共查询到19条相似文献，搜索用时 114 毫秒
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高岭石插层复合物作为新型矿物材料现已被广泛应用。然而,插层复合物热稳定性较难控制使其在聚合物中的应用一直受到限制。本文应用热分析、X射线衍射、质谱及发射红外光谱等表征技术对煤系高岭石/醋酸钾插层复合物受热分解产物及微结构变化进行了研究。结果表明,煤系高岭石/醋酸钾插层复合物热相变主要经历以下几个阶段:插层水脱嵌(约350℃),插层剂醋酸钾脱嵌(约400℃),脱羟基(约450℃),偏高岭石形成(450~550℃),KHCO3出现(约600℃),KHCO3热分解形成K2CO3和KAl Si O4出现(约700℃),热解产品K2Al2Si O4出现(约800℃),K4Al2Si2O3出现(900~1000℃),大量K3Al O3形成阶段(1100℃及以上)。此外,还发现通过控制插层率和加热温度,可实现高岭石插层复合物的可控分解、新物相合成与转变,从而有利于新材料的合成。 相似文献
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25～75℃酸性NaCl溶液中方铅矿的溶解动力学 总被引：4，自引：0，他引：4
在25～75℃、pH=0.43～2.45的1mol/LNaCl溶液中进行了方铅矿的溶解动力学实验。发现在远平衡条件下,方铅矿的溶解速率r与氢离子活度犤H+犦呈线性关系,溶解速率方程(速率定律)为:r=k犤H+犦,即对H+而言,溶解反应为一级。其中速率常数k为2.344×10-7mol/m2·s(25℃)、1.380×10-6mol/m2·s(50℃)、7.079×10-6mol/m2·s(75℃)。溶解反应的活化能为43.54kJ/mol,方铅矿的溶解机理为表面化学反应,速率决定步骤为表面配合物的离解。 相似文献
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C-800氨基羧酸树脂对铬(Ⅲ)的吸附性能研究 总被引：2，自引：1，他引：1
研究了C-800树脂对Cr(Ⅲ)离子的吸附性能。结果表明,在pH=4.0时树脂对Cr(Ⅲ)的吸附效果最佳,等温吸附服从Freundlich经验式,静态饱和吸附容量为212.4 mg/g,吸附反应的表观活化能Ea=27.1 kJ/mol,热力学函数ΔH=7.39 kJ/mol,ΔG298=-2.65 kJ/mol。用2 mol/L盐酸溶液能定量洗脱。树脂功能基上的N与Cr(Ⅲ)发生配位键合,配位摩尔比为2:3。 相似文献
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本文对电气石-水体系氢同位素动力分馏进行了实验研究。研究表明,电气石-水体系氢同位素交换以扩散交换为主。在温度为800～450℃范围内,该体系的氢扩散动力学方程为:logD=-5.96-6.68×10~3/T(圆柱模式),logD=-5.64-6.42×10~3/T(薄板模式),扩散活化能为128.0 kJ/mol(圆柱模式)和123.1 kJ/mol(薄板模式)。 相似文献
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通过CaCl2添加剂对KAlSi3O8-CaSO4-CaCO3体系研究反应温度和反应时间的影响研究,结果表明:随着CaCl2加入量的增多,体系的反应温度下降,反应时间缩短,当CaCl2的加入量为10%时,反应温度可降至1000℃,反应时间降至25min,此时KAlSi3O8的转化率仍可高达83.24%。研究CaCl2的加入对KAlSi3O8-CaSO4-CaCO3反应体系动力学过程的影响,得出反应体系符合金斯特林格动力学方程:FK(G)=1-2/3G-(1-G)2/3=KKt,反应受扩散过程控制,计算出当CaCl2的加入量为10%时,体系的表观活化能可从原来的128.921kJ/mol下降至58.320kJ/mol。 相似文献
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氨基膦酸树脂对镥(Ⅲ)的吸附性能 总被引：2，自引：0，他引：2
考查介质pH、温度、吸附时间、树脂量等因素对吸附过程的影响。实验结果表明:氨基膦酸树脂(APAR)对镥(Ⅲ)的吸附在pH=5.64的HAc-NaAc的缓冲溶液中为最佳。25℃时静态饱和吸附量为330.5 mg/g(树脂)。用0.5 mol/L的HC l溶液作为解析剂,解析率为95.4%;氨基膦酸树脂对镥(Ⅲ)的表观吸附活化能Ea=37.3 kJ/mol,表观吸附速率常数k298=2.47×10-5-s1,测得热力学参数分别为ΔH=7.86 kJ/mol,ΔG=-4.42 kJ/mol,ΔS=42.5 Jmo-l1K-1,等温吸附服从Freundlich经验式。树脂功能基与镥(Ⅲ)的配位比约为2∶1。 相似文献
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Kinetic Parameters of Methane Generated from Source Rocks in the Kuqa Depression of Tarim Basin and Their Application 总被引：2，自引：0，他引：2
LI Xianqing XIAO Xianming MI Jingkui TANG Yongchun XIAO Zhongyao LIU Dehan SHEN Jiagui YANG Yunfeng WANG Yan DONG Peng 《《地质学报》英文版》2008,82(1):154-163
In a thermal simulation experiment of gold tubes of closed-system, calculating with the KINETICS and GOR-ISOTOPE KINETICS software, kinetic parameters of gas generation and methane carbon isotopic fractionation from Triassic-Jurassic hydrocarbon source rocks in the Kuqa depression of Tarim Basin are obtained. The activation energies of methane generated from Jurassic coal, Jurassic mudstone and Triassic mudstone in the Kuqa Depression are 197-268 kJ/mol, 180-260 kJ/mol and 214-289 kJ/mol, respectively, and their frequency factors are 5.265×10^13 s^-1, 9.761×10^11 s^-1 and 2.270×10^14 s^-1. This reflects their differences of hydrocarbon generation behaviors. The kinetic parameters of methane carbon isotopic fractionation are also