O2/CO2气氛下CO2和H2O气化反应对煤及煤焦燃烧特性的影响

利用热天平对比研究了大同煤及煤焦在O₂/N₂、O₂/CO₂和O₂/H₂O/CO₂中的燃烧行为,探讨CO₂和H₂O气化反应对其富氧燃烧特性的影响。结果表明,在5%氧气浓度下,煤粉在O₂/N₂、O₂/CO₂和O₂/H₂O/CO₂中的燃烧速率按顺序依次降低。氧气浓度降低到2%,由于CO₂和H₂O气化反应的作用,煤粉在高温区的整体反应速率按顺序依次增大。当氧气浓度为5%时,煤焦在O₂/CO₂中的燃烧速率要低于O₂/N₂中的燃烧速率,但燃烧反应推迟后气化反应的参与使得煤焦在O₂/H₂O/CO₂中的整体反应速率显著升高。当氧气浓度降低到2%后,随着温度的升高,在CO₂气化反应的作用下,煤焦在O₂/CO₂中的整体反应速率逐渐高于O₂/N₂中的燃烧速率。在O₂/H₂O/CO₂中,由于H₂O在共气化中起主要作用,煤焦在O₂/H₂O/CO₂高温区的整体反应速率进一步升高。动力学分析表明,在5%氧浓度时,煤焦在O₂/N₂、O₂/CO₂和O₂/H₂O/CO₂中的表观活化能依次升高。随着氧气浓度的降低,在不同反应气氛中的表观活化能均有所下降。     

In/HZSM-5催化剂上CH4选择还原NO机理研究

考察了CH⁴+O₂,NO+CH₄(+O₂)与NO₂+CH₄(+O₂)反应体系中CH₄的转化活性.结果表明,浸渍法制备的In/HZSM₅催化剂上CH₄选择还原NO过程中,NO₂的形成起到了活化甲烷的作用.根据NO和NO₂在In/HZSM₅与HZSM₅样品上的TPD及IR研究结果,认为在载体HZSM₅的酸性位及In/HZSM₅催化剂的活性中心In位上均可形成NO₂,NO₂与CH₄的反应在In位上进行.     

Ag-ZSM-5催化剂上CH4选择催化还原NOx的研究

摘要研究Ag-ZSM-5催化剂上CH₄选择性催化还原NO_x的反应性能,采用TPD和TPSR技术研究NO和O₂共吸附于Ag-ZSM-5催化剂表面形成的吸附物种及其和CH₄之间的反应。结果表明,Ag-ZSM-5催化剂上CH₄选择性还原NO_x活性和选择性较高。NO和O₂共吸附在Ag-ZSM-5催化剂上形成的NO₃(s)吸附物种能被CH₄还原生成N₂.在NO₃(s)和O₂共存的体系中,CH₄能优先并选择性还原NO₃(s)生成N₂.     

2-(三甲氧基苯基)色胺盐酸盐的合成

2,3,4-及3,4,5-三甲氧基苯乙酮苯腙在多聚磷酸存在下进行Fischer反应,可生成相应的吲哚(1_a,1_b),但2,4,6-三甲氧基苯乙酮苯腙必须用无水氯化锌催化环化才能得到相应的吲哚(1_c)。1_a、1_b、1_c经Vilsmier反应生成相应的吲哚-3-醛(2_a,2_b,2_c);经与硝基甲烷缩合得到相应的2-(三甲氧基苯基)-3-(2-硝基乙烯基)吲哚(3_a,3_b,3_c);3_a及3_b用LiAlH₄还原即可制备成相应的色胺盐酸盐(4_a和4_b),3_b还被制成苦味酸盐(4_b)。     

基于镍基载氧体的串行流化床煤化学链燃烧实验

以NiO/Al₂O₃为载氧体,在1 kW_th串行流化床反应器上进行了煤化学链燃烧实验,通过四个参数:碳转换效率η_C,coal、煤气化产物的转换效率、碳捕集效率η_C,cap及煤燃烧效率η_combust对煤燃烧过程进行表征,考察了燃料反应器温度t_FR、过量空气系数α、隔离器水煤比S_LS/C、燃料反应器水煤比S_FR/C和热负荷等参数的影响。结果表明,t_FR和S_LS/C的增大有利于煤气化产物的转换;t_FR、α和S_LS/C的增大有助于η_C,coal的提高,随着S_FR/C由0.8增加到1.8,η_C,coal呈先增加再减小的趋势,并在S_FR/C=1.2达到最大值;η_combust和η_C,coal变化趋势保持一致,主要受飞灰含碳量中残碳损失的影响;t_FR提高有助于提高η_C,cap,而α和S_LS/C的增大使得η_C,cap降低。     

