Acidity effects of Hβ zeolite on olefin alkylation of thiophenic sulfur in gasoline

Olefin alkylation of thiophenic sulfur process was carried out in model gasoline, using Hβ zeolites with different Si/Al2 ratios as catalysts. In particular, the influence of acid properties of Hβ zeolites on its catalytic ability for the thiophene alkylation, xylene alkylation and hexene oligomerization was investigated. The results showed that the acidity of the Hβ zeolite was increased with the decrease of Si/Al2 ratio, but its catalytic ability was not always increased. In fact, it reached the maximal catalytic ability at Si/Al2 ratio of 66, and under the reaction conditions of 60 ℃, 1.5 MPa, WHSV 3.0 h-1and time on stream 2 h. At the ratio, the conversion of thiophene, xylene, and oligomerized hexene were 96.6%, 2.7% and 2.8%, respectively. An optimal Si/Al2 ratio exists for the catalytic performance of H/3 zeolite. By investigating the coke deposition of the used H/3 zeolite catalysts, it has been found that the optimal Si/Al2 ratio is attributed to the combined effect of the carbocation activation capability and the hydrogen transformation capability of the H/3 zeolite catalyst.     

In situ FT-IR spectroscopy investigations of carbon nanotubes supported Co-Mo catalysts for selective hydrodesulfurization of FCC gasoline

To better understand the nature of carbon nanotubes supported Co-Mo catalysts （Co-Mo/CNTs） for selective hydrodesulfurization （HDS） of fluid catalytic cracking （FCC） gasoline, studies are carried out using in situ Fourier transform infrared spectroscopy （FT-IR）. The catalytic performances of Co-Mo/CNTs catalysts were evaluated with a mixture of cyclohexane, diisobutylene, cyclohexene, 1-octene （60 ： 30 ： 5 ： 5, volume ratio） and thiophene （0.5%, ratio of total weight） as model compounds to simulate FCC gasoline. The HDS experimental results suggested that the HDS activity and selectivity of Co-Mo/CNTs catalysts were affected by Co/Mo ratio; the optimal Co/Mo atomic ratio is about 0.4, and the optimum reaction temperature is 260 ℃. The in situ FT-IR studies revealed that 1-octene can be completely saturated at 200 ℃. In the FT-IR spectra of diisobutylene, the characteristic absorption peak around 3081 cm^-1 for the stretching vibration peak of =C-H bond was still clear at 320 ℃ indicating that diisobutylene is difficult to be hydrogenated. As for the thiophene, no characteristic absorption peak could be found around 3092 cm^-1 and 835 cm^-1 when the reaction temperature was raised to 280 ℃, indicating that thiophene had been completely hydrodesulfurized. On the basis of FT-IR results, it can be deduced that thiophene HDS reaction occurred mainly through direct hydrogenolysis route, whereas thiophene HDS and diisobutylene hydrogenation reaction over Co-Mo/CNTs catalysts might occur on two different kinds of active sites.     

Probing the sulfur content in gasoline quantitatively with terahertz time-domain spectroscopy

Terahertz time-domain spectroscopy(THz-TDS)was used for the quantitative detection of sulfur content in gasoline.Models of chemo metrics methods and partial least squares(PLS)were built to measure THz-TDS and the sulfur content.All of the samples were divided into two parts.One part was used for calibration and the other one for validation.In order to evaluate the quality of the models,the correlation coefficient(R)and root-mean-square errors(RMSE)of calibration and validation models were calculated.The value of R and RMSE were close to 1 and 0 within acceptable levels,respectively,indicating that the combination of THz-TDS and PLS is a potential method for further quantitative detection.     

Screening Brazilian commercial gasoline quality by hydrogen nuclear magnetic resonance spectroscopic fingerprintings and pattern-recognition multivariate chemometric analysis

The identification of gasoline adulteration by organic solvents is not an easy task, because compounds that constitute the solvents are already in gasoline composition. In this work, the combination of Hydrogen Nuclear Magnetic Resonance (¹H NMR) spectroscopic fingerprintings with pattern-recognition multivariate Soft Independent Modeling of Class Analogy (SIMCA) chemometric analysis provides an original and alternative approach to screening Brazilian commercial gasoline quality in a Monitoring Program for Quality Control of Automotive Fuels. SIMCA was performed on spectroscopic fingerprints to classify the quality of representative commercial gasoline samples selected by Hierarchical Cluster Analysis (HCA) and collected over a 6-month period from different gas stations in the São Paulo state, Brazil. Following optimized the ¹H NMR-SIMCA algorithm, it was possible to correctly classify 92.0% of commercial gasoline samples, which is considered acceptable. The chemometric method is recommended for routine applications in Quality-Control Monitoring Programs, since its measurements are fast and can be easily automated. Also, police laboratories could employ this method for rapid screening analysis to discourage adulteration practices.     