different in Jurassic coal, Jurassic mudstone and Triassic mudstone, whose average activation energies are 228 kJ/mol, 205 kJ/mol and 231 kJ/mol, respectively. Combined with the geological background, the origin of natural gas in the Yinan-2 gas pool is discussed, and an accumulation model of natural gas is thus established. The Yinan- 2 gas is primarily derived from Jurassic coal-bearing source rocks in the Yangxia Sag. Main gas accumulation time is 5-0 Ma and the corresponding Ro is in the range from 1.25 %-1.95 %. The loss rate of natural gas is 25 %-30 %. 相似文献
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Roy Trittschack Bernard Grobéty Pierre Brodard 《Physics and Chemistry of Minerals》2014,41(3):197-214
The dehydroxylation reactions of chrysotile Mg3Si2O5(OH)4 and brucite Mg(OH)2 were studied under inert nitrogen atmosphere using isothermal and non-isothermal approaches. The brucite decomposition was additionally studied under CO2 in order to check the influence of a competing dehydroxylation/carbonation/decarbonisation reaction on the reaction kinetics. Isothermal experiments were conducted using in situ high-temperature X-ray powder diffraction, whereas non-isothermal experiments were performed by thermogravimetric analyses. All data were treated by model-free, isoconversional approaches (‘time to a given fraction’ and Friedman method) to avoid the influence of kinetic misinterpretation caused by model-fitting techniques. All examined reactions are characterised by a dynamic, non-constant reaction-progress-resolved (‘α’-resolved) course of the apparent activation energy E a and indicate, therefore, multi-step reaction scenarios in case of the three studied reactions. The dehydroxylation kinetics of chrysotile can be subdivided into three different stages characterised by a steadily increasing E a (α ≤ 15 %, 240–300 kJ/mol), before coming down and forming a plateau (15 % ≤ α ≤ 60 %, 300–260 kJ/mol). The reaction ends with an increasing E a (α ≥ 60 %, 260–290 kJ/mol). The dehydroxylation of brucite under nitrogen shows a less dynamic, but generally decreasing trend in E a versus α (160–110 kJ/mol). In contrast to that, the decomposition of brucite under CO2 delivers a dynamic course with a much higher apparent E a characterised by an initial stage of around 290 kJ/mol. Afterwards, the apparent E a comes down to around 250 kJ/mol at α ~ 65 % before rising up to around 400 kJ/mol. The delivered kinetic data have been investigated by the z(α) master plot and generalised time master plot methods in order to discriminate the reaction mechanism. Resulting data verify the multi-step reaction scenarios (reactions governed by more than one rate-determining step) already visible in E a versus α plots. 相似文献
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采用热分析方法研究了菱镁矿、高岭石分解过程动力学参数活化能Ｅ、反应级数ｎ,由ＴＧ、ＤＴＡ两种实验数据,用Ｃｏａｔｓ,Ｒｅｄｆｅｒｎ和Ｋｉｓｓｉｎｇｅｒ计算方法对比计算,从而得出高岭石活化能Ｅ＝１８８．７１２ｋＪ／ｍｏｌ,菱镁矿活化能Ｅ＝１８０．８２８ｋＪ／ｍｏｌ。 相似文献
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The chemical potential of oxygen (µO2) in equilibrium with magnesiowüstite solid solution (Mg, Fe)O and metallic Fe has been determined by gas-mixing experiments at 1,473 K supplemented by solid-cell EMF experiments at lower temperatures. The results give:
