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烟草果胶和纤维素含量^(13)C MultiCP/MAS NMR同时测量
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作者 王鹏 唐杰 +5 位作者 杨明宇 朱立军 汪长国 陈昆燕 王鹏 杨俊 《安徽农业大学学报》 CAS CSCD 2024年第3期516-522,共7页
果胶和纤维素是烟草细胞壁的重要组成成分,其含量对烟草品质与安全性产生重要影响。传统分析方法难以实现果胶和纤维素的同时定量。本文在优化核磁共振波谱序列条件的基础上,采用固体^(13)C多重交叉极化/魔角旋转核磁共振波谱分析技术(^... 果胶和纤维素是烟草细胞壁的重要组成成分,其含量对烟草品质与安全性产生重要影响。传统分析方法难以实现果胶和纤维素的同时定量。本文在优化核磁共振波谱序列条件的基础上,采用固体^(13)C多重交叉极化/魔角旋转核磁共振波谱分析技术(^(13)C MultiCP/MAS NMR)建立了烟草果胶和纤维素含量的同时测量新方法。方法以聚半乳糖醛酸和微晶纤维素为标准物质,以3-(三甲基甲硅烷基)丙酸-d4钠盐(TMSP)做为内标物质,分别建立内标法标准曲线,相关系数R2为0.999 0和0.998 2。果胶测量的检出限和定量限分别为0.38和1.28 mg·g^(–1),精密度(RSD,n=5)小于3.05%。纤维素测量的检出限和定量限为1.01和3.32 mg·g^(–1),精密度(RSD,n=5)小于2.74%。应用本方法测量烟梗、烟草薄片和烟叶等不同类型样品中的果胶和纤维素含量,并对比烟草行业标准方法的测量结果,果胶含量的相对误差在-0.95%至4.51%之间,纤维素含量的相对误差在0.77%至2.46%之间。表明^(13)C MultiCP/MAS NMR方法快速,准确,适合批量样品的分析测量,为果胶和纤维素等细胞壁类大分子的同时定量分析提供重要技术支持。 展开更多
关键词 果胶 纤维素 ^(13)C MultiCP/mas nmr 烟草
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木薯蚕丝的13C CP/MAS NMR分析 被引量:1
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作者 陈静 黄继伟 +1 位作者 彭泽冶 宁晚娥 《丝绸》 CAS CSCD 北大核心 2021年第1期1-7,共7页
木薯蚕丝作为一种极具开发利用价值的野蚕丝,其结晶结构、热学性质和力学性能显著不同于桑蚕丝,对木薯蚕丝二级结构的研究有助于进一步认识其构效关系,拓展其应用领域。13C CP/MAS NMR技术是研究蚕丝丝素蛋白结构的有效方法之一。文章通... 木薯蚕丝作为一种极具开发利用价值的野蚕丝,其结晶结构、热学性质和力学性能显著不同于桑蚕丝,对木薯蚕丝二级结构的研究有助于进一步认识其构效关系,拓展其应用领域。13C CP/MAS NMR技术是研究蚕丝丝素蛋白结构的有效方法之一。文章通过13C CP/MAS NMR测试,分析了木薯蚕丝丝素蛋白的二级结构特征,并将其与桑蚕丝和柞蚕丝进行了对比。结果表明:桑蚕丝中Gly的含量较柞蚕丝和木薯蚕丝高,木薯蚕丝与柞蚕丝相近;Ala的含量及其β-sheet结构较柞蚕丝和木薯蚕丝低,木薯蚕丝最高,三者的α-螺旋结构相差不大;桑蚕丝的不定形区含量最高,木薯蚕丝最低,与柞蚕丝接近。 展开更多
关键词 木薯蚕丝 桑蚕丝 柞蚕丝 丝素蛋白 二级结构 13 C CP/mas nmr
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固态^(13)C CP/MAS NMR光谱测定烟草中果胶含量的分析方法研究 被引量:2
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作者 牛凡超 谢卫 +4 位作者 黄朝章 蓝洪桥 黄延俊 高淼 杨俊 《中国科学技术大学学报》 CAS CSCD 北大核心 2021年第8期637-646,共10页
通过固态^(13)C CP/MAS NMR技术,成功地建立了一种新方法用于烟草果胶的定量分析研究.首先,将二甲基硅橡胶设计成5.5 mm外径的硅胶管用作强度参考,再装填到5.5 mm内径的二氧化锆转子内以制成NMR样品管.然后,对样品管中的果胶样品进行检... 通过固态^(13)C CP/MAS NMR技术,成功地建立了一种新方法用于烟草果胶的定量分析研究.首先,将二甲基硅橡胶设计成5.5 mm外径的硅胶管用作强度参考,再装填到5.5 mm内径的二氧化锆转子内以制成NMR样品管.然后,对样品管中的果胶样品进行检测以获得相应的^(13)C CP/MAS NMR光谱,再利用波谱去卷积技术分别对171 ppm处的C-6峰进行处理,以此消除重叠峰的干扰.最后,用指定的C-6峰与强度参考峰的面积比为纵坐标,聚半乳糖醛酸(PGA)标准样品的质量为横坐标,以此来建立工作曲线.获得工作曲线方程为I=0.0082m-0.2470,r2=0.9981,检出限和定量限分别为1.81 mg·g^(-1)、6.04 mg·g^(-1).方法的加标回收率在94.33%~102.77%范围内,平均回收率为98.11%,RSD(n=5)小于2.32%.该方法用于测定6种不同烟草样品中的果胶含量,结果发现:与标准方法测量的结果相比,其相对误差在-4.94%~3.84%之间.研究表明,通过固态^(13)C CP/MAS NMR光谱和硅橡胶管建立的新方法准确、快速、简单,适用于烟草及其制品中果胶含量的定量分析. 展开更多
关键词 果胶 二甲基硅橡胶管 固态^(13)C CP/mas nmr 烟草
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Infrared and MAS NMR Spectroscopic Studies of Al_(18)B_4O_(33)
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作者 YOU Hong-peng, HONG Guang-yan and ZENG Xiao-qing (Laboratory of Rare Earth Chemistry and Physics, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China) DENG Feeng and YE Zhao-hui (Laboratory of Magnetic Reso 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2000年第4期301-305,共5页
