Abstract

Pyrolysis oils contain various types of organic acids that may cause corrosion issues to the constructional materials of oil containers. In this work, immersion tests were performed at 60°C for 7 days to identify the corrosion susceptibility of a carbon steel UNS K02700 to pyrolysis oils provided by different suppliers. The acidity of pyrolysis oils was characterized using total acid number (TAN), carboxylic acid number (CAN) and phenolic acid number (PhAN). The corrosion rates were measured using weight loss method, and the corroded surfaces were examined using scanning electron microscopy combined with the energy dispersive X-ray spectroscopy (SEM/EDS). Acid corrosion seems to be influenced by CAN based on the preliminary results. Recommendations were made for future work.

Introduction

Due to the increase in world's population and technologies, and the limited fossil fuel reserves, efforts have been taken to seek alternative energy resources, such as bioenergy that is produced from renewable biomass, to meet the increasing need for energy. The feedstocks for bioenergy production can include the waste biomass from forestry and agricultural sectors and various industries such as food processing industry and pulp and paper industry, making a profit while saving costs from waste management.

The methods for converting biomass mainly contain biochemical conversion and thermochemical conversion.1 Under biochemical pathway, the cellulose and hemicellulose fractions in the raw biomass undergo hydrolysis to be broken down into simple sugars, which are then fermented and distilled to produce ethanol.2 Thermochemical conversion uses heat to break raw biomass into various types of bioenergy such as syngas (a mixture of carbon monoxide and hydrogen), liquid bio-oils and/or solid bio-char with or without the presence of catalysts. Pyrolysis is a promising thermochemical conversion technology because of reusable by-products and fewer emissions; it is also an effective and practical method to convert biomass into liquid bio-fuels which have higher energy density than bio-gas and bio-char.3, 4 In the process of pyrolysis, the chemical bonds in biomass are thermally broken through depolymerization, ring-opening and cleavage reactions in the absence of oxygen.5

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