酚酞型聚芳醚砜(Ⅶ):K2C03存在下PP/DCDPS体系聚合反应机理的研究

 利用¹³C-NMR方法研究了弱碱K₂CO₃存在下酚酞成盐反应及其与活性双卤砜亲核缩聚反应过程中的结构特征。对一系列碱性条件下酚酞(PP)与4,4'-二氯二苯砜(DCDPS)的缩聚反应的研究表明任何影响内酯结构酚酞盐生成的因素都会严重阻碍聚合反应的进行。对模型化合物存在下K₂CO₃在极性非质子溶剂中的溶解/解离行为的研究结果表明酚酞类Card。双酚与固体K₂CO₃之间可能存在着一种特殊的络合作用。基于我们系列研究结果,本文中总结提出了弱碱K₂CO₃存在下酚酞的反应机理。     

弱碱K~2CO~3体系中酚酞盐的结构特征

用红外光谱、核磁共振谱鉴定了弱碱K~2Co~3体系和强碱KOH体系中制备的酚酞钾盐, 在弱碱K~2Co~3体系中, 酚酞成盐以完全内酯式结构为特性, 而在强碱KOH体系中,酚酞成盐主要是醌式结构。从而发现成盐反应中所使用的碱本身的性质是决定生成酚酞盐结构的关键因素。     

酚酞型聚芳醚砜 Ⅳ.含羧基聚芳醚砜的合成

离子性聚合物的合成方法主要集中于通过一些含芳环聚合物的大分子反应,引入不同的离子基。如聚苯乙烯、聚芳醚砜、聚芳醚酮的磺化反应及聚苯醚的羧化反应等。但伴随大分子反应,聚合物要发生严重的化学降解,并且引入离子基团数目也不易控制。 本工作将酚酞啉引入酚酞型聚芳醚砜,发现在弱碱K_2CO_3体系中酚酞啉仍能保持一定的反应活性,且不至于发生交联反应。通过与酚酞的共聚反应可方便地控制聚合物的羧化度。     

钾负载量对CuO/K_2CO_3/MgAl_2O_4催化剂高温NO_x储存还原性能的影响

制备了适用于高温氮氧化物储存还原(NSR)反应的Cu O/K_2CO_3/MgAl_2O_4非贵金属催化剂,考察了钾负载量对催化剂NSR性能的影响,发现钾主要以高分散K_2CO_3和体相K_2CO_3的形式存在.在稀燃条件下,NOx在体相K_2CO_3上形成了高温稳定的硝酸盐物种,而高分散K_2CO_3上形成的硝酸盐的高温稳定性则较差.当钾负载量较低时,催化剂的NOx储存能力有限,K_2CO_3主要以高分散形式存在,稀燃阶段形成的硝酸盐的热稳定性较低,高温NSR活性较低;而钾负载量过高时,K_2CO_3则会覆盖Cu O活性位,从而降低催化剂的NSR活性.在450℃的高温条件下,钾负载量为10%时,所制备催化剂的NOx储存还原能力最佳,NOx还原效率达到99.9%,是一种具有潜在应用前景的高温NSR催化剂.     

用封闭循环反应器对碳与二氧化碳气化反应中碱金属催化作用的研究

用封闭循环式反应器考察了在K_2CO_3存在下用二氧化碳气化碳的反应,并在反应进行过程中测定了吸附于焦表面的氧量,并对焦表面吸附氧量与K_2CO_3添加量和气化反应速率的关系以及反应温度和压力对焦表面吸附氧量的影响进行了研究。结果表明,反应过程中的焦表面吸附氧量与K_2CO_3添加量成正比,气化速率随反应时间的变化与焦表面吸附氧量随时间的变化具有很好的对应关系。根据实验结果,认为在反应过程中CO_2首先在催化金属形成的活性中心被解离吸附,形成表面氧化物,气化反应速率由该表面氧化物的数量决定,并认为碳与CO_2的反应是以包括有非催化反应的表面金属氧化物的氧化还原机理进行。     

五元体系Li~+,K~+//CO_3~(2-),SO_4~(2-),B_4O_7~(2-) -H_2O在288 K时的介稳相平衡研究

采用等温蒸发法研究了五元体系Li~+,K~+//CO_3~(2-),SO_4~(2-),B_4O_7~(2-) -H_2O在288 K时的介稳相平衡关系,测定了该五元体系在288 K条件下的介稳平衡的溶解度和溶液密度,根据实验数据绘制了相应的介稳平衡相图和水图,相平衡研究结果表明该五元体系介稳相平衡中有复盐K_2SO_4·Li_2SO_4生成,其介稳相图(Li_2CO_3饱和)有4个共饱和点,9条单变量曲线,6个Li_2CO_3饱和的结晶区分别为LiBO_2·8H_2O,K_28_4O_7·4H_2O,K_2CO_3·3/2H_2O,K_2SO_4,Li_2SO_4·H_2O和复盐K_2SO_4·Li_2SO_4.     

