提高催化重整氢收率的途径分析

随着加工原油质量变重变劣,且环保要求日趋严格,以及市场对优质汽、柴油需求量的增加,炼油厂需要进一步提高加氢工艺装置的加工能力和深度。催化重整装置的副产氢气可为炼油厂加氢精制、加氢改质、加氢裂化等加氢装置提供氢源。催化重整氢气收率与工艺过程类型、原料组成、催化剂类型和操作参数等有关。催化重整工艺过程类型选用连续再生式重整,氢气收率和氢气纯度均比半再生重整高。选用环烷烃含量高的催化熏整原料,有利于提高重整氢的收率,这是由于产生氢气的环烷脱氢反应发生的越多,氢气收率越高。催化重整催化剂选用高选择性、低积炭的催化剂,有利于提高重整氢收率,并可提高催化剂的选择性和寿命。改善重整过程的操作参数（如适当提高反应温度和降低反应压力等）,可以提高重整氢收率,但是不推荐采用提高空速和降低氢油比的方法来提高氢气收率。此外,实践证实,从重整原料中脱除大部分c。烃（包括环烷烃、苯和己烷）,有利于增加催化重整氢气净收率,同时可以提高汽油收率,增大汽油辛烷值,并降低炼油厂苯的生成。     

TiO2/CdS composite hollow spheres with controlled synthesis of platinum on the internal wall for the efficient hydrogen evolution

Solar driven semiconductor photocatalytic water splitting to produce hydrogen is an extremely charming process by storing photon energy in chemical bonds. In the present study, composite semiconductor TiO₂/CdS was structured into uniform and porous double-shelled hollow sphere with cocatalyst platinum selectively loaded onto the internal wall. The SEM, TEM, STEM, XRD, BET and EDS elemental distribution etc. were employed to evidence the formation of the targeted photocatalyst. It was demonstrated that the material has a high efficiency of visible-light-driven hydrogen evolution (296 μmol·h⁻¹/10 mg) with an apparent quantum efficiency (QE) of 14.5% at wavelength of 420 nm. Comparative experiment analysis and time-resolved infrared absorption study suggested that the high photocatalytic activity of the catalyst is attributed to the vectorial electron transfer (CdS → TiO₂ → Pt) and the spatial separation of reduction and oxidation active surfaces achieved by the special morphology.     

A technical method to improve NOx/NH3 mixing ratio in SCR system and its engineering applications

A technical method for diagnosing the distribution of NO_x flux within the cross-section area in front of ammonia injection grid (AIG) was proposed for guiding the valve-tuning of AIG branch-pipes, in order to optimize the NO_x/NH₃ mixing ratio in the selective catalytic reduction (SCR) system of power plant. The weight coefficient of each branch-pipe in AIG system can be quantitatively determined with regard to the distribution of NO_x flux in the corresponding sub-zone of the cross-section area. The control strategy of the valves for different AIG branch-pipes can be achieved for guiding the NH₃ injection and improving the NO_x/NH₃ mixing ratio within the whole cross-section area in front of AIG. The technology has been applied on one side of the SCR system flue-gas tunnels (normally two tunnels for the SCR system called as A-side and B-side) of a 660 MW plant for more than one year. The ammonia consumption rate of the SCR system was reduced about 12.62% and the uniformity of outlet NO_x distribution was estimated to be greatly improved by about 79.01% with regard to the standard deviation. The rising rate of the flue gas resistance of the air preheater was slown down by 39.18% compared to that of the other flue-gas tunnel of SCR system. This implied that the formation of the sticky ammonium bisulfate (ABS) on air preheater was significantly inhibited through the application of this technology.     

车用增压柴油机瞬态性能及排放模拟

为使柴油机排放能够满足越来直工严格的排放法规要求,不仅要研究稳态工况下的排放性能,同时要研究瞬态工况下的排放性能。由于汽车在行驶中工况变化频繁,其排放问题相对稳态工况而言更为严重。作者建立了一个增压柴油机气缸内燃烧的准维模型,将其与增压柴油机瞬态工作过程模型相结合,用来预测增压柴油机瞬态工况下的综合性能及排放变化规律,根据所建模型编制了模块化的鬃态性能模拟程序,通过计算,表明此程序有较好的预测能力,并且有较强的通用性,易于扩充,修改和继承。     

