共查询到18条相似文献,搜索用时 171 毫秒
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为了降低六苄基六氮杂异伍兹烷(HBIW)氢解脱苄反应中钯催化剂的用量,提出沉淀-还原法合成钯基双金属催化剂的方法。对不同载体负载的催化剂进行筛选和优化,研究不同载体、金属助剂、催化剂中钯的质量分数、催化剂与原料HBIW的质量比对产物收率的影响。结果表明,在0.5 g HBIW、0.4 MPa H2、15℃反应8 h,随后升温至45℃,继续反应24 h的条件下,以Pd质量分数为5%的催化剂(记为5%Pd-Ni/γ-Al2O3)为最优催化剂、催化剂的质量为0.037 5 g时,催化HBIW的氢解脱苄反应,产物获得85%收率,此时催化剂中钯与原料HBIW的质量比为0.375%。在声共振强化下进行氢解脱苄反应,在加速度为392 m·s-2、0.5 g HBIW、0.4 MPa H2的条件下,反应时间缩短至100 min,产物仍保持了85%收率。 相似文献
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在六苄基六氮杂异伍兹烷(HBIW)的催化氢解反应中,所用催化剂是Pd(OH)2/C,而Pd属于贵金属,它的回收利用直接影响着最终产品的成本核算。对HB研的催化氢解反应中产生的废催化剂进行了回收,并将回收所得金属钯重新制备成催化剂。再次用于HBIW的催化氢解反应,其活性与以PdCl2为前体制备的催化剂活性相当。回收的金属钯纯度为99.6%,回收率为92%-94%。 相似文献
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四乙酰基二苄基六氮杂异伍兹烷亚硝解脱苄反应 总被引:1,自引:3,他引:1
利用市售无机亚硝解试剂,采用3种不同的方法,在温和条件(30℃左右)下,使四乙酰基二苄基六氮杂异伍兹烷(TADBIW)脱除苄基,转化成HNIW的前体——四乙酰基二亚硝基六氮杂异伍兹烷(TADNSIW),并用FT-IR、MS、^1HNMR及元素分析法对TADBIW的脱苄产物进行了结构鉴定。提出了TADBIW亚硝解脱苄反应的机理,TADBIW作为三级胺脱除苄基的反应是以生成烯胺正离子(或称亚胺正离子)为中间体的反应,并由所获得的副产物苯甲醛证明该反应机理。 相似文献
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TADB氢解脱苄合成TADF的反应动力学 总被引:1,自引:0,他引:1
采用Pd(OH)2/C催化剂,研究了常压下四乙酰基二苄基六氮杂异伍兹烷(TADB)在甲酸介质中氢解脱苄合成四乙酰基二甲酰基六氮杂异伍兹烷(TADF)的反应动力学。通过空白实验消除催化剂及溶剂对吸氢量的影响,以吸氢量来表征反应程度。通过积分反应速率方程,对不同温度下该反应的实验数据进行了动力学计算。实验结果表明,在实验条件下,TADB的氢解脱苄对于TADB是一级反应,反应表观活化能为50.41kJ/mol,指前因子为4.5326×106min-1。而用Pd/C催化剂时,该溶液放出氢气且反应不完全。 相似文献
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制备六硝基六氮杂异伍兹烷的硝解工艺近期进展 总被引:3,自引:0,他引:3
六硝基六氮杂异伍兹烷(HN研)是当今已工业化生产的能量水平最高的炸药,HNIW的制备包括基本母体的合成、母体的氢解、氢解产物(硝解底物)的硝解(即生成HN研)及HNIW的转晶4步。综述了近几年来制备HNIW的硝解工艺的进展(包括作者的若干研究成果),详细报道了硝解3种底物([四乙酰基二苄基六氮杂异伍兹烷(TADBIW)、四乙酰基二甲酰基六氮杂杂异伍兹烷(TADFIW)及四乙酰基六氮杂异伍兹烷(TAIW])以制备HNIW的工艺条件,并评价了各自的优、缺点。 相似文献
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采用溶胶-凝胶法首先制备出Zr(OH)4凝胶,再将凝胶用乙醇进行醇化处理,经烘干和焙烧制得ZrO2纳米载体。载体颗粒粒径均匀,大小为20 nm左右。以ZrO2为载体,采用浸渍法分别负载Fe2O3、CuO、NiO和Mo2O3等不同金属氧化物,制得负载型催化剂。通过XRD、TEM、SEM和IR等对催化剂进行表征。以乙醇氧化脱氢合成乙醛为探针反应,考察了催化剂的催化性能。实验结果表明,催化剂Fe2O3/ZrO2在反应温度为573 K时,乙醇转化率为75.8%,乙醛选择性为97.3%。 相似文献
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采用浸渍-还原法制备三氧化二铝负载钯催化剂(Pd/Al2O3),通过ICP-AES、XRD、XPS等分析手段对催化剂的结构和组成进行了表征。考察了溶剂、溶剂与水的比例、碱的种类、反应温度以及反应时间等反应条件对上述制备的催化剂催化Suzuki偶联反应的影响,筛选出最适宜的反应条件。实验结果表明,在1mmol对溴苯乙酮,1.5mmol苯硼酸,2mmol碳酸钾,乙醇∶水=6∶6,反应温度为60℃,反应时间为60min,催化剂加入量为3.5×10-3mmol钯的反应条件下,Suzuki反应收率可达97%以上。 相似文献
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A. Drelinkiewicza A. Waksmundzka W. Makowski J.W. Sobczak A. Król A. Zieba 《Catalysis Letters》2004,94(3-4):143-156
Catalytic properties of Pd supported on two polymers of similar basicity but different electrical properties, a π-conjugated conducting-polypyrrole (PPY) and the electro-inactive poly(4-vinylpyridine) (PVP) have been studied in the hydrogenation of acetophenone (ACT) and compared with that of γ-Al2O3 supported Pd. Experimental evidences provided by several techniques: X-ray photoelectron spectroscopy (XPS), scanning (SEM) and transmission electron (TEM) microscopy, X-ray diffraction (XRD) and temperature programmed desorption (TPD) of hydrogen show that both polymers PVP and PPY exhibited ability to stabilize finely dispersed palladium nanoparticles, better this ability is offered by electro-inactive PVP. Palladium nanoparticles