BeSO4-Al2(SO4)3-Na2SO4三元熔盐体系相图的研究

热分析法研究了BeSO₄-Al₂(SO₄)3-Na₂SO₄三元熔盐体系的状态图。体系中存在三元转熔(包晶)点P,温度490℃,组成为BeSO₄18.8Wt%,Al₂(SO₄)₃15.0%,Na₂SO₄66.2%;三元低共熔(共晶)点E₁,温度为476℃,组成为BeSO₄20.0%,Al₂(SO₄)₃11.2,%,Na₂SO₄68.8%。另一低共熔点E₂温度为595℃,组成未能确定。体系中无三元化合物生成。     

气相色谱法研究配位化合物的热稳定性(Ⅶ)——Ni(Ⅱ)、Co(Ⅱ)草酸配合物的热分解及产物的催化性能

镍(Ⅱ)、钴(Ⅱ)草酸配合物在氢气中热分解时产生CO₂和CO,并发生加氢催化反应.CoC₃O₄和NiC₂O₄的分解产物CO₂加氢活性很快降低;K₂O等具有分散金属的作用。CoC₂O₄/Al₂O₃和K₂^{[Co(C₂O₄)₂]}/Al₂O₃体系具有Al₂(C₃O₄)₃的分解特征。C₂O₄^2-在Al₂O₃表面能形成表面配合物,在Al₂O₃表面Co(Ⅱ)的还原较为困难。     

Ni2P和MoS2催化剂在二苯并噻吩加氢脱硫反应中的氢溢流效应

对分层装填的Ni₂P//MoS₂催化剂上的二苯并噻吩加氢脱硫反应进行了研究。结果表明,分层装填的Ni₂P/Al₂O₃和MoS₂/Al₂O₃催化剂在二苯并噻吩加氢脱硫反应中存在氢溢流效应,氢溢流有助于提高MoS₂催化剂的活性位密度和加氢脱硫反应速率。由于Ni₂P比NiS_x具有更强的氢分子解离能力,Ni₂P//MoS₂催化体系的氢溢流因子略高于NiS_x//MoS₂;相对于NiS_x,Ni₂P对MoS₂催化剂是更好的助剂。     

三苯基膦：转换硫醇保护的纳米粒子成[Au25(PPh3)10(SR)5Cl2]2+

我们在此报道了一种未曾发现的有趣现象：尽管[Au₂₃(SC₆H₁₁)₁₆]⁻、Au₂₄(SC₂H₄Ph)₂₀ (Ph:苯环)、Au₃₆(TBBT)₂₈ (TBBTH:对叔丁基苯硫酚)、Au₃₈(SC₂H₄Ph)₂₄、混合Au_x(SC₂H₄Ph)_y团簇及3 nm的金纳米粒子有不同的组成、结构、尺寸和保护性硫醇配体,但它们在三苯基膦(PPh₃)作用下,均能统一地经由亚稳的[Au₁₁(PPh₃)₈Cl₂]²⁺最终转化为稳定的双二十面体[Au₂₅(PPh₃)₁₀(SR)₅Cl₂]²⁺ (SR:硫醇配体)。换句话说,三苯基膦是这些硫醇保护的纳米粒子的统一转化器。然而,聚乙烯吡咯烷酮(PVP)/柠檬酸盐(Citrate)保护的金纳米粒子和[Ag₂₅(SPhMe₂)₁₈]⁻ (Me:甲基)在同样的条件下,却不能转化为[Au₂₅(PPh₃)₁₀(SR)₅Cl₂]²⁺或[Ag₂₅(PPh₃)₁₀(SR)₅Cl₂]²⁺,暗示了硫醇保护的金纳米粒子具有与三苯基膦反应的独特性能。另外,我们考察了配体对双二十面体[Au₂₅(PPh₃)₁₀(SR)₅Cl₂]²⁺团簇荧光性能的影响。     

钾对CuSO4/TiO2脱硝催化剂的失活效应(英文)

为了减少碳排放，在世界各地兴建了越来越多的生物质电厂。钾元素是生物质电厂烟气中的一种典型元素并且可以引起脱硝催化剂的失活。具有优异抗SO₂性能的CuSO₄/TiO₂催化剂被认为是一种有前景的非钒基脱硝催化剂。但是，钾对CuSO₄/TiO₂催化剂的影响仍不清楚。本文研究了钾对CuSO₄/TiO₂催化剂的影响并且与商业V₂O₅-WO₃/TiO₂ (VWTi)催化剂作了比较，采用多种表征方法对催化剂样品进行了表征。钾可以引起CuSO₄/TiO₂和VWTi催化剂的失活，但是CuSO₄/TiO₂催化剂对钾的抵抗能力明显高于商业VWTi催化剂。钾会与CuSO₄/TiO₂催化剂中的CuSO₄发生反应生成CuO和...     

