射流冷却下氧化二叔丁基瞬时热解反应的研究

采用射流冷却和高温瞬时热解技术研究了过氧化二叔丁基产物的质量分布和飞行时间谱。ＤＴＢＰ解离率与热解温度的关系表明，１３００Ｋ时ＤＴＢＰ全部解离。     

高温瞬时热解法产生甲基自由基束

Chen等提出了用脉冲分子束快速通过高温加热管与射流冷却相结合的高温瞬时热解法可产生高纯度自由基,当以偶氮甲烷为前体时可获得性能良好的CH_3·自由基束,并成功地用于生长金刚石薄膜。但偶氮甲烷的制备比较复杂,且价格昂贵,不易长期保存。为此,我们选择2-叔丁基过氧化物(Di-t-butyl peroxide,DTBP)为前体,该化合物在1100K时热解速率比偶氮甲烷大100倍。本文用该化合物经高温瞬时热解获得了射流冷却和高纯度的甲基自由基,并由四极质谱测定了DTBP的热解产物及加热温度对解离率的影响。 1 实验 将4％(摩尔比)DTBP/He混合气体。(总压强101.3 kPa)经脉冲阀(General Valve Series 9)喷出,瞬时流过隔热用的Al_2O_3座管和Hexoloy SA高密度SiC加热管,由热解产生的产物和载气从加热管喷出经绝热膨胀进入真空室,形成的分子束通过2个漏勺准直后进入四极质谱(QMS)探测室,其中离子化器电子轰击能量为70eV。对解离产物作质量扫描,信号经放大器输入信号均分器(Boxcar PAR-162)录谱。加热管温度用Pt-Pt/Rh热电偶或灯丝辐射高温计测量。     

二硫代乙酰丙酮和某些金属离子络合反应的研究

报导CH₃COCH₂COCH₃/H-2S/C₂H₅OH-HCl体系和十六种金属离子以及Fe(CO)₅的反应,用X射线衍射法测定了九种反应产物的分子和晶体结构.本文结果总结出了该反应的规律性.研究表明,在该反应条件下,钼是唯一能够形成原子簇化合物的元素.     

神府烟煤快速热解特性研究

利用高频电炉对神府煤进行快速热解,研究了不同热解温度和停留时间下,固相和气相产物的性质。结果表明,煤焦的失重率及真密度随温度升高和时间的延长而增长。红外光谱结果表明,热解过程中,煤中含氢/含氧官能团分解,生成H₂、CO、CO₂、CH₄等气体,并且其分解程度随温度的升高和时间的延长而加深。气相产物中H₂和CO的释放量随温度的升高和时间的延长而增加,而CO₂和CH₄存在释放量的峰值。气相产物随温度的升高和时间的延长而增多,导致高温煤焦出现大量的孔隙和裂缝。     

基于Py-GC联用的煤快速热解实验研究

采用居里点裂解仪-气相色谱仪(Py-GC)联用的方法研究了4种煤的快速热解特性,分析了挥发分主要气相产物及其析出规律.结果表明,大于等于50%的挥发分在热解初期(t ≤ 2 s)释放,采用箔片装载方式的居里点裂解仪完全热解1 mg煤样需要10 s;挥发分主要气相产物中,各气体组分的生成量(mmol/g_coal)顺序为H₂ > CH₄ > CO > CO₂ > C2(C₂H₆、C₂H₄)> C3(C₃H₈、C₃H₆);挥发分释放量随热解温度的升高而增加,相同热解条件下,次烟煤挥发分的释放率高于贫煤和无烟煤;H₂和CH₄的生成量依赖于热解温度,热解温度越高,H₂和CH₄的生成量越多;CO和CO₂的生成量不仅与热解温度相关,而且与煤中的氧含量紧密相关,氧含量越高的煤热解生成的CO和CO₂越多;C2和C3气体的生成量相对于其他气体很少,体积占挥发分气相产物的5%.     

乙醛热解的动力学研究

在流动系统中,以甲苯为载气,于680～780℃范围内,对乙醛热解进行了动力学研究.结果表明,在此条件下乙醛热解是单分子一级分子分解反应,其动力学表达式如下:k_ACH=1.22×10¹³exp(- 68,000/RT)sec^-1(680～780℃) 与此同时,我们还得到甲苯热解的动力学表达式如下:k_ΦCH3=2×10¹³exp(- 77,000/RT)sec^-1(680～780℃) 从实验结果推导出,在乙醛热解的分子分解机理中,实际参加活化的仅11～12个振动自由度,还有3～4个振动自由度未参加活化.     

