酸洗脱矿对胜利褐煤热解过程中N迁移转化的影响

在石英管流化床反应器中对胜利褐煤进行快速热解实验,考察了773~1 173 K下酸洗脱矿对胜利褐煤热解过程中N迁移转化规律的影响。通过比较原煤和酸洗后煤中N的不同逸出规律可以得出,影响酸洗前后胜利褐煤热解过程中N迁移转化规律的主要是碱金属Na及碱土金属Ca;热解过程中,煤中的Na和Ca促使煤中的N向NH3转化并有效抑制了HCN的生成,金属离子的存在对催化焦油N转化为NH3的作用较为明显;原煤中的碱金属和碱土金属的赋存使半焦裂解反应加剧,降低了固体半焦的产率,半焦N的产率也随之减少;与原煤相比,酸洗煤热解半焦中的吡啶型N(N-6)含量较多,而吡咯型N(N-5)和季N(N-Q)相对较少。     

TG-MS与Py-GC相结合法研究惰性气氛下含硫模型化合物热解过程中硫的脱除及释放行为研究

采用热重-质谱法(TG-MS)和热解-气相色谱法(Py-MS)相结合的方法对模型化合物(十四硫醇、二丁基硫醚、苯硫醚、二甲基噻吩、苯并噻吩和二苯并噻吩等)在惰性气氛下硫的脱除及释放行为进行研究。惰性气氛下硫的脱除顺序为:十四硫醇>二丁基硫醚>二甲基噻吩>苯并噻吩>苯硫醚>二苯并噻吩,苯硫醚除外,该顺序与含硫官能团的热分解顺序一致。在热解过程中,所有模型化合物在质谱和气相色谱仪上均被检测到SO₂;除苯硫醚和二苯并噻吩外,其他模型化合物中均检测到了COS;而只在十四硫醇、二丁基硫醚和二甲基噻吩中检测到了H₂S。且热解气中SO₂含量要显著高于H₂S和COS。这是由于活性炭作载体时,惰性气氛下内部氢的含量显著小于内部氧的含量,所以大多数的含硫自由基易与内部氧结合以SO₂的形式逸出。对于苯硫醚、苯并噻吩和二苯并噻吩中没有检测到H₂S,是由于内部氢的不足,使得含硫自由基不能与内部氢结合,所以没有检测到H₂S逸出。     

煤热解过程中含氮产物的析出及金属离子的催化特性研究

选择3种典型煤种为研究对象,通过脱灰和添加含Fe、Ca、Na等金属盐,研究煤热解过程中金属离子对含氮气相产物析出特性的影响以及与煤种和温度的交互关联。结果表明,脱灰煤HCN和NH3的产率均比原煤样下降,而随温度的升高HCN的产率逐渐增大,NH3的产率则先增加后减小,在800℃有最大值。金属离子对不同变质程度煤的含氮气相产物析出的催化作用不同;Fe和Na抑制中等变质程度煤HCN的析出,而对低变质程度煤起促进作用,Ca则对HCN的析出均有一定的促进作用。而对于NH3的形成,3种离子均对中等变质程度煤有抑制作用,而对低变质程度的煤则有促进作用。不同金属离子对HCN和NH3析出的催化作用均有一定的范围。煤热解时含氮气相产物的析出是煤中固有多种金属离子共同作用的结果。     

名义组分为Y_6Ba_(11)Cu_(16)O_x的纳米超导材料

采用柠檬酸盐热分解法制备了名义组分为Y6Ba11Cu16Ox的纳米超导材料。利用XRD对其粉体进行物相表征,发现其相是Y123和Y211的混合相,并测得两者之间的摩尔比为1∶0.14,同时把其XRD图谱与Y1Ba2Cu3O7-x的XRD图谱进行了对照分析。利用标准的四端引线法对其块体进行R-T分析,测出其起始转变温度Tonset=86.0K,转变宽度△Tc=6.7K,并表现出良好的超导电性,也相应地把其与Y1Ba2Cu3O7-x进行了对比。根据Scherrer公式计算得到样品的平均晶粒尺寸约为67.1nm。文中也分析了所制材料为混合物的原因。     

On the rank-dependence of coal tar secondary reactions

The secondary reactions of volatile compounds, including coal tar and light gases, accounts for a great portion of soot formation and the subsequent heat release and pollutant emissions in the combustion zone. While coal primary pyrolysis has been extensively studied over the last few decades and several network pyrolysis models has been developed to describe this process, coal secondary pyrolysis is still not well understood. The Babcock and Wilcox Company has been investigating coal secondary pyrolysis in order to develop a comprehensive mechanism for inclusion in predictive computational fluid dynamics and coal combustion models. Supportive experiments were carried out in an entrained-flow reactor. Tar was extracted from the pyrolysis byproducts of seven coals of widely-distributed rank at temperatures ranging from 923 to 1473 K, and analyzed by ¹³C NMR. Tars formed from higher rank coals generally demonstrated higher sooting propensities. This rank-dependent sooting propensity is associated with tar’s chemical structure properties. With increased heat treatment severity, tar molecules lose a substantial amount of aliphatic attachments, and the average size of substitution per cluster decreases. Compared to tars formed from high-rank bituminous coals, those formed from low-rank sub-bituminous coals have a larger attachment portion, higher averaged substitution, and higher oxygen-containing functional groups. These differences contribute to the higher cracking propensity observed for low-rank coal tars.     

