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催化苯直接羟基化是开发绿色苯酚生产新技术的高原子经济性的挑战性课题,但该工艺存在芳香C-H键难活化、产物酚的选择性较低等问题,其中高效催化剂的研制是核心问题之一。根据含铁催化剂独特的化学结构和催化性能,本文从配合物均相催化剂、仿生催化剂、负载型非均相催化剂等方面综述了含铁催化剂催化苯直接羟基化制备苯酚的研究进展,并着重介绍了Fenton体系和仿生催化体系的反应机理。分析表明,以氧化物及天然矿物作为载体的含铁催化剂合成简单,活性高,有较大的研究及工业开发价值。此外,研究催化机理对设计合成高效苯羟基化的催化剂具有指导意义。 相似文献
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采用共沉淀法制备了类水滑石CuNiAl,450 ℃焙烧后得到复合氧化物催化剂,利用XRD和FT-IR对其结构进行表征。研究了该催化剂体系对苯直接氧化制苯酚反应的催化性能,并考察了反应温度、反应时间、催化剂用量、溶剂用量和n(C6H6)∶n(H2O2)对收率的影响。结果表明,类水滑石CuNiAl经焙烧后,催化苯直接氧化制苯酚反应的转化率提高,适宜的反应条件为:反应温度65 ℃,反应时间6 h,催化剂用量10 mg,溶剂用量15 mL,n(C6H6)∶n(H2O2)=3∶1,产物中没有发现副产物,苯转化率达6.5%。 相似文献
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The Fe/Mo/partially deboronated borosilicate molecular sieve catalyst prepared by the chemical vapor deposition (CVD) method was active for the selective formation of phenol by gas-phase N2O oxidation of benzene. The impregnated counterpart exhibited lower activity than the CVD catalyst. The borosilicate molecular sieve itself also was active. Two mechanistic paths are postulated based on reactive oxygen species such as O–, which can be generated via interaction of N2O with the iron sites in the CVD-borosilicate molecular sieve catalyst, or OH+, which can be generated by Brønsted sites on the borosilicate molecular sieve itself. 相似文献
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Atsutaka Kunai Tomoyuki Kitano Yasushi Kuroda Jiang Li-Fen Kazuo Sasaki 《Catalysis Letters》1990,4(2):139-144
Usefulness of silica supported palladium catalysts applied for the hydroxylation reaction of benzene under ambient conditions has been demonstrated. Two types of catalyst, Pd alone and CuPd composite catalysts both being supported on silica, were found to behave in remarkably different ways which are dependent also on the mode of reactant gas feeding. The Pd single component catalyst is powerful when hydrogen and oxygen are simultaneously present in the reacting system and produces phenol almost exclusively. On the other hand, the composite catalyst can be used irrespective of the mode of gas feeding. If quinones are desired, the use of the composite catalyst is recommended but if phenol is desired the Pd single component catalyst seems to be advantageous. 相似文献
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Wet air oxidation of phenol using active carbon as catalyst 总被引:6,自引:0,他引:6
Catalytic wet air oxidation is a promising alternative for the treatment of phenolic waste water which cannot be treated in conventional sewage plants. Catalytic wet air oxidation of an aqueous phenol solution was conducted in a fixed bed reactor operating in trickle flow regime. Either active carbon or a commercial copper oxide supported over γ-alumina was used as catalyst. The performance of both materials was compared in terms of phenol conversion in 240 h tests. The results showed that the active carbon, without any active metal supported, gives the highest phenol conversion. The supported copper catalyst undergoes a rapid deactivation due to the dissolution of the metal active species in the acidic medium in which the reaction takes place. On the other hand, the active carbon maintains a higher activity throughout the test, although a decrease of the phenol conversion was also observed due to both the loss of active carbon by combustion and the reduction of its surface area. The phenol oxidation was proved to occur through a first order mechanism with respect to phenol. After the ten-day run, the catalytic activity of the active carbon was found to be about eight times higher than that of the commercial catalyst, also showing high selectivity to the production of carbon dioxide. 相似文献
