Properties of bio-oil and bio-char from high-intensity microwave-assisted pyrolysis of oil palm shell waste

• Published in: Bioresources 2023-02, Vol.18 (1), p.1420-1435
• Main Authors: Jansuwan, Kanokporn, Jumrat, Saysunee, Punvichai, Teerasak, Karrila, Seppo, Sirikitputtisak, Tule, Songthongkaew, Nitipong, Pianroj, Yutthapong
• Format: Article
• Language: English
• Subjects: Acetic acid; Activated carbon; bio-char; Biomass; Calibration; Calorific value; Chemical composition; crude bio-oil; Design factors; Design of experiments; Dielectric properties; Electric fields; Energy consumption; Experimental design; Magnetrons; microwave-assisted pyrolysis (map); Minimum cost; Mixtures; oil palm shell (ops); Phenols; Plastics; Pyrolysis
• ISSN: 1930-2126; 1930-2126
• DOI: 10.15376/biores.18.1.1420-1435

Microwave-assisted pyrolysis was applied using four magnetrons to implement a high intensity at a power density of 0.3107 W/m3 with 800 g specimen size. The 23 full factorial experimental design manipulated the factors temperature, mixture ratio, and pyrolysis time, seeking to maximize %yield at minimum cost of crude bio-oil. The optimum according to model fit had a temperature of 611 °C with a 70:30 sample mixture ratio of oil palm shell (OPS) to activated carbon (AC), and time 39.6 min for a yield of 15.3% and 8.48 Thai-Baht/cc cost. The coefficients of determination were R2 = 93.99% and 94.00% for the respective models. In the aqueous phase of crude bio-oil, acetic acid was the dominant chemical component at 55.2%, whereas phenol was dominant in the bio-oil phase at 44.2%, from 400 °C pyrolysis temperature. The assessed properties of bio-char were proximate composition, heating value, specific surface, and pore volume, and these were improved compared to the raw OPS. However, these properties must be improved further to match commercial-grade activated carbon.