乙炔氢氯化均相催化反应动力学和机理的研究

本文研究了以HgCl₂为催化剂时乙炔氢氯化制氯乙烯均相反应的动力学。获得该反应速率方程为:r=k′[HgCl₂][H⁺]³[CH≡CH],表观活化能为13.6千卡/摩尔。根据实验结果提出了该催化反应的机理。     

Hydrochlorination of acetylene using expanded multilayered vermiculite (EML-VMT)-supported catalysts

Catalyst supports have very important effects on catalyst performance.A novel expanded multilayered vermiculite(EML-VMT) is successfully used as the catalyst support for the acetylene hydrochlorination.By mixing carbon on the surface of EML-VMT[i.e.,EML-VMT-C),the HgCl_2/EML-VMT-C achieved a high acetylene conversion of 97.3%,a vinyl chloride selectivity of 100%and a turn over frequency(TOF) value of 8.83 × 10~(-3)s~(-1) at a temperature of 140 C,an acetylene gas hourly space velocity(GHSV) of 108 h~(-1)',and a feed volume ratio V(HC1)/V(C_2H_2) of 1.15.Moreover,the HgCl_2/EML-VMT-C shows good stability.The EML-VMT also shows potential in the preparation of other EML-VMT-supported catalysts.     

One-pot synthesis of nitrogen and sulfur co-doped activated carbon supported AuCl3 as efficient catalysts for acetylene hydrochlorination

Commercialization of acetylene hydrochlorination using AuCl₃ catalysts has been impeded by its poor stability. We have been studying that nitrogen-modified Au/NAC catalyst delivered a stable performance which can improve acetylene hydrochlorination activity and has resistance to catalytic deactivation. Here we show that nitrogen and sulfur co-doped activated carbon supported AuCl₃ catalyst worked as efficient catalysts for the hydrochlorination of acetylene to vinyl chloride. Au/NSAC catalyst demonstrated high activity comparative to Au/AC catalyst. Furthermore, it also delivered stable performance within the selectivity of acetylene, reaching more than 99.5%, and there was only a 3.3% C₂H₂ conversion loss after running for 12 h under the reaction conditions of a temperature of 180℃ and a C₂H₂ hourly space velocity of 1480 h 1. The presence of the sulfur atoms may serve to immobilize/anchor the Au and also help prevent reduction and sintering of the Au and hence improve the catalytic activity and stability. The excellent catalytic performance of the Au/NSAC catalyst demonstrated its potential as an alternative to mercury chloride catalysts for acetylene hydrochlorination.     

乙炔氢氯化均相催化反应动力学和机理的研究——氯化汞、氯化铋复合催化剂体系

本文研究了在HgCl₂-BiCl₃复合催化剂作用下,乙炔氢氯化制氯乙烯均相催化反应的动力学,获得该反应速率方程为:r=(k+k'[BiCl₃]/[H⁺])[HgCl₂]·[H⁺]^3[CH≡CH].在25℃时k=0.00239,k'=0.0269,根据实验结果,提出了由两个复杂的连串反应组成的平行反应机理,相应的表观活化能为13.4Kcal/mol及14.8Kcal/mol.     

Synergistic effect of ferric chloride and silicon mixtures on the thermal stabilization enhancement of ABS

A previous study from this laboratory has shown that Lewis acid-type transition metal chlorides (NiCl₂, CoCl₂, ZnCl₂, and FeCl₃) are effective char forming catalysts for ABS terpolymer in an inert atmosphere [Jang J, Kim JH, Bae JY. Polym Degrad Stab 2005;88(2):324.]. However, transition metal chloride catalysed char formation (and flame-retardance enhancement) of ABS in air was unsuccessful due to the oxidative degradation of the char at a higher temperature. In order to overcome these undesirable phenomena, we incorporated silicon with transition metal chlorides as co-catalyst and a series of ABS/transition metal chloride/silicon compounds were made from them and their flame retardancy was evaluated by measuring the limiting oxygen index (LOI) values. Our results showed that among various transition metal chloride/silicon catalyst systems the incorporated mixture of ferric chloride and silicon is very effective in enhancing the thermal stabilization of ABS and LOI value as high as 33 is obtained. The reason for this synergistic effect by ferric chloride and silicon was postulated to come from the interaction between ferric chloride and silicon at elevated temperatures, probably generating silicon tetrachloride and hydrogen chloride.     

