热解条件对煤焦气化活性影响的研究进展

简述了原煤性质与温度、压力和热解气氛等热解条件对煤焦结构和气化反应活性的影响;参考该领域的国内外研究成果,分析了热解条件影响煤焦气化反应活性的机理.由于实验设备和研究方法的差异,对温度和压力等热解条件对煤焦气化反应活性影响的评价不尽相同,但总体来讲,热解终温越高、停留时间越长、升温速率越快、热解压力越大,煤焦的气化反应活性越低;热解过程中,原煤性质的差异也会影响煤焦的结构和气化反应活性.煤焦的石墨化应该是导致煤焦气化反应活性下降的主要原因,因此,热解条件的改变,特别是温度和压力的改变对煤焦石墨化进程的影响值得进一步研究.     

生物质型煤热解半焦的燃烧特性研究

为开拓低阶粉煤资源高效分质利用途径,在前期制备的能满足直立炉热解要求的生物质型煤的基础上,利用同步热分析仪研究了生物质型煤热解半焦的燃烧性能,并与原煤、原煤半焦及型煤的燃烧性能进行了对比,考察了热解温度对半焦燃烧性能的影响规律。由结果可知,生物质型煤热解半焦的燃烧特征温度低于原煤半焦;随热解温度的升高,原煤半焦的燃烧特征温度呈线性增加,而型煤半焦燃烧特征温度的增加幅度较小;在热解温度较高时,型煤半焦的燃尽性能较好;型煤半焦的综合燃烧特性略差于相同热解温度的原煤半焦,但差别很小。热解温度为650℃的型煤半焦具有最好的燃尽性能和综合燃烧特性。     

一种褐煤热解煤焦的CO2气化反应特性

针对褐煤的热解-部分气化-残炭燃烧梯级利用工艺,以宁夏石沟驿褐煤为原料,采用水平管式炉在700℃～950℃温度范围内分别制备快速和慢速热解煤焦,考察了煤焦微晶结构和比表面积随制焦条件的变化.利用热重-质谱联用技术研究煤焦CO2气化反应特性,并采用不同评价指标对煤焦气化活性进行了表征.结果表明:气化温度每升高50℃,煤焦CO2气化反应速率增加50％以上;热解温度升高,虽然煤焦微晶结构的有序化程度加深,比表面积减小,但煤焦CO2气化反应活性主要受气化温度影响;快速热解煤焦的CO2气化反应活性高于慢速热解煤焦,二者的差异随着气化温度升高而增大;表征煤焦CO2气化活性的平均比气化速率和反应性指数存在线性关系.     

褐煤热解及半焦成型特性研究

以褐煤为原料,通过原煤热解与半焦成型实验,研究了热解终温对产物分布的影响及半焦的成型特性与反应活性;利用气体在线分析仪、GC-MS对热解产物进行表征;研究结果表明,热解温度由450℃提高到750℃,热解气体产率持续增大,半焦收率则持续减少,焦油收率在550℃时最高;气相组分中H2含量持续增加,CO2和CH4含量减小,CO含量在650℃时最高;热解焦油主要由萘及其衍生物、高碳数直链烷烃、苯酚及其衍生物、蒽、菲及衍生物、稠环芳烃和中性含氧化合物(醛、酮、呋喃)组成,随热解温度升高,多侧链取代化合物含量减少,稠环化合物含量增加;热解改质后,半焦型煤强度提高了3 MPa,半焦型煤的CO2反应活性高于半焦。     

碱金属对煤热解和气化反应速率的影响

通过对原煤、酸洗原煤、负载碱金属的酸洗原煤在800～1050℃热解制得焦样,用X射线衍射技术考察了碱金属对煤焦微晶结构的影响,在加压热天平（PTGA）上考察了煤样的热解过程,以及焦样的二氧化碳气化活性。结果表明：碱金属对煤的热解和气化阶段都有影响。在热解阶段,碱金属的存在抑制了煤焦的石墨化进程,降低了热解反应活化能,促进了热解反应的进行;在气化阶段,作为催化剂的碱金属,降低了气化反应活化能,延长了反应速率达到最大值的时间。修正的随机孔模型可以较好地描述煤焦-CO₂的气化反应过程。     

