共查询到19条相似文献,搜索用时 109 毫秒
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Raney-Fe催化加氢制备4-氯-2-氨基苯酚 总被引:2,自引:1,他引:1
将4-氯-2-硝基苯酚溶于乙醇,置于反应釜中,加入Raney—Fe催化剂,在温度67℃、1.0MPa的氢气压力下,反应110~120分钟,制备4-氯-2-氨基苯酚。 相似文献
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以10mgw(Pd)=5%的Pd/C为催化剂,在35℃和1 01×105Pa下,ρ(三氯新)=4g/L的三氯新水/乙醇〔V(水)∶V(乙醇)=1∶1〕溶液20mL反应30min就100%脱氯。在乙醇中,三氯新加氢1h氯的去除率为68%。水的存在,改善了三氯新的反应环境,消除了NaCl在催化剂上的富集,使催化剂保持了较高的活性。在水溶液中,ρ(氯化物)=5g/L的碱金属或碱土金属氯化物的存在,对三氯新的加氢脱氯反应没有影响,这是因为这些无机氯化物在水中完全电离,离子化的无机氯化物不会堵塞反应孔道,也不会在催化剂表面吸附,因此不会阻碍三氯新的加氢脱氯。 相似文献
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用化学还原法制备了活性炭负载Pd、Pt和 Ru共3种贵金属催化剂,在没有添加任何脱氯抑制剂和助剂的前提下,比较研究了3种催化剂在邻氯硝基苯(o-CNB)加氢制邻氯苯胺(o-CAN)反应中的催化性能,发现Pd/C催化剂效果更佳。以Pd/C为催化剂,考察了溶剂种类、反应温度、反应时间和重复使用次数等因素对邻氯硝基苯转化率及邻氯苯胺选择性的影响。实验结果表明:常压条件下,Pd与邻氯硝基苯的质量比为1/2120,反应时间90min,邻氯硝基苯转化率和邻氯苯胺选择性分别可达100%和 87.4%。催化剂在重复使用6次后仍保持较高的活性。该工艺具有反应压力低、催化剂用量少、反应时间短和脱氯少等特点,适合工业化生产。 相似文献
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催化加氢制备含卤芳胺化合物工艺研究 总被引:2,自引:0,他引:2
采用BCA为防脱氯剂,甲醇为溶剂,用自制催化剂进行加氢还原2,5-二氯硝基苯制备了2,5-二氯苯胺。最佳工艺条件为:反应温度70~75℃,氢气压力0·7~0·8MPa,w(2,5-二氯硝基苯)∶w(自制催化剂)=63·4∶1·0。在此最佳工艺条件下,得到的产品含量(气相色谱外标法)99·3%,产品收率达96·2%。 相似文献
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溶剂对Pd/C催化四氯化碳液相加氢反应的影响 总被引:1,自引:0,他引:1
考察了活性组分、载体、Pd含量及溶剂对四氯化碳液相催化加氢转化为氯仿反应的影响。实验结果表明,质量分数0.5%的Pd/C是四氯化碳液相催化转化的较优催化剂。溶剂对该反应的速率和产品分布有显著影响,在正庚烷、甲苯和甲醇3种溶剂中,甲醇最利于提高Pd/C催化剂的活性,且四氯化碳转化的平均反应速率随着甲醇含量的增加呈现先增大后减小的趋势,氯仿的选择性随着甲醇含量的增加有所降低。当甲醇和四氯化碳的体积比为2∶1时,四氯化碳转化速率最高。甲醇和四氯化碳的体积比为1∶10时,氯仿的选择性达90%。 相似文献
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Dipak D. Payal 《Chemical Engineering Communications》2018,205(5):657-666
Effluents from the pharmaceutical and dye industries contain chlorinated organic pollutants. The effective treatment of such effluents constitutes a challenging task. In this work, 4-chlororesorcinol (PCRE) and 4-chloro-2-aminophenol (PCAP) were selected as model chloro-organic compounds. Catalytic hydrodechlorination (HDC) of PCRE and PCAP in the aqueous phase was investigated in a slurry reactor using commercial carbon supported ruthenium catalyst. HDC reactions of PCRE and PCAP were studied over the ranges in temperature, 313–353?K, H2 partial pressure, 0.69–2.76?MPa, and catalyst loading, 0.2–1.2?kg/m3. The performance of Ru/C catalyst for hydrodechlorination and ring saturation was promising. The kinetic data were modeled using Langmuir–Hinshelwood–Hougen–Watson kinetics. The HDC reaction of PCRE and PCAP using Ru/C catalyst proceeds via a dual-site mechanism, wherein atomic H2 reacts with the adsorbed organic substrate. The activation energy for the hydrodechlorination reactions of PCRE and PCAP was 41.6 and 49.4?kJ/mol, respectively. 相似文献
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卤代芳胺是重要的有机中间体,广泛应用于合成染料、农药、医药、香料及橡胶助剂等。卤代芳香硝基化合物通过液相催化加氢制备卤代芳胺的技术以其环境友好、产品质量稳定和工艺先进而受到重视。用负载型贵金属催化剂催化芳香硝基化合物选择加氢制备相应的芳胺有广泛的应用价值。采用邻硝基苯胺为原料,Pd/C为催化剂,低压催化加氢还原合成邻苯二胺,考察不同溶剂、反应压力、反应温度和反应时间对产物收率的影响。结果表明,在甲醇为溶剂、反应温度100 ℃、反应压力0.8 MPa和反应时间100 min条件下,邻苯二胺平均收率为97%。与传统硫化碱还原或铁粉化学法还原工艺相比,以甲醇为溶剂,Pd/C催化剂催化加氢法在减少废水和降低成本等方面有较大优势。 相似文献
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Pd/C催化剂对生物质基丁酮催化加氢制取仲丁醇 总被引:2,自引:0,他引:2
研究了生物质基丁酮经Pd/C催化加氢制备仲丁醇的工艺条件,考察了反应时间、反应温度、氢压和催化剂用量对仲丁醇收率的影响。结果表明,Pd/C可催化丁酮进行加氢反应,主要产物为仲丁醇。在一定温度条件下,仲丁醇收率随温度的升高而增大,但超过一定范围,继续增加反应温度,收率反而下降。加氢压力1 MPa,反应8 h后,90 ℃、120 ℃和150 ℃条件下仲丁醇收率分别为53.1%、52.8%和45.5%;增大氢压,仲丁醇收率反而明显降低。增加催化剂用量,反应速率加快,反应时间缩短,但对最终仲丁醇收率的影响不大。 相似文献
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Liquid phase hydrodechlorination of chlorophenols over Pd/C and Pd/Al2O3: a consideration of HCl/catalyst interactions and solution pH effects 总被引:1,自引:0,他引:1
