MoS2光电催化剂活性位点的优化和效能研究进展

MoS₂是一类典型的后石墨烯二维材料,具有优异的光电性能及良好的化学稳定性,是近年来被广泛研究的一类新型光电催化剂,有关其催化活性位点的构效关系和反应机理是目前的研究热点。本文介绍了MoS₂的结构特性和活性位点分布,重点归纳分析了近年来有关MoS₂活性位点的构筑方法,包括利用降低维度、晶相调控、特殊形貌设计和非晶化等方法对MoS₂本体进行改造,以及采用原子掺杂、缺陷工程的方式对MoS₂进行协同修饰。通过对催化性能及反应机理的研究,表明这些方法能有效提高MoS₂的催化性能。最后,结合研究现状对目前存在的挑战和研究方向进行了分析总结,指出在MoS₂上构造有序分布的活性位点并平衡其稳定性以及催化性能的构效关系是未来MoS₂在光电催化领域中的研究重点。     

催化加氢改性生物质油轻质组分

以稻壳为原料热解得到的生物质原油是一种成分复杂、物理化学性能不稳定的混合物,只有经过物理或化学改性的生物质燃料才可以在现代柴油机中应用。采用减压蒸馏的方式分离出生物质油轻质组分,在4个温度（150、250、350和150/350℃）和压力2 MPa条件下,以MoS₂为催化剂,在间歇反应釜中进行催化加氢改性。从改性油产率、加氢前后油品性能及nH/nC的变化来判断不同温度条件下MoS₂对生物质油轻质油的催化加氢效果。结果表明,随着反应温度的升高,改性油产率逐渐降低,150℃下所得改性油产率为80.3%,而350℃下产率仅为65.4%,但此时的改性油具有较高的nH/nC（3.80）,150/350℃两段式反应条件在脱氧方面更具优势。催化加氢机理归结为化合物中含有的不饱和化学键(C=C和C=O)容易在MoS₂催化剂条件下发生加氢或加氢脱氧反应。     

聚苯硫醚复合涂层的耐磨性能

研究了用固体润滑石墨、碳化硅、二硫化钼等填料改性的聚苯硫醚 (PPS)涂层的耐磨性能。实验结果表明 ,聚苯硫醚复合涂层具有优良的耐磨性 ;加入适量 ( 3 0 % )的石墨、碳化硅等固体润滑剂 (石墨 :碳化硅 =2∶3 ) ,可以有效提高涂层的耐磨性能 ,而二硫化钼和三氧化二铬的减摩效果更佳     

Effect of Welsh Onion (Allium fistulosum L.) on Breadmaking Properties

Breadmaking properties, such as bread height and specific volume, were improved in bread, made with wheat flour blended with Welsh onion (Allium fistulosum L.) powder, which is high in di‐n‐propyl disulfide (Pro₂S₂). Breadmaking properties also were improved in bread prepared from wheat flour blended with Pro₂S₂ alone. Brabender farinographs of Welsh onion powder/wheat flour and Pro₂S₂/wheat flour showed interesting properties in modifying the width of the tail. Size‐exclusion high performance liquid chromatography of the wheat proteins in the control and blended flours showed a profile of low, medium, and high molecular weight peaks. The area of the high molecular weight peak was larger in the 2 blended flours than in control, indicating this protein was important for the improvement.     

硫醇、硫醚类化合物在白油中对环烷酸腐蚀性的影响

采用静态失重法研究了不同烷基结构和含量的硫醇、硫醚和二硫醚类化合物在工业白油体系中对环烷酸腐蚀性的影响。实验结果表明,当硫醇含量小于9.0μmo/g时对环烷酸的腐蚀性有一定的抑制作用,反之,则促进环烷酸腐蚀,不同结构硫醇腐蚀速率快慢的顺序为:环己硫醇>正丁硫醇>十二硫醇>苄硫醇;当硫醚含量小于19.7μmol/g时加剧了环烷酸的腐蚀,随硫醚含量的增加,腐蚀速率减慢,抑制了环烷酸的腐蚀,含量大于98.6μmol/g后腐蚀速率基本趋于不变,固定硫醚的一个烷基改变另一烷基的结构,其腐蚀速率快慢的顺序为:丁基苄基硫醚>丁基十二烷基硫醚>丁基环己基硫醚>二丁基硫醚;二硫醚中的二环己基二硫醚、二丁基二硫醚及双十二烷基二硫醚加剧了环烷酸腐蚀且随含量的增加腐蚀速率加快,而二苄基二硫醚对腐蚀的影响表现为没有促进也没有减弱腐蚀。     