The IR spectrum and 11B and 27Al MAS NMR spectra of Al18B4O33 are presented and discussed in relation to the possible existence of boron atoms substituting for aluminum atoms. The IR spectrum shows that the strong vi... The IR spectrum and 11B and 27Al MAS NMR spectra of Al18B4O33 are presented and discussed in relation to the possible existence of boron atoms substituting for aluminum atoms. The IR spectrum shows that the strong vibrations of the BO3 groups are present in the 1 500-1 200 cm-1 region, and very weak bands of BO4 units are present in the region from 1 000 to 1 100 cm-1. 11B MAS NMR spectrum indicates that the strong signal for BO3 units appears in the region from δ+5 to δ+20, and the very weak signal for BO4 units is at about δ- 1, while 27Al MAS NMR spectrum shows five peaks at about δ+62, +42. 1, +14, -4. 7 and -6. 4, originating from AlO4, AlO4, AlO5, AlO6 and AlO6, respectively. These results reveal that there are minor BO4 units in Al18B4O33, indicating that a small amount of B atoms substitute for Al atoms in the 4-fold coordination. 展开更多
关键词 Al-18B_4O_33 IR spectrum ^(11)B ^(27)Al mas nmr spectrum
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Study of Surface Modification Mechanism of Calcined Kaolin by MAS NMR
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作者 杨晓杰 邓飞皇 张蓓 《Journal of China University of Mining and Technology》 2002年第2期222-224,共3页
The 29 Si and 27 Al in modified and unmodified calcined kaolin were researched and compared by using MAS NMR. The result shows that the chemical shift of -106×10 -6 of 29 Si almost keeps unchanged after being mod... The 29 Si and 27 Al in modified and unmodified calcined kaolin were researched and compared by using MAS NMR. The result shows that the chemical shift of -106×10 -6 of 29 Si almost keeps unchanged after being modified, but 27 Al changes obviously. The chemical shift of 5.44×10 -6 and 65.69×10 -6 of 27 Al are separately shifted to 3.8×10 -6 -4.4×10 -6 and 54.6×10 -6 -59.9×10 -6 after being modified. And the chemical modification of kaolin is completed by linking with Al on the surface of it. 展开更多
关键词 calcined kaolin surface modification mas nmr
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Qualitative and quantitative analysis of Brønsted and Lewis acid sites in zeolites:A combined probe-assisted ^(1)H MAS NMR and NH_(3)-TPD investigation
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作者 Runze Liu Yankai Bian Weili Dai 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2024年第4期24-30,共7页
Zeolite is one of the most important heterogeneous catalysts in acid catalytic reactions.Considering that the catalytic behaviors of zeolites are mostly related to their acidic characteristics,extensive attention has ... Zeolite is one of the most important heterogeneous catalysts in acid catalytic reactions.Considering that the catalytic behaviors of zeolites are mostly related to their acidic characteristics,extensive attention has been attracted to the measurements of acid type,strength and concentration in zeolites.Numerous techniques including Fourier-transform infrared(FTIR)spectroscopy,probe-assisted^(1)H,^(13)C and^(31)P magic angle spinning nuclear magnetic resonance spectroscopy(MAS NMR)as well as temperature programmed desorption of ammonia(NH_(3)-TPD)have been developed for determining the acid sites.Nevertheless,a single approach is defective to characterize the acid sites comprehensively.Herein,combining