M/C3N4/AC (M=Au,Pt,Ru)催化乙炔与二氯乙烷耦合反应:双功能催化剂性能如何?

聚氯乙烯是世界上产量最大的通用塑料,在日常生活的诸多领域具有广泛应用.按照原料来源划分,聚氯乙烯的工业生产方法主要有基于煤炭的电石法和基于石油的"平衡法".我国有丰富的煤炭资源,因此,电石乙炔法是合成聚氯乙烯的主要途径.该方法采用乙炔与氯化氢在活性炭担载氯化汞催化剂上进行氢氯化反应得到聚氯乙烯的单体氯乙烯.然而,由于汞...     

The origin of the extraordinary stability of mercury catalysts on the carbon support: the synergy effects between oxygen groups and defects revealed from a combined experimental and DFT study

Thermal stability of HgCl₂ has a pivotal importance for the hydrochlorination reaction as the loss of mercuric compounds is toxic and detrimental to environment. Here we report a low-mercury catalyst which has durability over 10000 h for acetylene hydrochlorination under the industrial condition. The stability of the catalyst is carefully analyzed from a combined experimental and density functional theory study. The analysis shows that the extraordinary stability of mercury catalyst is resulted from the synergy effects between surface oxygen groups and defective edge sites. The binding energy of HgCl₂ is increased to be higher than 130 kJ/mol when adsorption is at the edge site with a nearby oxygen group. Therefore, the present study revealed that the thermal stability problem of mercury-based catalyst can be solved by simply adjusting the surface chemistry of activated carbon. Furthermore, the reported catalyst has already been successfully applied in the commercialized production of vinyl chloride.     

Mo/Fe3O4(111)表面对燃煤烟气汞吸附的密度泛函研究

利用CASTEP软件包采用密度泛函理论计算研究了过渡金属Mo掺杂Fe_3O_4(111)Fe_(tet)表面对Hg~0、HgCl和HgCl_2的吸附特征,分析了Mo掺杂前后Fe_3O_4(111)Fe_(tet)表面上不同汞物种的吸附形态。结果表明,Mo掺杂Fe_3O_4(111)Fe_(tet)表面对HgCl和HgCl_2为化学吸附,而对Hg~0的吸附为物理吸附;与纯净表面相比,HgCl在Mo原子掺杂表面上的吸附能提高了40%-66%。HgCl_2在纯净Fe_3O_4(111)Fe_(tet)表面形成"M"形结构;而掺杂Mo原子后,由于Cl原子与Mo原子之间更强的相互作用,使得HgCl_2发生了完全解离,两个Cl原子分别与Mo原子和Fe原子成键吸附在表面,Hg脱附。相关研究结果可为脱除燃煤烟气中的汞提供一定的理论指导。     

Cu/HY催化剂在乙炔氢氯化反应中的性能及其失活原因

采用等体积浸渍法制备了以分子筛为载体的铜基无汞催化剂(Cu/HY),在固定床反应器中,考察了Cu/HY催化剂用于乙炔氢氯化反应制取氯乙烯的催化性能,并采用扫描电子显微镜(SEM)、能量散射光谱(EDS)、电感耦合等离子光谱(ICP-AES)、氮气吸脱附(BET)、热重分析(TG)、透射电子显微镜(TEM)、X射线粉末衍射(XRD)和X射线光电子能谱(XPS)表征手段对反应前后的催化剂进行了表征和分析。 结果表明,反应温度为160 ℃,常压,空速为120 h^-1,V(HCl)/V(C₂H₂)=1.25,Cu的负载质量分数为15%时,Cu/HY催化剂的乙炔氢氯化性能最佳,乙炔转化率可达84%,氯乙烯选择性始终大于95%,且具有较好的稳定性;通过表征分析,认为催化剂表面形成积碳,铜活性物种的还原、团聚和流失是导致Cu/HY催化剂活性下降的主要原因。     