元素硫与其它硫化物共存时银片腐蚀的研究

考察了元素硫对喷气燃料银片腐蚀的影响程度,对元素硫与其它硫化物共存时银片腐蚀性能进行了研究。试验结果表明,元素硫浓度为0.5μg/g时就能产生严重的银片腐蚀,而不同结构的硫醇和二硫化物在低温下（50℃）不会产生银片腐蚀,但它们与元素硫共存时,硫醇能加剧元素硫对银片的腐蚀,二硫化物对元素硫腐蚀则无影响。     

Thermodynamic analyses of hydrogen production from sub-quality natural gas: Part I: Pyrolysis and autothermal pyrolysis

Sub-quality natural gas (SQNG) is defined as natural gas whose composition exceeds pipeline specifications of nitrogen, carbon dioxide (CO₂) and/or hydrogen sulfide (H₂S). Approximately one-third of the U.S. natural gas resource is sub-quality gas [1]. Due to the high cost of removing H₂S from hydrocarbons using current processing technologies, SQNG wells are often capped and the gas remains in the ground. We propose and analyze a two-step hydrogen production scheme using SQNG as feedstock. The first step of the process involves hydrocarbon processing (via steam–methane reformation, autothermal steam–methane reformation, pyrolysis and autothermal pyrolysis) in the presence of H₂S. Our analyses reveal that H₂S existing in SQNG is stable and can be considered as an inert gas. No sulfur dioxide (SO₂) and/or sulfur trioxide (SO₃) is formed from the introduction of oxygen to SQNG. In the second step, after the separation of hydrogen from the main stream, un-reacted H₂S is used to reform the remaining methane, generating more hydrogen and carbon disulfide (CS₂). Thermodynamic analyses on SQNG feedstock containing up to 10% (v/v) H₂S have shown that no H₂S separation is required in this process. The Part I of this paper includes only thermodynamic analyses for SQNG pyrolysis and autothermal pyrolysis.     

旋转密封环表面二硫化钼膜制备工艺研究

为解决某传动装置可靠性及寿命问题,在旋转密封环基体表面沉积了一层二硫化钼固体润滑膜,探讨了基体材料预处理工艺和真空室预处理参数,以及沉积工艺参数对其表面二硫化钼镀膜性能的影响,得到了最佳的二硫化钼膜制备工艺.结果表明,烘烤工艺参数为温度350 ℃,时间30 min,真空度3.0×10-2 Pa;离子轰击工艺参数为氩气压强4.5 Pa,负偏压1 000 V,时间20 min;沉积工艺参数为负偏压200 V,钼靶电流200 A,混合气体分压1.5 Pa时,获得的二硫化钼膜膜层致密,膜基结合强度高.台架试验表明,在旋转密封环基体表面沉积二硫化钼固体润滑膜,明显降低了密封环的摩擦因数.     

Development of anti-insect multilayered films for brown rice packaging that prevent Plodia interpunctella infestation

The aim of this study was to develop a multilayered insect-proof film that prevents contamination with Plodia interpunctella (Hübner; Lepidoptera: Pyralidae) insect larvae. The anti-insect activities of five essential oils (EOs), allyl disulfide (AD), and allyl mercaptan isolated from garlic and onion, respectively, were evaluated. Subsequently, fumigation insecticidal assays were performed to identify the anti-insect agents, their optimal concentrations. Garlic, onion EOs and their compounds were chosen as efficient anti-insect agents for application to rice flour-based multilayered plastic films. Penetration tests were then used to evaluate the ability of multilayered films to resist invasion by P. interpunctella larvae. Films containing 5% AD (AD-5) had the strongest resistance to penetration by insects. Thus, AD-5 was applied to brown rice packaging to measure protection from insects and to assess sensory properties. In these analyses, AD-5 showed insect-proofing effects and no undesirable changes to the sensory properties of the rice after cooking. Hence, this novel multilayer film could be used as an active packaging material with effective anti-insect activities and desirable physical properties.     

80%代森锌可湿性粉剂在苹果和土壤中的残留安全性评价

目的评价80%代森锌可湿性粉剂在苹果和土壤中使用后的残留安全性。方法在北京市、安徽省、山东省、辽宁省、宁夏自治区和河南省进行了80%代森锌可湿性粉剂在苹果上的消解动态和最终残留实验。结果代森锌在苹果上的降解半衰期为20.4～36.5 d,最终残留浓度为0.120～3.964 mg/kg;在土壤中的降解半衰期为12.6～15.1 d,最终残留浓度为0.028～3.874 mg/kg。一年6地区监测结果表明,80%代森锌可湿性粉剂防治苹果溃疡病,最高制剂用药量1600 mg/kg,最多施药次数为3次,安全间隔期为28 d。结论在规定最大限度条件下,苹果上代森锌的残留量小于我国规定的食品安全最大允许残留限量5.0 mg/kg,食用苹果是安全的。