the probe-assisted(e.g.,NH_(3)and CD_(3)CN)^(1)H MAS NMR and NH_(3)-TPD,the acid sites in different zeolites including the acid type,density and strength were determined.The commonly utilized NH_(3)-TPD to determine the acid strength of zeolite samples with different topologies should be rigorously considered owing to zeolite confinement effect.Controlling the desorption temperature of NH_(3)probe molecules,the acid type(Le.,Brønsted acid sites(BAS)and Lewis acid sites(LAS))and the corresponding density could be determined by NH_(3)probe-assisted^(1)H MAS NMR spectroscopy,while the acid strength could be investigated via CD_(3)CN probe-assisted^(1)H MAS NMR spectroscopy. 展开更多
关键词 ^(1)H mas nmr NH_(3)-TPD BAS LAS Zeolites
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11B 3Q MAS NMR Study on Glucose-Responsive Micelles Self-assembled from PEG-b-P(AA-co-AAPBA) 被引量:2
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《Chinese Journal of Chemistry》 SCIE CAS CSCD 2014年第1期97-102,共6页
Phenylboronic acid (PBA) based glucose-responsive materials have attracted great interests in recent years for developing insulin delivery systems.It is desired to obtain PBA based materials that can response to gluco... Phenylboronic acid (PBA) based glucose-responsive materials have attracted great interests in recent years for developing insulin delivery systems.It is desired to obtain PBA based materials that can response to glucose under physiological pH and understand the mechanism.By using 11B triple-quantum magic-angle spinning nuclear magnetic resonance (11B 3Q MAS NMR) measurements,the glucose-responsive mechanism of micelles self-assembled from poly(ethylene glycol)-b-ploy(acrylic acid-co-acrylamidophenylboronic acid) PEG-b-P(AA-co-AAPBA) is deeply investigated.Different configurations of phenylboronic acid during various steps of glucose-responsive behaviors are clearly analyzed in the 11B 3Q MAS NMR spectra and coordination between carboxyl and PBA is confirmed.By increasing the AA units in PEG-b-P(AA-co-AAPBA),the carboxyl can coordinate with PBA moieties and cause the glucose-responsiveness of micelles even in the weak acid environment. 展开更多
关键词 11B 3Q mas nmr COORDINATION glucose-responsiveness micelles SELF-ASSEMBLY
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Direct Observation of Various Al Sites in SAPO-34 by ^(27)Al Multiquantum (MQ) Magic Angle Spinning (MAS) NMR 被引量:2
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作者 Zhi Min +4 位作者 YAN Jian Qin ZHUANG 《Chinese Chemical Letters》 SCIE CAS CSCD 2003年第1期87-90,共4页
The elegant 2D multiquantum (MQ) MAS NMR has been applied to investigate the coordination of Al atoms in SAPO-34. The results show that the effects of the template and/or water on the coordination of Al atoms are sig... The elegant 2D multiquantum (MQ) MAS NMR has been applied to investigate the coordination of Al atoms in SAPO-34. The results show that the effects of the template and/or water on the coordination of Al atoms are significant, which lead to the formation of various Al species. Up to four kinds of Al species are distinctly resolved. 展开更多
关键词 SAPO-34 ^(27)Al MQ mas nmr ^(27)Al mas nmr structure.
