STUDY OF STRUCTURAL FEATURE OF PEAT,LIGNITE AND HUMIC ACID BY SOLID STATEl3C NMR SPECTROSCOPY

Abstract

Four low rank coals (peat and lignite) and their derived humic acids have been investigated by the^l3C CP/MAS/TOSS NMR technique. The NMR analysis indicates that the peat contains a significant amount of unaltered plant components including cellulose, hemicellulose, lignin, waxes, and resins.

Variable contact time and dipolar dephasing experiments were performed on each sample. The data from above experiments, together with normal CP/MAS integration over selected chemical shift range, were used to derive 12 parameters of carbon skeletal structure including the aromaticity.From the ratio of aromatic bridgehead carbons, f_a ^cp, to the aromatic peripheral carbons, f^cpxBp as measured by NMR, the aromatic cluster size may be estimated for each coal.     

CHARACTERIZATION OF THE STRUCTURAL FEATURES OF OXIDIZED BEYPAZARI LIGNITE USING DECONVOLUTED SOLID STATE 13C NMR SPECTRA

The solid state ¹³C NMR method have been used to investigate the structural changes occurred in Beypazari lignite while oxidizing at 150°C in a dynamic air atmosphere. Least squares curve fitting techniques have been used to resolve the overlapping bands in the 0-220 ppm region of the 13_c NMR spectra. Measurements of the relative intensities of the functional groups observed in the oxidized coals were used to follow the progress of air oxidation. Oxidation reactions seemed to decrease the total intensities of both aliphatics and aromatics, though the reduction in aliphatics was more pronounced. The relative intensities of the total aliphatics decreased from 1.0 to 0.9 and 0.6 in the original and lignites oxidized for 12 and 312 hours, respectively. The relative intensities of Ar-C-C in the 130-148 ppm region for the same set of samples were 1.0, 0.9 and 0.8. The least-squares bands resolved in the carbonyl region were at 175 ppm and 190 ppm in the original lignite; at 180 ppm (carboxylic acids), 195 ppm (meta substituted ketones) 210 ppm (di orto substituted ketones) in the lignite oxidized for 12 hours and at 170 ppm (esters), 180 ppm, 200 ppm (aldehydes) and 210 ppm in the lignite oxidized for 312 hr. Carbonyl intensity increased from 1.0 in the original lignite to 2.3 and 3.3 in the oxidized lignites. The intensity of aromatic ethers increased from 1.0 in the original lignite to 1.9 and 1.6 for the oxidized samples. The mechanism of oxidation ether. Aldehydes are easily oxidized to carboxylic acids in the presence of air by the free radical formation of a peroxy acid. The carboxylic acid formed by disproportionation reactions between the peroxy acid and aldehydes might combine with phenols to produce esters as it was observed in the present work. The presence of high free radical concentration in the oxidation atmosphere probably caused to abstract hydrogen atoms from the aromatic structures thus degrading aromatics to produce hydroperoxides which acted later as it was described above. The gradual degradation of aromatic structures observed in the present study indicated that the oxidation reactions of the aromatic rings should less probable when compared to the oxidation of aliphatic structures.     