方波伏安法测定酚酞片含量

研究了酚酞在0.5 mol/L氨水-氯化铵缓冲溶液(pH 10)介质中汞膜电极上的电化学行为,并依此建立了酚酞含量的方波伏安法测定.酚酞于-0.98 V(VS.Ag/AgCl)处出现一灵敏的阴极还原峰,峰高与酚酞的浓度在3.0×10-7-5.0×10-5mol/L范围内有良好的线性关系.方法的最低检出限为1.0×10-7mol/L,方法用于酚酞片中酚酞含量的测定,结果满意.     

用热天平法研究煤的催化气化Ⅰ.几种碳酸盐在碳与水蒸汽气化中的催化作用

在热天平实验装置上,于600℃—750℃下考察了碳与水蒸汽在K_2CO_3、Na_2CO_3、CaCO_3三种催化剂存在下的气化反应,并对气化速率、转化率、气体组成与反应温度及气化时间的关系进行了研究。实验结果表明,采用催化气化方法,不但可以大大提高气化速率,降低反应温度,而且可以降低煤气中的CO含量。在本实验条件下,上述三种催化剂的活性顺序与文献报导不同,为:Na_2CO_3≥K_2CO_3>CaC_3。而CaCO_3在反应中表现出与钾、钠碳酸盐不同的催化特性。最后,根据实验结果对催化气化之反应机理进行了探讨。认为其反应历程为:     

轻质氧化镁的制备,表征与活性研究

选用不同可溶性镁盐(MgCl_2·6H_2O和MgSO_4·7H_2O)和沉淀剂(NH_3·H_2O、NaHCO_3、NH_4HCO_3和K_2CO_3)为原料,采用水热法制备氧化镁前驱体,之后经过600℃煅烧获得微纳米级活性氧化镁,通过改变物料比例制备系列氧化镁。产品采用FI-IR,XRD和SEM进行表征,并对活性进行检测。结果表明:氧化镁主要呈片状晶体,适当比例硫酸镁和氯化镁与氨水及碳酸氢钠可以制备出活性和产率都较高的微纳米级活性氧化镁,当MgCl_2·6H_2O和NaHCO_3摩尔比为1:1时,制得的氧化镁具有更好活性,对应柠檬酸法中酚酞变红时间为15sec。     

用磺酸型阳离子交换树脂为催化剂合成酚酞的探讨

在磺酸型阳离子交换树脂催化下,用邻苯二甲酸酐(Ⅰ)和苯酚(Ⅱ)为原料,以较高的产率合成了酚酞。实验条件为:1摩尔(Ⅰ),7摩尔(Ⅱ)和Ⅰ当重的D61树脂,在120～125℃回流20小时。酚酞的产率为80～85％(以Ⅰ为基准计算)。     

KOH/4A分子筛催化剂对环氧丙烷、二氧化碳和甲醇合成碳酸二甲酯反应的催化性能

 首次开发出对环氧丙烷、二氧化碳和甲醇合成碳酸二甲酯反应具有较高活性和稳定性的KOH/4A分子筛固体催化剂,考察了反应温度和催化剂活性组分KOH的负载量等因素对催化剂性能的影响. 在优化的实验条件下,环氧丙烷可以完全转化,碳酸二甲酯的收率为168%. 从实验结果推测,产物碳酸二甲酯是由环氧丙烷和二氧化碳加成生成碳酸丙烯酯,然后与甲醇发生酯交换反应生成的,甲醇对环氧丙烷和二氧化碳合成碳酸丙烯酯反应具有助催化作用.     

Synthesis and characterization of the novel type of polymerizable bisphthalonitrile monomers

Three new bisphthalonitrile derivatives are prepared by the nucleophilic displacement of the nitrosubstituent from 4-nitrophthalonitrile with 9,9-bis(4-hydroxyphenyl)fluorene; 9,9-bis(3,5-dimethyl-4-hydroxyphenyl)fluorene, and phenolphthalein in the presence of potassium carbonate. The reaction has been carried out in dimethylsulfoxide solvent. These monomers are characterized by elemental analysis, FT-IR, ¹H NMR, TGA, DSC, and mass spectral studies. A tentative mechanism for the fragmentation of the compounds is given to explain the mass spectral data. The compounds are expected to be useful to prepare thermally stable thermosetting phthalocyanine polymers.     

煤催化气化工艺中碱金属腐蚀刚玉质耐火材料的实验研究

针对煤催化气化反应器设计中遇到的材料问题,采用碳酸钾及催化气化工况富含碱金属气化灰渣为实验原料,进行了碱金属腐蚀刚玉质耐火材料的实验研究。着重考察了有氧空气气氛和无氧还原性气氛、反应温度、反应时间、碱金属存在形态对腐蚀行为的影响,并结合SEM-EDX、XRD、核磁Al谱等表征手段,研究了反应前后碱金属和刚玉质耐火材料的成分、物相及结构变化。结果表明,碱金属对耐火材料腐蚀行为受反应的温度、气氛、时间及碱金属存在形态等因素影响较大。分析表明,有氧空气气氛下腐蚀尤为严重的原因是,原料中存在的钾与刚玉耐火材料发生化学反应生成新的钾的铝酸盐物相,且其含量随温度升高、反应时间延长而增加。     

Promotion of Ionic Liquid to Dimethyl Carbonate Synthesis from Methanol and Carbcn Dioxide

Promotion of ionic liquid, 1-ethyl-3-methylimidazolium bromide (emimBr), to the synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide in the presence of potassium carbonate and less amount of methyl iodide under mild conditions was investigated. The results showed that the high selectivity and raised yield of DMC was achieved due to the addition of emimBr in the reaction system. And effect of several reaction conditions such as temperature, pressure and amount of emimBr was discussed.     