The liquid phase hydrodechlorination (HDC) of 2-chlorophenol (2-CP) and 2,4-dichlorophenol (2,4-DCP) has been studied over 1% (w/w) Pd/C and Pd/Al2O3 under conditions of minimal mass transport constraints. The HDC of 2,4-DCP generated HCl and 2-CP as the only intermediate partially dechlorinated product which reacts further to yield phenol; cyclohexanone was formed over Pd/Al2O3, but not over Pd/C, prior to complete dechlorination. Pd/Al2O3 is characterized (on the basis of TEM analysis) by a narrow distribution of smaller Pd particles to give a surface area weighted mean particle DIAMETER = 2.4 nm that is appreciably lower than the value of 13.2 nm established for Pd/C, where the latter is characterized by a broader distribution of larger (spherical) particles. The addition of NaOH served to increase fractional dechlorination by suppressing HDC inhibition due to the HCl that is generated. Reuse of the catalysts revealed an appreciable deactivation of Pd/C and a limited loss of activity in the case of Pd/Al2O3. Deactivation of Pd/C can be linked to a decrease (up to ca. 60%) in the initial BET surface area allied to appreciable leaching (up to ca. 40%) of the starting Pd content through the corrosive action of HCl and, while the average Pd diameter is essentially unaffected, there is evidence of a preferred leaching of larger Pd particles. The stronger metal/support interactions prevalent in Pd/Al2O3 results in limited Pd leaching and comparable initial HDC activities during catalyst reuse with/without NaOH addition. Inclusion of HCl in the reaction mixture (pH 5–1.5) resulted in a marked decline in the initial HDC rate associated with Pd/Al2O3 and a lesser drop in HDC activity for Pd/C. The difference in response to bulk solution pH variations are discussed in terms of the nature of the reactive species in solution and the amphoteric behavior of the Pd supports. 相似文献
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Zhonghao Jin Xingyi Wang Songtao Wang Dao Li Guanzhong Lu 《Catalysis communications》2009,10(15):2027-2030
The hydrodechlorination (HDC) of chlorophenols on 5 wt.% Pd/C catalyst was investigated at low temperature under ordinary pressure by using triethylamine (Et3N) as a base additive. The inhibition effect of Et3N on the HDC existed obviously and can be efficiently reduced by stepwise addition of Et3N. For the first time, the high activity of Pd/C for HDC of chlorophenols was observed at 258 K. 相似文献
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《Catalysis communications》2010,11(15):2027-2030
The hydrodechlorination (HDC) of chlorophenols on 5 wt.% Pd/C catalyst was investigated at low temperature under ordinary pressure by using triethylamine (Et3N) as a base additive. The inhibition effect of Et3N on the HDC existed obviously and can be efficiently reduced by stepwise addition of Et3N. For the first time, the high activity of Pd/C for HDC of chlorophenols was observed at 258 K. 相似文献
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采用Raney Ni催化剂,选择50%乙醇-水(50/50,体积比)作为溶剂体系,考察了不同类型碱及其添加量对Raney Ni催化4-氯苯酚(4-CP)还原脱氯反应的影响。结果表明,强碱(NaOH和KOH)和Et3N更有利于Raney Ni催化下还原脱氯反应的进行,而且当n(NaOH/Et3N)∶n(4-CP)=1.1~2.2时,Raney Ni能够保持较高的催化活性,可以在30min内实现4-CP的彻底还原脱氯,并建立了Raney Ni-50%乙醇-水(50/50,体积比)-NaOH催化体系。将该体系应用于研究取代基对Raney Ni催化芳香氯代物还原脱氯的影响,研究表明,Raney Ni催化剂对4-CP和4-氯苯胺(4-CA)的还原脱氯具有较高的选择性。进一步将Raney Ni-50%乙醇-水(50/50,体积比)-1.5NaOH催化体系应用于高浓度氯酚工业危废的还原脱氯处理,发现在该催化体系中氯酚工业危废中的氯代有机污染物可以彻底还原脱氯,且催化剂可以至少重复使用5次。该催化体系可以有效、彻底地还原脱氯降解氯酚工业危废,对高浓度氯酚工业危废的还原脱氯降解具有良好的应用前景。 相似文献