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• Pressurized oxy-fuel combustion performance of a typical bituminous coal is investigated. • The thermodynamics parameters and the most probabilistic kinetic model for the pressurized oxy-fuel combustion process are analyzed. • Elevating pressure can significantly improve the combustion performance of coal but the promotion effect gradually alleviates. • The ignition mechanism transforms from heterogeneous to homogeneous when the oxygen concentration reaches 50% at 0.5 MPa. Pressurized oxy-fuel combustion is one of the emerging clean technologies that can efficiently separate and recover CO 2 , and this combustion mechanism differs significantly from atmospheric air combustion. In this paper, the effects of reaction conditions such as total pressure, oxygen concentration and atmosphere gas composition on the combustion characteristics of Xinjiang Bostan coal were investigated using thermogravimetric methods. Furthermore, the thermodynamics parameters and the most probabilistic kinetic model for the pressurized oxy-fuel combustion process were explored. The results showed that the system pressure rising from 0.1 to 1 MPa could enhance the combustion process of coal; however, when the system pressure exceeds 0.5 MPa, the promoting effect is clearly weakened. The ignition mechanism transforms from heterogeneous to homogeneous when the oxygen concentration reaches 50% at 0.5 MPa. The mechanism functions of pressurized oxy-fuel combustion reaction varied as the reaction progressed. In addition, the rise of pressure and oxygen concentration correspond to the higher chemical reaction order of pulverized coal combustion and the pressure has less influence on the reaction mechanism than oxygen concentration. The results obtained may assist with the optimization of pressurized oxy-fuel combustion and guide its industrial applications. [Display omitted] [ABSTRACT FROM AUTHOR]

A two-stage system involving alkaline thermal gasification of cellulose with Ca(OH) 2 sorbent and catalytic reforming with Ni/Fe dual-functional CaO based catalysts is proposed and applied to enhance H 2 production and in-situ CO 2 capture. The results show that the H 2 concentration is maximized at a considerably lower temperature (500 °C) than commercialized biomass gasification processes, reducing energy consumption. Sol-gel method is deemed better than impregnation method for its lower cost and higher-concentration H 2 production. Among the prepared catalysts, sol-NiCa catalyst exhibits the best performance in CO 2 absorption, resistance to carbon deposition, and cyclic stability, creating maximum H 2 concentration (79.22 vol%), H 2 yield (27.36 mmol g−1 cellulose), and H 2 conversion (57.61%). Introduction of Ni rather than Fe on the CaO based catalyst promotes steam methane reforming at moderate temperature range of 400–600 °C, generating low contents of CH 4 (5.38 vol%), CO 2 (4.82 vol%), and CO (10.58 vol%). [Display omitted] • A two-stage system involving alkaline thermal gasification and catalytic reforming. • Sol-gel shows higher-concentration H 2 production and lower cost than impregnation. • Introduction of Ni rather than Fe on CaO catalysts promotes SMR at 400–600 °C. • Sol-NiCa catalyst exhibits good carbon deposition resistance and cyclic stability. • Maximum H 2 concentration (79.22 vol%) is achieved at moderate temperature of 500 °C. [ABSTRACT FROM AUTHOR]

Abstract To study the characteristics of positive and negative DC discharge under coal pyrolysis gas media at 20 °C–600 °C, the I V characteristics and the current composition are analyzed under different conditions. Due to the difference of ionization mechanism, the corona onset voltage of negative corona is lower than that of positive corona under air gas medium. Under non-electronegative gas media, no corona occurs during negative discharge. However, during positive discharge, with the increase of output voltage, three types of discharge are successively observed, namely corona, glow and arc. Under N 2 gas media and at 400 °C, the maximum collection efficiency of positive electrostatic precipitator is 98%, while that of negative electrostatic precipitator is 82%. When the collection efficiency is 70%, the energy consumption index of negative electrostatic precipitator is about 200 times higher than that of positive electrostatic precipitator. A linear relationship between I/V and V is observed and the ionic mobility can be calculated through the slope. At 350 °C, the ionic mobility under H 2 gas medium is 5.25 cm2/(V*s) while the ionic mobility under N 2 gas medium is 0.1 cm2/(V*s). The ionic mobility is proportional to the absolute temperature according to the discharge experimental data at 350 °C–600 °C. The factor β i , which is only related to gas media, is 0.0001653 cm2/(V*s*T) for N 2 and 0.0087308 cm2/(V*s*T) for H 2. These results assist in understanding the property of ESP at high temperatures. Graphical abstract Unlabelled Image Highlights • Under coal pyrolysis gas medium, corona only occurs in positive discharge. • Under N 2 gas medium, the positive ESP is better than negative ESP. • The ionic mobility under H 2 is about 52 times higher than that of N 2. [ABSTRACT FROM AUTHOR]