where IW refers to the Fe-"FeO" equilibrium. The previous work of Srecec et al. (1987) and Wiser and Wood (1991) agree well with this equation, as does that of Hahn and Muan (1962) when their reported compositions are corrected to a new calibration curve for lattice parameter vs. composition. The amount of Fe3+ in the magnesiowüstite solid solution in equilibrium with Fe metal was determined by Mössbauer spectroscopy on selected samples. These data were combined with literature data from gravimetric studies and fitted to a semi-empirical equation:
These results were then used to reassess the activity-composition relations in (Mg, Fe)2SiO4 olivine solid solutions at 1,400 K, from the partitioning of Mg and Fe2+ between olivine and magnesiowüstite in equilibrium with metallic Fe experimentally determined by Wiser and Wood (1991). The olivine solid solution is constrained to be nearly symmetric with
, with a probable uncertainty of less than ±0.5 kJ/mol (one standard deviation). The results also provide a useful constraint on the free energy of formation of Mg2SiO4.Editorial responsibility: B. Collins 相似文献
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The standard enthalpies of formation of FeS (troilite), FeS2 (pyrite), Co0.9342S, Co3S4 (linnaeite), Co9S8 (cobalt pentlandite), CoS2 (cattierite), CuS (covellite), and Cu2S (chalcocite) have been determined by high temperature direct reaction calorimetry at temperatures between 700 K and 1021 K. The following results are reported: $$\Delta {\rm H}_{f,FeS}^{tr} = - 102.59 \pm 0.20kJ mol^{ - 1} ,$$ $$\Delta {\rm H}_{f,FeS}^{py} = - 171.64 \pm 0.93kJ mol^{ - 1} ,$$ $$\Delta {\rm H}_{f,Co_{0.934} S} = - 99.42 \pm 1.52kJ mol^{ - 1} ,$$ $$\Delta {\rm H}_{f,Co_9 S_8 }^{ptl} = - 885.66 \pm 16.83kJ mol^{ - 1} ,$$ $$\Delta {\rm H}_{f,Co_3 S_4 }^{In} = - 347.47 \pm 7.27kJ mol^{ - 1} ,$$ $$\Delta {\rm H}_{f,CoS_2 }^{ct} = - 150.94 \pm 4.85kJ mol^{ - 1} ,$$ $$\Delta {\rm H}_{f,Cu_2 S}^{cc} = - 80.21 \pm 1.51kJ mol^{ - 1} ,$$ and $$\Delta {\rm H}_{f,CuS}^{cv} = - 53.14 \pm 2.28kJ mol^{ - 1} ,$$ The enthalpy of formation of CuFeS2 (chalcopyrite) from (CuS+FeS) and from (Cu+FeS2) was determined by solution calorimetry in a liquid Ni0.60S0.40 melt at 1100 K. The results of these measurements were combined with the standard enthalpies of formation of CuS, FeS, and FeS2, to calculate the standard enthalpy of formation of CuFeS2. We found \(\Delta {\rm H}_{f,CuFeS_2 }^{ccp} = - 194.93 \pm 4.84kJ mol^{ - 1}\) . Our results are compared with earlier data given in the literature; generally the agreement is good and our values agree with previous estimates within the uncertainties present in both. 相似文献
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干酪根、煤以及显微组分生烃过程中的动力学参数(如活化能分布特征等)是其内部分子结构的宏观反映,据此可以判断有机质内部成键特征,评价生油门限、生油高峰,计算不同温度范围油气生成量等。笔者利用岩石热解仪(Rock-Eval型)对贵州水城含树皮体煤中的主要组成——基质镜质体的成烃动力学特征进行了研究,并与树皮体、丝质体进行比较,结果表明,基质镜质体的平均活化能为200kJ/mol,大于树皮体的平均活化能(177kJ/mol),而小于丝质体的平均活化能(324kJ/mol),由此推断,在相同的热演化条件下,基质镜质体、树皮体、丝质体三者的生烃顺序为树皮体→基质镜质体→丝质体。从基质镜质体生烃活化能分布特征图上可以看出,基质镜质体有4次主要生烃期,其对应的活化能分布范围及产烃率分别为191.25—192.5kJ/mol、12.19%,195—196.25kJ/mol、7.25%,197.5—198.75kJ/mol、39.82%,216.25kJ/mol、18.64%,据此可以认为:基质镜质体主要由4种不同类型键组成。在活化能191.25—198.75kJ/mol范围内,基质镜质体的累计生烃率达60%左右,这说明基质镜质体产烃较集中(在较短的地质剖面或温度范围内形成大量烃类物质),其含量高(煤岩三大组分之一),因此对煤成烃资源有较大的贡献。 相似文献