H2气氛下褐煤快速热解过程中CH4逸出规律的分析

在带有输送煤样的管式反应器上进行了霍林河褐煤加压快速氢解实验,分析了H₂对煤/半焦的化学键断裂和对CH₄生成规律的影响。在加压快速氢解条件下,CH₄产率随着热解温度升高、压力的增大而增大;在50% H₂气氛下,操作压力为1.0 MPa、温度为900 ℃时,CH₄产率为8.08%,达到最大,较N₂气氛下的提高了72.5%。H₂或H·自由基诱发了芳环的开裂、侧链、脂肪链和醚键的断裂,促进了煤热解。CH₄产率的增加主要是由于外部供H的结果;热解温度低于700 ℃时,H₂对煤结构中活性基团的作用促进了煤热解,导致了CH₄产率的增加;而热解温度高于700 ℃后,煤/半焦加氢气化促进了CH₄产率的增加。     

印刷电路板中环氧树脂热解的ReaxFF反应动力学模拟

采用ReaxFF动力学方法模拟了非交联固化环氧树脂在不同温度和升温速率下的热解特性. 结果表明, 含N和含O桥键的断裂是热解的引发反应. 观察到H₂O的4种主要的生成途径, 而这些反应途径都涉及到含羟基的前驱体. 当反应温度较低时, H₂O为热解的主要产物. 而在高温条件下, 热解的主要产物为H₂, 它主要为分子内/分子间脱氢反应和氢自由基的夺氢反应的产物; 高温同时促进了含石墨烯结构且分子量较大的碳团簇的形成. 除此之外, 还观察到了CH₄, HCN, NH₃和CO等小分子产物. 本文用ReaxFF动力学方法模拟所得的气体产物以及含类似石墨烯结构的碳团簇与实际实验结果一致, 说明ReaxFF动力学方法能为从分子水平上研究有机物高温热解反应提供了一种有效的途径.     

溴甲烷在强激光场中的电离和解离

利用自制的反射式飞行时间质谱仪(RTOF-MS)研究了多原子分子CH₃Br在强激光场中的电离解离. 得到了溴甲烷在强激光场中电离解离的飞行时间质谱, 基于RTOF-MS的高分辨率(M/ΔM>2000), 测量了分子库仑爆炸产生的系列碎片离子的动能释放(KER), 用多光子解离和库仑爆炸解释了实验结果. 与碘甲烷在强场中的实验结果对比发现: (1) 在相同的激光场强下, 碘甲烷电离解离的最高价碎片离子为I⁶⁺而溴甲烷为Br³⁺; (2) 溴甲烷质谱中存在母体离子的脱氢产物CH_mBr⁺ 和CH_mBr²⁺, 而对于碘甲烷, 没有检测到这些通道, C-I键首先断开; (3) 质谱中存在H⁷⁹Br⁺和H⁸¹Br⁺, 而碘甲烷的电离解离中不存在HI产物; (4) 溴甲烷库仑两体爆炸的有效电荷间距随着两碎片电荷乘积的增大而增大, 而对于碘甲烷此间距几乎不随电荷乘积变化; (5) CH_m⁺(m=0, 1, 2)的主要生成通道可能与碘甲烷不同, 不是来自CH₃⁺的顺序脱氢, 而是来自脱氢母体离子的直接解离.     

不同气氛下煤连续热解产物的分配规律及产品品质分析

在连续进出料的流化床中研究了热解温度为850 ℃时,含有O₂、H₂、CO、CO₂、CH₄的反应气氛对热解产物分配规律及产品组成的影响。采用Raman、BET等测试方法对不同热解气氛下制得半焦的品质进行了评价,结合热重分析了影响半焦反应活性的因素。结果表明,无O₂气氛下,H₂与CO₂存在时降低了焦油产率,而CO与CH₄促进了焦油的生成。CH₄的裂解析碳使半焦产率上升。O₂的加入使CO₂、CO含量明显增加,半焦及焦油产率降低。N₂中引入O₂时,PAHs含量降低。CH₄促进了烷基萘与苯类的生成,CO则抑制酚类裂解生成苯类。CO₂的气化作用促进了微孔的生成,相应地,半焦的比表面积快速增加,半焦的反应活性也最高。CO歧化与CH₄热裂解产生的析碳堵塞了部分孔道,降低了比表面积。H₂与CH₄所产生的氢自由基能渗透到半焦内部,引起半焦结构的缩聚,进而影响氧化反应活性。     

稀土硝酸盐冠醚配合物(ⅩⅥ)——冠醚B12C4与稀土硝酸盐配合物的合成与性质

在乙腈和丙酮中合成了冠醚B₁₂C₄与稀土硝酸盐的配合物RE(NO₃)·B₁₂C₄·xH₂O。通过金属离子的配位滴定、冠醚B₁₂C₄的分光光度测定、溶剂的气相色谱分析以及红外光谱、差热(DSC)与热重分析和X-射线衍射分析等方法研究了配合物的组成和性质。还在15±0.1℃测定了各配合物在乙腈中的溶解度。考察了重稀土(Tm、Yb和Lu)配合物1:1型向2:1型的转变。     

