Today, the principles of green chemistry are being fundamentally applied in the chemical industry, such as the nitrobenzene industry, which is an essential intermediate for various commercial products. Research on the application of response surface methodology (RSM) to optimize nitrobenzene synthesis was conducted using a sulfated silica (SO4/SiO2) catalyst and batch microwave reactor. The nitrobenzene synthesis process was carried out according to RSM using a central composite design (CCD) design for three independent variables, consisting of sulfuric acid concentration on the silica (%), stirring time (min), and reaction temperature (°C), and the response variable of nitrobenzene yield (%). The results showed that a three-factorial design using the response surface method could determine the optimum conditions for obtaining nitrobenzene products in a batch microwave reactor. The optimum condition for a nitrobenzene yield of 63.38 % can be obtained at a sulfuric acid concentration on the silica of 91.20 %, stirring time of 140.45 min, and reaction temperature of 58.14 °C. From the 20 experiments conducted, the SO4/SiO2 catalyst showed a selectivity of 100 %, which means that this solid acid catalyst can potentially work well in converting benzene to nitrobenzene.

1. Introduction
2. Experimental Procedure
    2.1. Materials
    2.2. Preparation of SO4/SiO2 catalysts
    2.3. Catalyst acidity test by ammonia vapor-gravimetricmethod
    2.4. Optimization of nitrobenzene synthesis yieldusing 3-variables CCD-RSM experimental design
    2.5. Nitrobenzene synthesis catalyzed by SO4/SiO2
3. Results and Discussion
    3.1. Experimental design
    3.2. Fourier transform infrared (FTIR) characterizationof the catalysts
    3.3. Crystallinity study of the catalysts
    3.4. Acidity test of the catalysts
    3.5. Textural properties analysis
    3.6. Characterization by field emission scanningelectron microscope (FESEM)
    3.7. RSM analysis
    3.6. Benzene nitration reaction study over SO4/SiO2catalyst
4. Conclusion
Acknowledgement
References
Author Information

• Aan Sabilladin(Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia)
• Aldino Javier Saviola(Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia)
• Karna Wijaya(Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia) Corresponding author
• Aulia Sukma Hutama(Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia)
• Mokhammad Fajar Pradipta(Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia)
• Wahyu Dita Saputri(Research Center for Quantum Physics, National Research and Innovation Agency (BRIN), The B. J. Habibie Science and Technology Area, South Tangerang 15314, Indonesia)
• Hilda Ismail(Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia)
• Budhijanto Budhijanto(Department of Chemical Engineering, Faculty of Engineering, Universitas Gadjah Mada, Yogyakarta 55281, Indonesia)
• Won-Chun Oh(Department of Advanced Materials and Engineering, Hanseo University, Seosan 39162, Republic of Korea)
• Balasubramani Ravindran(Department of Environmental Energy and Engineering, Kyonggi University, Suwon 16227, Republic of Korea, Department of Medical Biotechnology and Integrative Physiology, Institute of Biotechnology, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences, Chennai 602 105, India)