CHARACTERIZATION OF THE STRUCTURAL FEATURES OF OXIDIZED BEYPAZARI LIGNITE USING DECONVOLUTED SOLID STATE 13C NMR SPECTRA

ABSTRACT

The solid state ¹³C NMR method have been used to investigate the structural changes occurred in Beypazari lignite while oxidizing at 150°C in a dynamic air atmosphere. Least squares curve fitting techniques have been used to resolve the overlapping bands in the 0-220 ppm region of the 13_c NMR spectra. Measurements of the relative intensities of the functional groups observed in the oxidized coals were used to follow the progress of air oxidation. Oxidation reactions seemed to decrease the total intensities of both aliphatics and aromatics, though the reduction in aliphatics was more pronounced. The relative intensities of the total aliphatics decreased from 1.0 to 0.9 and 0.6 in the original and lignites oxidized for 12 and 312 hours, respectively. The relative intensities of Ar-C-C in the 130-148 ppm region for the same set of samples were 1.0, 0.9 and 0.8. The least-squares bands resolved in the carbonyl region were at 175 ppm and 190 ppm in the original lignite; at 180 ppm (carboxylic acids), 195 ppm (meta substituted ketones) 210 ppm (di orto substituted ketones) in the lignite oxidized for 12 hours and at 170 ppm (esters), 180 ppm, 200 ppm (aldehydes) and 210 ppm in the lignite oxidized for 312 hr. Carbonyl intensity increased from 1.0 in the original lignite to 2.3 and 3.3 in the oxidized lignites. The intensity of aromatic ethers increased from 1.0 in the original lignite to 1.9 and 1.6 for the oxidized samples. The mechanism of oxidation ether. Aldehydes are easily oxidized to carboxylic acids in the presence of air by the free radical formation of a peroxy acid. The carboxylic acid formed by disproportionation reactions between the peroxy acid and aldehydes might combine with phenols to produce esters as it was observed in the present work. The presence of high free radical concentration in the oxidation atmosphere probably caused to abstract hydrogen atoms from the aromatic structures thus degrading aromatics to produce hydroperoxides which acted later as it was described above. The gradual degradation of aromatic structures observed in the present study indicated that the oxidation reactions of the aromatic rings should less probable when compared to the oxidation of aliphatic structures.     

STRUCTURAL STUDIES OF SHORT PATH DISTILLATES AND SUPERCRITICAL FLUID EXTRACT OF PETROLEUM SHORT RESIDUE BY NMR SPECTROSCOPY

Four short-path distillates obtained at different evaporator temperatures (240, 270, 300, and 330° C) and a supercritical fluid extract (with CO₂ as solvent) of petroleum short residue (North Gujarat Mix) have been separated into saturates and aromatics. Each fraction of all the said samples has been studied by ¹H- and ¹³C-NMR spectrometry and the distributions of various types of hydrogens and carbons are reported. Several reliable average structural parameters have been computed and their relative variation is discussed.     

STRUCTURAL STUDIES OF SHORT PATH DISTILLATES AND SUPERCRITICAL FLUID EXTRACT OF PETROLEUM SHORT RESIDUE BY NMR SPECTROSCOPY

Abstract

Four short-path distillates obtained at different evaporator temperatures (240, 270, 300, and 330° C) and a supercritical fluid extract (with CO₂ as solvent) of petroleum short residue (North Gujarat Mix) have been separated into saturates and aromatics. Each fraction of all the said samples has been studied by ¹H- and ¹³C-NMR spectrometry and the distributions of various types of hydrogens and carbons are reported. Several reliable average structural parameters have been computed and their relative variation is discussed.     

STRUCTURE AND REACTIONS OF BEYPAZARJ LIGNITE I. CHARACTERIZATION BY 13C NMR AND IR STUDIES

ABSTRACT

The solid state ¹³C NMR and infrared spectra of Beypazan lignite were deconvoluied by the least squares curve fitting techniques to resolve the overlapping bands in the 0-220 ppm region of the ¹³C NMR spectra and in the 4000-2700 cm^-1, 1860-900 cm^-1 and 900-400 cm^-1 regions of the infrared spectra to gain information about the structure of the lignite. Measurement of integral absorptivities of some of the functional groups present in the infrared spectra was attempted. Measured values of integral absorptivities are in good agreement with those reported previously.     

STRUCTURE AND REACTIONS OF BEYPAZARJ LIGNITE I. CHARACTERIZATION BY 13C NMR AND IR STUDIES

The solid state ¹³C NMR and infrared spectra of Beypazan lignite were deconvoluied by the least squares curve fitting techniques to resolve the overlapping bands in the 0-220 ppm region of the ¹³C NMR spectra and in the 4000-2700 cm^-1, 1860-900 cm^-1 and 900-400 cm^-1 regions of the infrared spectra to gain information about the structure of the lignite. Measurement of integral absorptivities of some of the functional groups present in the infrared spectra was attempted. Measured values of integral absorptivities are in good agreement with those reported previously.     