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~1H MAS NMR characterization of hydrogen over silica-supported rhodium catalyst
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作者 晁自胜 吴廷华 +2 位作者 叶剑良 陈国周 万惠霖 《Science China Chemistry》 SCIE EI CAS 2001年第1期103-112,共10页
Hydrogen species in both SiO2 and Rh/SiO2catalysts pretreated in different atmospheres (H2, O2, helium or air) at different temperatures (773 or 973 K) were investigated by means of1H MAS NMR. In SiO2 and O2-pretreate... Hydrogen species in both SiO2 and Rh/SiO2catalysts pretreated in different atmospheres (H2, O2, helium or air) at different temperatures (773 or 973 K) were investigated by means of1H MAS NMR. In SiO2 and O2-pretreated catalysts, a series of downfield signals at ~7.0, 3.8–4.0, 2.0 and 1.5–1.0 were detected. The first two signals can be attributed to strongly adsorbed and physisorbed water and the others to terminal silanol (SiOH) and SiOH under the screening of oxygen vacancies in SiO2lattice, respectively. Besides the above signals, both upfield signal at ~?110 and downfield signals at 3.0 and 0.0 were also detected in H2-pretreated catalyst, respectively. The upfield signal at ~?110 originated from the dissociative adsorption of H2 over rhodium and was found to consist of both the contributions of reversible and irreversible hydrogen. There also probably existed another dissociatively adsorbed hydrogen over rhodium, which was known to be β hydrogen and in a unique form of “delocalized hydrogen”. It was presumed that the β hydrogen had an upfield shift of ca. ?20–?50, though its1H NMR signals, which, having been masked by the spinning sidebands of Si-OH, failed to be directly detected out. The downfield signal at 3.0 was assigned to spillover hydrogen weakly bound by the bridge oxygen of SiO2. Another downfield signal at 0.0 was assigned to hydrogen held in the oxygen vacancies of SiO2 (Si-H species), suffering from the screening of trapped electrons. Both the spillover hydrogen and the Si-H resulted from the migration of the reversible hydrogen and the β hydrogen from rhodium to SiO2 in the close vicinity. It was proved that the above migration of hydrogen was preferred to occur at higher temperature than at lower temperature. 展开更多
关键词 SILICA RHODIUM CATALYST HYDROGEN SPILLOVER 1H mas nmr
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含铬β-C_2S水化过程的MAS/NMR研究
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作者 郭俊才 《国外建材科技》 1994年第4期26-27,共2页
近年来,有不少的学者采用MAS/NMR技术(魔法角自旋/核磁共振),涉足于水泥水化的研究领域。而且也能对硅键的结构提供一些可用的信息资料。但真正研究重金属对硅酸盐化合物的水化过程的影响则为数不多,特别是研究与水泥混合的金属沉淀物... 近年来,有不少的学者采用MAS/NMR技术(魔法角自旋/核磁共振),涉足于水泥水化的研究领域。而且也能对硅键的结构提供一些可用的信息资料。但真正研究重金属对硅酸盐化合物的水化过程的影响则为数不多,特别是研究与水泥混合的金属沉淀物的稳定/结晶是一种很重要的凋整污染控制的方法。 展开更多
关键词 水泥 水合 mas/nmr技术
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^(13)C NMR研究LA-2型催化剂的积炭行为
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作者 杨一青 孔祥铭 +1 位作者 金照生 姜兴茂 《工业催化》 CAS 1996年第2期57-59,共3页
利用积炭样品的(13)CCP/MASNMR及其浸洗液的1H、(13)CNMR测试,研究环氧丙烷与醇合成丙二醇醚时催化剂(LA-2)的积炭结构及床展不同部位样品积炭的相对量,从而探讨其积炭的机理及催化剂失活的原因.
