共查询到17条相似文献,搜索用时 203 毫秒
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石油焦作为碳基吸附剂脱除燃煤烟气中Hg~0的研究近年来得到发展,本文建立了表征煅烧石油焦表面的四碳环并噻吩饱和簇模型,运用量子化学密度泛函理论B3LYP-D3方法,基于6-31g(d)/lanl2dz混合基组水平,从微观层面研究了煅烧石油焦吸附Hg~0的机理,同时计算了Hg在煅烧石油焦上的吸附能及Mayer键级,并分析了石油焦中噻吩硫在脱汞中的作用。研究结果表明,Hg~0在煅烧石油焦上的吸附以物理吸附为主,噻吩硫对Hg~0的吸附有促进作用。量子化学理论计算是研究煅烧石油焦吸附剂脱除Hg~0机理的一种有效方法。 相似文献
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《工程热物理学报》2017,(2)
采用量子化学密度泛函理论中B3LYP方法,研究了单质汞在卤素改性活性炭表面的氧化反应机理。选定七环锯齿形苯环簇为活性炭表面模型,设计了两种卤素改性活性炭模型X-AC和X-AC-X(X=Cl、Br、I)。通过得到氧化反应过程的过渡态,明确了氧化反应过程,并计算单质汞在改性活性炭表面的吸附能和氧化反应的能垒。研究结果表明:单质汞在负载三种不同卤素原子活性炭表面的吸附能的大小顺序均为:ClBrI,且从吸附强度角度分析,氯改性活性炭表面对单质汞的吸附最稳定。单质汞在负载三种不同卤素原子活性炭表面发生氧化反应的能垒大小顺序均为:ClBrI,且从反应发生难易角度分析,碘改性活性炭表面对单质汞的氧化反应最容易发生。单质汞在改性活性炭表面氧化反应的难易顺序可以正确解释改性活性炭脱除单质汞的实验现象。研究单质汞在改性活性炭表面氧化反应过程中的能垒,对于正确全面揭示改性活性炭脱除单质汞机理至关重要。 相似文献
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基于第一性原理密度泛函理论(DFT)方法研究了Cu12Fe团簇的结构稳定性、热力学稳定性和反应活性.计算得出正二十面体Fe原子核心团簇Ih-core比正二十面体Fe原子壳层团簇Ih-shell的热力学稳定性更强.通过分析吸附能讨论了CO和H2在Ih-core团簇上的吸附构型.计算结果表明,Ih-core团簇以顶角Corner位吸附CO时吸附能最大,吸附模型最稳定,H2吸附过程中发生了解离,两个氢原子均形成表面Facet位吸附构型.最后,通过分析前线轨道得到吸附过程的轨道信息. 相似文献
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《化学物理学报》2020,(1)
本文利用量子化学计算方法,研究了甲胺和水复合离子团簇[(CH_3NH_2)(H_2O)_n]~+的几何结构、能量和红外光谱,揭示了结构生长模型、氢键作用机制和质子转移机理.研究结果表明,在[(CH_3NH_2)(H_2O)_n]~+团簇中,甲胺甲基上的一个氢原子转移到氨基上,形成分子内质子转移的CH_2NH_3~+离子核心结构模型,水分子作为氢键受体,与质子化氨基NH_3~+形成氢键.CH_3NH_2~+离子核心结构模型没有CH_2NH_3~+离子核心结构模型稳定.在团簇的红外光谱中,CH振动、自由NH振动、氢键结合的NH振动和OH振动模式在CH_3NH_2~+和CH_2NH_3~+两种离子核心结构模型的理论计算红外光谱中明显不同,因此可用于鉴别甲胺水合离子团簇的结构模型,有助于理解甲胺和水复合团簇的氢键网络结构. 相似文献
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Artur P. Terzyk Magdalena S. ?wiertnia Marek Wi?niewski Piotr A. Gauden Gerhard Rychlicki Grzegorz S. Szymański 《Applied Surface Science》2007,253(8):4006-4009
We present the results of benzene adsorption at the acidic pH level determined on the series of chemically modified activated carbons and at three temperatures. The influence of carbon surface chemical composition on benzene adsorption is discussed. It is shown that the decrease in the pH level from 7 up to 1.5 increases benzene adsorption and the only exception is carbon modified with gaseous ammonia. Basing on the results of current work and those published previously (for phenol, paracetamol, acetanilide and aniline) and using the results of quantum chemistry calculations (DFT, Gaussian 98) we show, that the value of the energy of interaction with unit positive charge is crucial during the analysis of the influence of pH level on adsorption. Obtained results allow to predict the changes in adsorption of aromatics on carbons with the decrease in the pH level. 相似文献
