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In order to improve the efficiency of oil shale pyrolysis and the utilization value of semi-coke, this paper co-pyrolyzed Huadian oil shale and waste tire.The weight loss behavior, product yield and composition properties of co-pyrolysis were investigated by thermogravimetric analyzer and aluminum retort reactor.The synergistic effect was analyzed based on the difference between experimental and calculated values.The results show that co-pyrolysis can promote the release of volatile matter, the actual weight loss is higher than the calculated value at 500 ℃, and reaches the maximum value of 2.86 % when the proportion of waste tire is 80 %.The mixed pyrolysis of oil shale and waste tire has the effect of "increasing oil and reducing water".When the waste tire accounts for 50 %, the actual oil yield is 32.91 %, which is 1.5 % higher than the calculated value, and the actual water yield is 1.20 % to 1.77 % lower than the calculated value.Meanwhile, the content of heavy components with boiling point higher than 350 ℃ in the pyrolysis oil increases.There is higher yield of C1~C4 hydrocarbons from waste tire pyrolysis, and the calorific value of semi-coke is up to 30.43 MJ/kg.Co-pyrolysis can also improve the calorific value of pyrolysis gas and semi-coke.

China has rich reserves of deep coal resources, and underground coal gasification can transform coal into gas and transport it to the ground, which is an important way for in-situ fluidized mining of deep coal.This article introduces the development history and technical status of underground coal gasification technology (UCG), as well as typical cases of underground coal gasification in the middle and deep parts.Based on the modern underground coal gasification technology system, the key technologies and technical research directions of deep underground coal gasification was analyzed and the prospect of deep coal gasification mining with the goal of natural gas production was outlooked.The development trend of UCG is from the mine type to the drilling type, from shallow coal seams to deep coal seams, from single power generation to comprehensive utilization.The practice of UCG in the middle and deep coal seams has verified the technical feasibility.The key technologies of deep underground coal gasification mainly include geological evaluation and scientific site selection, gasifier construction, deep coal seam high-pressure ignition, controllable mobile injection and deep fire zone geophysical detection.Deep coal gasification to produce natural gas can not only realize the clean and efficient use of deep coal resources, but also solve the contradiction between supply and demand caused by the increase in natural gas consumption.

The impact of various modification methods on enhancing the adsorption performance of coal gangue (CG) for hazardous heavy metals has not been thoroughly investigated. In this study, three CG samples were first modified by calcination, followed by acid washing, alkali washing, and hydrothermal treatment, to obtain modified CG samples. The adsorption performance was assessed based on the adsorption capacities for Cd2⁺ and Pb2⁺ (i.e., qe,Cd and qe,Pb), and the kinetics of the adsorption processes were analyzed using kinetic equations. XRD, SEM-EDX, FTIR, and N2 adsorption–desorption isotherms were used to elucidate the adsorption mechanisms. Results indicated that qe,Cd and qe,Pb of raw CG samples were approximately 10 and 25 mg/g, respectively, with only slight changes observed after calcination, acid washing, and alkali washing. In contrast, hydrothermal treatment yielded NaP and NaA zeolites, which significantly enhanced qe,Cd and qe,Pb to values of 48.5–72.7 and 214.9–247.5 mg/g, respectively. The hydrothermally treated CG samples primarily adsorbed Cd2⁺ and Pb2⁺ through ion exchange with Na⁺ within the zeolite structure, facilitating the entry of these ions into the zeolite's pore channels. The adsorption processes were effectively described by the pseudo-second-order kinetic model. By optimizing the conditions of hydrothermal modification, the adsorption performance of CG samples is anticipated to further improve due to the creation of additional adsorption sites. [ABSTRACT FROM AUTHOR]

Step-wise acid washing was applied to eliminate the indigenous minerals of Huadian and Balikun oil shales.The pyrolysis experiments of raw and demineralized oil shales were carried out by using a thermogravimetric analyzer.The effects of demineralization on pyrolysis were investigated by comparing the thermal weight loss characteristics and kinetic parameters of different oil shale samples.Results showed that after removal of carbonate minerals，the onset temperature of weight loss was decreased by 92 ℃ and 40 ℃，respectively，and the maximum weight loss rate and weight loss were reduced.These indicated that carbonate minerals inhibited the release of small organic molecules at low temperatures and promoted the thermal decomposition of kerogen at high temperatures.Further de-silicate of carbonate-free oil shale increased the maximum weight loss rate of Huadian oil shale，which suggested that silicate minerals suppress kerogen pyrolysis at high temperatures.As to the pyrolysis reaction of oil shale at 350 ℃-510 ℃，de-carbonate decreased and de-silicate increased the apparent activation energy value by about 10 kJ/mol and 30 kJ/mol，respectively.This indicated that carbonates increased while silicates decreased the temperature sensitivity of weight loss rate and silicates played a more pronounced effect than carbonates.