关键词 ^(13)C CP/mas nmr 积炭 丙二醇醚
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A SOLID NMR STUDY OF POLYETHERESTER-UREAS
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作者 陈群 王源身 +1 位作者 邬学文 余学海 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 1992年第4期287-293,共7页
The morphology of some polyetherester-ureas were studied by ^(13)C CP/MAS and ~1H wide-line NMR spectroscopy. It was found that the HDI and MDI based polymers have well crystallized hard segments, whereas the TDI and ... The morphology of some polyetherester-ureas were studied by ^(13)C CP/MAS and ~1H wide-line NMR spectroscopy. It was found that the HDI and MDI based polymers have well crystallized hard segments, whereas the TDI and HMDI based ones have not. For HDI/MDI based polymers, the presented results suggest that the distribution of two kinds of hard segment units is mainly in a block form. The influences of the different hard segment and chain length on the mobility of the soft segment were also studied. 展开更多
关键词 Polyetherester-urea MORPHOLOGY ^(13)C CP/mas nmr spectroscopy ~1H wideline nmr
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H-SAPO-34分子筛催化醇类转化的差异性研究 被引量:1
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作者 顾雅婷 张雯娜 +5 位作者 韩晶峰 楼才溢 陈慧慧 徐舒涛 魏迎旭 刘中民 《波谱学杂志》 CAS 北大核心 2022年第4期428-438,共11页
本文研究了H-SAPO-34催化甲醇和丁醇转化反应及其产物分布的差异,结合气相色谱-质谱(GC-MS)联用、^(13)C交叉极化魔角旋转核磁共振(^(13)C CP MAS NMR)技术捕获了反应过程中生成的重要反应中间物种.甲醇转化过程以乙烯、丙烯和丁烯为主... 本文研究了H-SAPO-34催化甲醇和丁醇转化反应及其产物分布的差异,结合气相色谱-质谱(GC-MS)联用、^(13)C交叉极化魔角旋转核磁共振(^(13)C CP MAS NMR)技术捕获了反应过程中生成的重要反应中间物种.甲醇转化过程以乙烯、丙烯和丁烯为主要产物;而丁醇转化过程中主要产物是丁醇脱水生成的丁烯,反应初期以丙烯和丁烯作为主要产物.两种醇类转化均以低碳烯烃作为主要产物,且存留物种和^(13)C CP MAS NMR分析均观察到芳烃物种,说明H-SAPO-34催化甲醇和丁醇转化存留在催化剂上的有机物种相近.虽然起始于不同的醇类反应,但H-SAPO-34上限域空间的酸催化环境都能引导甲醇和丁醇制取低碳烯烃的反应过程. 展开更多
关键词 ^(13)C交叉极化魔角旋转核磁共振(^(13)C CP mas nmr) 醇类转化 分子筛催化 反应中间物种
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Synthesis of C_3S by Sol-Gel Technique and Its Features 被引量:3
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作者 何真 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2010年第1期138-141,共4页
Sol-gel method is a technique to synthesize inorganic materials based on wet-chemical reaction theory. The results have shown that reactants tetraethyl orthosilicate (TEOS) and Ca(NO3)2·4H2O can form sol and ... Sol-gel method is a technique to synthesize inorganic materials based on wet-chemical reaction theory. The results have shown that reactants tetraethyl orthosilicate (TEOS) and Ca(NO3)2·4H2O can form sol and gel in solution at 50-60 ℃, and the cosolvents are propyl alcohol (NPA) and H2O, the catalyst is HNO3. This sol-gel is burned for 12 hat 1 350-1 450 ℃ so that the organic matter, free water (moisture) in sol-gel system are removed and a solid reaction has taken place to form the resulting product. The product has been confirmed to be C3S by XRD, SEM and 29Si MAS NMR, as well as free lime content of the product which is less than 0.2% was determined by propanetriol-ethanol-method. The analysis determined by EDXA has indicated that the n(Ca)/n(Si) ratio in corresponding to micro-region is close to theoretical value of 3∶1. This resulting product is C3S with Si sites of Q0 polymerization, and has higher purity and hydraulic activities at earlier age of hydration. 展开更多
关键词 sol-gel technique synthesization PURITY tricalcium silicate MORPHOLOGY 29Si mas nmr
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Unraveling the reaction mechanism of low dose Mn dopant in Ni(OH)_(2) supercapacitor electrode 被引量:2