SOLID STATE 13 C NMR STUDY OF CHINESE COALS

Ten coals of different metamorphic degree have been investigated by the use of ¹³ C CP/MAS NMR technique, of which the spin-lattice relaxation, variable contact time and dipolar dephasing experiments were performed on each coal. The data from above experiments, together with normal CP/MAS integration over selected chemical shift ranges, were used to derive 12 parameters of carbon skeletal structure including the aromaticity. These parameters are correlated with carbon content (weight per cent) in coal and we find that there are close relations between the NMR parameters and metamorphic degree of coals- From the ratio of aromatic bridgehead to aromatic peripheral carbons as measured by NMR, the aromatic cluster size may be estimated for each coal.     

工业α-烯烃中异构体结构的核磁共振分析

针对已知结构α-烯烃的标准谱图缺少的问题，提出了归属工业α-烯烃中异构体的核磁共振碳谱的“三步法”，即按强度把各谱峰归属给各组分；按双键碳原子化学位移加和规律归属各组分的不饱和碳原子，初步确定各组分结构；根据双键对饱和碳原子化学位移的取代效应计算烷链碳原子的化学位移，佐证各组分的结构。通过对4种工业α-烯烃样品C10^=，C12^=，C16^=和C24^=的组成和各组分结构的测定实例说明该方法可行。     

用S—甲基化反应和^2H NMR,^13C NMR表征石油中有机硫的结构

提出用衍生物－ＮＭＲ表征石油中的有机硫结构的方法，在四氟硼酸银的存在下，分别用＾２Ｈ或＾１３Ｃ同位素富集的碘甲烷，把石油中的有机硫定量地转变为相应的甲基镀盐，然后用＾２ＨＮＭＲ和＾１３ＣＮＭＲ表征硫化物的结构，给出了一些模型甲工铳盐的＾２ＨＮＭＲ和＾１３ＣＮＭＲ化学位移值。分析结果表明，石油中噻吩类为苯并噻吩型等结构，硫醚为脂肪硫醚，二苯硫醚及α－萘基甲基硫醚等，阿拉伯原油样品中，大约７０％的硫化     

在NKC-1A固体酸催化剂上合成丙二醇醚类的研究

研究了环氧丙烷与脂肪醇在 NKC-1A 固体酸催化剂上合成丙二醇醚类的反应。结果表明,NKC-1A 催化剂在室温下,对合成丙二醇醚类具有较高的活性,测定了该催化剂的活化能。反应温度和空速对环氧丙烷的转化率影响不大。     

DENITROGENATION OF LUBRICATING BASE OILS BY SOLID ACID

Oxidation stability is one of the most important properties of lubricating base oils. Nitrogen compounds especially basic nitrogen compounds play a negative role to the oxidation stability of lubricating base oils. A new method to remove the nitrogen compounds of lubricating base oils is suggested in the paper. A type of solid acid was employed as an effective reagent to get rid of the basic and non-basic nitrogen compounds while it removes relatively less sulfur compounds. Clay treating after the solid acid denitrogenation can apparently improve the oxidation stability of denitrogenated base oils. Appropriate conditions are found for the solid acid denitrogenation.     

酸法合成拟薄水铝石的研究与表征

研究了硫酸铝为原料合成拟薄水铝石的酸法工艺及影响因素，总工程师 化学分析，XRD，IR对所制备的拟备的拟薄水铝石与目前工业使用的山东拟薄水铝石进行比较，结果表明：以酸法合成的拟薄水铝石具有氧化铝含量高，比表面积大，杂质少的特点，但结晶度略低。     