Rapid detection of gasoline by a portable Raman spectrometer and chemometrics

Identification of the gasoline purity is important for quality control and detection of gasoline adulteration. Principal component analysis and Raman spectroscopy were used to authenticate gasoline adulterated with methyl tert‐butyl ether (MTBE) and benzene. Gasoline could be clearly distinguished from gasoline adulterated with MTBE and benzene by a plot of the first principal component (x‐axis) against the second principal component (y‐axis). And the radial basis function neural network was used for quantitative prediction of the volume percentages of MTBE and benzene in gasoline based on Raman Spectra. The correlation coefficient (r) and mean absolute percentage error between predictive values and spiked values were 0.9907 and 0.9934 and 15.73 and 8.19%, respectively. Moreover, the Raman spectra of the samples were obtained with a portable Raman spectrometer. Therefore, the method is simple, effective, fast, does not require sample pre‐processing, and is promising for rapid gasoline detection. Copyright © 2012 John Wiley & Sons, Ltd.     

混氢改善汽油机稀燃性能的试验研究

针对汽油机稀燃条件下循环变动大,燃料燃烧不充分的问题,本文在一台加装了电控氢气喷射系统的四缸汽油机上就混氢对改善汽油机稀燃条件下燃烧与排放性能的作用进行了试验研究。在发动机1400r/min,进气道绝对压力为61.5 kPa的条件下,就1%与3%两种进气混氢体积分数对稀燃汽油机燃烧与排放特性的影响进行了研究。试验结果表明,稀燃时发动机制动热效率随混氢分数增加而提高;滞燃期与速燃期随混氢分数增加而缩短;发动机稀燃极限所对应的过量空气系数由原机的1.45提高至混氢1%与3%时的1.55和1.96。混氢后发动机HC与CO排放降低,但NO_x排放有所升高。     

废气进口位置对汽油机性能和NOx排放影响的研究

为同时兼顾排放性、经济性和动力性,提高汽油机废气再循环率,提出改变EGR进气方式,将EGR废气通过管路直接通到进气门处的方案。在一台四气门汽油机上对进气门处单侧通废气与中央通废气的方式进行了对比试验。试验结果表明,与中央进气方式的EGR相比,单侧EGR进气方式在降低同样NOx的排放的情况下,具有更高的燃油经济性、动力性和EGR率。另外,单侧EGR不必降低EGR进气温度,即能获得较较好的发动机性能。     

有机进样–电感耦合等离子体质谱法测定汽油中锰、铁、铅

建立有机进样-电感耦合等离子体质谱法(ICP-MS)测定汽油中锰、铁、铅含量的分析方法。以乙醇为稀释剂,选择水性无机元素标准溶液为标准物质,采用标准加入法并加入内标校正、补偿基体干扰效应后直接稀释进样分析,用碰撞模式消除多原子离子质谱干扰。锰、铁、铅的含量在0.00~20.00 μg/kg范围内具有良好的线性关系,相关系数均大于0.999,检出限分别为0.20,0.50,0.05 μg/kg。按标准加入法进行回收试验,加标回收率分别为81.9%~95.5%,85.4%~103.1%,97.4%~101.4%,测定结果的相对标准偏差均小于6%(n=6)。该方法快速、准确,灵敏度高,操作简便,试剂用量小,能满足实际汽油样品中微量锰、铁、铅含量的分析要求。     

THz wave sensing for petroleum industrial applications

We present the results of terahertz (THz) sensing of gasoline products. The frequency-dependent absorption coefficients, refractive indices, and complex dielectric constants of gasoline and xylene isomers were extracted in the spectral range from 0.5–3.0 THz. The THz spectra of gasoline (#87, #89, #93) and related BTEX (benzene, toluene, ethylbenzene, and xylene) compounds were studied by using Fourier transform infrared spectroscopy (FTIR) in the 1.5–20 THz (50–660 cm⁻¹). The xylene isomers, which are used as antiknock agent in gasoline were determined quantitatively in gasoline in the THz range. Our investigations show the potential of THz technology for the petroleum industrial applications.     

气相色谱-表面电离检测器分析汽油中含氮化合物的分布

采用液液萃取的方法分别从90#、93#、97#汽油中提取了含氮化合物,并将气相色谱(GC)和作者所在研究组研制的表面电离检测器(SID)联用对含氮化合物进行了分析。结合GC-氢火焰离子化检测器(FID)、GC-氮磷检测器(NPD)和GC-质谱(MS)的分析结果,可鉴定出GC-SID谱图中的峰基本为含氮化合物,且大部分为NPD和FID未检出的峰,说明SID的选择性和灵敏度更好。分析结果表明,这3种汽油含氮化合物种类相似,含量有所差异;所提取的含氮化合物主要是苯胺类化合物;SID能从汽油样品中检出多种痕量的高沸点含氮组分,对于检测含氮组分而言,SID具有优于商品NPD的灵敏度和选择性。SID为GC分析提供了一种性能优异的选择性检测器。