采用液相还原法，以甲酸为还原剂制备了负载量为5%的Pd/C催化剂。考察了还原过程中pH值对Pd/C上硝基苯液相催化加氢性能的影响，并用XRD、SEM、TEM等手段对催化剂的结构进行了表征。结果表明，制备过程中随着 pH 的增大，催化剂活性先增大后减小；适宜的 pH 值能加快 Pd 还原反应的速率，有利于粒子快速成核，降低生成大粒径 Pd 粒子的几率，减少团聚，使Pd 粒子均匀分散在活性炭载体上，获得较高的催化活性。pH=9时制得的催化剂上 Pd 晶粒分布均匀，平均粒径为3.63 nm；在50℃、H2压力0.8 MPa、搅拌速率100 r/min，反应45 min的条件下，这一催化剂对硝基苯加氢液相催化为苯胺的转化频率(TOF)达到8758 h-1。
Pd/C catalysts with a loading of 5%Pd content were prepared by liquid-phase reduction method using formic acid as a reducing agent, and characterized by means of XRD, SEM and TEM techniques. The effect of pH values in the reduction preparative process on the performance of catalysts for the liquid phase hydrogenation of nitrobenzene was investigated. The results show that, the catalytic activity firstly increases and then decreases with the augment of pH value during preparation. Suitable pH value can accelerate the rate of Pd reduction reaction and promote rapid nucleation of Pd particles, which will reduce the probability of generating large particles and aggregation phenomenon, producing uniform Pd particles required for higher activity. Pd particles with a mean diameter of 3.63 nm were found to be distributed uniformly on activated carbon carrier when reduction was carried out at pH 9. Catalyzed by the catalyst such prepared, the turnover frequency (TOF) reached 8758 h-1 in the reaction of liquid phase hydrogenation of nitrobenzene to aniline at 50℃for 45 min, when H2 partial pressure was 0.8 MPa with stirring at 100 r/min.
参考文献
| [1] | 张超林.硝基苯液相催化加氢制苯胺催化剂研究进展[J].工业催化,2008(01):5-9. |
| [2] | 张超林.硝基苯液相催化加氢制苯胺技术进展[J].现代化工,2007(12):11-14. |
| [3] | 姜新亮.Cu-SiO2催化剂在苯胺生产中的应用[J].氯碱工业,2009(09):30-34. |
| [4] | N.Mahata;A.F.Cunha;J.J.M.Orfao.Hydrogenation of nitrobenzene over nickel nanoparticles stabilized by filamentous carbon[J].Applied Catalysis, A. General: An International Journal Devoted to Catalytic Science and Its Applications,20082(2):204-209. |
| [5] | Zhao, Y.;Zhang, H.;Huang, C.;Chen, S.;Liu, Z..Pt/titania/reduced graphite oxide nanocomposite: An efficient catalyst for nitrobenzene hydrogenation[J].Journal of Colloid and Interface Science,2012:83-88. |
| [6] | Yun Zhao;Chun-Hua Li;Zhen-Xing Yu;Ke-Fu Yao;Sheng-Fu Ji;Ji Liang.Effect of microstructures of Pt catalysts supported on carbon nanotubes (CNTs) and activated carbon (AC) for nitrobenzene hydrogenation[J].Materials Chemistry and Physics,20072/3(2/3):225-229. |
| [7] | N.Bouchenafa-Saib;F.Addoun;P.Grange;P.Verhasselt;V.Dubois.Effect of oxidant treatment of date pit active carbons used as Pd supports in catalytic hydrogenation of nitrobenzene[J].Applied Catalysis, A. General: An International Journal Devoted to Catalytic Science and Its Applications,20052(2):167-174. |
| [8] | P. Sangeetha;K. Shanthi;K.S. Rama Rao.Hydrogenation of nitrobenzene over palladium-supported catalysts—Effect of support[J].Applied Catalysis, A. General: An International Journal Devoted to Catalytic Science and Its Applications,20092(2):160-165. |
| [9] | Maria Turakova;Milan Kralik;Peter Lehocky.Influence of preparation method and palladium content on Pd/C catalysts activity in the liquid phase hydrogenation of nitrobenzene to aniline[J].Applied Catalysis, A. General: An International Journal Devoted to Catalytic Science and Its Applications,2014:103-112. |
| [10] | 刘青 .Ni-B催化剂的制备及其在硝基苯加氢中的应用[D].四川大学,2007. |
| [11] | Pellegrini, R.;Agostini, G.;Groppo, E.;Piovano, A.;Leofanti, G.;Lamberti, C..0.5 wt.% Pd/C catalyst for purification of terephthalic acid: Irreversible deactivation in industrial plants[J].Journal of Catalysis,20112(2):150-160. |
| [12] | 梁琨 .Pd/C催化剂工业化研究及其在催化转移加氢反应中的应用[D].兰州大学,2008. |
| [13] | 刘时杰.从炭载体废催化剂回收铂钯[J].贵金属,2014(01):84-89. |
| [14] | 陈祥;周立进;顾沛国;曾崇余.制备方法对钯碳催化剂表面性质及其加氢性能影响[J].南京工业大学学报（自然科学版）,2005(5):93-96. |
| [15] | 曹剑瑜;汤佳丽;宋玲政;许娟;王文昌;陈智栋.EDTA对活性炭的功能化处理及其对炭载Pd催化剂电催化性能的影响[J].物理化学学报,2013(1):144-150. |
| [16] | 陈滢;唐亚文;高颖;刘长鹏;邢巍;陆天虹.用改进液相还原法制备炭载Pd催化剂[J].应用化学,2009(8):985-988. |
| [17] | 肖成建;胡胜;傅中华;罗阳明;王和义.用Pt/C催化剂通过浸渍-还原法制备疏水催化剂[J].应用化工,2007(9):855-859. |
| [18] | 曾宪春;孟家明.Pd/C催化剂的SEM、EDS研究[J].电子显微学报,2000(1):60-64. |
| [19] | 堵文斌;王继元;朱庆奋;陈韶辉.pH值对粗对苯二甲酸加氢精制Pd/C催化剂性能的影响[J].石油炼制与化工,2011(3):38-41. |
| [20] | 梁秋霞;马磊;郑遗凡;卢春山;张群峰;李小年.浸渍法制备Pd/C催化剂过程中Pd前驱体的平衡吸附量与吸附态[J].催化学报,2008(2):145-152. |
- 下载量()
- 访问量()
- 您的评分：
-
10%
-
20%
-
30%
-
40%
-
50%