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The heterogeneity of activated carbons (ACs) prepared from different precursors is investigated on the basis of adsorption isotherms of aniline from dilute aqueous solutions at various pH values. The APET carbon prepared from polyethyleneterephthalate (PET), as well as, commercial ACP carbon prepared from peat were used. Besides, to investigate the influence of carbon surface chemistry, the adsorption was studied on modified carbons based on ACP carbon. Its various oxygen surface groups were changed by both nitric acid and thermal treatments. The Dubinin-Astakhov (DA) equation and Langmuir-Freundlich (LF) one have been used to model the phenomenon of aniline adsorption from aqueous solutions on heterogeneous carbon surfaces. Adsorption-energy distribution (AED) functions have been calculated by using an algorithm based on a regularization method. Analysis of these functions for activated carbons studied provides important comparative information about their surface heterogeneity. 相似文献
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Chaojun Liu Xiaojun Liu Qin Wang Liang Zhan Rui Zhang Wenming Qiao Licheng Ling 《Applied Surface Science》2008,254(21):6701-6705
Surface chemistry of pitch-based spherical activated carbon (PSAC) was modified by chemical vapor deposition of NH3 (NH3-CVD) to improve the adsorption properties of uric acid. The texture and surface chemistry of PSAC were studied by N2 adsorption, pHPZC (point of zero charge), acid-base titration and X-ray photoelectron spectroscopy (XPS). NH3-CVD has a limited effect on carbon textural characteristics but it significantly changed the surface chemical properties, resulting in positive effects on uric acid adsorption. After modification by NH3-CVD, large numbers of nitrogen-containing groups (especially valley-N and center-N) are introduced on the surface of PSAC, which is responsible for the increase of pHPZC, surface basicity and uric acid adsorption capacity. Pseudo-second-order kinetic model can be used to describe the dynamic adsorption of uric acid on PSAC, and the thermodynamic parameters show that the adsorption of uric acid on PSAC is spontaneous, endothermic and irreversible process in nature. 相似文献
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M. Petrantoni A. Hemeryck J.-M. Ducéré A. Estève C. Rossi M. Djafari Rouhani D. Estève G. Landa 《Journal of Physics and Chemistry of Solids》2010,71(2):130-133
The adsorption of a Ni atom on the Al(1 1 1) surface, considered as the first elementary step of the formation of the energetic bimetallic model-system Ni/Al, is studied using two techniques: a plane-wave periodic boundary model and a quantum cluster approach. Geometric structures and associated adsorption energies are detailed and systematically compared. The penetration of Ni atoms in the Aluminium surface in interstitial sites is generally observed. From a modelling point of view, results indicate that precaution must be taken with the cluster approach as the results depend strongly on the constraints imposed on the cluster edges. 相似文献
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燃煤烟气汞的大量排放对公众健康和生态系统造成了严重威胁,开发新型高效脱汞技术和材料对汞污染防治具有重要意义。本文采用原位硒化方法制备了泡沫硒化铜(Cu-hs),与采用水热法制备的泡沫硒化铜(Cu-hd-1和Cu-hd-12)相比,Cu-hs具有更优的单质汞(Hg0)吸附性能。Cu-hs具有良好的抗H2O和SO2干扰能力,O2对Cu-hs吸附Hg0有一定的促进作用,而HCl的存在对Hg0吸附没有明显影响。Cu-hs表面的汞饱和吸附量为3743 g/m3(约为15 mg/g),显著高于目前文献中报道的活性炭的饱和吸附量,具有很好的燃煤烟气脱汞应用潜力。 相似文献