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作者 Zhiguo Zhang Hua Huo +5 位作者 Zhenjiang Yu Lizhi Xiang Bingxing Xie Chunyu Du Jiajun Wang Geping Yin 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2021年第10期497-506,I0013,共11页
Mn doping is deemed as a promising strategy to improve the electrochemical performance of the a-Ni(OH)_(2)battery-type supercapacitor electrode.However,the internal structure evolution,the pathways and the dynamics of... Mn doping is deemed as a promising strategy to improve the electrochemical performance of the a-Ni(OH)_(2)battery-type supercapacitor electrode.However,the internal structure evolution,the pathways and the dynamics of the proton/intercalated anion migration,as well as the functioning mechanism of Mn dopant to stabilize the layered structure during cycles remain unclear.Here,we unveil that irreversible oxidization of Mn^(3+)at the initial CV cycles,which will remain as Mn^(4+)in the NiO_(2)slabs after the first oxidization to effectively suppress the phase transformation fromα-Ni(OH)_(2)/γ-NiOOH toβ-Ni(OH)_(2)/β-NiOOH and further maintain the structural integrity of electrode.With a synergistic combination of theoretical calculations and various structural probes including XRD and^(2)H MAS solid state NMR,we decode the structure evolution and dynamics in the initial CV(cyclic voltammetry)cycles,including the absorption/desorption of hydrogen containing species,migration of intercalated anions/water molecules and the change of interlayer space.This present work elucidates a close relationship between doping chemistry and structural reliability,paving a novel way of reengineering supercapacitor electrode materials. 展开更多
关键词 Reaction mechanism Structure evolution ^(2)H mas nmr Layered double hydroxides Local environments
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Structure and Infrared Radiation Properties of Substituted Cordierites 被引量:1
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作者 徐庆 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2006年第4期68-70,共3页
Zn^2+ - or Ti^4+ -substituted cordierites with the nominal compositions of Mg1 .6 Zn0.4 Al4 Si5 O18 and Mg1.8 Ti0.2 Al4.4 Si4.6 O18 respectively, were prepared by a conventional solid state reaction method. The stru... Zn^2+ - or Ti^4+ -substituted cordierites with the nominal compositions of Mg1 .6 Zn0.4 Al4 Si5 O18 and Mg1.8 Ti0.2 Al4.4 Si4.6 O18 respectively, were prepared by a conventional solid state reaction method. The structure of the substituted eordierites was characterized by X- ray diffraction ( XRD ), infrared ( 1R ) spectroscopy and 29 Si magic angle spinning ( MAS ) nuclear magnetic resonance ( NMR ). The infoared radiation properties were investigated in the bands within 2.5-25μm. Compared with the na-substituted cordierite composition ( Mg2 Al4 Si5 O18 ), Zn^2+ - or Ti^4+ -substituted cordierites show superior infrared properties. XRD and IR results confirm the formation of hexagonal a-eordierite as the main eo'stal phase for the substituted cordierites. 29 Si MAS NMR result indicates that Zn^2+ or Ti^4+ Substitutions for partial Mg^2+ of a-eordierite promoted the ordering of the distribution oral and Si atoms in T1 ( tetrahedra connecting six-raembered rings together with [ MgO6] octahedra ) and T2 ( tetraheda forming six-reentered rings) tetrahedral sites. This resulted in a lattice deformation and increased the anharmonicity of polarization vibration, which is responsible for the improvement of infrared radiation properties of the substituted eordierites. 展开更多
