A Microwave-Sensitive Solid Acid Catalyst Prepared from Sweet Potato via a Simple Method

Abstract

Abstract:In this study, a microwave-sensitive solid acid catalyst was successfully synthesized from sweet potatoes via a simple process.The catalyst was proven to have superior microwave-sensitive and homogeneous properties.The physicochemical properties were characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), Fourier-transform infrared spectra (FT-IR), thermogravimetric (TGA), scanning electron microscope (SEM) and elemental analysis (EA). Results showed that the total acid density and specific surface area for the catalyst were 6.35 mmol/g and 78.35 m 2 /g, respectively. The elemental sulfur content reached 7.449% after sulfonation and the catalytic activity could reach over 91% within 30 min with microwave power density of 1.0 W/mL. The catalytic reaction temperature should not exceed 200 • C, as shown in TGA curve, and the moisture content in the oil raw material should be within 1%-2%. The catalyst deactivated gradually to 64.38% after reutilization five times, but the catalytic activity could be simply regenerated by re-sulfonation, albeit slightly reduced (87.56%). The shift of diffraction peaks in the XRD patterns and new absorption peaks at 619.98 and 1190.49 cm −1 of FT-IR spectra demonstrated that the -SO 3 H group was effectively attached to the catalyst. The SEM images displayed a loose and porous amorphous structure in the end catalyst.

A Two-Step SO3H/ICG Catalyst Synthesis for Biodiesel Production: Optimization of Sulfonation Step via Microwave Irradiation

“…In contrast, if microwave output was too low, most of the microwave power would be used to warm up the reaction mixture, and the temperature would be lower than required in most cases, resulting in a lower yield. The appropriate microwave power density and its dissipation control were very important to maximize ester yield and minimize reaction time and microwave energy consumption [23].…”

Development of Microwave-Assisted Sulfonated Glucose Catalyst for Biodiesel Production from Palm Fatty Acid Distillate (PFAD)

“…The development of the carbon sheet will basically increase with the rise of the temperature or power level during carbonization [43]. However the microwave power level should not be too high since high radiation of the microwave exhibits accumulated discontinuities thus shortening the molecular orientation and vibration [44]. The FAME obtained was then confirmed by went through several test from Laboratory Services Unit (UNIPEM) and the test reported was tabulated in Table 4.…”

A Review of Microwave-Assisted Reactions for Biodiesel Production

“…Domestic applications such as microwave ovens are approved to be operated at a frequency of 2.45 GHz, while the industrial applications are between 0.915 GHz and 2.45 GHz. Most of the reported microwave chemistry experiments are carried out at 2450 MHz [ 32 , 33 , 34 ], as the maximum microwave energy is absorbed by liquid water near to this frequency. There are numerous studies that have been carried out on microwave applications in the organic synthesis sector; for instance, the application of microwaves in the synthesis of polymer [ 35 ] and metal oxides [ 7 ], solvent free reactions [ 36 ], homogeneous and heterogeneous catalytic reactions [ 37 ], and many other reactions involved in medicinal [ 38 ] and green chemistry [ 8 ].…”