排序方式: 共有7条查询结果,搜索用时 46 毫秒
1
1.
Yong-Hyun Kim Ki-Hyun Kim Jan E. Szulejko Min-Suk Bae Richard J.C. Brown 《Analytica chimica acta》2014
For the quantitative analysis of ‘compounds lacking authentic standards or surrogates’ (CLASS) in environmental media, we previously introduced an effective carbon number (ECN) approach to develop an empirical equation for the prediction of their response factor (RF). In this research, a series of laboratory experiments were carried out to benchmark the reliability of an ECN approach for sorbent tube/thermal desorption/gas chromatography (GC)/mass spectrometry (MS) applications. First, the ECN values were determined using external calibration data from 25 reference volatile organic compounds (VOCs) using two MS dectectors (quadrupole (Q) and time-of-flight (TOF)). Then, a certified standard mixture of 54 VOCs was analyzed by each system as a simulated unknown sample. The analytical bias, assessed in terms of percentage difference (PD) between the certified and ECN-predicted mass values, averaged 19.2 ± 16.1% (TOF-MS) and 28.2 ± 27.6% (Q-MS). The bias using a more simplified carbon number (CN)-based prediction increased considerably, yielding 53.4 ± 53.3% (TOF-MS) and 61.7 ± 81.3% (Q-MS). However, the bias obtained using the ECN-based prediction decreased significantly to yield average PD values of 9.84 ± 7.28% (TOF-MS) and 16.8 ± 8.35% (Q-MS), if the comparison was limited to 26 (out of 54) VOCs with CN ≥ 4 (i.e., 25 aromatics and hexachlorobutadiene). 相似文献
2.
3.
4.
TiO2/AC复合光催化剂对苯和丁醛的气相光催化降解机理 总被引:1,自引:0,他引:1
利用溶胶-凝胶并水热处理法制备了TiO2光催化剂和TiO2/AC复合光催化剂,在静态光催化反应器中研究了苯和丁醛的气相吸附和光催化降解,利气相色谱分析确定了生成的中间体. 结果表明, TiO2/AC复合光催化剂比TiO2光催化剂具有较强的吸附能力和较高的光催化活性; 在TiO2和TiO2/AC上,苯(或丁醛)光催化降解产生相同的中间体,表明在两种催化剂上发生的光催化反应遵循相同的机理,进而讨论了其可能的光催化氧化途径. 相似文献
5.
ZHANG Jing-chang GAO Xi-xin CAO Wei-liang 《高等学校化学研究》2005,21(6):687-691
Supercritical carbon dioxide(SC-CO2 ) is considered in green chemistry as a substitute for conventional solvents in chemical reactions due to its environmentally benign character. Recently we have reported the homogeneous hydroformylation of propylene in supercritical carbon dioxide( SC-CO2 ) , which is an example of this kind of application of carbon dioxide. The determination for the critical parameters of carbon dioxide + butyraldehyde mixtures is necessary for this reaction design which is the focus of the present paper. The critical parameters of the binary systems were determined via the static visual method at a constant volume with the molar fraction of butyraldehyde ranging from 1.0% to 2. 2% and the pressure ranging from 5 to 10 MPa. The experimental results show that the critical pressure and temperature increased with increasing the molar fraction of butyraldehyde. The bubble(dew) temperatures and the bubble (dew) pressures for the binary systems were also determined experimentally. The p-T Figures at different compositions of the binary systems were described. In addition, the critical compressibility factors Zc of the binary systems at different concentrations of n-butyraldehyde were calculated. It was found that the critical compressibility factor values of the binary systems decreased with increasing the molar fraction of n-butyraldehyde in the experimental range. 相似文献
6.
Ya. I. Isakov Kh. M. Minachev R. Tome A. Tissle G. Oehlmann V. P. Kalinin T. A. Isakova 《Russian Chemical Bulletin》1994,43(12):2004-2010
It is found that zeolite-like crystalline aluminophosphates VPI-5, Si-VPI-5, and Mn-VPI-5 as well as those dirived from them, AlPO{in4}-8, SAPO{in4}-8, and MnAPO{in4}-8, are capable of catalyzing aldol condensation and crotonization of butyraldehyde (BA). Pd/AlPO{in4}-8 is catalytically active in hydrocondensation of BA with H{in2} at atmospheric pressure. The activities in BA conversion to 2-ethylhexane-3-ol-1-al increase in the following order: Mn-VPI-5 < Si-VPI-5 < VPI-5. The same order of activities is also found for AlPO{in4}-8, SAPO{in4}-8, and MnAPO{in4}-8. These catalysts are characterized by a lower initial activity in crotonization of BA than M{su+}NaX (CsNaX), but they are much more stable. Pd/AlPO{in4}-8 catalyzes BA conversion to 2-ethylhexanal even in the absence of H{in2} feed to the reaction zone. The influence of catalyst pretreatments and experimental conditions on the catalyst structures and catalytic activities is discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khmicheskaya, No. 12, pp. 2123–2129, December, 1994. 相似文献
7.
1