快速热解温度下的淮南煤焦与水蒸汽气化反应的研究

考察了淮南煤在不同温度下快速热解制得的煤焦与水蒸汽的气化反应,研究发现煤焦的气化反应速率不仅与转化率有关也与气化反应时间有关,对不同热解温度煤焦在x = 0.2、t =2 min附近时,化学反应速率存在极值或转折点(Q),即反应速率开始急剧减少的点.用未反应芯缩核模型和随机孔模型对实验数据拟合,结果表明随机孔模型对实验数据的拟合更为准确,并将拟合得到的结构参数ψ与煤焦气化反应活性之间的关系进行分析,发现同一种煤焦ψ相近,但ψ与煤焦的气化反应活性不存在必然的联系.用SEM和XRD考察了不同热解终温下的煤焦表面孔隙结构与微晶结构的变化及其对煤焦气化反应活性的影响,不同热解温度下制得的煤焦,其形态结构存在很大的差异,热解温度越高,煤焦表面壳状凸起越多,化学反应性降低.此外,随着热解温度的升高,煤焦的微晶结构趋于石墨化,化学稳定性增强.     

碱金属及灰分对煤焦碳微晶结构及气化反应特性的影响

通过对原煤、酸洗原煤、酸洗后负载NaOH的原煤在750~1050℃热解制得焦样,用X射线衍射技术考察了热解温度、NaOH负载量以及灰分对热解过程中煤焦微晶结构变化的影响,并运用高温高压热天平(PTGA)考察了热解后煤焦的气化反应活性。结果表明碱金属及灰分的存在可以明显减小煤焦的微晶结构参数的变化(堆垛高度Lc、微晶尺寸La、及晶层间距d002),阻碍煤焦的石墨化进程,提高煤焦的气化反应性。随着热解温度的升高,堆垛高度Lc增大显著,而微晶尺寸La和晶层间距d002变化较小。煤焦的气化反应性k0和煤焦微晶结构参数Lc、d002存在如下关系:lnk0=a(Lc/d002)+b;研究还表明用氧化还原循环机理来描述碱金属的催化作用机理是不恰当的,但碱金属Na的存在可以明显降低煤焦的石墨化程度,提高煤的活性,对煤焦的气化起到部分催化作用。     

煤焦二氧化碳气化反应活性影响因素研究现状

煤二氧化碳气化反应是一种煤清洁利用的手段,其关键是提高反应活性。综述了原煤性质、热解过程、反应温度与压力、催化剂,以及二氧化碳气速、煤焦的粒度等因素对反应活性的影响,并对煤焦气化技术进行了展望。     

高温下兖州煤焦/CO2气化反应性

在常压、温度为950 ℃～1 400 ℃范围内,以二氧化碳为气化剂,用等温热重法研究了我国兖州煤的高温气化反应性.主要考察了反应温度、热解终温和热解速率对兖州煤焦高温反应性的影响,并把兖州煤焦的高温反应性和神府煤焦的高温反应性作了比较.结果表明:随气化温度的提高,兖州煤焦反应性的总体趋势增强;快速热解焦的反应性优于慢速热解焦;热解温度对兖州煤焦反应性的影响甚微;在低温段,兖州煤焦的反应性比神府煤焦略差,但在高温段,兖州煤焦的反应性与神府煤相近.     

热解条件对煤焦结构及气化反应活性的影响

在不同热解条件下制得5种煤焦,考察了热解温度、升温速率对煤焦结构性质及CO2气化反应活性的影响.其中4组煤焦由神木煤和华亭煤在1 100℃和1 500℃常压沉降炉中快速热解制得,还有1组煤焦在固定床中以10℃/min加热到900℃,并停留30 min得到.慢速热解煤焦孔隙结构不发达,BET比表面积仅为1.58 m2/g,而快速热解煤焦存在大量的微孔和中孔结构,得到的比表面积要大得多,但随热解温度的增大而减小.煤焦与CO2在0.1 MPa和3.1 MPa系统压力下的反应速率均随热解终温的升高而减小,但与慢速热解煤焦的结构性质无法直接关联.热解温度对煤焦炭微观结构及矿物质催化性能的影响导致了反应活性的下降.     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。