Influence of molecular weight and polydispersity on phase behaviour of polyesters with laterally fixed or cross-shaped mesogens

To supplement previous studies of polyesters with laterally attached and cross-shaped mesogens the influence of molecular weight and molecular weight distribution on the phase behaviour has been investigated. For that purpose two polyesters have been fractionated by preparative gel permeation chromatography under high pressure and observed by polarizing microscopy and DSC measurements. A monotropic nematic polyester with laterally attached mesogens shows changing phase transitions up to a molecular weight of 10 000 (M_w); at higher molecular weight only the clearing transition is still slightly influenced. The molecular weight distribution at an average molecular weight of 15 000 (M_w) has no influence on the melting and clearing temperatures, but does effect recrystallization. The tendency to recrystallize decreases with increasing polydispersity, with increasing aberration from a monomodal molecular weight distribution. The recrystallization and the melting enthalpy are most distinguished at molecular weights around 12 000 (M_w) and crystallization disappears at molecular weights under about 5000 (M_w). In this way, fractions with stable nematic phases are obtained. Additionally, the broadness of the biphasic region shows a distinct dependence on molecular weight. Clearing temperatures show the most significant dependence on the molecular weight of an enantiotropic polyester with crossshaped mesogens dropping significantly below a molecular weight of about 20 000 (M_w). Oligomers with molecular weights below 10 000 (M_w) do not exhibit a mesophase. Polyesters with laterally attached mesogens as well as with crossshaped mesogens show no new liquid-crystalline phases by varying the molecular weight or the molecular weight distribution.     

Effect of different donors on kinetics of Zn catalysts and molecular weight of the obtained polypropylene

This paper studies MgCl₂/internal donor/TiCl₄//external donor/AlEt₃ catalytic systems where ethyl benzoate (E.B.) or 2,2,6,6 tetramethylpiperidine (TMPiP) are used as internal and external donors. E.B. as external donor does not change the molecular weight of the product with TMPiP as internal donor. The molecular weight of polypropylene decreases drastically and global productivity and stereoselectivity are very low with MgCl₂/internal Donor/TiCl₄//external donor/AlEt₃ when TMPiP is the external and internal donor. In this case the insoluble fraction in n-heptane is highly stereospecific and the molecular weight is similar to commercial products. We present a new explanation of these results, based on Ystenes proposal, comparing both precatalysts.     

Influence of molecular weight on the thermal decomposition of hydroxyl terminated polybutadiene

Thermogravimetric analysis of hydroxyl terminated polybutadiene (HTPB) and its fractions of different molecular weights separated by preparative GPC shows two major stages of weight loss of different nature in a nitrogen atmosphere. The first stage is primarily depolymerisation, cyclisation and crosslinking of molecules and the second stage is mainly the decomposition of the residue from the first stage. The kinetic parameters, viz. activation energy E and pre-exponential factor A using four different non-isothermal integral equations show a systematic increase with increase in molecular weight for the first stage, whereas for the second stage, the effect of molecular weight on E and A values is not prominent. The increase in E and A values for the first stage is attributed to the formation of greater number of cyclised and crosslinked products from molecules of higher dimensions. Quantitative correlations between the kinetic constants and the molecular weight parameters were derived for the first stage as a quadratic curve following the equation: E or ln A = K₁ − K₂/M (where K₁ and K₂ are empirical constants whose values are different for the different molecular weight averages, viz. M_n, M_w and M_z and for the different equations).     

Studies on molecular weight distribution of carbon fiber polymer precursors synthesized using mixed solvents

The molecular weight distributions were estimated for carbon fiber polymer precursors such as poly（acrylonitrile-co -itaconic acid） synthesized by semi batch solution polymerization in mixed solvents media with the azonitrile compounds as initiator under the different ratios of solvent and non solvent from 0.75 to 2.5 in weight.The copolymer was characterized by using Fourier transform infrared spectroscopy（FTIR） and nuclear magnetic resonance（¹H-NMR） analyses.The molecular weight distributions were evaluated by M_v/M_n ratios estimated from viscosity and osmotic measurements,and M_w/M_n estimated from size exclusion chromatography.The molecular weight distributions of these polymers as determined from M_v/M_n and M_w/M_n are 2.9 to 3.2 and 2.0 to 2.5 respectively.The molecular distributions were close to a narrow distribution of 2.0 when the solvent/non-solvent ratio was varied between 1.4 and 2.0.Intrinsic viscosity[?]as a function of molecular weight of poly（acrylonitrile-co-itaconic acid） was evaluated by means of low angle laser light scattering with size exclusion chromatography（SEC-LALLS） and viscometry with SEC（SEC-VISCO）.The relationship between[?]and M_w for poly（acrylonitrile-co-itaconic acid） in DMF at 50℃was[?]= 1.1×10^-5M_w^0.79,where[?]is obtained in dL/g.     

