Preparation Of Carbon-Based Solid Acid For Syntesis Of P-Aminophenol

In view of energy and environmental crisis, developing efficient and eco-friendly catalysthas become a major area of research. In this paper, a kind of carbon-based solid acid catalyst wasprepared to solve the problems caused by liquid acid, such as equipment corrosion, environmentpollution, difficulty in separation of product, etc.A kind of carbon-based solid acid catalyst was prepared by sulfonation of incompletelycarbonized sucrose with sulfuric acid, and characterized by means of IR, XRD, ¹³C MAS NMR,elemental analysis and acid-base neutralization titration, et al. The results indicated that thecarbon-based solid acid catalyst was amorphous carbon structure of polycyclic aromatic with–SO3H. All the S element was presented in the form of–SO3H. The maximum acid density ofcarbon-based solid acid catalyst was 2.8 mmol/g. Then, the conditions for preparing thecarbon-based solid acid catalyst were optimized. The optimum conditions were carbonizationtemperature 350℃, carbonization time 15 h, sulphonation temperature 150℃, sulphonationtime 15 h, the amount of sulfuric acid 100 mL/(g carbon materials).The carbon-based solid acid catalyst and Pt/SiO₂ build a novel micron-scale catalyst systemthrough mixing, which was applied to the synthesis of p-aminophenol(PAP) by nitrobenzenecatalysis hydrogenation instead of liquid acid. The effects of the amount of catalyst and reactionconditions were investigated, suggesting a optimized conditions: 1.0 g of carbon-based solid acid,reaction temperature 115℃, reaction time 4 h, hydrogen partial pressure 0.4 MPa. Under theoptimized conditions, the conversion of nitrobenzene was 76.2% and selectivity of PAP was 54.4%.In addition, a novel nano-scale metal/carbon-based solid acid bifunctional heterogeneouscatalyst was prepared by loading Pt on the carbon-based solid acid. And the catalyst wascharacterized by XRD, IR, ICP and acid-base neutralization titration. Then it was applied to thesynthesis of PAP to investigate its catalytic properties. The yield of PAP was 22.4% under theconditions of reaction temperature 115℃, reaction time 4 h, hydrogen partial pressure 0.4 MPaand 1.0 g of bifunctional catalyst. Moreover, the stability of bifunctional catalyst wasinvestigated. The results showed that nitrobenzene conversion and PAP selectivity decreasedgradually when the catalyst was reused three times subsequently.