EHMO Studies of Chemisorbed Dioxygen Species on Na＿2O and K＿2O and of Their Interaction with CH＿4 and CH＿3－Radical

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Intermolecular potentials obtained from high-energy alkali scattering

Intermolecular potentials have been obtained from high-energy total cross sections for several alkali metal systems: CS + He, Ne, Ar, CH₃NO₂; K + CH₄, C(CH₃)₄, C₆H₆, c-C₆H₁₂, CH₃I, CCl₄, SF₆, N₂. For the CS-rare gas cases and K + N₂ only the repulsive part was determined. For the rest both attractive and repulsive parts were seen.     

Heterobimetallic Mo---Sn complexes. Reactions of [Mo(CO)3(CH3CN)2(Cl)(SnRCl2)] (R = Me, Ph) with 4(4-XC6H4)3 (X = Cl, F, H, Me, MeO)

Three families of heterobimetallic compounds were obtained by reaction of [Mo(CO)₃(CH₃CN)₂(Cl)(SnRCl₂)] (R = Ph, Me) with P(4-XC₆H₄)₃ (X = Cl, F, H, Me, MeO). The type of compound obtained dependent on the solvent and concentration of the starting compound. So, [Mo(CO)₂(CH₃COCH₃)₂(PPh₃)(Cl)(SnRCl₂)]·nCH₃COCH₃ (R = Ph, n = 0.5; R = Me, n = 1) (type I) and [Mo(CO)₃{P(4-XC₆H₄)₃}(μ-Cl)(SnRCl₂)]₂ (R = Ph, X = Cl, F, H, Me, MeO; R = Me, X = Cl, F) (type II) were isolated from acetone solution in ca 0.05 M and 0.1 M concentrations, respectively. However, [Mo(CO)₃(CH₃CN) {P(4-XC₆H₄)₃}(Cl)(SnRCl₂)] (R = Ph, X = H; R = Me, X = Cl, F, H) (type III) were obtained from dichloromethane solution independently of the concentration used. All new complexes showed a seven-coordinate environment at molybdenum, containing Mo---Cl and Mo---Sn bonds. Mössbauer spectra indicated a four-coordination at tin for type III complexes.     

煤炭解耦燃烧过程N迁移与转化Ⅲ:多组分气相化学反应实验

在理想平推流反应器中进行了模拟热解气对模拟烟气中NO、N₂O的还原实验研究,考察了反应温度、过剩空气系数,模拟热解气中CH₄、CO、H₂、NH₃入口浓度与模拟烟气中NO、N₂O入口浓度对NO、N₂O与总氮转化率的影响。结果表明,向NH₃添加可燃气体CO、H₂、CH₄可使NO还原窗口向低温方向移动150~200 K,该温度窗口为1 073~1 223 K;但NH₃-CO-H₂-CH₄-O₂体系对NO、N₂O的还原分解作用依赖于体系的O₂浓度,仅在富燃料情形(过剩空气系数λ为0.6)下可分别达60.6%、100%的NO、N₂O脱除率;在反应温度1 073~1 223 K及过剩空气系数λ为0.6条件下,较高的热解气CH₄、CO、H₂浓度可增加NO排放,但有利于还原N₂O;增加NH₃入口浓度可增加NO分解率。     

New heterometallic copper zinc alkoxides: synthesis, structure properties and pyrolysis to Cu/ZnO composites

The copper compound [(THF)KCu(O^tBu)₃]_∞ 1 was obtained by interaction of a 1:1 mixture of ZnCl₂/CuCl₂ with KO^tBu. Bi- and trifunctional aminoalcohols were used to synthesize the intramolecularly donor stabilized Cu(II) alkoxides Cu(OCH(R)CH₂NMe₂)₂ (3: R=Me, 4: =CH₂NMe₂) where 4 was structurally characterized. Lewis acid–base adduct formation with (Me₃Si)₃CZnCl gave the heterodinuclear compounds (Me₃Si)₃CZnCl · Cu(OCH(R)CH₂NMe₂)₂ (5: R=Me, 6: R=CH₂NMe₂), which were characterized by X-ray single-crystal structure analysis. The two metal centers Cu and Zn of 5 and 6 are bridged by two oxygen atoms to form a Cu–O–Zn core. Pyrolysis of compounds 5 and 6 in dry argon or a H₂/N₂ mixture at atmospheric pressure forms metallic copper and zinc oxide, whereas pyrolysis under O₂/Ar forms additionally oxidized copper species. Elemental analysis of the pyrolysis products showed carbon and nitrogen contamination. Scanning electron microscopy and energy dispersive X-ray analysis were performed to get information on the morphology and the chemical composition of the pyrolysis products.     