In this paper, the zeolite was synthesized from a combination of oil shale ash and coal fly ash and was used to remove heavy metals from aqueous solution. The structural characterization of product was conducted by XRD and SEM, which proved that the ashes can be converted into zeolite. The adsorption performance of synthetic zeolite for heavy metals was evaluated by the batch experiment. The results showed that the adsorption kinetic data conformed to the pseudo-second-order kinetics model, and the Langmuir isotherm model described well the isotherm data. Based on the equilibrium studies, the selectivity sequence was in following order: Pb2+ > Cr3+ > Cu2+ > Cd2+ > Zn2+. The results of XPS indicated that the mechanism of synthetic zeolite removal of heavy metals was ion exchange. [ABSTRACT FROM AUTHOR]

Co‐pyrolysis of direct coal liquefaction residue (DCLR) and low rank coals was regarded as reliable and efficient method to process DCLR. The treatment of the derived co‐pyrolysis char is important for the comprehensive utilization of DCLR. In this study, the non‐isothermal co‐pyrolysis of Shenhua DCLR and Huolinhe lignite, and the isothermal CO2 gasification of the co‐pyrolysis char were performed by the thermogravimetric analysis method. The interactive effect of co‐pyrolysis and the CO2 gasification behavior of the derived char were explored by comparing the experimental and calculated thermogravimetric/derivative thermogravimetric (TG/DTG) curves and reactivity – conversion (R ‐ x) curves, respectively. The results show that the devolatilization pattern at 200–600 °C was modified and part of volatiles were released in advance. As the experimental co‐pyrolysis Tmax was lower by 7–13 °C than the calculated value, while it was almost equal to the Tmax of lignite pyrolysis. We tentatively concluded that lignite devolatilization could promote the evaporation of molten components of DCLR. Moreover, DCLR and lignite could polymerize or condensation with each other at 650–900 °C. The lignite char within co‐pyrolysis char could support the char skeleton and hold a high porosity. Therefore, the CO2 gasification reactivity of co‐pyroysis char was promoted and the experimental reactivity exceeded the calculated value over the conversion range of 12–90 %. [ABSTRACT FROM AUTHOR]

Alkaline fusion is a pivotal process influencing the cost of synthesizing zeolite from coal gangue. This study examined the effects of alkaline fusion temperature ( X 1 ), treatment duration ( X 2 ) and the NaOH/coal gangue weight ratio ( X 3 ) on the composition and properties of the products, as well as their adsorption capacities for Cd 2+ ( q e,Cd ) and Pb 2+ ( q e,Pb ). Response surface methodology (RSM) was employed to analyze the interactions among these factors, and the adsorption mechanisms for Cd 2+ and Pb 2+ were investigated using X-ray diffraction, scanning electron microscopy-EDS, Fourier transform infrared, X-ray photoelectron spectroscopy, and N 2 adsorption-desorption techniques. The results reveal that (1) under optimized conditions- X 1 of approximately 800 °C, X 2 of around 2.8 h and X 3 of 1.2-the maximum q e,Cd and q e,Pb for the synthesized NaX zeolite can reach 181.3 and 419.9 mg/g, respectively. (2) The RSM models indicate that increasing the X 3 value can lower the required X 1 . For q e,Cd and q e,Pb of 150 and 350 mg/g, respectively, with X 2 fixed at 2 h, increasing X 3 from 0.976 to 1.134 and from 0.900 to 1.289 enables a reduction in X 1 from 800 to 600 °C. (3) NaX zeolite primarily adsorbs Cd 2+ and Pb 2+ through ion exchange, allowing these ions to enter the zeolite's cage structure. Pb 2+ can also precipitate as hydrocerussite (Pb 3 (CO 3 ) 2 (OH) 2 ) within the zeolite channels, while Cd 2+ has a more significant impact on the [SiO 4 ] and [AlO 4 ] tetrahedra. (4) The synthesized NaX zeolite effectively reduces the exchangeable Cd content in contaminated soil from 3.51 to below 1.5 mg/kg. The remediation performance of the NaX zeolite for Cd and Pb in water and soil can be further enhanced by optimizing its Si/Al ratio and pore structure., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

The present study attempted to prepare modified oil shale ash and oil shale ash zeolite from oil shale ash, which were characterized by X-ray diffraction, scanning electron microscopy, and N 2 adsorption-desorption. Detailed kinetics and isotherm studies of Cd 2+ adsorption onto modified oil shale ash and oil shale ash zeolite were examined. The adsorption capacity was determined as a function for the adsorption system. The results showed that the adsorption capacity of oil shale ash zeolite was higher compared to modified oil shale ash and that the time required to reach equilibrium was shorter. The kinetics studies showed that Cd 2+ adsorption was well fit by the pseudo-second-order kinetics model. Both the Langmuir and the Freundlich isotherms described the adsorption data well. And the maximum monolayer adsorption capacity determined by the Langmuir adsorption isotherm was found to be 108.70 and 169.49 mg/g for Cd 2+ adsorption onto modified oil shale ash and oil shale ash zeolite, respectively. It was concluded that Cd 2+ in aqueous solutions was more efficiently removed by oil shale ash zeolite, which could be employed as a low-cost and effective alternative adsorbent for wastewater treatment than modified oil shale ash.