Paper spray tandem mass spectrometry: A rapid approach for the assay of parabens in cosmetics and drugs

A fast methodology for the assay of parabens in drug and cosmetic preparations has been presented. The procedure developed is based on paper spray tandem mass spectrometry and isotope dilution approach. For each investigated paraben, the corresponding labeled standard has been used in order to improve the accuracy and reproducibility of the analyses. The MS experiments have been performed under MRM conditions, monitoring the transitions [M‐H]^? → m/z 92 and [M‐H]^? → m/z 98, respectively, for each analyte and the corresponding labeled internal standard. The quantitative assay has been performed using a calibration curve built from 2 to 15 mg/L. The method accuracy, in all case near 100%, was evaluated using fortified samples at two concentration levels, which are representative of the lower and the higher portion of calibration curve. The good values of LOQ, LOD, and reproducibility confirm the consistency of the developed approach.     

不同烟草生物质热解释放致香物质的研究

采用烟叶和烟梗为原料,使用热裂解气相色谱法对烟草的燃烧时间、燃烧温度进行控制,精确模拟实际烟草致香物质释放环境,精确捕获、并半定量物质,从而在实验室模拟、分析、研究烟草燃烧物中致香物质的组成和特点。研究分别考察了两种生物质在500℃、550℃下释放的致香物质组成。结果表明,烟梗、烟叶中元素组成中硫、氮两种元素含量低,而C/H比值两种烟草生物质均较高。两个热解温度下烟叶的热解产物中致香物质的含量均明显高于烟梗。升高热解温度均有利于获得更高相对含量的热解成分。烟叶热解产物中烯烃类物质相对含量比烟梗中多,而烟梗热解产物中酚类物质含量比烟叶中多。提高热解温度有利于酮类致香物质含量产生。     

Sensing of LPG with nanostructured zinc oxide thin films grown by spray pyrolysis technique

Nanostructured zinc oxide thin films were prepared by spray pyrolysis technique using Zn(NO₃)₂·6H₂O as the precursor solution. The resulting films were investigated by X-ray diffraction and scanning electron microscopy to know crystal structure, size of crystallites and surface morphology. The films have been found to be polycrystalline zinc oxide, possessing hexagonal wurtzite crystal structure and nanocrystallite with grain size of approximately 30-35 nm. The LPG sensing performance of the films has been investigated at various concentrations of LPG in air at operating temperatures varying from 225 to 400 °C. At 325 °C the maximum responses of 46.3% and 48.9% have been observed, respectively, for concentrations of 0.8 and 1 vol% of LPG in air (1 vol% of LPG in air corresponds to 50% LEL of LPG in air). The recovery time has been found to be less than the response time for all concentrations of LPG. A possible reaction mechanism of LPG sensing has been proposed.     

Influence of strain/stress on the nonlinear-optical properties of sprayed deposited ZnO:Al thin films

Nanocrystalline ZnO:Al thin films were deposited by reactive chemical pulverization spray pyrolysis technique on heated glass substrates at 450 °C to study their crystalline structure, composition, strain, stress, roughness characteristics and nonlinear optical susceptibility as a function of Al concentration (0, 2, 3, 5 at.%). The films were characterized by X-ray diffractometer (XRD), EDAX 9100 analyser, atomic force microscopy (AFM) and third harmonic generation (THG). The Al (3 at.%) doped ZnO thin films exhibited the lower strain/stress than undoped films. The nonlinear properties of the ZnO:Al thin films have been found to be influenced by the films strain/stress.     

CO_2气氛对燃料N析出特性的影响

在水平管式炉上进行徐州烟煤在Ar和CO_2气氛下的热解试验,研究CO_2气氛对燃料N析出特性的影响。结果发现,两种气氛下,NH_3的收率随温度的升高均先升高后减小,在800℃时达到一个最大值,Ar气氛下此最大值比CO_2气氛下大很多;两种气氛下,HCN的收率均随温度的升高而升高。两种气氛下随着温度的升高,HCN与NH_3的收率比均升高,但在CO_2气氛下收率比更大,说明CO_2的氧化作用和气化作用促进了燃料N向HCN的转化。