在Ru/C和甲酸(甲酸盐)体系中碱木质素水热解聚特性研究

在Ru/C和甲酸(甲酸盐)的共同作用下,275~350℃的亚临界水中,进行碱木质素的水热解聚反应。通过GC-MS定性分析和GC-FID定量分析,探究了供氢试剂及用量、反应温度、木质素分子级分对木质素水热解聚的影响。结果表明:在甲酸和Ru/C条件下,木质素解聚液相产物得率最高,组成较简单,具有较好催化降解效果;在甲酸添加量为0.8 mol/L,反应30 min时,木质素解聚液相产物最多,其中含量最高的单酚类物质为4-甲基愈创木酚,在主要单酚类物质中占32.77%,木质素水热解聚液相产物得率随温度升高而先增后减,并在325℃时取得峰值;L1、L2和L3是碱木质素的3个不同的分子级分,L1级分对木质素解聚液相产物得率贡献最大,达61.80%,且产物中单酚类物质总得率最高,为112.71 mg/g。其中,愈创木酚与4-甲基愈创木酚所占比例最高,可分别为35.38和35.52 mg/g;对木质素进行分级分离处理后再进行水热转化反应,有利于液相产物和单酚类物质得率的进一步提高。     

木质素CP-GC-MS法裂解行为研究

采用居里点热裂解-气相色谱-质谱(CP-GC-MS)联用分析技术,以碱木质素为原料,研究了裂解温度对木质素快速裂解产物组成及其含量的影响。结果表明,木质素居裂解主要生成酚类化合物,GC含量可达60%。低温主要生成愈创木酚结构单元为主体的酚类化合物;在300~360℃之间,酚类化合物GC含量随裂解温度升高而提高,愈创木酚基本单元类化合物占主体,占酚类化合物的90%左右;裂解温度进一步提高,酚类化合物GC含量稳定在60%左右,而愈创木酚基本结构单元类化合物GC含量随温度升高而降低,主要由于愈创木酚基本结构单元断裂成其他酚类和小分子化合物。     

木质素在异丙醇中的降解研究

采用正交试验法对有机溶剂木质素在异丙醇中的降解进行了研究,得出木质素在异丙醇中降解的较优水平为:催化剂Ru/C用量0.20 g、温度280℃、压力2.5 MPa、时间8 h。在该条件下,降解产物中生物油的产率最高可达74.13%,生物油中酚类和醇、酮以及烃类的GC含量总和接近60%。木质素原料和生物油的元素分析说明解聚过程中发生了脱氧;傅里叶红外光谱分析表明木质素的解聚过程中有酚羟基、烷基等新的结构基团产生。     

基于TG-FTIR和Py-GC-MS分析的椰壳热解特性研究

采用热重-红外光谱(TG-FTIR)和裂解-气相色谱-质谱联用(Py-GC-MS)技术对椰壳粉的热失重、热裂解行为及其裂解产物进行了研究。在对N2和空气气氛下椰壳的TG和DTG曲线进行分析的基础上,采用三维红外光谱对热解过程中气体产物进行在线检测,结果表明:N2气氛下,椰壳的最大失重峰温度(Tm)为347.8℃,固体残余量为32.0%,主要的气体产物是CO2;而空气气氛下椰壳的热解更完全,固体残余量仅为6.5%,且最大热失重温度为282.1℃,释放的气体除了CO2,还有CO、H2O和CH4等。Py-GC-MS分析结果表明:酚类化合物是主要的裂解产物,当温度为400℃时共检测到39种裂解产物,其中酚类化合物12种(GC含量40.0%);当温度为700℃时共检测到56种裂解产物,其中酚类化合物18种(GC含量45.8%)。     

马尾松木质素快速热解及产物分析

以针叶材马尾松木质素(Pinus massoniana)为快速热解的原料,采用热解-气相色谱-质谱联用(PyGC-MS)技术,分别对磨木木素(MWL)、碱木素(AL)以及酸不溶木素(Klason木素)三种不同种类的木质素及磨木木素在不同热裂解温度下进行了热裂解实验,分析了不同条件下热裂解产物中主要酚类组分相对含量的变化。结果显示,裂解温度为500℃时,马尾松不同类型木质素热裂解产物存在较大差异,磨木木素、碱木素和酸不溶木素裂解产物中总酚相对含量分别为62.3%、44.86%和16.25%,结果说明磨木木素最易裂解,碱木素次之,酸不溶木素最难裂解。热裂解温度从400℃升高到500℃再升高到600℃的过程中,磨木木素裂解产物中总酚相对含量仅从59.78%升高到62.31%再升高到65.72%,主要酚类组分为愈创木酚及其衍生物,各酚类组分相对含量随温度升高呈现出不同的变化趋势。     