Highlights • Novel type of biphasic solvent with low costs and high cyclic capacity is proposed. • DEEA-AEEA solvent shows regeneration energy as low as 2.58 GJ/tCO 2. • Phase split time as short as minutes enables fast phase separation. • Driving and resistance forces dominating the phase split dynamics are analyzed. • CO 2 reactions and phase split mechanism are revealed by NMR analysis. Abstract Using biphasic solvents for carbon dioxide (CO 2) capture is regarded as a promising technology to drastically reduce the regeneration energy. However, this technology hasn't been put into commercial application due to lack of the biphasic solvents with high stabilities and low costs. To overcome this challenge, we developed a novel type of biphasic solvent based on alkanolamine-alkanolamine blends, i.e., aqueous blends of 2-(diethylamino)-ethanol (DEEA, 50 wt%) and monoethanolamine (MEA, 25 wt%) or 2-((2-aminoethyl) amino) ethanol (AEEA, 25 wt%). The aqueous DEEA-AEEA solvent demonstrated a cyclic capacity as high as 0.64 mol CO 2 /mol which is significantly higher than those of 30 wt% MEA and other reported biphasic solvents. In addition, a phase split time as short as a few minutes is obtained. The phase split dynamics were analyzed to investigate the effects of CO 2 loading, temperature, gas flow rate and height-to-diameter ratio. Quantitative 13C NMR analysis was then performed to reveal the reaction and phase split mechanism of CO 2 absorption in the DEEA-AEEA solvent. It indicated that the reaction of AEEA with CO 2 dominated at the beginning of CO 2 absorption and the products are formed as carbamates. Then, DEEA began reacting with CO 2 to yield bicarbonate and carbonate. The phase split mechanism indicated that the reaction products of carbamates and HCO 3 −/CO 3 2− migrated to the lower phase while DEEA and unreacted AEEA migrated to the upper phase. Finally, the cyclic tests were repeated and the energy consumption was evaluated. The regeneration energy of the biphasic solvent, without process optimizations, is 2.58 GJ/tCO 2 , which is 32% lower than that of the traditional 30 wt% MEA solvent. [ABSTRACT FROM AUTHOR]

• Novel alkanolamine-based biphasic solvent with low regeneration energy and viscosity is proposed for CO 2 capture. • Tertiary amine 3-(dimethylamino)propan-1-ol(3DMA1P) is firstly introduced to decrease regeneration energy. • Phase separation mechanism is revealed by NMR and LogP analysis. • Molecular dynamics simulation is applied to study liquid structure and monitor the phase separation process. Biphasic solvents for CO 2 capture have received significant attention due to their potential for energy conservation. However, traditional biphasic solvents result in highly viscous CO 2 rich-phases and high amine losses. To overcome these drawbacks, we have developed a novel alkanolamine-based biphasic solvent by blending 2-(methylamino) ethanol (MAE), 3-(dimethylamino)propan-1-ol (3DMA1P), diethylene glycol dimethyl ether (DGM), and water. The aqueous MAE/3DMA1P/DGM solvent showed a cyclic capacity of 0.45 mol CO 2 /mol amine, which is 1.8 times that of monoethanolamine (MEA), and a desorption rate and regeneration efficiency twice those of MEA. The viscosity of the biphasic solvents can be reduced to 13.12 mPa⋅s at 313 K, which is lower than that of reported biphasic solvents. The evaluated regeneration energy was 2.33 GJ/ton CO 2. Cation chromatography measurements revealed the tendency of MAE to accumulate in the CO 2 -rich phase with increasing CO 2 absorption loading. Quantitative 13C NMR analyses were performed to investigate the species distribution in both phases, and DGM was found to be the major component of the CO 2 -lean phase. Different solubilities of the MAE molecules and MAE carbamate in DGM resulted in phase separation. Molecular dynamics (MD) simulations on the CO 2 -unloaded and CO 2 -loaded solutions verified the phase separation mechanism. MAE molecules tended to cluster, and the interactions between MAE and DGM dropped significantly, with increasing DGM concentration. [ABSTRACT FROM AUTHOR]

A series of Ni-rich bimetallic phosphides incorporating different metals were successfully prepared by initial wetness impregnation, followed by temperature-programmed reduction. Catalyst characterization indicates that the bulk structure and physical properties maintained after adding 2.5 mol% another metal on Ni 2 P. Electron transfer from the second metal to Ni was found on Mo 0.05 Ni 1.95 P, Co 0.05 Ni 1.95 P, and Fe 0.05 Ni 1.95 P, except on W 0.05 Ni 1.95 P. Simultaneous hydrodenitrogenation (HDN) of quinoline and hydrodesulfurization (HDS) of dibenzothiophene (DBT) over phosphides and a commercial metal sulfide were studied at 320–380 °C, 3 MPa, weight hourly space velocity of 6 h − 1 , and H 2 /feed ratio of 500:1. Metal phosphides show higher HDN of quinoline and the same HDS of dibenzothiophene activities than that of a commercial catalyst at 380 °C. Mo 0.05 Ni 1.95 P shows the best performance and lowest N and S content adsorbed on the catalyst, due to the active M(2) sites. HDS conversion and product selectivities are seriously impacted by the adsorption of N-containing compounds on active sites of catalysts. Increasing temperature to 360 °C or/and decreasing N content to less than 1000 ppm quinoline in the feed are suggested to obtain simultaneous efficient removal of N and S. [ABSTRACT FROM AUTHOR]