煤炭解耦燃烧过程N迁移与转化Ⅱ:单组分气相化学反应实验

在理想平推流反应器中进行了模拟热解气对模拟烟气中NO、N₂O的还原实验研究,考察了反应温度、过剩空气系数λ、热解气中CH₄、CO、H₂、NH₃浓度、烟气中NO、N₂O浓度变化对NO、N₂O出口浓度的影响。实验结果表明,当模拟热解气仅含其中一种气体时,在反应温度973~1 223 K时热解气中CH₄、CO、H₂基本不与NO发生反应,当λ小于或等于1.0时可降低N₂O浓度0%~30%;热解气中NH₃可降低NO 10%~60%,但NH₃不与N₂O发生反应。     

Microwave spectroscopic and ab initio studies of pyrolysis products of 2-nitrosopropene (syn form) and its pyrolysis mechanism

The pyrolysis products of CH₂=C(CH₃)---NO (syn form) have been determined by microwave spectroscopy. The pyrolysis products of CH₂=C(CH₃)---NO (syn form) and its ¹⁵N isotopic species were found to be CH₂=O, CH₃CN, and CH₃C¹⁵N. The produce of formaldehyde and methyl cyanide suggests that the C=C and N=O double bonds of CH₂=C(CH₃)---N=O (syn form) were broken. To explain the generation of the two molecules, a four-membered ring molecule (9) as an intermediate, is proposed. The four-membered ring molecule as an intermediate is also supported by ab initio MO calculation. Applying the pyrolysis mechanism obtained for 2-nitrosopropene (syn form) to that of 1,1,2-trichloronitrosoethane, one of its complicated pyrolysis mechanisms was explained. The rotational constants and geometrical parameters of two intermediates, 9 and CH₂=CCl---NO (13), were obtained by ab initio MO calculation (MP2/6-31G**) to predict their microwave spectra.     

Etude des reactions de srn1—partie 10 : Action de sulfanions sur les halogenures d''aryle fonctionnalises. synthese directe de benzothiophenes et thienopyridines

Functionalized aromatic halides Ar₁XY (Ar₁ = C₆H₄, Y = OCH₃, CONH₂, CN, COCH₃, CHO, COC₆H₅) undergo S_RN1 reactions with sulphur anions ^-SR, either simple (R=C₂H₅, CH₂C₆H₅) or functionalized (R = (CH₂)₂OH, (CH₂)₂CO₂Et, CH₂CO₂Et). Products Ar₁YS^- formed from the fragmentation of the radical anion Ar₁YSR^- are related to the redox potential of the aryl moiety Ar₁Y and with the energy of the bond S-R. In the heterocyclic series (Ar₂ = pyridine, Ar₃ = quinoline) a similar relationship appears but a competitive S_N(Ar) reaction occurs for pyridine substrates bearing an electron withdrawing group. A direct synthesis of benzothiophen via S_RN1 reaction and an improved synthesis of thienopyridines based on the S_N(Ar) reaction are reported.     

Synthesis and structures of heterobimetallic Ir2M (M=Pd, Pt) sulfido clusters and their catalytic activity for regioselective addition of alcohols to internal 1-aryl-1-alkynes

The heterobimetallic trinuclear sulfido clusters [(Cp*Ir)₂(μ₃-S)₂MCl₂] (M=Pd (3), Pt (4); Cp*=η⁵-C₅Me₅) were synthesized from the dinuclear hydrogensulfido complex [Cp*IrCl(μ-SH)₂IrCp*Cl] (2) and [MCl₂(COD)] (COD=cycloocta-1,5-diene), while the reaction of 2 with [Pd(PPh₃)₄] afforded the cationic trinuclear cluster [(Cp*Ir)₂(μ₃-S)₂PdCl(PPh₃)]Cl (5). Clusters 3 and 4 reacted with PPh₃ to give a series of mono and dicationic clusters including 5, while the dicationic clusters [(Cp*Ir)₂(μ₃-S)₂M(dppe)][BPh₄]₂ (M=Pd (9), Pt (10); DPPE=Ph₂PCH₂CH₂PPh₂) were obtained by the reaction with dppe followed by anion metathesis. The molecular structures of 5·CH₂Cl₂, 9·CH₃COCH₃, and 10·CH₃COCH₃ were determined by X-ray crystallography. Clusters 3 and 4 were found to catalyze the addition of alcohols to alkynes to give the corresponding acetals. Internal 1-aryl-1-alkynes were transformed by cluster 3 into the corresponding 2,2-dialkoxy-1-arylalkanes with high regioselectivity up to 99:1, while cluster 4 was a much less regioselective catalyst.