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采用固相法制备了新型催化剂铜锰复合氧化物催化剂。利用高效液相色谱法对苯酚过氧化氢氧化反应产物进行分析,以苯酚转化率和苯二酚收率为评价指标,对催化剂进行了评价。结果表明,催化剂性能随铜与锰物质的量比、焙烧温度、焙烧时间和研磨时间等因素的增大呈先升高再降低的趋势,并与络合剂的还原性有关。确定最佳工艺条件为:室温下,按锰与铜物质的量比1:2将Cu_2(OH)_2CO_3、MnCO_3和适量H_2C_2O_4·2H_2O混匀,置于研钵匀速研磨10 min,马弗炉400℃焙烧2 h。最佳条件下,苯酚转化率为63.7%,苯二酚收率为59.1%。 相似文献
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实验室合成了吡啶类三支架配体(4-btapa),与镉离子自组装合成三维多孔金属有机骨架材料(Cd-MOF-cat),并对合成的催化剂进行表征。分析Cd-MOF-cat的三维通道结构以及通道内壁的化学环境,并以Cd-MOF-cat为催化剂、H2O2为氧化剂、水-乙醇为溶剂催化苯酚羟基化选择性制备对苯二酚。实验结果表明,Cd-MOF-cat为催化剂时,反应有较好的转化率和选择性,苯酚转化率为85%~86%,对苯二酚选择性(对苯二酚与邻苯二酚物质的量比)达到2.6~2.8,结合苯酚和1-萘酚羟基化催化实验结果,初步探讨了催化机理,推断该反应机理可能是催化剂对苯酚的尺寸和形状选择性催化。催化剂“滤去”实验说明该催化为异相催化。 相似文献
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The oxygen activated by the active vanadium species for the selective oxidation of benzene to phenol
The activation of oxygen is a key step for the selective oxidation of benzene to phenol and the reason is discussed. The active
oxygen species is produced from molecular oxygen in a so-called “reductive activation” process. The vanadium oxide supported
on alumina was pre-reduced by hydrogen or ascorbic acid to lower valence vanadium species acting as reduction source and the
activity is investigated in the reaction. It is found that the V4+ valence vanadium (VO2+) is effective for the reaction from the characterization of catalysts by XPS. 相似文献
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Fe2O3催化甲基化合成2,3,5-三甲基苯酚 总被引:1,自引:0,他引:1
制备并考察了甲醇甲基化法合成2,3,5-三甲基苯酚的固体酸催化剂,进行了甲基化反应工艺条件的优化研究。实验结果表明,最优工艺条件:反应温度370 ℃、液空速0.2 h-1、n(3,5-二甲基苯酚)∶n(甲醇)∶n(水)=1∶2∶1;原料3,5-二甲基苯酚的转化率达95.96%,目的产物2,3,5-三甲基苯酚的收率为72.01%。并采用XRD、SEM、DTA和TG等测定方法对催化剂进行了研究,发现催化剂表面上积炭污染是造成催化剂活性下降的主要原因。 相似文献
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Vapour phase butylation of phenol was carried out over a sulfated zirconia solid superacid catalyst in the temperature range 448–473 K using t-butyl alcohol as the alkylating agent. A good substrate (phenol) conversion and excellent product (para-tertiary BP) selectivity was obtained. The catalytic activity remains nearly the same on repeated use of the catalyst. Further, the catalyst was not deactivated when the reaction was carried out for a longer duration, i.e., even after several hours of reaction. 相似文献
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苯羟基化制苯酚是C—H键向C—O键转变富有挑战性的课题之一。该文论述了钒基催化剂催化苯羟基化制苯酚反应机理的研究进展。以钒活性中心为主线,着重从自由基、非自由基和双活性催化机理三个方面进行详细分析归纳,同时分析中涵盖了此类催化剂高效性的本质和催化微环境的重要性。由于此类催化体系及催化机理能够为解决苯环上C—H键难活化和苯酚的深度氧化等科学问题提供理论指导。因此,很有必要聚焦经济与安全并存的苯酚合成方法,同时依托已有的催化反应机理,开发更稳定且高性能的催化剂,促进我国丰富的烃类有机化合物资源利用的原始创新。 相似文献
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苯加氢制备环己烷的催化剂研究进展 总被引:3,自引:1,他引:2
介绍了苯加氢制备环己烷的一般工艺,对苯加氢制备环己烷催化剂的研究进行了综述,包括镍系、铂系、钌系等,且对今后催化剂的研究方向进行了展望。 相似文献
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Two wet-proofed catalysts were prepared by subsequent coating steps with polytetrafluoroethylene fibers over a CuO/Al2O3 catalyst. They were tested for the oxidation of phenol solutions in a semi-batch reactor. Phenol conversion as well as Chemical Oxygen Demand (COD) was recorded. The hydrophobic coverage reduces the loss of active phase by leaching. Therefore, deactivation was attributed to the deposition of carbonaceous residues on the catalytic surface. 相似文献
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以凹凸棒土(APT)为载体,NH3·H2O为沉淀剂,采用沉积-沉淀法制备Pd-Cu/APT催化剂。在连续流动微反装置上,考察不同沉淀温度对Pd-Cu/APT催化剂CO常温催化氧化性能的影响。利用N2物理吸附-脱附、XRD、FT-IR和H2-TPR等对Pd-Cu/APT催化剂进行表征。结果表明,不同沉淀温度制备的催化剂均含有Cu2Cl(OH)3和CuO两种形式的Cu物种,但与沉淀温度25℃和90℃制备的催化剂相比,沉淀温度70℃制备的催化剂具有更多的活性Cu2Cl(OH)3物种,这有利于Pd2+物种的再生,显著提高其CO常温催化氧化活性。 相似文献
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综述了钌催化剂上苯选择性加氢的反应机理、催化剂制备过程中前躯体、制备方法、载体、添加剂(水,有机添加剂,无机添加剂)对催化剂催化性能的影响和反应过程中温度、压力、搅拌速率、催化剂用量及反应时间等对苯转化率、环己烯选择性和环己烯收率的影响。 相似文献