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A.Yu. Likhacheva S. A. Veniaminov E. A. Paukshtis 《Physics and Chemistry of Minerals》2004,31(5):306-312
The thermal decomposition of ammonium-exchanged natural analcime is characterized by gas chromatography, IR spectroscopy and X-ray diffraction. The de-ammoniation and dehydroxylation proceed in parallel throughout the decomposition, which evidences the instability of the protonated analcime framework. The mechanism of degassing of NH4-analcime changes throughout its decomposition. At the initial step, the mechanism of de-ammoniation consists in thermal dissociation of NH4+ molecule onto NH3 and proton (framework OH group) and diffusion of NH3 out of the structure. Subsequent decomposition and removal of the OH groups lead to a progressive loss of crystallinity. At this step, an apparent activation energy for NH3 desorption is estimated to be 145(±13) kJ mol–1. This value is within the upper limit of the activation energy characteristic for the NH3 desorption from proton centres in large-pore zeolites. At the final step, the adsorption of NH3 and protons onto the defect centres in the amorphosed aluminosilicate framework results in a significant increase of an apparent activation energy for the de-ammoniation and dehydroxylation up to 270(±20) kJ mol–1. 相似文献
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Ftima Gonzlez Snchez Luc R. Van Loon Thomas Gimmi Andreas Jakob Martin A. Glaus Larryn W. Diamond 《Applied Geochemistry》2008,23(12):3840-3851
The effect of temperature and ionic strength on the diffusion of HTO parallel to the direction of compaction through 5 highly compacted clay minerals (bulk dry density, ρb,d = 1.90 ± 0.05 Mg/m3), namely montmorillonite (Na- and Ca-form), illite (Na- and Ca-form), and kaolinite, was studied. The diffusion experiments were carried out at temperatures between 0 °C and 60 °C and at ionic strengths of 0.01 M and 1 M NaCl for the Na-form clays and kaolinite, and of 0.005 M and 0.5 M CaCl2 for the Ca-form. The ionic strength had an insignificant influence on the values of the effective diffusion coefficient (variation by less than 10%) for the clays under study at this degree of compaction. The effective diffusion coefficients followed the order Na-montmorillonite < Ca-montmorillonite < Ca-illite < Na-illite kaolinite. It is thought that the differences between Na- and Ca-montmorillonite originate from the larger size particles, and thus the lower tortuosity of the latter; whereas the differences between Na- and Ca-illite are related to the different degree of solvation of the Na and Ca cations. The activation energies were successfully calculated using the Arrhenius law. Swelling clays (Na- and Ca-montmorillonite) had slightly larger activation energy values (20 kJ/mol) compared to bulk water (17 kJ/mol); Ca-illite (16 kJ/mol), Na-illite (13 kJ/mol) and kaolinite (14.4 kJ/mol) lower values than that of bulk water. The low activation energies of the last three clays may be related to weaker H-bonds between water and the clay surfaces compared to those in bulk water. 相似文献
