Institutional Repository of Institute of Process Engineering, CAS (IPE-IR）
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Pyrolytic stage evolution mechanism of Zhundong coal based on reaction consistency analysis of mono/multi molecular models
No full textZhundong coalfield is the largest coalfield in China and the unclear stage evolution mechanism of Zhundong coal pyrolysis is the key factor restricting its coal fire control. Here, the monomolecular model (299 atoms) and large-scale multimolecular model (5083 atoms) were constructed for Liu huanggou (LHG) coal from Zhundong coalfield. The pyrolysis processes of the two models were calculated by ReaxFF MD method. Based on the re-action consistency analysis, the reaction paths tracing on pyrolysis stage evolution and toxic gases formation mechanisms were obtained. The LHG coal pyrolysis process is mainly because of the breakages of the ether oxygen bridge bonds, thioether bridge bonds and aliphatic hydrocarbon bridge bonds. It begins with the shed-ding of small molecules and then undergoes the thermal decomposition of the main structure and pyrolytic fragments. During the pyrolysis process, the LHG coal has constantly broken out tars, gases and other key products, accompanied by a large number of free radicals and intermediates produced. The main sources of CO are the active reaction sites where the carbonyl group and the carboxyl group located; H2S is directly produced from the sulfhydryl group. The research results will guide the staged control and directional transformation of coal fire
The simultaneous removal of NOx and SO2 from flue gas by direct injection of sorbents in furnace of waste incinerator
No full textA effective pollution source control technology (called SDNS) has been developed to simultaneously remove NOx and SO2 from flue gas by direct injection of fine denitration (DeNO(x)) and desulfuration (DeSO(x)) agents (named DNS and DSS, respectively) into the furnace of 300 t.d(-1) waste incinerator. 75 % DeNO(x) efficiency and 95 % DeSO(x) efficiency could be acquired by simultaneous injection of 0.4 g.m(-3) DNS and 0.6 g.m(-3) DSS, and the SDNS system can run steadily with less than 80 mg.m 3 NOx and 10 mg.m(-3) SO2 left in flue gas, which can be comparable with the complex and expensive tail-end purification processes of flue gas. The interaction and interspersion between the active components and the polymer in DNS and DSS facilitate their high reactivity with NOx and SO2 at high temperatures, and the synergistic effect between DNS and DSS in furnace further decreases their consumption. The composition analysis of ash demonstrates that the majority of injected fine DNS and DSS particles flowed out with the flue gas, and only a fraction of them was left in furnace. In addition, the simple SDNS process can not only lower the sorbent consumption but also cut down two-thirds of the investment and operating costs compared with the traditional DeNO(x) and DeSO(x) process. The demonstrated technological and economic advantages of the SDNS process signify its promising application prospect for the source control of NOx and SO2 emissions from small and medium-sized waste incineration projects
Tailored nitrogen-defect induced by diels-alder reaction for enhanced electrochemical hydrogen evolution reaction
No full textElectrocatalytic water splitting in an alkaline medium is recognized as the promising technology to sustainably generate clean hydrogen energy via hydrogen evolution reaction (HER), while the sluggish water dissociation and subsequent *H adsorption steps greatly retarded the reaction kinetics and efficiency of the overall hydrogen evolution process. Whilst nitrogen (N)-doped carbon-based materials are attractive candidates for promoting HER activity, the facile fabrication and gaining a deeper insight into the electrocatalytic mechanism are still challenging. Herein, inspired by the Diels-Alder reaction, we precisely tailored six-membered pyridinic N and five-membered pyrrolic N sites at the edge of the carbon substrates. Comprehensive analysis validates that the participation of pyridinic N (electron-withdrawing) and pyrrolic N (electron-releasing) will induce the charge rearrangements, and further generate local electrophilic and nucleophilic domains in adjacent carbon rings, which guarantees the occurrence of water dissociation to generate protons and the subsequent adsorption of *H intermediates through elec-trostatic interactions, thereby facilitating the overall reaction kinetics. To this end, the optimal NC-ZnCl2- 25 % electrocatalysts present excellent alkaline HER activity (l10 = 45 mV, Tafel slop of 37.7 mV dec-1) superior to commercial Pt/C. (c) 2022 Elsevier Inc. All rights reserved
Quantum chemistry insight into the interactions of 1,3-diisopropoxycalix[4]arenecrown-6 with alkali metal cations: Structure, selectivity, and solvation
No full textDouble-hybrid functional PWPB95-D3 with precise description of dispersion is employed to calculate the thermodynamic properties of complexes with 1,3-Diisopropoxycalix[4]arenecrown-6 (BPC6) and alkali metal cations (Li', Na', K', Rb', and Cs') in the gas phase and solutions (chloroform, methanol, and ace-tonitrile). Moreover, symmetry-adapted perturbation theory (SAPT) and IGM based on Hirshfeld partition of molecular density (IGMH) are for the first time used to reveal the interactions of complexes due to the accuracy energy decomposition and markedly graphical effect, respectively. For the complexes of BPC6 with alkali metal cations in the gas phase, the electrostatic energy takes up nearly 70% of the total energy. The electrostatics energy dominated attractive part of the interaction energy. The dielectric screen of sol-vents leads to the decrease of the absolute value of binding Gibbs free energy (|AG|). The protic solvent provides a further decrease of |AG|. The |AG| of each M'/BPC6 complex in solvents follow the order of | AG|(gas) > |AG|(chloroform) > |AG|(acetonitrile) > |AG|(methanol). In complex Cs'/BPC6, the ratio of dis-persion is as high as 26%. Thus, the dispersion interaction is non-negligible for complexation with large cations in the solvents. Because the AG of complex Cs'/BPC6 is less affected by solvation effect than that of other cations, Cs'/BPC6 is the most stable complex in all the three solvents. The |AG| of complexes with alkali metal cations decreases with the increase of the cationic radii in the gas phase, and increases with that in the solvent solutions. The regulars of |AG| are well match that of the experimental results in literatures.(c) 2022 Elsevier B.V. All rights reserved
Data-driven discovery of the governing equation of granular flow in the homogeneous cooling state using sparse regression
No full textWith the arrival of the era of big data and the rapid development of high-precision discrete simulations, a wealth of high-quality data is readily available, but discovering physical laws from these data remains a great challenge. In this study, an attempt is made to discover the governing equation of the granular flow for the homogeneous cooling state from discrete element method (DEM) data through sparse regression. It is shown that not only the governing equation but also the energy dissipation rate can be obtained accurately from DEM data for systems having different physical properties of particles and operating conditions. The present work provides the evidence that the macroscopic governing equation and the constitutive relation of granular flow can be discovered from microscopic data using a purely data-driven method