太阳能吸附制冷用复合吸附剂制备及其吸附机理探讨

以乙醇为吸附质，选取13X分子筛、凹凸楱土和氯化锶等为主要吸附材料．通过混合法制备了一系列有着优良吸附能的复合吸附剂。测定了乙醇在主要吸附材料和自制复合吸附剂上的吸附量，用TG-DTA法对主要吸附材料的热稳定性和自制吸附剂DTA脱附乙醇峰端温度进仃了分析.对吸附剂原料复合比例和扩孔剂种类等制备条件进行了实验研究。结果表明：自制复合吸附剂比单一吸附材料对乙醇确着更大的吸附能力；DTA分析的脱乙醇峰端温度明显低于单一吸附材料；加入扩孔剂E1或E2，可增加自制复合吸附剂孔容和孔径，改善其吸附性能；自制复合吸附剂对乙醇的吸附量显著高于活性炭。其中，M4-0003和M1-0001复合吸附剂对乙醇的平衡吸附量约为活性炭的2．5～4倍；M1-0001—乙醇工质对的吸附制冷量是活性炭—乙醇的2～6倍。对吸附剂复合的机理初步探讨表明：增加复合吸附剂弱吸附中心数，可降低其脱附温度。     

4102ZL型柴油机燃烧生物柴油的排放特性

生物柴油属可再生资源,可缓解石油资源紧缺的矛盾.本文选用4102ZL型柴油机测定生物柴油的排放性能,并与0~#柴油的排放进行了对比分析.试验表明,燃用B100大豆生物柴油的各项排放指标均有不同程度的改善.     

Effect of equivalent and non-equivalent Al substitutions on the structure and electrochemical properties of LiNi0.5Mn0.5O2

Pristine, equivalently and non-equivalently Al substituted LiNi_0.5Mn_0.5O₂ materials were prepared by a combination of co-precipitation and solid-state reaction. As shown by XRD and XPS, lattice volume shrinkage of LiNi_0.5(Mn_0.45Al_0.05)O₂ was attributed to the presence of Ni in both 2+ and 3+, while the lattice volume expansion of Li(Ni_0.45Al_0.05)Mn_0.5O₂ was caused by lowering the average oxidation state of Mn. Electrochemical performance of LiNi_0.5Mn_0.5O₂ materials can be greatly affected by the change of oxidation states of the transition metals by Al substitution. Non-equivalent substitution of Al for Ni leads to deteriorated discharge performance and cyclic stability due to the reduction of the electrochemical active Ni²⁺ and structure supported Mn⁴⁺, while an increase in the amount of Ni²⁺ in LiNi_0.5(Mn_0.45Al_0.05)O₂ brings obvious improvement of the electrochemical properties. EIS analyses of the electrode materials at pristine and charged states indicate that the poor electrochemical performance of Li(Ni_0.45Al_0.05)Mn_0.5O₂ material can be ascribed to the higher charge transfer resistance and surface film resistance, and the observed higher current rate capability of LiNi_0.5(Mn_0.45Al_0.05)O₂ can be understood due to the better charge transfer kinetics.     

A study on electrical conductivity of chemosynthetic Al2O3–2SiO2 geoploymer materials

Al₂O₃–2SiO₂ amorphous powders are synthesized by sol–gel method with tetraethoxysilane (TEOS) and aluminum nitrate (ANN) as the starting materials. The microstructure and phase structure of the powders are investigated by SEM and XRD analysis. Geopolymer materials samples are prepared by mechanically mixing stoichiometric amounts of calcined Al₂O₃–2SiO₂ powders and sodium silicate solutions to allow a mass ratio of Na₂O/Al₂O₃ = 0.4, 0.375, 0.35, 0.325, 0.288, 0.26, 0.23 or 0.2 separately, and finally to form a homogenous slurry at a fixed H₂O/Na₂O mole ratio = 11.7. The results show that the synthetic Al₂O₃–2SiO₂ powders have polycondensed property and their compressive strengthes are similar to that of nature metakaolin geopolymer materials. The results also show that the water consumption is not the main influencing factor on electrical conductivity of harden geopolymer materials but it can intensively affect the microstructure of geopolymer materials. In addition, the electrical conductivity of harden geopolymer sample is investigated, and the results show that the geopolymer materials have a high ionic electrical conductivity of about 1.5 × 10⁻⁶ S cm⁻¹ in air at room temperature.     

于都县黄麟地区绿色富硒土壤分布选区评价

通过于都县黄麟地区1:5万土地质量地球化学调查,基本査明该地区农作物中硒元素及其他元素的地球化学特征,综合分析岀绿色富硒土壤分布,并优选出绿色富硒地块,为特色农产品基地建设的开发与利用提供理论依据。     

磨矿方式对方解石颗粒形貌及浮选行为的影响

磨矿是浮选分离成功的前提。通过磨矿试验、单矿物浮选试验、润湿性测试、扫描电镜测试,研究了陶瓷棒磨与陶瓷球磨,不同磨矿方式对方解石颗粒表面形貌及浮选行为的影响。试验结果表明,经过陶瓷球磨处理后的方解石矿物颗粒相较于经过陶瓷棒磨处理后的方解石矿物颗粒有着更大的疏水性,更好的浮选回收率,更大的扁平率与伸长率,以及更小的圆度和相对宽度。