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

Abstract

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.

High‐Intensity Microwave‐Assisted Pyrolysis Liquid Subjected to Supercritical Fluid Extraction with Carbon Dioxide (Case Study: Bio‐phenol)

“…The crude bio-oil was a dark brown, sticky liquid with a foul smell. It was the bio-oil phase that was separated from the aqueous phase in the optimized [6] microwaveassisted pyrolysis of a 70:30 mixture of OPS and activated carbon (AC) with oper-ating temperature set at 611.0 °C and microwave irradiation for 40.0 min.…”

“…Note that the cost of materials came from the price of raw material (crude bio‐oil). The operating cost of crude bio‐oil was 8.48 THB mL −1 for a yield of 15.3 % at near‐optimal operating point of 611 °C, mixture ratio (OPS:AC) of 70:30, and pyrolysis time of 39.6 min 6; moreover, carbon dioxide gas usage in the scCO 2 extraction and the price of dispersing material ( Spe‐ed Matrix™) were considered. A watt‐hour meter was connected to the scCO 2 system for monitoring the electricity consumption.…”

“…Biomass can provide organic fuels, chemicals, and materials, depending on conversion technologies such as pyrolysis, liquefaction, and gasification [1,2]. These technologies transform cellulosic materials into liquid fuels or crude bio-oil by using a thermochemical process with rapid heating and rapid cooling in the absence of oxygen, with conventional [3] or modern heating methods such as microwave irradiation [4][5][6]. The crude bio-oil from thermochemical processing is composed of complex oxygenated compounds, such as phenolics, alcohols, carboxylic acids, aldehydes, and ketones, and polyaromatic hydrocarbons [7], having undesirable properties such as high viscosity, high water content, high oxygen mass fraction, low heating value, low miscibility with fossil fuels, and instability on storage or exposure to heat [8].…”