基于Fisher-Pry模型的纤维素预处理技术成熟度分析

为了研究纤维素预处理技术成熟度情况，基于多源文献数据利用&nbsp;Fisher-Pry&nbsp;模型对蒸汽爆破法、酸处理法、碱处理法和生物法等主要预处理技术成熟度进行了研究。结果表明，蒸汽爆破法、酸预处理法及碱预处理法从&nbsp;2005&nbsp;年之后快速展，目前基本处于成熟阶段，但由于这些方法本身存在水解产生抑制性产物、腐蚀性、成本高等缺陷，很难取得进一步的突破。生物法目前还正处于快速成长阶段，具有很大的前景，经过&nbsp;Fisher-Pry&nbsp;曲线拟合，预计生物法到&nbsp;2043&nbsp;年左右达到成熟。</p

主要资源国家政治生态情况及其对铝土矿政策的影响

Vesuvius, dominating the densely-populated Neapolitan area, is one of the most dangerous volcanoes in the World. Its destructive power derives from energetic subplinian and plinian eruptions, such as the one which occurred in 79 A.D. Generally such large-scale events follow a long period of quiescence; a behaviour interpreted as the gradual build-up of magma volumes between periods of major activity. After the 1631 subplinian eruption until the last 1944 A.D. eruption, it experienced an almost continuous and less energetic explosive/effusive activity. The erupted magmas are characterized by undersaturated potassic to ultrapotassic nature, and compositional and Sr-isotopic variability. Furthermore geobarometric studies indicate two different crystallization depths located at 4 and >11 km, respectively. According to most of the recent literature, the eruptions were triggered by the injection in a shallower magma chamber, of isotopically distinct magma batches derived from heterogeneous mantle source(s) and/or contamination processes occurred within the deep reservoir. In our review of petrochemical data, we consider the period between the 3550 years BP plinian eruption and the 472 A.D. sub-plinian eruption, which includes 79 A.D. event, and the most recent period of activity which started in 1631 A.D. and lasted up to the 1944 A.D. eruption, characterized by a near continuous effusive/explosive activity. For both periods we identify a correlation between Sr-isotopical features of magmas and their crystallization depth. In particular, we show that pyroxenes have Sr-isotopic ratios lower than 0.7074 and an equilibrium crystallization depth of 22-11 km. Moreover feldspars have higher 87Sr/86Sr values (0.7075-7) and an equilibrium crystallization depth of about 4 km. Therefore the most radiogenic magmas did not derive from a deeper reservoir but their higher Sr-isotopic ratios have been acquired at a shallower depth likely by crustal contamination during magma evolution. In contrast, the lower Sr-isotope compositions characterise the less contaminated magmas coming from deeper crustal levels. On the basis of this evidence, the temporal Sr-isotopical variation of magma which erupted in the 1631-1944 A.D. period probably derives from the progressive withdrawal of the shallow magma chamber, which was completely empty before the 1805-1944 A.D. period of volcanism. Therefore the effusive and explosive events of the most recent 1805-1944 A.D. period were fed directly by the deep reservoir located at a depth exceding 11 km

Concentration and distribution of polycyclic aromatic hydrocarbons in surface sediments collected in the Southern Yellow Sea

采用气相色谱与质谱联用(gC/MS)技术,在一个航次内对南黄海表层沉积物中16种优先监控的PAHS的污染状况进行了调查,采用菲/蒽、荧蒽/芘、荧蒽/(荧蒽+芘)、吲哚芘/(吲哚芘+苯并(g,H,I)苝)等特定比值对PAHS来源进行了分析.结果表明,南黄海表层沉积物中检出PAHS的总含量为90.4~732.65ng·g-1,各站点均以4~6环为主;与其它站位相比,倾废区的H01站位受到PAHS污染较为明显,无论是16种PAHS总量还是高分子量组分最高值都出现在该站点,虽然该海区沉积物中PAHS的含量没有超出生物影响低值,但苯并(b)荧蒽、吲哚芘和苯并(g,H,I)芘等一些没有最低安全标准的PAHS也有不同程度的检出,对海洋生物具有潜在的毒副作用.PAHS可能来源于原油、生物和煤燃烧造成的污染.The concentrations of sixteen representative Polycyclic Aromatic Hydrocarbons(PAHs) in surface sediment samples collected from the Southern Yellow Sea were determined by GC-MS.The distribution and potential sources of PAH contamination in the region were investigated.The types of PAHs found in the surface sediments were mainly 4～6 ring PAHs,and they are unevenly distributed among the different sampling sites covering an area of 139 km2.The area is known for continuous waste dumping activities in recent years,and indeed sites adjacent to such activities were found to have high levels of PAHs.Some high molecular weight PAH compounds such as benzo$$b$$fluoranthene,dibenzo$$a,h$$anthracene and benzo$$g,h,i$$perylene were detected in some samples.The health implication of these contaminants needs careful assessment since toxicity guidelines are not available for these species.The potential sources of PAHs are discussed using various source-specific PAH indexes such as Phenathrene/Anthracene、Fluoranthene/Pyrene、Fluoranthene/(Fluoranthene+Pyrene) and Indeno [1,2,3-cd] pyrene/(Indeno[1,2,3-cd] pyrene+Benzo [g,h,i] perylene).The composition of the observed PAHs reflects that they originate from both petroleum utilization and incomplete combustion.海洋公益性行业科研专项(No.200705011);中国海监技术支撑体系项目;2008年海洋环境保护及节能减排专项---