SOLID STATE 13C NMR STUDY OF THERMALLY UPGRADED LOW RANK COALS

ABSTRACT

The results of solid-state ¹³C NMR study aimed at evaluating the chemical changes and extent of upgrading achieved in the thermal treatment of two western Canadian low rank coals are discussed. The coals were thermally treated at varying temperatures (200 - 500°C) using different process media (nitrogen, steam and products of combustion)

Apparent aromaticity of the two coals was increased after the thermal treatment and increased with treatment temperature. Significant chemical changes, such as loss of the protonated aromatic carbons, quaternary carbons in alkylated rings and aliphatic ethers, were observed at 400°C and above. Condensation and polymerization of the chemical components were also evident. The effect of process medium was found to depend on the coal feed and the treatment temperature.     

SOLID STATE 13C NMR STUDY OF THERMALLY UPGRADED LOW RANK COALS

The results of solid-state ¹³C NMR study aimed at evaluating the chemical changes and extent of upgrading achieved in the thermal treatment of two western Canadian low rank coals are discussed. The coals were thermally treated at varying temperatures (200 - 500°C) using different process media (nitrogen, steam and products of combustion)

Apparent aromaticity of the two coals was increased after the thermal treatment and increased with treatment temperature. Significant chemical changes, such as loss of the protonated aromatic carbons, quaternary carbons in alkylated rings and aliphatic ethers, were observed at 400°C and above. Condensation and polymerization of the chemical components were also evident. The effect of process medium was found to depend on the coal feed and the treatment temperature.     

DETERMINATION OF THE GERMANIUM CONTENT OF LIGNITE BY ATOMIC ABSORPTION SPECTROMETRY USING A SOLID SAMPLE AND A GRAPHITE FURNACE ATOMISER

ABSTRACT

The germanium content of lignite is directly determined using a solid lignite sample. A standard solution of Ge was added to powdered coal samples which were then dried. A simple metallic bar with a cavity in it was used to introduce the sample into the furnace. Optimum temperature programming was determined to obtain Ge signals as free as possible from matrix interferences. Under optimum conditions 1 ng of Ge could be determined in a solid sample. The sensitivity of Ge as (Absorbancs/g Ge) was about 500 times greater in solid sample analysis then in liquid sample analysis.     

DETERMINATION OF THE GERMANIUM CONTENT OF LIGNITE BY ATOMIC ABSORPTION SPECTROMETRY USING A SOLID SAMPLE AND A GRAPHITE FURNACE ATOMISER

The germanium content of lignite is directly determined using a solid lignite sample. A standard solution of Ge was added to powdered coal samples which were then dried. A simple metallic bar with a cavity in it was used to introduce the sample into the furnace. Optimum temperature programming was determined to obtain Ge signals as free as possible from matrix interferences. Under optimum conditions 1 ng of Ge could be determined in a solid sample. The sensitivity of Ge as (Absorbancs/g Ge) was about 500 times greater in solid sample analysis then in liquid sample analysis.     

浓硫酸改性煤基活性炭催化合成丙二酸二丁酯

以浓硫酸改性煤基活性炭为催化剂,丙二酸和正丁醇为原料合成了丙二酸二丁酯,考察了醇酸物质的量比、催化剂用量、反应时间等因素对酯化率的影响。最佳工艺条件为:丙二酸50 mmol,n(酸):n(醇)=1:2.5,催化剂用量0.8g,反应时间1.5h,酯化率达99.0%。催化剂可回收使用,具有较高的催化活性     

改性腐植酸合成油基钻井液降滤失剂

采用有机胺对腐植酸进行改性,用做油基钻井液降滤失剂,以替代沥青类产品,提高机械钻速和保护环境。探索了合成产物性能的影响因素,并评价了在油基钻井液中的性能。改性腐植酸降滤失剂最佳合成条件为:腐植酸与有机胺 H60B 摩尔比15:6,反应温度190℃,反应时间8～9 h。改性腐植酸降滤失剂具有良好的降滤失效果,在加量为3%时,150℃高温高压滤失量为6.8 mL,好于沥青类降滤失剂,并且对钻井液流变性影响较小。