关键词 α-eordierite infrared radiation properties SUBSTITUTION 29 Si mas nmr
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Coalification and coal alteration under mild thermal conditions 被引量:1
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作者 Pavel Straka Ivana Sykorova 《International Journal of Coal Science & Technology》 EI 2018年第3期358-373,共16页
Coalification temperatures are often considered to be approximately 100-170 ℃ for bituminous coal and 170-275 ℃ for anthracite. However, our micropetrographic observations, solid state ^27Al magic-angle spinning nuc... Coalification temperatures are often considered to be approximately 100-170 ℃ for bituminous coal and 170-275 ℃ for anthracite. However, our micropetrographic observations, solid state ^27Al magic-angle spinning nuclear magnetic resonance measurements, interpretation of δ^13C values for whewellite in pelosiderite concretions from Carboniferous sediments, and assessment of whewellite thermal stability show that coalification temperatures can be significantly lower. Also the temperatures of coal alteration may be substantially lower than is stated. Ordinarily, high- temperature alteration is reported, but microthermometric measurements of fluids temperatures and micropetrographic observations show that the coal alteration can take place at low temperatures. For this reason, coals from the Kladno- Rakovnik Basin, part of Late Paleozoic continental basins of the Czech Republic, were analyzed. Regarding coalification, micropetrographic characterizations of unaltered coals, the presence of thermally unstable Al complexes in the coal organic mass documented using ^27Al MAS NMR method, and proven occurrence of whewellite in pelosiderite concretions suggest a lower coalification temperature, max. -70 ℃. Regarding coal alteration, micropetrographic observations revealed (a) the weaker intensity of fluorescence of liptinite, (b) mylonitic structures and microbreccia with carbonate fluid penetration, and (c) high oxygen content in coals (37-38 wt.%). These phenomena are typical for thermal and oxidative alteration of coal. As the temperature of carbonate fluids inferred from fluid inclusion analysis was evaluated as -100-113 ℃, the temperature of coal alteration was suggested as -113℃; the alteration was caused by hot hydrothermal fluids. 展开更多
关键词 COALIFICATION Thermal and oxidative alteration Kladno-Rakovn Basin - Al complexes ^27Al mas nmr Fluid inclusions Δ^13C Whewellite
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Characterization of Aluminum(III) Complexes in Coal Organic Matter
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作者 Pavel Straka 《American Journal of Analytical Chemistry》 2016年第4期378-394,共17页
For geochemical purposes, complex aluminum compounds in coal organic matter in different types of coal were identified by solid state nuclear magnetic resonance measurements of <sup>27</sup>Al. Low ash sam... For geochemical purposes, complex aluminum compounds in coal organic matter in different types of coal were identified by solid state nuclear magnetic resonance measurements of <sup>27</sup>Al. Low ash samples of anthracites, bituminous coals and altered coals from the Czech Republic, Russia, Ukraine, China and Australia were tested;further, low ash lignite and