V2O5/AC捕获的Hg在再生过程中的释放行为研究

研究了V₂O₅/AC捕获的Hg在再生和程序升温脱附（TPD）过程中的释放行为,考察了再生后V₂O₅/AC对Hg⁰的捕获能力。结果表明,热再生（Ar,400℃）或NH₃再生（NH₃/Ar,300℃）过程会使V₂O₅/AC捕获的大部分Hg重新释放,释放率分别为81%和94%。由于AC的还原作用,再生过程中释放的Hg以Hg⁰的形式为主。TPD结果表明,V₂O₅/AC捕获的Hg在Ar和NH₃/Ar气氛下的释放行为明显不同。气氛中NH₃对Hg的释放具有明显的促进作用,使Hg的释放在300℃前基本结束。但在Ar气氛下,Hg在400℃后仍有释放,致使热再生时Hg的释放率低于NH₃再生时的释放率。但当NH₃的体积分数由1%增加到5%时,汞的释放率变化很小。温度足够高时,两种气氛下Hg的释放率趋于一致。再生方法对V₂O₅/AC二次捕获Hg⁰的能力影响不大,两种气氛下再生后的V₂O₅/AC对Hg⁰的捕获能力差别很小,较新鲜V₂O₅/AC对Hg⁰的捕获能力有所降低,但仍高于载体AC对Hg⁰的捕获能力.     

Sequential molecular vapor elution analysis for the separation and determination of LiCl and NaCl in river waters

The determination of alkali metal chloride in river waters by sequential molecular vapor elution analysis (SMVEA) using a molecular absorption detector (MA) is reported. An improved molybdenum column was developed for SMVEA. An optimum flow rate of carrier gas (pure argon or nitrogen) for separation of metal vapors was 12.0 ml min⁻¹. Lithium chloride and sodium chloride peaks completely separated from potassium, rubidium, and cesium chlorides but CaCl₂, FeCl₂, MgCl₂, and MnCl₂ peaks did not appear at a column temperature of 1000 °C and vaporization temperature of 1000 °C. The appearing order of these metal chlorides was LiCl, NaCl, KCl, RbCl, and CsCl. It was not understood by considering the boiling points of these metal chlorides. The delay of appearing time is due to an interaction between the molecular vapors and inside surface of the column. Under the experimental conditions, the number of theoretical plates was 247 for LiCl and 268 for NaCl in the improved column. Under the optimal experimental conditions, river waters were analyzed for lithium and sodium chlorides. The analytical results agreed well with the recoveries were in the range of 94–105%. By SMVEA, it was found that lithium and sodium chlorides in waters were determined without interference of matrix elements, no chemical treatment for river water samples.     

符合独立五元环规则的C100(417)Cl28形成机理的密度泛函理论研究

实验上捕获到C₁₀₀(417)Cl₂₈,但其形成机理仍不清楚。本文采用密度泛函理论(DFT)方法研究了生成C₁₀₀(417)Cl₂₈的反应机理,考虑了可能的经Stone-Wales (SW)转化、直接氯化和来自于骨架转变等反应路径。结果表明：C₁₀₀(417)Cl₂₈形成的最主要来源是通过C₁₀₂(603)骨架转变,即经历氯化、C₂失去和SW转变而来。该结果能很好解释实验结果,对富勒烯氯化物的合成提供了理论依据。     

燃煤电站锅炉颗粒Hg形态及其释放动力学参数

采集了一台320 MW机组锅炉在三个过量空气系数下的飞灰样品,将采集的飞灰筛分为四个粒径,测定了各飞灰样品的含炭量;对各飞灰样品进行两种加热方式的热处理,利用LUMEX全自动测汞仪测定了处理前后各飞灰样品的汞含量。根据飞灰中汞随温度的释放规律确定了飞灰中汞的形态,对加热过程颗粒Hg释放动力学参数进行了计算。测试与分析结果表明,粒径小的灰颗粒中汞浓度较高;过量空气系数增加后,飞灰含碳量降低,但飞灰中汞随过量空气系数的变化随粒径的不同有所不同;飞灰中含汞化合物的主要形态为HgCl₂和HgS,过量空气系数增加,飞灰中HgCl₂比例减少,HgS比例增加,HgO与HgSO₄的比例基本不变。停留时间是影响颗粒Hg生成的关键因素。过量空气系数越大,灰颗粒Hg释放的活化能就越大,大颗粒飞灰Hg释放活化能相对较大。     