麦草碱木质素烷基化反应的研究

用不同的卤代烷烃与碱木质素进行烷基化反应。探讨了烷基化试剂种类，反应温度、时间、PH值等因素对产物性质的影响，发现，当烷基化试剂为溴代十二烷，反应时间3h、反应温度170℃，PH12时，木质素的反应率和反应产物表面活性较高，对烷基化碱木质素进行磺化，可以改善其水溶性，进一步提高其表面活性。     

超临界甲醇中复合金属氧化物催化木质素的解聚

以类水滑石为前驱体制备了Cu/Ni掺杂的层状双金属氧化物(Cu/Ni-LDO)催化剂,探讨了超临界甲醇中,反应条件对Cu/Ni-LDO催化木质素解聚产物的影响。结果表明:在n(Cu)∶n(Ni)=1∶1,反应时间8 h,温度280℃,30%Cu0.5Ni0.5Mg3Al-LDO为催化剂的条件下,单体得率高达67.5%,而四氢呋喃(THF)不溶残渣和残炭的得率最少。采用GC-MS对木质素解聚的液体产物进行了定性和定量分析,结果显示环状化合物的得率为64.43%,非环状结构的产物只占10.65%,Cu/Ni-LDO催化剂能够有效断裂木质素结构单元间的连接键,但对芳环结构的断裂能力有限。Cu/Ni-LDO催化剂能够有效的抑制木质素解聚产物的成炭反应,并能显著地提高单体的收率。高温可以有效促进木质素解聚过程中的氢解和加氢反应,获得了更高的单体收率。温度对超临界甲醇木质素解聚反应有显著的影响,反应温度高于240℃时,单体的收率显著增加,THF不溶残渣和炭的得率则明显减少。催化剂循环使用3次后,木质素的降解率依然保持90%以上。通过XRD、ICP及N2吸/脱附实验分析表明Mg的浸出是催化剂失活的主要原因。Cu/Ni-LDO催化剂在超临界甲醇介质中能够有效地促进木质素解聚为小分子的单体化合物。     

竹材居里点快速热裂解研究

利用JHP-5型居里点裂解仪,在358、445、590和670℃4种居里点温度下快速热裂解竹材,通过GC-MS在线分析裂解产物。结果表明竹材居里点裂解液相主要产物为糠醛和酚类物质,其中445℃时2,3-二氢苯并呋喃的相对含量多达21%,并且液相主要产物的相对含量随温度的提高呈现先增后减的变化规律,裂解温度为445~590℃更利于液相产物的生成。裂解机理分析得知糠醛是由纤维素和半纤维素裂解产生,而酚类物质则来源于木质素。     

杉木屑分段热解制备木醋液及其特性研究

以杉木屑为原料,在固定床反应器上研究了分段热解制备木醋液及其特性。实验结果表明:≥150～250℃为杉木屑热解最活跃阶段,木醋液得率最高,达到34.09%;在该温度段木醋液组分中GC含量最高为酚类物质,其次为酸类物质。木醋液中有机物GC含量随热解温度升高而增加,当热解温度大于150℃后,有机物可达48%左右。不同热解温度段各类有机物GC含量不同,酸类物质在0～150℃最高(64.84%),酚类(54.13%)和酮类(17.95%)物质在≥250～350℃最高,醛类物质在≥150～250℃最高(17.15%)。     

制浆黑液固形物与工业木质素热解液化产物分析

采用管式炉研究了纯化后的工业碱木质素和制浆黑液固形物在不同温度下的热解产物分布规律.借助热解-色谱-质谱(Py-GC-MS)联用、元素分析仪、ICP等离子发射光谱等分析了热解液相产物(热解油)和固体残余物的主要组成.研究表明,在600℃下热解,纯化后的工业碱木质素和黑液固形物热解油产率最高,且工业木质素热解油产率明显高于黑液固形物.热解油的产物非常复杂,纯化后的工业碱木质素和黑液固形物的热解油化学组成有较大的差异.纯化后的工业碱木质素热解油主要由各种低相对分子质量(Mr)的酚类、酮类、有机酸等物质组成,这些物质的相对含量明显高于黑液固形物热解产物中的含量,其中不含有黑液固形物的热解产物中相对含量较高的左旋葡萄糖,却出现了可能因热解缩合而形成的联苯结构.说明在黑液固形物热解液化前,对试样进行适当前处理,可在很大程度上调控其热解产物的组成.     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。     