within a narrow range of size 2–20nm as well as very high surface concentration of Pd (22.2at %) in agglomerates were established in the latter polymer supported catalysts. Distinctly lower surface concentration of Pd (1.8at %) and crystalline Pd particles of dimension within a wide range, from 5nm up to ca. 1500nm appeared in the matrix of electroactive polymer – PPY. The hydrogenation of ACT to ethylbenzene (ETB) via 1-phenylethanol (ACP) (as the intermediate) proceeded over all studied catalysts. The effects of solvents, Pd content, ACT concentration and the additives of ACP, ETB were also studied. The catalytic properties of Pd/PPY in terms of activity and selectivity significantly differ from those of Pd/PVP and Pd/Al2O3. Both latter catalysts offered high activity and selectivity in the C=O in ACT to C–OH reduction. Definitely lower activity and higher tendency towards the hydrogenolysis of C–OH in ACP reflected Pd/PPY catalysts. Such unprofitable properties of Pd/PPY can be attributed to relatively strong adsorption of all organic reactant ACT, ACP, ETB. A competition of the ACP and ETB with the ACT occurred only in the case of Pdcentres created in the electroactive polymer, whereas Pd sites dispersed in the electro-inactive PVP similarly as the ones in Al2O3 exhibited definitely more substrate – ACT specific character. 相似文献
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合成苹果酯-B的催化剂研究进展 总被引:1,自引:0,他引:1
综述了硫酸铝,无水AlCl3、FeCl3、CuCl2、ZnCl2,固体超强酸SO2-4/ZrO2、SO2-4/TiO2、SO2-4/TiO2 La2O3、SO2-4/TiO2 MoO3、SO2-4/TiO2 WO3,固载杂多酸,H3PW12O40/PAn,TiSiW12O40/TiO2,HY型分子筛以及高分子复合催化剂FeCl3 AlCl3 UR等十余种不同催化剂催化合成苹果酯 B的实验结果。结果表明:硫酸铝,固体超强酸SO2-4/TiO2 La2O3、SO2-4/TiO2 WO3,活性炭固载的杂多酸(HPA/C)和高分子复合催化剂FeCl3 AlCl3 UR五种催化剂对苹果酯 B的收率较高,具有实际应用价值。 相似文献
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Conversion of CCl2F2 in the presence (hydrogenolysis) and absence of hydrogen was investigated on Al2O3, AlF3 and Pd/Al2O3 xerogel and aerogel catalysts. CCl2F2 was found to form CClF3 and CCl3F on Al2O3 and AlF3 in the presence and absence of hydrogen as well as on the Pd/Al2O3 catalysts in the absence of hydrogen. Overall activity increased during the hydrogenolysis reactions at 230°C as a function of time which was paralleled by a significant increase in the yield of CClF3 formed through a Cl/F-exchange reaction. X-ray diffraction patterns of the spent catalyst recovered after 3 h of hydrogenolysis confirmed the presence of Pd(C) (Pd–carbon solid solution) and AlF3 phases on Pd/Al2O3 catalysts indicated that the carbon incorporation into the Pd lattice and the transformation of Al2O3 to AlF3 starts at the initial stage of the reaction. It was concluded that AlF3 is responsible for the Cl/F-exchange reactions. CH4, a complete hydrogenation product, is formed during hydrogenolysis. Another route for its formation is the reaction between hydrogen in the gas phase and the interstitial carbon. 相似文献
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通过对不同Pd负载量、温度以及寿命的考察,评价了负载型Pd/γ-Al2O3催化剂在乙醇蒸汽重整制氢的催化反应中的性能。试验表明较高的Pd负载量或者较高的反应温度可以获得理想的氢气选择性。在650℃反应温度下,对含Pd为5%(质量分数)的Pd/Al2O3催化剂进行考察获得了最高的氢气选择性136%。而且在反应温度为750℃条件下,含Pd为1%(质量分数)的Pd/Al2O3催化剂对氢气的选择性可以达到110%。通过NH3-TPD,TGA分析手段对催化剂进行表征分析。 相似文献