不同前驱体制备的SO_4~(2-)/AC催化剂在二甲醚直接氧化合成聚甲氧基二甲醚中的反应性能

分别用硫酸、硫酸铵作为前驱体,活性炭(AC)作为载体,采用浸渍法制备了SO_4~(2-)/AC双功能催化剂(SO_4~(2-)离子和AC载体分别提供催化剂的酸性和氧化还原性),考察了其在二甲醚(DME)直接氧化合成聚甲氧基二甲醚(DMMx)反应中的催化性能。结果表明,不同前驱体制备的SO_4~(2-)/AC催化剂表现出显著的催化活性差异。40%H_2SO_4/AC催化剂具有较好的反应活性,DME转化率为8.4%,DMM1-2的选择性达到59.7%,并且没有COx的生成;而在40%(NH_4)_2SO_4/AC催化剂上,反应主要生成了COx,DMM选择性仅2.7%,且无DMM2生成。XRD、BET、NH_3-TPD及O_2-TPD-MS等表征结果显示,H_2SO_4/AC催化剂中适量的弱酸性位和氧化还原性位有利于DME直接氧化合成DMMx。经过SO_4~(2-)修饰的催化剂促进了O2在活性炭表面的活化;前驱体H_2SO_4的加入提高了催化剂表面的弱酸性位数量,而(NH_4)_2SO_4的引入却促使催化剂表面产生中强酸性位。     

硅胶支载稀土氯化钐一步催化合成多取代Mannich碱

采用硅胶与稀土氯化钐在甲苯或四氯化碳中反应,制备了硅胶支载稀土氯化钐. 与已报道的支载型催化剂相比,所制备的硅胶支载稀土氯化钐作为催化剂具有支载量稳定、催化反应时间短、产率高和选择性强等优点,同时催化反应条件温和、操作简便、不污染环境且催化剂重复利用率高. 室温条件下,以硅胶支载稀土氯化钐作为催化剂催化对甲氧基苯乙酮、芳香醛和芳香胺的三组分体系,利用“一锅法”合成了28种新的β-氨基酮类化合物,并探索了不同反应条件对产率的影响. 催化剂经过IR和XRD表征,催化反应产物通过IR、¹H NMR和元素分析确定.     

NaBH4/MCl x 体系对液体端羧基氟橡胶的还原及还原机理

以液体端羧基氟橡胶(LTCFs)为原料, 硼氢化钠与金属氯化物(NaBH₄/MCl _x )为还原体系, 采用一锅法成功将LTCFs还原为液体端羟基氟橡胶(LTHFs). 研究了多种稀土金属氯化物(LaCl₃, CeCl₃, NdCl₃和SmCl₃）和过渡金属氯化物(MnCl₂, NiCl₂, CoCl₂和CuCl₂)对LTCFs还原效果的影响及变化规律. 采用傅里叶变换红外光谱(FTIR)、 核磁共振氢谱(¹H NMR)、 核磁共振氟谱(¹⁹F NMR)和化学滴定法对原料和产物的分子链结构和官能团含量进行了表征. 结果表明, 稀土金属MCl _x 还原体系对LTCFs的还原效果均高于过渡金属MCl _x 还原体系, LTCFs中的—C=C—和—COOH均可以被还原为—C—C—和—OH, 其中NaBH₄/SmCl₃还原体系还原效率最高, 达到92%. 机理研究表明, NaBH₄/MCl _x 对—COOH的还原性能与MCl _x 中金属阳离子和羰基氧间的结合力有关, 结合力越大越有利于—COOH的还原.     

Effects of potassium promoter on the performance of PdCl_2–CuCl_2/AC catalysts for the synthesis of dimethyl carbonate from CO and methyl nitrite

The effect of potassium(K) promoter on the catalytic performance of activated carbon(AC) supported Wacker-type catalysts(Pd Cl2–Cu Cl2/AC) for the synthesis of dimethyl carbonate(DMC) from CO and methyl nitrite(MN) was investigated by means of N2 adsorption, H2-temperature-programmed reduction(H2-TPR), and X-ray photoelectron spectroscopy(XPS). The experimental results showed that the space time yield of DMC on Wacker-type catalysts with different K promoters ranked in the following order: KCl KOH CH3 COOK K2CO3. Especially, the addition of KCl significantly improved the catalytic activities of Pd Cl2–Cu Cl2/AC catalyst for DMC synthesis from CO and MN. N2 adsorption data indicated that the addition of K promoters did not change the textural properties of Wacker-type catalysts greatly. H2-TPR and XPS results demonstrated that the existence of KCl promoted the reducibility of Cu2+species and increased the proportion of Cu2+species on catalyst surface, which is favorable for oxidizing Pd0 to active Pd2+. Further, the addition of KCl benefited the reactivity of Pd Cl2–Cu Cl2/AC catalyst for DMC synthesis from CO and MN.     

