微波消解-原子吸收光谱法测定汽油中的铁

采用微波方法消解汽油样品,将汽油样品置于密闭容器内,加入一定量的硝酸,放在微波消解系统内进行消解。用正交试验研究了压力、消解时间、微波功率和酸度对消解效果的影响,确定了微波消解的最佳工作参数。对铁元素的测定进行了背景吸收干扰及化学干扰影响的研究。建立了用微波消解．原子吸收光谱法测定汽油中铁的方法。研究结果显示：该法测定精度高,相对标准偏差（n=5）≤1．45％,加标回收率为96．3％～104．4％,具有取样量少、消解用酸量少、操作简单、减少环境污染等优点。     

降低我国车用汽油烯烃含量的措施探讨

降低我国车用汽油烯烃含量的关键是降低催化裂化汽油的烯烃含量,而国内目前广泛采用的在催化裂化装置上使用降烯烃催化剂的方法是降低FCC汽油烯烃含量,此外国内开发的一些新型的催化裂化反应工艺,如MIP、MGD、FDFCC等也能明显降低FCC汽油的烯烃含量。指出为了进一步降低汽油烯烃含量,以应对更加严格的车用汽油标准,我国炼油业应在大力推行加氢工艺的基础上优化加工流程,发展重整、烷基化、醚化等多种工艺,彻底改变我国车用汽油池组成单一的现状。     

渗透汽化汽油脱硫技术研究进展

随着环保法规的日益严格,世界各国对清洁汽油中硫含量做出了严格的规定,汽油的低硫化甚至无硫化已成为一种必然趋势,汽油的深度脱硫技术已成为各石油公司和相关研究者的研究热点。渗透汽化是一种新型高效的膜分离技术,其在汽油深度脱硫技术方面具有独特优势。介绍了渗透汽化汽油脱硫技术的基本原理、工艺特点及国内外有关研究进展情况。     

The physical character of coal char formed during rapid pyrolysis at high pressure

Rapid pyrolysis was conducted in a drop tube reactor using seven coals under various operating conditions. In addition to dense char, porous chars (network char and cenospheric char) were formed by the rapid pyrolysis under certain conditions. Porous char was mainly composed of film-like carbon and skeleton carbon. The pyrolyzed coal char particles were characterized in detail. Morphology and bulk density of porous char were quite different from the dense char formed under the same conditions, but elemental composition and BET surface area were similar to each other. CO₂ gasification reactivity of porous char was lower than dense char in the later gasification stage, and this was ascribed to the low reactivity of skeleton carbon.     

A predictive thermodynamic model for the Brazilian gasoline

In Brazil, as in many other countries, the fuel quality control is made according to standard assays, which depend on some of the fuel properties, such as specific gravity, Reid vapor pressure and distillation curve. These properties are intimately related to the fuel composition and their prediction relies on the knowledge of its components characteristics. In Brazil, 25% (v/v) of anhydrous ethanol is added to the mixture of hydrocarbons that is usually called gasoline, according to the local regulations. In this work, the composition of the gasoline was obtained by gas chromatography as a small series of pseudo-components. Given the gasoline composition, its volatility properties and specific gravity were calculated using the Peng-Robinson equation of state with the Fisher-Gmehling mixing rule. The model provided excellent predictions for specific gravity, Reid vapor pressure and most of the distillation curve. However, important deviations are observed at the end of the distillation curve (90+%). These deviations are due to chemical alterations of the fuel caused by the high temperatures occurring at the end of the distillation curve. The model, as proposed, is efficient to forecast the fuel properties; as a consequence, it can be applied as a tool in the study of gasoline formulations and as an alternative tool in quality control.     

Pyrolysis of brown coal under different process conditions

Pyrolysis tests were performed under laboratory conditions, simulating possible processes in the burning of brown coal mines. These tests focused on gaseous products of thermal decomposition of coal and how their concentrations changed depending on pyrolysis temperature. Results obtained can help to quantify the contributions of particular gases to overall explosiveness of a gaseous mixture and can explain the process of explosive gas release during conflagration.     

Carbon-encapsulated Fe nanoparticles from detonation-induced pyrolysis of ferrocene

Carbon-encapsulated Fe nanoparticles with size between 5 and 20 nm were synthesized via a picric acid-detonation-induced pyrolysis of ferrocene, which is characterized by a self-heating and extremely fast process. The nanoparticles exhibit well-constructed core-shell structures, with bcc-Fe cores and graphitic shells. The graphitic shells can protect effectively the cores against the attack of HNO₃ solution. The formation of the core-shell nanoparticles can be selectively controlled by adjusting the composition of the picric acid-ferrocene mixture, which determines C/Fe atomic ratio of the reaction system. The core-shell nanoparticles are preferably formed at low C/Fe atomic ratios, while tubular structures are formed at high C/Fe ratio. The possible pathway for the carbon-encapsulated Fe nanoparticles formation is discussed briefly.     

An investigation of the effects of pyrolysis parameters on gas separation properties of carbon materials

A significant extension of an earlier analysis of molecular sieving carbons formed from polymeric precursors is reported for separation of important gas pairs including O₂/N₂, CO₂/CH₄ and C₃H₆/C₃H₈. Previously, it was shown that changing the time or temperature of the pyrolysis protocol for a commercially available polyimide (Matrimid^®) altered the final properties of the carbons produced. Changing the precursor material was shown in this study to also affect the final carbon material obtained for a given final pyrolysis temperature. Analysis of low temperature carbon dioxide adsorption isotherms using density functional theory was employed to characterize the microporosity of the materials. Results are given here for a totally different packing-inhibited polyimide precursor (6FDA/BPDA-DAM). Sorption, permeation and diffusion data are compared with those obtained using the more densely packed commercial polyimide precursor Matrimid^® studied earlier. Thermal soak was also investigated and the effect on permeation properties determined for carbons using both precursors. The results indicate that carbons from both precursors have size-selective ultramicropores as well as larger nonselective micropores that provide high capacity sorption sites for penetrants. High permselectivities, combined with high permeabilities are found for some of the samples when compared with conventional polymer materials. A hypothetical ultramicropore size distribution is shown to be useful to relate transport data to results from more commonly used characterization techniques such as pore size distribution analysis.