xylite from the Czech Republic and gagatite from Poland were analyzed. In acquired <sup>27</sup>Al MAS NMR spectra, two significant peaks at chemical shifts were recorded, at 3.5 - 4 and 13.5 - 15 ppm. It was found that the significant peak at chemical shift at 3.5 - 4 ppm in spectra of bituminous coals, lignite, gagatite and a thermally weakly altered coal corresponds to that obtained for triaquo-hydroxo-diphenoxido-Aluminum(III) complex. The existence of triaquo-triphenoxido-Aluminum(III) complex in the spec- tra of anthracites, some bituminous coals and another thermally altered coal can be approved by the chemical shift at 13.5 - 15 ppm. These findings indicate that at least two different Al complexes were identified in coal organic matter. Further it was found that these complexes are concentrated in vitrinite fraction (alicyclic-aromatic part of coal), notably in collotelinite (gelified and homogenous vitrinite constituent). Ways of Al complexes formation in coal are suggested and their thermal stability is discussed. 展开更多
关键词 ALUMINUM Complex 27Al mas nmr COAL LIGNITE Altered Coal
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Characterization of humic acids extracted from the sediments of the various rivers and lakes in China 被引量:36
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作者 HE Mengchang SHI Yehong LIN Chunye 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2008年第11期1294-1299,共6页
The humic acids (HAs) isolated from the sediments of the various rivers,lakes,and reservoirs in China were studied using elemental analyzer,fourier transform infrared (FT-IR),and CP/MAS 13C nuclear magnetic resonance ... The humic acids (HAs) isolated from the sediments of the various rivers,lakes,and reservoirs in China were studied using elemental analyzer,fourier transform infrared (FT-IR),and CP/MAS 13C nuclear magnetic resonance (NMR) spectroscopy.The results showed that the HAs were characterized by some common chemical and physicochemical properties,but they also pose some differences in the C-containing functional groups.The C/N,C/H,O/C,and O/H ratios differ widely for the various HAs,showing that the elemental comp... 展开更多
关键词 CP/mas 13C nmr spectroscopy elemental analysis fourier transform infrared spectroscopy humic acids surficial sediment structural characteristics
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白洋淀沼泽区与开阔水域区颗粒物组分特征与沉降通量研究 被引量:3
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作者 季恺悦 李琦 +1 位作者 单保庆 张超 《环境科学学报》 CAS CSCD 北大核心 2022年第8期271-281,共11页
选取白洋淀的沼泽区(烧车淀)与开阔水域区(采蒲台)为研究区域,分析了水体中新生沉降颗粒物组分组成、沉降通量及其来源.结果表明,两种典型水域中水体颗粒物组分差异显著,其中,烧车淀水域颗粒物成分以有机质(OM)为主,质量占比达到49.59%~... 选取白洋淀的沼泽区(烧车淀)与开阔水域区(采蒲台)为研究区域,分析了水体中新生沉降颗粒物组分组成、沉降通量及其来源.结果表明,两种典型水域中水体颗粒物组分差异显著,其中,烧车淀水域颗粒物成分以有机质(OM)为主,质量占比达到49.59%~74.14%;而采蒲台水域颗粒物以无机组分为主,占比为54.52%~79.27%.烧车淀沉降颗粒物中总碳(TC)、总氮(TN)含量分别为(221.16±39.73)g·kg^(-1)和(21.10±1.67)g·kg^(-1);采蒲台沉降颗粒物中TC和TN的含量分别为(172.28±91.22)g·kg^(-1)和(15.72±8.12)g·kg^(-1).由固相^(13)C CP/MASNMR光谱结果分析出白洋淀沉降颗粒物中碳组分以烷基碳、烷氧基碳为主,其中,烧车淀淀面水域颗粒物中以易分解碳烷氧基碳为主(65.65%),采蒲台淀面水域颗粒物中以较稳定烷基碳为主(50.76%).开阔水域区颗粒物沉降通量高于沼泽化区,均值分别为10.63 g·m^(-2)·d^(-1)和6.07 g·m^(-2)·d^(-1);开阔水域区不同水域类型颗粒物沉降通量排序为水道((19.91±8.87)g·m^(-2)·d^(-1))>沟壕((7.06±2.94)g·m^(-2)·d^(-1))>淀面((4.92±3.48)g·m^(-2)·d^(-1)).沉降颗粒物的C/N和C/P比值结果表明,白洋淀沉降颗粒物中有机质主要来源可能为维管束植物和浮游植物.颗粒物沉降通量与组分特征研究有利于剖析白洋淀典型区域湖泊沉积和物质转化过程,为白洋淀能量流动和物质流动研究提供支撑. 展开更多
关键词 白洋淀 颗粒物 组分特征 沉降通量 ^(13)C CP/mas nmr
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