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1.
采用后合成法制备Hβ/Al-SBA-15复合分子筛,利用XRD、N_2吸附、Py-IR、NH_3-TPD、SEM和TEM等手段进行表征。用浸渍法将Ni-W活性组分担载在Hβ/Al-SBA-15载体上,制备Ni-W/Hβ/Al-SBA-15催化剂,以萘为模型化合物,考察该催化剂的加氢裂化性能。结果表明,所合成的Hβ/Al-SBA-15复合分子筛既有介孔结构又有微孔结构,并同时具有B酸和L酸中心,酸性强于SBA-15。具有适度酸性位和介微孔结构的Ni-W/Hβ/Al-SBA-15催化剂,对萘加氢裂化具有较高的萘转化率和BTX选择性,分别为96%和61.1%。  相似文献   
2.
通过不同孔特征的分子筛(HZSM-5、HY沸石和MCM-41)实现生物油催化转化为三苯(苯、甲苯和对甲苯). 基于三苯的产率和选择性,芳香化合物逐次降低顺序为: HZSM-5>MCM-41>HY沸石.用HZSM-5催化裂解生物油产生芳香化合物的最大产率为33.1%,选择性为86.4%. 研究了反应条件对生物油催化裂解的影响,结合催化剂表征结果,讨论了催化剂的结构与性能之间的关系.  相似文献   
3.
Effect of Atmospheric Interfering Absorption on Measurement of BTX by DOAS   总被引:1,自引:0,他引:1  
利用差分吸收光谱技术(DOAS)研究了去除BTX(大气中芳香烃污染物的主要成分)测量中O2、O3和SO2的干扰吸收. 针对O2的非线性吸收以及特征吸收结构随柱浓度的不同而变化的特点,研究了O2吸收组成成份-各个吸收带的非同步变化,即三个Herzberg吸收带与O2二聚体吸收带间的非同步变化,以及三个Herzberg吸收带之间,O2-O2和O2-N2两种二聚体吸收带之间也存在的非同步变化;结合各个吸收带的来源与特点研究了各个吸收带在O2吸收中的比重,以及对O2吸收在大气谱中校准误差的影响,最后得出最佳去除方法并证明了光程插值去除O2吸收的可能性. 针对大气中含量较高的O3与SO2的吸收,主要研究了吸收谱主要的影响因素-温度效应对于O3和SO2吸收结构去除误差的影响,讨论了用插值方法去除O3吸收结构时应选择的最佳温度条件. 最后,通过对实际大气进行了实际监测,获得了与点式仪器GC的检测结果的较好相关性,并得到了较低的BTX的检测限,验证了该方法的可行性.  相似文献   
4.
In this study, the analytical compatibility of the gas chromatographic (GC) approach was evaluated through a cross‐calibration exercise. To this end, three aromatic volatile organic compounds (VOCs: benzene, toluene, and p‐xylene (BTX)) were simultaneously analyzed with four individual instrumental setups (type I = GC with MS plus solid phase microextraction (SPME) method, II = GC with flame ionization detection (FID) plus SPME, III = fast GC‐FID plus SPME, and IV = GC‐FID plus air server/thermal desorption (AS/TD) method). A comparison of basic quality assurance (QA) data revealed considerable differences in DL values among the methods with moderate variabilities in the intercompound sensitivity. In light of the differences in detection properties, the analytical bias involved for each methodological approach was assessed by the relative relationship between analytes and basic operating conditions. The results suggest that the analysis of environmental samples at ultra‐low concentration levels (at or below ppb level) can be subject to diverse sources of bias. Although detection properties of target compounds seem to be affected by the combined effects of various factors, changes in the sample concentration levels were seen to be the most consistent under the experimental setups analyzed in this study.  相似文献   
5.
SK Corporation developed an advanced pyrolysis gasoline (pygas) upgrading (APUSM) technology based on a catalytic process for producing valuable benzene, toluene and xylenes (BTX) and liquefied petroleum gas (LPG) from pygas containing aromatics and non-aromatic hydrocarbons. Hydrodealkylation of heavy aromatics and hydrocracking of non-aromatic hydrocarbons occurred with facility in the conversion of pygas over a proprietary catalyst, metal promoted zeolite. This catalytic process produced benzene and toluene with high purity corresponding to chemical grade while giving mixed xylenes with reduced ethylbenzene. In the present study, we described novel features of the APUSM technology in terms of the process and catalyst. The influence of the process conditions was also examined. This technology has been commercially proven, and hence is available for licensing through Axens, which is a major engineering and licensing company.  相似文献   
6.
A new device has been developed for the trapping of volatile pollutants in trapping solvents. The device allows solvent recirculation and cryogenic trapping of evaporated volatiles to minimize the stripping effect and any losses of volatile analytes. Due to solvent recirculation, the trapping solvent column height remains constant during the extraction without any need for replenishment. Also mass transfer conditions are favorable due to the flattened shape of bubbles of CO2 and the longer extraction time. The bubbles have higher interfacial area and they have to pass a three times longer distance in the solvent column. The device produces more concentrated extracts, reduces solvent consumption, and reduces or eliminates its evaporation to the environment. The cryotrapping part reduces losses of volatile analytes and the stripping effect. It also enables single-phase extraction into much smaller solvent volumes. Due to constant and favorable extraction conditions, the precision of the method was also greatly improved (RSDs decreased from 2.2 to 0.8%). As proved by a set of rapid spiked-sample extractions of highly volatile compounds at very high flow rates, the relative standard deviation of the experiments performed in the new device is 3.5 times lower.  相似文献   
7.
采用纳米碳纤维(CNF)作为固相涂层制备了固相微萃取探头(SPME)并进行了评价.该涂层对苯系物(BTX)富集能力强,最高使用温度可达260℃,250℃解析条件下使用50次以上涂层无脱落现象.与活性碳涂层相比,尽管萃取量略小,但其解析时间仅为活性炭的60%,具有更高的精密度和准确度.对BrIX固相微萃取.气相色谱分析结果表明,样品质量浓度在0.1~38.7μg/L范围内与色谱峰面积呈良好线性关系(r=0.9891~0.9940),相对标准偏差为3.9%~5.3%,方法的检出限为2.5×10~(-3)μg/L.  相似文献   
8.
Summary N-Formylmorpholine, which is a solvent used in the extraction of benzene, toluene and xylenes extraction from petroleum feedstocks, is determined in trace amounts in water and in aromatic hydrocarbons by gas-liquid chromatography using two stationary phases. Traces of N-formylmorpholine in hydrocarbons was determined on a column packed with 2.3% Bentone 34+4.6% DEGA on Chromosorb W AW treated with 1% KOH. Traces of N-formylmorpholine in water was determined on 20% SE-30 on Chromosorb W AW. The developed methods were examined and proved to give quantitative results.  相似文献   
9.
The gas selectivities of highly ordered mesoporous silicates and commercially-obtained porous silicates with respect to benzene, toluene and xylene were studied. After studying the porosities, pore uniformities, and surface silanol structures of the silicates and their relationships to gas selectivity in detail, we found that we could achieve high benzene selectivity by controlling the micropore size (less than 1 nm). Concluding that mesoporous silicate has a suitable micropore size and structure for benzene selectivity, we also observed that mesoporous silicate SBA-16 exhibited a high (>6) benzene selectivity from toluene and xylene even in a pseudo-atmospheric environment. A benzene detection limit of about 100 ppb was achieved by introducing SBA-16 into a microfluidic device originally developed for the separate detection of benzene, toluene, and xylene gases.  相似文献   
10.
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