香菇多糖的成分及其分子量研究

从香菇子实体中用0.9%NaCl水溶液、85%乙醇、热水、1%草酸铵、5%NaOH/0.05%NaBH₄和2%NaOH/2%尿素分别提取出四种杂多糖(L-FⅠ-L-FⅣn)和两种葡聚糖(L-FⅤ和L-FⅥn).红外光谱和高效液相色谱分析结果表明杂多糖主要由葡萄糖、葡萄糖醛酸、木糖、甘露糖、半乳糖和鼠李糖组成,而且按照分离过程的进行多糖中葡萄糖含量递增.由光散射和膜渗透压法研究了多糖的重均分子量Mw、均方根旋转半径2>^1/2、第二维利系数A₂及数均分子量M_n.L-FⅡ、L-FⅢ、L-FⅤ及L-FⅥn的M_w值依次为19.7×10⁴、192.3×10⁴、136.4×10⁴和136.7×10⁴,它们的多分散系数-Mw/-Mn在3～5范围.     

短链药物聚电解质稀溶液行为

本文用改良型Bruss膜渗透计及动态渗透压、粘度和电导法研究了一种主链含5-氟尿嘧啶的磷酸酯缩聚物盐PPA和PPB(24000较小,溶液显示正常渗透压行为,由此得到数均分子量及第二维利系数A₂。它们在水和甲醇中的A₀变大,溶液显示一般聚电解质的性质,但是当溶液浓度相当低时,η_SP/C～C和A～C曲线均出现反常变化。     

Solution properties of polyurethane

Polyurethane was fractionated and the fractions were characterized by gel permeation chromatography (GPC) and viscometry. The intrinsic viscosities of polyurethane in ten solvents varying in their polarity were determined and are in the order of mineral spirit < acetone < cyclohexane < cyclohexanone < xylene < ethyl benzene < toluene < benzene < methyl ethyl ketone < tetrahydrofuran. The Mark-Houwink relations suggested that solvent blend MEK: n-heptane (1:3) is a poor solvent with an a value of 0·52 and tetrahydrofuran is a good solvent with an a value of 0·78. The weight average molecular weight has been estimated by an extrapolation technique based on a linear relationship between the viscosity average molecular weight _v and the Mark-Houwink constant. The weight average molecular weights obtained from viscosity studies were used to evaluate the unpertureb dimension of the chain.     

聚合物共混物的超高效液相色谱-空间排阻色谱在线联用分离与表征

黏合剂和涂料行业中, 聚合物共混物表征是分析的难题, 分离技术的研究一直备受关注. 本文设计并搭建了超高效液相色谱-空间排阻色谱在线联用系统(UHPLC-SEC), 采用羟基聚丁二烯(HTPB)考察了二维色谱系统的溶剂兼容性及正交性, 以苯乙烯-丁二烯嵌段共聚物(SBS)、 苯乙烯-异戊二烯嵌段共聚物(SIS)和聚甲基丙烯酸酯(PMMA)共混物研究了二维色谱系统的适用性. 结果表明, HTPB分子量及分布的UHPLC-SEC测定结果与SEC测定结果一致, 峰尖分子量(M_p)为3407 Da, 重均分子量(M_w)为6573 Da, 分散系数(PDI)为2.36, 相对标准偏差(RSD)均小于5.7%, 系统的溶剂兼容性和正交性良好. UHPLC-SEC法测得聚合物共混物中PMMA, SBS和SIS的M_p, M_w和PDI与单个聚合物的SEC测定结果的相对误差均小于7.1%. PMMA, SBS和SIS共混物在200 °C加热3 h后, PMMA 稳定不变, SBS和SIS组分明显降解. UHPLC-SEC在线联用方法对聚合物共混物的表征结果准确、 重复性好, 为聚合物配方产品的失效分析提供了一种重要且有效的手段.     

相同软硬段质量配比聚醚酯弹性体PEG/PBT的结构与表征

以熔融缩聚法合成了一系列聚乙二醇(PEG)/聚对苯二甲酸丁二醇酯(PBT)聚醚酯热塑性弹性体,用NMR,FTIR,DSC及力学性能测试等方法表征了材料的结构及性能.讨论了在相同软硬段质量配比下,不同软硬段长度对材料性能的影响.结果表明,随着软段PEG长度增加,硬段PBT长度相应增长,弹性模量基本保持不变,抗拉强度、屈服应力及特性粘度增加.     

富勒烯(C60/70)-丙烯酸的自由基共聚

富勒烯及其衍生物在超导、光电、磁学等领域展现出奇特性能[1],富勒烯的化学修饰成为化学工作者们关注的热点之一,而其中合成含富勒烯的新型聚合物是一个非常重要的方面.