Synthesis of nanorods and mixed shaped copper ferrite and their applications as liquefied petroleum gas sensor

Present paper reports the preparation and characterization of nanorods and mixed shaped (nanospheres/nanocubes) copper ferrite for liquefied petroleum gas (LPG) sensing at room temperature. The structural, surface morphological, optical, electrical as well as LPG sensing properties of the copper ferrite were investigated. Single phase spinel structure of the CuFe₂O₄ was confirmed by XRD data. The minimum crystallite size of copper ferrite was found 25 nm. The stoichiometry was confirmed by elemental analysis and it revealed the presence of oxygen, iron and copper elements with 21.91, 12.39 and 65.70 atomic weight percentages in copper ferrite nanorods. The band gap of copper ferrite was 3.09 and 2.81 eV, respectively for nanospheres/nanocubes and nanorods. The sensing films were made by using screen printing technology and investigated with the exposure of LPG. Our results show that the mixed shaped CuFe₂O₄ had an improved sensing performance over that of the CuFe₂O₄ nanorods, of which a possible sensing mechanism related to a surface reaction process was discussed. Sensor based on mixed shaped copper ferrite is 92% reproducible after one month. The role of PEG in the synthesis for obtaining nanospheres/nanocubes has also been demonstrated.     

液化石油气蒸汽爆炸的模拟实验研究

液化石油气蒸汽爆炸是对其安全储运构成很大威胁的一种观象。本文设计了一个实验装置用以检测液化石油气容器在突然出现裂口后压力急剧变化的过程。该装置可模拟液化石油气容器发生蒸汽爆炸的现象。实验结果表明,液化石油气的突然泄放过程中确实可能出现压力的急剧反弹,有时甚至超过初始压力,很可能导致剧烈的蒸汽爆炸。     

LPG发动机首循环对冷起动排放的影响

分析了电控LPG发动机首循环供气量及点火提前角对冷起动排放的影响.试验在一台四冲程、风冷125 mL单缸电控发动机上进行.试验结果表明,在冷起动工况下,首循环喷油量和首循环点火角对NO排放影响主要体现在前几个循环;首循环喷油量相同时,HC排放随首循环点火角的提前而减小,首循环点火角对CO排放的影响有限;首循环点火角固定时,首循环过量空气系数0.546时HC、CO排放最少.     

初始温度对CO2抑爆作用的影响

将CO₂充入的液化石油气中并进行点火,研究不同初始温度下CO₂对多元混合气液化石油气爆炸的抑制作用。实验显示:初始温度15℃时CO₂体积分数达到36%时,混合气体退出可爆范围,临界氧浓度为12.8%;初始温度50℃时CO₂体积分数达到39%时,混合气体退出可爆范围,临界氧浓度为12.2%。结果表明:CO₂对液化石油气爆炸的抑制效果在一定程度上要受环境温度的影响。     

单模光纤LPG对的MZ干涉仪U波段实验研究

全光纤型MZ干涉仪是未来高速光器件和光信号处理技术的基本部件。在单模光纤中采用周期压力方式写入LPG对,构成一种光纤型MZI,可实现U波段的波长调制。在实验中得到了1650nm的MZI的干涉光谱。LPG的写入方式简陋,实验结果对1650nm处U波段光开关、滤波器等全光器件的研究有参考意义。     

Cu/ZnO@H-β-P催化剂在合成气制备液化石油气反应中的性能研究

采用共沉淀法制备Cu/ZnO催化剂、水热合成法制备H-β分子筛、通过物理包膜法制备了具有核壳结构的Cu/ZnO@H-β-P催化剂,并用于合成气制备液化石油气(LPG)反应。通过XRD、NH3-TPD、BET和SEM-EDS等手段对催化剂进行了表征,利用固定床连续反应装置对催化剂进行了活性评价。结果表明,Cu/ZnO@H-β-P催化剂是具有中孔的核壳结构材料,其协同作用打破了原有的热力学平衡,促进了甲醇→DME→LPG串联反应的连续进行。与物理混合的Mix-Cu/ZnO-H-β催化剂相比,Cu/ZnO@H-β-P催化剂的CO转化率和LPG选择性更高,空速和反应温度对催化剂活性影响明显,最佳空速和反应温度分别为2 400 h~(-1)和350℃。使用Cu/ZnO@H-β-P催化剂在最佳条件下进行合成气制备LPG反应,CO转化率达到了57.22%,LPG选择性达到了60.52%。     

Room temperature soft chemical route for nanofibrous wurtzite ZnO thin film synthesis

Room temperature soft chemical deposition route has been utilized to grow thin films of ZnO on glass substrate. Annealing at 673 K removed zinc hydroxide phase and nanofibrous ZnO films with wurtzite crystal structure were obtained. Decrease in the room temperature electrical resistivity from 10⁷ to 10⁴ Ω cm was observed after annealing. The nanofibrous ZnO thin films were sensitive to the explosive liquefied petroleum gas (LPG) and the maximum response of 17% at 698 K under the exposure of 6500 ppm of LPG was obtained.     

Catalytic cracking of C5+ gasoline over hy zeolite

The catalytic conversion of a C5+ natural gasoline over the HY zeolite has been studied. The results show the formation of C2, C3 and C4 hydrocarbons with an apparent activation energy of ca. 39 kJ mol^-1. This revised version was published online in June 2006 with corrections to the Cover Date.     

液化石油气自然气化钢瓶中组分变化的模拟计算

根据化学相平衡原理、质量守恒定律和实际气体状态方程，建立了液化石油气自然气化过程气相和液相组分变化理论计算的模型，可对多组元LPG自然气化过程中各组分的变化进行准确的计算，同时可计算组分变化引起饱和蒸气压、热值、华白数和燃烧势的变化。     

Pathways of liquefied petroleum gas pyrolysis in hydrogen plasma: A density functional theory study

A density functional theory (DFT) study has been conducted in this work to investigate the pyrolysis pathways of propane and n-butane, which are the main components of liquefied petroleum gas (LPG), for better understanding the pyrolysis behavior of LPG in hydrogen thermal plasma. Over 60 possible reactions are considered. The reaction enthalpies and activation energies of these reactions are calculated and analyzed with a Gaussian method of B3LYP and basic set of 6-31G (d,p). A most possible reaction pathway is brought up. According to this reaction pathway, the main products of LPG pyrolysis are acetylene, ethylene, methane, ethane and extra hydrogen. Acetylene mainly comes from the pyrolysis of propylene and ethylene, and hydrogen abstraction reactions are the main source of extra hydrogen gas. Active H· radicals are found to play a very important role in many reactions, and they can remarkably lower the energies needed for reactions.