Contents lists available at ScienceDirect Journal of Environmental Chemical Engineering journal homepage: www.elsevier.com/locate/jece Research Paper Experimental investigations on the effect of pyrolytic bio–oil during the liquefaction of Karanja Press Seed Cake Kotaiah Naik Dhanavath a,b , Md. Sakinul Islam b , Satyavathi Bankupalli a, ⁎ , Suresh K. Bhargava c , Kalpit Shah b , Rajarathinam Parthasarathy b, ⁎ a Chemical Engineering Division, CSIR–Indian Institute of Chemical Technology, Hyderabad 500007, India b Chemical and Environmental Engineering, School of Engineering, RMIT University, Victoria 3001, Australia c School of Science, RMIT University, Victoria 3001, Australia ARTICLE INFO Keywords: Karanja PSC Pyrolytic bio–oil Liquefaction Bio–crude Octadecanoic acid ABSTRACT In this study, experimental investigations on the liquefaction of Karanja Press Seed Cake (PSC) were carried out in the presence of Pyrolytic Bio–oil (PBO) produced from the slow pyrolysis of the same feedstock. The effects of PBO amount and temperature were studied with an aim to achieve the highest conversion in liquefaction ex- periments. Also, comparison has been established between the use of PBO and conventional solvent and acid catalyst such as phenol and sulphuric acid, respectively for achieving the highest liquefaction conversion. A detailed chemical analysis and a comparison of PBO and liquefied product (bio–crude) have been carried out using FT–IR, and GC–MS techniques. The results showed that the Karanja PSC could be directly liquefied in the presence of PBO at moderate reaction conditions. A maximum liquefaction conversion of 99% was obtained at a reaction temperature of 240 °C, a residence time of 120 min and a Karanja PSC to PBO ratio of 1:6. In contrast, ∼94% conversion was obtained for the same residence time but at significantly lower temperature of 160 °C when phenol and sulphuric acid were used in the ratio of Karanja PSC, phenol and H 2 SO 4 as 1:2:0.6. It was observed that aromatic structure with less oxygen was evident in bio–crude compared to PBO. 1. Introduction Biomass sources such as forestry products, marine products, energy crops, agricultural crops, aquatic plants, pulp derived black liquor, wood and wood waste, municipal solid waste, sewage waste, and an- imal waste are considered as potential resources for the production of biofuels and biochemicals [1]. The biomass currently provides ap- proximately 14% of the world’s total energy demand [2]. Among these feedstocks, Karanja biomass has been identified as a promising feed- stock for the production of renewable fuels due to its higher heating value and abundant availability in many developing countries such as India, Sri Lanka, Nepal, Pakistan and China [3]. Karanja biomass is used to produce biodiesel using a transesterification process [4]. However, during this process, it leads to the generation of a Press Seed Cake (PSC) as a solid residue which could weigh up to 60% of the original Karanja biomass weight. This PSC is normally treated as a waste and mainly being landfilled without any further treatment. It was recently estab- lished in the literature that PSC, due to its organically rich structure, has the potential to be used as a feedstock for liquefaction [3,5]. In liquefaction, relatively low temperatures but high pressures can be used for the valorisation of waste biomass compared to pyrolysis [6,7]. Additionally, liquefaction yields high–quality liquid products (bio–crude) with higher calorific value and lower water/oxygen con- tent. The bio–crude obtained from the direct liquefaction process is a dark–coloured, semi–liquid with the smoke–like smell, with viscosity 10–10,000 times greater than that of diesel or biodiesel. Bio–crude contains a significant amount of carboxylic acids such as acetic acid and formic acid as well as phenolic fractions and carbohydrates [8,9]. Liquefaction of solid biomass involves a complex mechanism con- trolled by several parameters. To carry out an efficient liquefaction process, which is measured in terms of product quality, conversion, cost–effectiveness, and energy efficiency, the selection of appropriate solvents and catalysts is very critical. Solvent has a considerable effect on the liquefaction reaction. Water and various organic solvents such as phenols, alcohols, glycols, ketones, etc., are established solvents that help in producing low viscosity heavy oil by effectively breaking down heterogeneous macromolecular structure of the biomass into light to moderate hydrocarbons. In addition, various co–solvents and acid cat- alysts such as sulfuric acid, hydrochloric acid, phosphoric and oxalic acid are also used for increasing bio–crude yields [10–12]. Akalin et al. http://dx.doi.org/10.1016/j.jece.2017.09.013 Received 24 May 2017; Received in revised form 18 August 2017; Accepted 8 September 2017 ⁎ Corresponding authors. E-mail addresses: drsatyavathib@gmail.com (S. Bankupalli), rajarathinam.parthasarathy@rmit.edu.au (R. Parthasarathy). Journal of Environmental Chemical Engineering 5 (2017) 4986–4993 Available online 08 September 2017 2213-3437/ © 2017 Elsevier Ltd. All rights reserved. MARK