Search

Carbazole compounds are widely used in determining the direction of petroleum migration, but the effect of thermal maturity on carbazoles is still ambiguity. In this paper, using compaction pyrolysis simulation experiments, artificial mature samples with vitrinite reflectance (R o ) range from 0.38 to 3.0% were acquired. And the content and composition change characteristics of carbazole compounds were analyzed in coal source rocks. The experimental results showed that thermal maturity controls the generation of a large amount of carbazole compounds in coal rocks. Compared with the low mature stage, the content of carbazole compounds was about 10-100 times higher in the mature stage. With the increasing maturity, in the coal sample, the content of carbazole compounds showed a trend of first increasing and then decreasing. In derivatives of carbazole, the corresponding maturity for the maximum generation of ethylcarbazole (EC), dimethylcarbazole (DMCA), methylcarbazole (MCA), carbazole (CA) and benzocarbazole (BCA) performed the increasing sequence. With the increasing maturity, the relative abundance of 2-MCA, 1,7-DMCA and benzo[a]carbazole increased with the increasing maturity, while 4-MCA, 1,4-DMCA and benzo[c]carbazole gradually decreased. Benzocarbazole ratio [a]/[a] +[ c] varies only in a narrow range 0.36-0.61 in the entire maturity range, suggesting limited maturity dependence. The experimental conclusion provides more theoretical basis for future geochemical analysis using carbazole compounds., (© 2024. The Author(s).)

This paper presents a small-scale column chromatography method for separating hopanes in crude oil or rock extracts using neutral alumina as a solid phase adsorbent and a Pasteur pipette as a separation device. Three oil samples were selected to study the effect of solid phase adsorbent type and column length on the separation of hopanes. The oil samples were eluted with mixed reagents (V hexane : V petroleum ether  = 8:2) and collected at intervals of 0.5 ml. Ten Fractions were collected and tested for the compounds using GC-MS. A quantitative approach was used to reveal distribution characteristics of compounds in each eluted Fraction. Experimental results showed that 100-200 um neutral alumina exhibited significant differences in the adsorptive capacity of biomarkers from oil samples and rock extracts. The elution order of the biomarkers in the chromatographic column (the length is 180 mm) was n-alkanes, steranes and hopanes. The separation of hopanes could be realized by collecting the eluted Fractions 4 and 5. Compared with the urea complexation, the purity of hopanes separated by column chromatography was higher. The concentration of n-alkanes (nC 16 -nC 34 ) could be reduced from 1.99 to 4.83 mg/ml to 0.79-0.94 mg/ml, and the content of steranes can be reduced from the original 12% to 0.45%. Residual n-alkanes and steranes were not visible in the GC-MS detection. The Total Ion Chromatography (TIC) of hopanes was consistent with the distribution characteristics of the m/z191 mass chromatogram. The isolated hopanes could meet the detection requirements of isotope ratio mass spectrometry. The C 29 Ts/C 29 αβ ratio of hopanes decreased gradually from 1.63 to 0.73 as the column length increased. It is speculated that the variation of the C 29 Ts/C 29 αβ ratio is not only affected by maturity but also by the oil and gas migration. This method is a new attempt in the field of compound purification and can be widely used in the study of stable carbon isotopes of hopanes monomeric hydrocarbons., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier B.V.)

Continuous improvement of rural human settlements is a major realistic requirement of China's economic and social development in the context of rural revitalization. Tracking and evaluating the phased progress of human settlement construction in stages represent important techniques for ensuring continual improvement. To improve the current objective data-based index system, this paper focuses on the villager-centered evaluation system at the village level. Factor analysis is used to screen the original data from the questionnaire and minimize the dimensions to synthesize common factors on the basis of empirical results. The main conclusions are as follows: (1) according to weight, the satisfaction evaluation system includes five common factors: living support facilities, nonagricultural industry income, agriculture production income, transportation infrastructure, and comprehensive ecological improvement. The results show that construction investment is beneficial, but not directly proportional to the villagers' satisfaction. Actual improvement is not keeping up with the demand for public fitness, cultural, and recreational facilities. On the other hand, changes in villagers' lifestyles may reduce the need for commercial facilities; (2) according to the evaluation model, the indicators can be classified into four categories on the basis of the weight assessment score, all of which can provide differentiated construction strategies to avoid duplication and inefficient resource waste. The survey data's indicators of major differences between villages, such as public transportation and sanitation, need further discussion; (3) the gap between actual improvement actions and villagers' needs gives an optimization path for rural construction. The experiences of sample villages in well-developed areas can be used as a model for policy formulation in other regions, and a long-term follow-up investigation should be included in future studies.