Textural and chemical characterizations of adsorbent prepared from palm shell by potassium hydroxide impregnation at different stages

Preparation and characterization of activated carbon from palm shell, a carbonaceous agricultural solid waste, by potassium hydroxide treatment at different stages were studied. The effects of activation temperature and chemical to sample ratio on the characteristics of the activated carbon were investigated. Fixed-bed adsorption of sulfur dioxide (SO(2)) gas was carried out to evaluate the adsorptive capacity of the samples. Desorption tests were conducted to verify the occurrence of chemisorption due to some surface functional groups or of chemical reaction between SO(2) and KOH. It was found that pre-impregnation of raw palm shell was involved in replacement of some hydrogen ions with potassium ions to form cross-linked complexes, which retarded the tar formation during carbonization, resulting in a relatively high yield. Moreover, these potassium ions accelerated the reaction as catalysts during gasification of chars by carbon dioxide. For chars with mid-impregnation, potassium hydroxide acted in two ways: (i) formation of metallic potassium by dehydration and (ii) conversion into potassium carbonate. Metallic potassium intercalated to the carbon matrix accounted for pore development and potassium carbonate layer prevented the sample from over burn-off. Post-impregnation of final products modified the textural characteristics of the sample as some pore entrances were blocked by chemicals. However, potassium hydroxide enhanced the amount of SO(2) uptaken via formation of potassium sulfite.     

几种无定型聚芳醚砜(酮)的成环解聚及产物的开环聚合

几种线性高分子量的无定型聚芳醚砜(酮)在非质子极性溶剂二甲基乙酰胺(DMAc)和二甲基甲酰胺(DMF)中,以氟化铯(CsF)为催化剂进行解聚成环,所得环状低聚物由凝胶渗透色谱(GPC)、高效液相色谱(HPLC)和激光质谱(MALDI-TOF-MS)确认,其中酚酞聚醚砜(PES-C)和酚酞聚醚酮(PEK-C)的解聚成环率分别高达86．3％和87．9％．讨论了影响成环率的各种因素．环状产物又在阴离子引发剂联苯双酚钾的作用下进行开环聚合重新得到高分子量的线性产物．     

Interaction of dimethyl carbonate with anilines in the presence of potassium methylate: Kinetics and the role of the base

The kinetic patterns of the reaction between dimethyl carbonate and anilines in the presence of a potassium methylate as a catalyst were studied. The mechanism of aminolysis was clarified, which includes the detachment of the proton from the amino group of aniline and the subsequent attack of the resulting anion on the carbonyl group of dimethyl carbonate. It is shown that when the reaction occurs in the dimethyl carbonate-methanol 3:1 system, the process can be described as an irreversible first-order reaction in the aniline though the target reaction is complicated by side interaction between potassium methylate and dimethyl carbonate. The rate constants of the target reaction with substituted anilines and of the side reaction in the temperature range of 70-90°C were determined. It is shown that the influence of the substituent on the reaction rate is described by the Hammett equation, with the constant of the reaction series being positive and the best correlation being achieved for σ-scale. The results obtained are consistent with the proposed mechanism of the reaction and are explained by the facilitation of the aniline deprotonation with increasing acceptor properties of the substituent. Effective activation energies for the reaction of various anilines with dimethyl carbonate are found.     

A new synthetic route to polycarbonate

A detailed study has been carried out on the new synthetic reaction of poly(p-xylylene carbonate) from potassium carbonate and p-xylylene dibromide by using a variety of crown ethers as a catalyst, which was recently found by the present authors. Crown ethers having 18-member ring showed the best catalytic property of the various crown ethers, and the reaction was conducted in various solvents at 50–160°C by using 18-crown-6-ether. Both the polymer yield and the molecular weight of the polymer increased in proportion to the amount of potassium carbonate, and they increased rapidly and reached constant values with increasing the concentration of 18-crown-6-ether. They also depended significantly upon the reaction temperature as well as the solvent used. A maximum yield with the highest molecular weight was obtained from the reaction at 100–120°C in diglyme solvent. The spectroscopic analysis of the polymer indicated that all the end groups of the resulting polymer had the structure of benzyl bromide. From these results, a plausible mechanism was proposed for the reaction. Similar reactions were also conducted by using several aliphatic dibromides, Br? (CH₂)_x? Br, in place of p-xylylene dibromide. The products were strongly dependent of the value of x: polycarbonate was obtained from dibromides with ≧4, and cyclic carbonates from dibromides with ≦3.