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161.
162.
The cracking of styrene derivative polymers dissolved in decalin was conducted with metal-supported carbon catalysts under
an inert gas atmosphere to recover monosubstituted styrene or monosubstituted ethylbenzene in higher yields than is obtained
by pyrolysis, and to elucidate the detailed reaction mechanisms in the solvent. Poly-(4-methylstyrene), poly-(4-t-butylstyrene), poly-(α-methylstyrene), and polystyrene were used. In decalin without a catalyst, each polymer was decomposed
into the monomer, dimer, and trimer derived from the corresponding polymer except for poly-(α-methylstyrene), which was decomposed
into the monomer and styrene. By using metal-supported carbon, the olefinic compounds derived from the corresponding polymer
were thoroughly hydrogenated to the saturated form in a nitrogen atmosphere by a hydrogen transfer reaction from decalin,
which was simultaneously dehydrogenated to tetralin and naphthalene with the evolution of hydrogen gas. In comparison with
metal species, Pd- and Ru-supported carbon catalysts maintained the hydrogenation activity for a longer time and with a lower
evolution of hydrogen than Pt or Rh. The dehydrogenation of decalin was mainly observed not on the metal surfaces, but on
the carbon surfaces over Pd-supported carbon. Stabilization of the monomers will be able to suppress the coking which occurs
with repolymerization in long running process.
Received: July 19, 2000 / Accepted: March 16, 2001 相似文献
163.
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166.
以非贵金属Cu、Fe、Mn和Ce为主要活性成分和TiO2、-γA l2O3为载体,制备了10种用于催化湿式氧化法处理糖蜜酒精废液的催化剂。考察了载体、焙烧温度、成分配比对催化剂催化活性与稳定性的影响,研究了氧气分压、催化剂投加量、反应温度和反应时间对催化湿式氧化过程的影响规律。结果表明:(1)Fe-Mn/-γA l2O3(3∶1∶1)催化剂是催化湿式氧化法处理糖蜜酒精废液的可选催化剂;(2)适宜的氧气供应量为理论需氧量的3.4~4.6倍,催化剂的投加量以10 g/L为佳;在300℃下反应30 m in或在280℃下反应60 m in,处理水可达到污水综合排放标准GB9878-1996的三级标准。 相似文献
167.
催化铁内电解法处理硝基苯废水的机理与动力学研究 总被引:2,自引:0,他引:2
对催化铁内电解法处理硝基苯废水降解动力学特性进行了研究。结果表明,降解过程符合准一级动力学规律。进水浓度、pH值和反应温度强烈影响硝基苯的降解速率。在实验pH值范围内,反应速率常数依次为:强酸性>弱碱性>弱酸性>中性;循环伏安扫描图显示了硝基苯可以在铜电极上直接得电子还原,该反应在强酸和弱碱性条件下效果较好。反应速率常数随进水浓度的增大而减小。提高反应温度可改善处理效果,在30~45℃范围内,提高温度对处理效果的改善并不显著;当温度升高到45℃以上时,升温可以显著改善处理效果。 相似文献
168.
Pd/CZ/Al2O3催化剂的制备、表征与三效催化性能 总被引:6,自引:0,他引:6
以共浸渍法制得的氧化铝负载铈锆固溶体为载体,并浸渍贵金属Pd得到了Pd/CZ/Al2O3催化剂.实验结果表明,该催化剂在老化前后都表现出良好的三效催化活性,新鲜样品Pd/CZ/Al2O3活性与Pd/CZ相当,老化后样品前者优于后者.结合XRD,BET,TPR等表征手段,讨论了Pd/CZ/Al2O3的催化活性特别是高温老化后活性与其组成结构之间的内在关系,揭示了其老化后仍具有较高活性的主要原因在于保持了Pd与CZ/Al2O3复合载体之间的强相互作用(SMSI). 相似文献
169.
Decomposition mass loss and pyrolysis products analyses of particles sampled at various locations along the tailpipe of a Euro-IV diesel engine were performed using a thermogravimetry in conjunction with Fourier transformation infrared spectrometry-mass spectrum. Diesel particles were collected at the same location with and without diesel oxidation catalyst (DOC) mounted on the test engine separately. The three poles in thermal gravity-differential thermal gravity images suggested that the decomposition process of diesel particles could be divided into three stages which correspond to the decompositions of lower boiling substances, higher boiling substances and soot respectively. It is noticed that no matter whether DOC was mounted or not, the further the particles were sampled away from the engine block, the lower the peak temperatures and the heavier the mass losses within the first two stages, which indicated that the soluble organic fraction in the particle samples increased and therefore lowering the activation energy of thermal decomposition. Hydroxyl, ammonia, CxHy fragments, benzene, toluene, and phenol were found to be the primary products of particle decomposition, which didn't change with the location of particle sample point. The employment of DOC increased the activation energy for particle oxidation and resulted in a higher peak temperature and lower mass loss within the first-stage. Moreover, the CO stretching bands of aldehyde and ketone at 1771 cm?1 was only detected without a DOC, while the NO2 peak at 1634 cm?1 was solely noticed with the presence of DOC. Compared to the first-stage pyrolysis products, more polycyclic aromatic hydrocarbons and less CxHy fragments were seen in the second-stage. 相似文献
170.
镍铜氧化物对吐氏酸废水臭氧氧化的催化作用 总被引:10,自引:0,他引:10
染料中间体废水等难生物降解废水是目前水处理研究的焦点。用浸渍法和附着沉淀法制备了以γ-Al2O3为载体的负载型镍、铜氧化物催化剂,并以催化吐氏酸废水的臭氧氧化。研究结果表明,镍、铜单组分和双组分氧化物催化剂能不同程度地提高臭氧的利用效率,其中附着沉淀法制备的Ni-Cu-Urea-1催化剂活性最高,当臭氧投加量为0.82g/L时,其臭氧化指数为1.1;助剂钾对催化剂活性的影响与制备方法有关,当用浸渍法制备时,助剂钾能提高催化剂活性,而附着沉淀法时则不利。 相似文献