate mass-exchange behaviors.The results showed that after three cycles of CO2 huff'n'puff,the total recovery degree increased from 30.28％to 34.95％as the matrix permeability of the core samples increased from 0.074 to 0.466 mD,indicating a positive correlation between CO2 extraction efficiency and matrix permeability.Under similar fracture conditions,the increase in matrix permeability further promoted CO2 extrac-tion efficiency during CO2 huff'n'puff.Specifically,the increase in matrix permeability of the core had the greatest effect on the extraction of the first-cycle injection in large pores,which increased from 16.42％to 36.64％.The findings from our research provide valuable insights into the CO2 huff'n'puff effects in different pore sizes following fracturing under varying permeability conditions,shedding light on the mechanisms of CO2-enhanced oil recovery in fractured shale oil reservoirs.
查看更多>>摘要：In order to study the problems of unreasonable airflow distribution and serious dust pollution in a heading surface,an experimental platform for forced ventilation and dust removal was built based on the similar principles.Through the similar experiment and numerical simulation,the distribution of airflow field in the roadway and the spatial and temporal evolu-tion of dust pollution under the conditions of forced ventilation were determined.The airflow field in the roadway can be divided into three zones:jet zone,vortex zone and reflux zone.The dust concentration gradually decreases from the head to the rear of the roadway.Under the forced ventilation conditions,there is a unilateral accumulation of dust,with higher dust concentrations away from the ducts.The position of the equipment has an interception effect on the dust.The maximum error between the test value and the simulation result is 12.9％,which verifies the accuracy of the experimental results.The research results can provide theoretical guidance for the application of dust removal technology in coal mine.
查看更多>>摘要：The objectives of this study were to explore the changes in soil stoichiometry and enzyme activities at different distances from an opencast coal mine in the Hulun Buir Grassland of China.Four transects were established on north and east sides of the opencast coal mining area,and samples were collected at 50 m,550 m,and 1550 m from the pit on each transect.Control samples were collected from a grassland station 8 km from the opencast coal mining area that was not disturbed by mining.Four replicate soil samples were collected at each point on the four transects.Soil physicochemical properties and enzyme activities were determined,and correlations between soil properties and stoichiometric ratios and enzyme activities were explored using redundancy analysis.The increase in distance from mining did not significantly affect soil properties,although soil urease activity was significantly lower than that of the control area.Soil properties 1550 m from the mine pit were similar to those at the grassland control.In addition,soil total nitrogen had the greatest effect on soil stoichiometry,and soil total potassium had the greatest effect on soil enzyme activities.Coal dust from opencast mining might be the main factor affecting soil stoichiometry and enzyme activities.The results of this study provide direction for the next step in studying the influence of mining areas on soil properties and processes.
查看更多>>摘要：This study aimed to investigate the effects of ammonia addition on ethylene counter-flow diffusion flames with different diluents on the fuel or oxidizer side,using kinetic analyses.A special emphasis was put on assessing the coupled chemical effects of NH3 and CO2 on C2H4 combustion chemistry.The chemical effects could be evaluated by comparing fictitious inert NH3 or CO2 with normal active NH3 or CO2.The results revealed that the addition of NH3 decreased the mole fractions and production rates of key soot precursors,such as acetylene,propynyl,and benzene.When CO2 was used as the dilution gas,the coupled chemical effects of NH3 and CO2 were affected by the chemical effects of CO2 to varying degrees.With the oxidizer-side CO2 addition,the coupled chemical effects of NH3 and CO2 reduced the mole fractions of H,O,OH radicals,acetylene,propynyl,and benzene,while the effects differed from the fuel-side CO2 addition.The coupled chemical effects of NH3 and CO2 also promoted the formation of aldehyde contaminants,such as acetaldehyde,to some extent,particularly with CO2 addition on the oxidizer side.
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