Benzylation of benzene and substituted benzenes by benzyl chloride over InCl3, GaCl3, FeCl3 and ZnCl2 supported on clays and Si-MCM-41

Liquid phase benzylation of benzene by benzyl chloride to diphenyl methane over InCl₃, GaCl₃, FeCl₃ and ZnCl₂ supported on commercial clays (viz. Montmorillonite-K10, Montmorillonite-KSF and Kaolin) or on high silica mesoporous MCM-41 (at 60, 70 and 80 °C) has been investigated. The supported InCl₃, GaCl₃ and FeCl₃ showed high activity for the benzylation of benzene. The redox function created due to the impregnation of the clays or Si-MCM-41 by InCl₃, GaCl₃, FeCl₃ or ZnCl₂ seems to play a very important role in the benzylation process. Among the catalysts, the InCl₃/Mont.-K10 showed both high activity and high selectivity for the benzylation. The activity of this catalyst for the benzylation of different aromatic compounds is in the following order: benzene>toluene>mesitylene>anisole. The InCl₃ (or GaCl₃)/Mont.-K10 (or Si-MCM-41) catalyst showed high benzene benzylation activity even in the presence of moisture in the reaction mixture. The catalyst can also be reused in the benzylation for several times. Kinetics of the benzene benzylation (using excess of benzene) over the supported metal chloride catalysts have also been thoroughly investigated. A plausible reaction mechanism for the benzylation over the supported metal chloride catalysts is proposed.     

C_9H_(10)O_2-0.5ZnCl_2/Al_2O_3的制备及其氧化脱硫性能

通过将C_9H_(10)O_2-0.5ZnCl_2双酸型低共熔溶剂固载到Al_2O_3上制备了C_9H_(10)O_2-0.5ZnCl_2/Al_2O_3催化剂。该催化剂采用XRD、FT-IR、SEM、EDS、N_2吸附-脱附技术进行了分析。以C_9H_(10)O_2-0.5ZnCl_2/Al_2O_3为催化剂,过氧化氢为氧化剂研究模拟油中芳香族硫化物的脱除性能。考察反应参数如温度、催化剂加入量、O/S物质的量比、硫化物类型等对催化剂脱硫活性的影响。实验结果表明,在模拟油为5 mL、催化剂量为0.2 g、O/S比为8、反应温度为60℃、反应时间为180 min的条件下,模拟油中二苯并噻吩(DBT)脱硫率为99.2%。此外,在模拟油氧化脱硫中催化剂循环使用六次,其氧化脱硫活性略有降低。研究了C_9H_(10)O_2-0.5ZnCl_2/Al_2O_3催化氧化脱硫的反应机理。     

梳形接枝共聚物的合成(Ⅱ)——载体化钌卡宾络合物催化降冰片烯基聚苯乙烯的开环岐化聚合

由石油化工副产C₅馏份提取双环戊二烯(DCPD)、以聚合物负载三氟化硼为催化剂进行DCPD与烯丙基氯(AC)的Diels-Alder反应合成5-氯甲基-2-降冰片烯(NBCH₂Cl),经锂代反应后用以引发苯乙烯的活性阴离子聚合合成了降冰片烯(NB)基聚苯乙烯(PS)大分子环烯单体NB-PS,在聚合物负载钌卡宾络合物[RuCl₂(PPh₃)₂(=C=CHtBu)]催化(引发)作用下进行大分子单体NB-PS的开环歧化聚合(ROMP)合成了梳形接枝共聚物PNB-g-PS.实验结果表明所合成聚合物负载硼、钌络合物催化剂的性能均明显优于对应非负载体.讨论了上述催化剂的聚合物载体效应的机理及温度、溶剂等对活性阴离子聚合反应的影响.