C–X(X = Cl, Br, I) bond dissociation energy as a descriptor for the redispersion of sintered Au/AC catalysts

负载型Au基催化剂在工业过程中具有非常广泛的潜在应用,如催化加氢/脱氢过程、精细化学品合成、能源催化转化及环境保护等过程,表现出很高的催化活性和选择性.Au基催化剂活性物种或活性中心基本由纳米粒子或化合物构成,但在应用过程中因Ostwald熟化效应或粒子迁移作用,尤其是高温高压等苛刻反应条件下,均随应用时间延长从小尺寸粒子逐渐长为大粒子,造成活性降低或完全失活,这也是负载型催化剂失活的最主要原因之一.其中因成本、稀缺等特性,负载型Au催化剂的烧结问题是影响和制约其应用的主要因素.除可通过载体改性、助剂和官能团配位稳定等方法来延缓其失活过程外,对已烧结催化剂的高效、快捷和绿色的再分散/再生过程也具有基础和应用研究的重要意义.活性炭载Au催化剂(Au/AC)广泛应用于乙炔氢氯化反应中,以期替代高毒性的汞基催化剂,但在反应过程中因高活性的Au~(3+)物种易被还原而形成Au~0物种进而烧结导致失活;如新鲜Au/AC催化剂表面的Au粒子尺寸为1-2 nm,经乙炔氢氯化反应后变为33 nm左右;随之在453 K、0.1 MPa、乙炔体积空速(GHSV)为600 h~(-1)、氯化氢与乙炔摩尔比为1.1的反应条件下,乙炔转化率从81.8%降至11.2%.如何有效对大粒子Au再分散/再生可为其应用提供有力支撑.有研究表明,气相CHI_3在甲醇羰基化反应过程中明显改变Au/AC表面的Au粒子尺寸;或采用浓盐酸或王水也可将烧结的Au/AC催化剂进行再分散/再生.但已有的Au基催化剂再分散/再生过程均伴随着强酸、强氧化或高毒性在分散剂的应用,对环境的影响及后续处理有明显的局限性,且再分散机理尚不明确.在前期工作基础上,本文采用系列卤代烃(碘代烃、溴代烃和氯代烃)对烧结的Au/AC进行再分散/再生研究.结果表明,在室温常压条件下CHI_3可以快捷高效地对烧结Au/AC催化剂进行再分散/再生,具有最优的再分散性能;通过对系列碘代烃C-I键的解离能分析,发现C-I解离能越低越有利于大粒子Au的再分散.同时,溴代烃和氯代烃对烧结的Au/AC催化剂也具有再分散能力,但比碘代烃的再分散效率低.C-X键的解离能与再分散效率有高相关性,即C-X键的解离能越低越有利于Au的再分散.总体上,三类卤代烃再分散效率高低顺序为C-I>C-Br>C-Cl.进而,通过不同分散过程中Au粒子分散状态推测了卤代烃对Au粒子的再分散机理,即卤代烃先在Au粒子表面化学吸附,然后C-X键解离,形成Au-X物种,小粒子Au在AC表面聚集并稳定,最后形成高分散Au粒子(粒径<1 nm)催化剂.以乙炔氢氯化反应考察了再生Au/AC催化剂性能,结果表明,该催化剂上乙炔转化率可达79.4%,基本恢复至初始水平,且该方法可对失活催化剂进行多次高效再生.Disintegration or redispersion of supported sintered gold nanoparticles(Au NPs) in the presence of alkyl halide can give catalyst regeneration or redispersion of sintered Au catalysts. The selectivity of alkyl halides, temperature and size distributions were investigated to elucidate the redispersion of Au NPs during halide-induced decomposition. This study proved that the alkyl halide induced the redispersion of sintered Au NPs which depended on the R–X(X = I, Br, Cl) bond dissociation energy(BDE) and thus provided a simple descriptor for the regeneration of inactive supported Au cata-lysts. A correlation between the BDE of R–X and dispersion efficiency was established. The tendency for disintegration and redispersion followed the R–X BDE of the alkyl halide. Compared to alkyl chlorides and bromides, iodides were more efficient for redispersing sintered Au NPs. As a descriptor, the BDE of R–I played a crucial role in particle redispersion. These findings provided insights into the mechanism of organic halide-induced Au NP disintegration and the effect of the halide type on the redispersion of sintered catalysts.国家自然科学基金(21403178,21473145,21503173,91545115);; 教育部创新团队发展计划(IRT_14R31);; 福建省青年教师教学科研基金(JA15003