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Bernd Wruck Ekhard K. H. Salje Ann Graeme-Barber 《Physics and Chemistry of Minerals》1991,17(8):700-710
The kinetic rate laws of Al-Si disordering under dry conditions (T = 1353K, 1253 K, 1223 K, 1183 K) and in the presence of water (p = 1 kbar, T = 1023 K, 1073 K, 1103 K) were studied both experimentally and theoretically. A gradual change of the degree of order was found under dry conditions. For intermediate degrees of order broad distributions of the order parameter Q od occur. The variations of Q od are correlated with structural modulations as observed in the transmission electron microscope. The time evolution of the mean value of Q od can be well described by the rate law: $$\frac{{dQ_{od} }}{{dt}} = - \frac{\gamma }{{RT}}\exp \sum\limits_{i = 1}^n {X_i^2 } \left[ {\frac{{ - (G_a^0 + \varepsilon (\Delta Q_{od} )^2 )}}{{RT}}} \right]\frac{{dG}}{{dQ_{od} }}$$ with the excess Gibbs energy G and G a 0 = 433.8 kJ/mol, ?= -27.4 kJ/mol, γ = 1.687 · 1014 h ?1. Under wet conditions, two processes were found which occur simultaneously. Firstly, some material renucleated with the equilibrium degree of order. Secondly, the bulk of the material transformed following the same rate law as under dry conditions but with the reduced activation energy G a 0 = 332.0 kJ/mol and ? = -43.0 kJ/ mol, γ = 1.047 · 1013 h?1. The applicability of the kinetic theory is discussed and some ideas for the analysis of geological observations are evolved. 相似文献
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Interaction of freshly precipitated silica gel with aqueous solutions was studied at laboratory batch experiments under ambient
and near neutral pH-conditions. The overall process showed excellent reversibility: gel growth could be considered as an opposite
process to dissolution and a linear rate law could be applied to experimental data. Depending on the used rate law form, the
resulting rate constants were sensitive to errors in parameters/variables such as gel surface area, equilibrium constants,
Si-fluxes, and reaction quotients. The application of an Integrated Exponential Model appeared to be the best approach for
dissolution data evaluation. It yielded the rate constants k
dissol ∼ (4.50 ± 0.68) × 10−12 and k
growth ∼ (2.58 ± 0.39) × 10−9 mol m−2 s−1 for zero ionic strength. In contrast, a Differential Model gave best results for growth data modeling. It yielded the rate
constants k
dissol ∼ (1.14 ± 0.44) × 10−11 and k
growth ∼ (6.08 ± 2.37) × 10−9 mol m−2 s−1 for higher ionic strength (I ∼ 0.04 to 0.11 mol L−1). The found silica gel solubility at zero ionic strength was somewhat lower than the generally accepted value. Based on the
and standard Gibbs free energy of silica gel formation was calculated as and −850,318 ± 20 J mol−1, respectively. Activation energies for silica gel dissolution and growth were determined as and respectively. An universal value for growth of any silica polymorph, is not consistent with the value for silica gel growth, which questions the hypothesis about one unique activated complex
controlling the silica polymorph growth. 相似文献