Natural Regeneration in Clear-cuts: Effects of Scarification,Slash Removal and Clear-cut Age

The effects of soil scarification (mounding), slash removal and clear-cut age on the natural regeneration in clear-cuts was evaluated using data from four sites in southern Sweden. The treatments were carried out during a good seed and establishment year for birch ( Betula pubescens Ehrh. and B. pendula Roth). Scarification had the strongest positive effect on the density of naturally regenerated seedlings, especially in birch, but also in pine ( Pinus sylvestris L.) and spruce [ Picea abies (L.) Karst]. Slash removal had a positive effect on birch density. No statistically significant effect of clear-cut age was found. In addition, no statistically significant interactions between clear-cut age and scarification or slash removal were found. The ingrowth of field vegetation was the fastest in areas that were not scarified, less rapid in areas scarified on old clear-cuts, and the slowest after scarification in fresh clear-cuts. In conclusion, it may be possible to control the density of birch during a good establishment year for birch. If birch is desired, the best combination of treatments is to remove the slash and scarify; otherwise, these treatments should be avoided.     

Risk Perception Among Non-industrial Private Forest Owners

Based on an enquiry, risk perception among non-industrial private forest owners is described in relation to climate change and forestry hazards. Of the respondents, 11% took action to remedy the effects of climate change. Out of a given set, hazards were ranked according to each respondent's experience of recent substantial financial loss to the estate and in relation to his or her willingness to make investments aimed at risk reduction. For each hazard, the respondent assessed the risk in four classes ranging from very high to negligible risk. Six hazards were considered most problematic in all three aspects: browsing damage, falling timber prices, damage by wind, spruce bark beetle, root rot and pine weevil. A majority of the respondents claimed to take action to reduce the risk associated with at least one hazard, while 35% did not know whether they did. Excluding climate change, the need for decision support was the largest in relation to damage by wind owing to a combination of perceived high risk and a high level of ignorance in relation to whether risk-reducing measures were taken.     

Interactions in decomposition and N mineralization between tropical legume residue components

In situ produced plant residues contain a mixture of different plant components of varying quality. To assess synergistic or antagonistic interactions occurring during the decomposition and mineralization of such mixtures, individual plant parts (stems, leaves, leaf litter and roots) or the mixture of stems, leaves and leaf litter of the agroforestry species pigeonpea (Cajanus cajan) or of crop residues of peanut (Arachis hypogaea) or of the weed hairy indigo (Indigofera hirsuta) were incubated in pots for 19 weeks. Periodically, remaining plant residues were sieved out (>2 mm), weighed and N content as well as soil mineral N determined. Above- and below-ground residues of peanut decomposed fastest and showed the largest N release in agreement with their high N concentration and low-acid detergent fibre (ADF) : N ratio. Hairy indigo was hypothesized to be of lower quality than pigeonpea because of its high-polyphenol content. However, it decomposed faster than pigeonpea, largely because of the higher N and lower lignin concentration of its components. Ranking of individual plant components for N mineralization resulted in the following pattern, leaves > leaf litter > roots > stems. In mixtures of the different plant components a similar species order in decomposition was obtained, e.g. peanut > hairy indigo > pigeonpea. The amount of N released from the mixture was dominated by stem material that comprised 46–61% of the mixture. The interactions in mixtures were relatively small for peanut (generally high-quality components) as well as for pigeonpea (low proportion of high-quality components, i.e. N rich leaf material). However, a positive interaction occurred during later stages of N mineralization in the mixture of hairy indigo as it had a significant proportion of N rich components and absence of highly reactive polyphenols. Thus, for plants with low to intermediate chemical quality attributes, manipulating plant composition (e.g. by varying harvest age, affecting stem and leaf proportions) will be important to obtain significant interactions during decomposition when its components are mixed.     

Pasture production and tree growth in a young pine plantation fertilized with inorganic fertilizers and milk sewage in northwestern Spain

The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization, (2) milk sewage sludge at 40 kg N ha⁻¹ target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha⁻¹. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹); (2) Lolium perenne L. var. Tove (25 kg ha⁻¹) + Trifolium repens L. group Ladino (4 kg ha⁻¹) + Trifolium pratense L. var. Marino (1 kg ha⁻¹). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea (Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m², with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral systems. This revised version was published online in June 2006 with corrections to the Cover Date.