Fig 7 - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
Source publication
In this study, the Powder River Basin (PRB) coal fast pyrolysis was conducted at 700 °C in the atmosphere of syngas produced by CH4–CO2 reforming in two different patterns, including the double reactors pattern (the first reactor is for syngas production and the second is for coal pyrolysis) and double layers pattern (catalyst was at upper layer an...
Context in source publication
Context 1
... tar yield at 700 °C in different atmospheres was shown in Fig. 7. It was 7.83% under N 2 atmosphere at 700 °C, and efficiently improved in reducing atmospheres. 10.29% of the tar yield was achieved under H 2 atmospheres, which was higher than 9.11% in CO and 10.01% in H 2 -CO. Thus, the value was increased by 31.3%, 16.4% and 27.8% in three reducing atmospheres. The performance of H 2 is better than ...
Similar publications
In this study, the composition of tars collected during a six-day underground coal gasification (UCG) test at the experimental mine ‘Barbara’ in Poland in 2013 was examined. During the test, tar samples were taken every day from the liquid product separator and analysed by the methods used for testing properties of typical coke oven (coal) tar. The...
Citations
... The extra apparatus indicate high cost and the economic benefits are therefore limited. In contrast, the CECB is usually employed to extract the coal body under BRW [58,59]. The filling body here is necessary and the CMFB is developed only by adhering CO 2 gas to the fresh slurry of the filling body. ...
The consumption of coal resources has caused an increase in CO2 emissions. A scientific concept that can realize CO2 sequestration, the harmless treatment of solid wastes, and coal extraction under buildings, railways, and water bodies (BRW) is proposed. First, a novel CO2 mineralized filling body (CMFB) is developed by employing CO2 gas, fly ash, silicate additives, and cement. It is then injected into the mined-out mining roadways (MRs) of the continuous extracting and continuous backfill (CECB) mining method to ameliorate the overburden migration and thus extract the coal body under the BRW. The AHP-fuzzy comprehensive evaluation method was employed to construct a prediction model for the suitability of this concept. Subsequently, the evaluation model is generalized and applied to the Yu-Shen mining area. Each indicator affecting adaptability is plotted on a thematic map, and the corresponding membership degree is determined. The aptness for 400 boreholes distributed in the entire area was determined and a zoning map which divides the whole area into good, moderate, slightly poor, and extremely poor suitability was drawn. This paper puts forward a mathematical model for predicting the suitability of using CECB and CMFB to sequestrate CO2. Research results can provide references for determining the site of CO2 sequestration under the premise of maximizing the economic and ecological benefits, which is conducive to constructing ecological, green, and sustainable coal mines.
The rapid economic and societal development have led to unprecedented energy demand and consumption resulting in the harmful emission of pollutants. Hence, the conversion of greenhouse gases into valuable chemicals and fuels has become an urgent challenge for the scientific community. In recent decades, perovskite-type mixed oxide-based catalysts have attracted significant attention as efficient CO2 conversion catalysts due to the characteristics of both reversible oxygen storage capacity and stable structure compared to traditional oxide-supported catalysts. In this review, we hand over a comprehensive overview of the research for CO2 conversion by these emerging perovskite-type mixed oxide-based catalysts. Three main CO2 conversions, namely reverse water gas shift reaction, CO2 methanation, and CO2 reforming of methane have been introduced over perovskite-type mixed oxide-based catalysts and their reaction mechanisms. Different approaches for promoting activity and resisting carbon deposition have also been discussed, involving increased oxygen vacancies, enhanced dispersion of active metal, and fine-tuning strong metal-support interactions. Finally, the current challenges are mooted, and we have proposed future research prospects in this field to inspire more sensational breakthroughs in the material and environment fields.
Herein, the desorption behaviors of CO2/CH4 onto kerogen atomistic representation at higher temperatures and pressures and its inspirations of dividing stages on deflagration fracturing was clarified quantitatively via molecular simulation and mathematical model, as well as the effects of temperature and pressure. Molecular probe detection results suggested that accessible free volume of kerogen macromolecule was generated among different aliphatic chains or between the aliphatic chains and aromatic clusters, where the former type provides the primary free volume within the kerogen macromolecule. The quantitative division of desorption stages suggested four desorption stages via the established three critical pressures, start pressure (Pst), transition pressure (Ptr), and sensitive pressure (Pse), dividing the desorption properties into four stages: low efficiency desorption stage (P > Pst), slow desorption stage (Ptr < P < Pst), rapid desorption stage (Pse < P < Ptr), and sensitive desorption stage (P < Pse) respectively. All these three critical pressures firstly increase slowly and then significantly with the increasing temperature, indicating that high temperature was favorable for the early arrival of the rapid desorption stage and sensitive desorption stage. Both the pressure reductions for the former two stages keep stable for the temperature < 458 K. However, for the temperature > 458 K, the required pressure reduction for rapid desorption stage increases, suggesting that high temperature was also favorable for enhancement of shale gas production. Thus, the reservoir pressure was rather high after the deflagration fracturing process, resulting in the long duration of slow desorption stage and low efficiency desorption stage. The pressure reduction rate should be extended as long as possible to ensure the complete desorption of CH4, which could make an extension of the rapid desorption stage. The outcome of this paper was of broad interest for CO2 enhanced shale gas recovery and deflagration fracturing, as well as carbon capture and utilization engineering.
The viscosity and stability of coal-oil slurry (COS) with different concentrations prepared by recycle solvent and low-rank coal were investigated. The effect of light solvent naphtha preheating treatment on the viscosity-temperature characteristics of high-concentration COS and properties of pulverized coal was studied. Results show that when the concentration is higher than 48 wt%, the viscosity and swelling viscosity peak value of conventional COS increase exponentially, resulting in the significant deterioration of the stability of COS. The concentration of COS can be increased to 50 wt% by preheating with light solvent. With the increase of preheating temperature and time, the viscosity of COS decreases as a whole. The viscosity of high-concentration COS with the optimum preheating temperature of 375 °C and time of 4 h is 383 mPa·s (60 °C), which is 30% lower than that of conventional COS (543 mPa·s (60 °C)) with 50 wt%. Due to the influence of the full swelling, irreversible swelling, and primary pyrolysis of pulverized coal, the physical structure and chemical composition of pulverized coal changes, the swelling viscosity peak no longer appears, and the stability of COS is improved.
