Acta Phys. -Chim. Sin. ›› 2009, Vol. 25 ›› Issue (10): 2045-2049.doi: 10.3866/PKU.WHXB20090926

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Nitration of Benzene in a Continuous-Flow Microreactor Integrated with Microfiber-Structured Nafion/SiO2 Solid Acid Catalyst

YANG Jiu-Long, LI Jian-Feng, LU Yong   

  1. Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry, East China Normal University, Shanghai 200062, P. R. China
  • Received:2009-04-20 Revised:2009-06-17 Published:2009-09-29
  • Contact: LU Yong


We prepared novel monolithic microfiber-structured Nafion/SiO2 solid acid catalysts with 60%-75% (φ, volume fraction) void volume by coating Nafion/SiO2 sol-gel onto a sinter-locked stainless steel (SS-316L) microfibrous network. We characterized the microstructured Nafion/SiO2 catalysts using Fourier transform-infrared spectrometry (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and NH3-chemisorption. Results show that the sol-gel technology results in highly dispersed Nafion particles which significantly increase the number of accessible acid sites. The Nafion/SiO2 catalyst coating layer is made up of 200-400 nmparticles and looks porous. The catalytic performance of the microstructured Nafion/SiO2 catalysts was tested using the nitration of benzene in a continuous-flow microreactor that integrated heat-exchange, mixture, and catalytic reactions. The best catalyst had a loading capacity of 36.3% (w, mass fraction) for the Nafion/SiO2 composite in which the Nafion content was 20% (w). At a reaction temperature of 75 ℃, this optimized microstructured solid acid catalyst resulted in a benzene conversion of 44.7% with a nitrobenzene selectivity of 99.9%. At an equivalent conversion level, the activity per acid site of the microstructured Nafion/SiO2 catalyst is nearly 600 times as that of liquid sulfuric acid.

Key words: Sol-gel, Microfiber, Microreactor, Nafion, Solid acid, Benzene, Nitration, Nitrobenzene


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