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  • Due to the emergence of various

    2018-10-26

    Due to the emergence of various food industries, restaurants all over the world, the amount of waste cooking oil (WCO) required for disposal is a major concern. Currently, about 29 million tons of WCO are generated annually in the world (Maddikeri et al., 2012). The base materials of WCO are plant-based lipids, such as soybean oil, corn oil, palm oil, or animal-fats. Chemically, the major components of WCO are triglycerides (tristearin, trimyristin, tripalmitin, tripalmitoleic, trioleate, etc.), with minor amounts of mono and diglycerides (Dale et al., 2008). Until recently, WCO was a significant environmental problem, and the management of this waste was a significant challenge. However, WCO cannot be discharged into sewers as its discharge will lead to blockages, odor or vermin problems and may also pollute watercourses, causing problems for wildlife (Lee et al., 2012). In this context, many scientists have intensively investigated WCO valorization in recent years. The biodiesel production via WCO transesterification remains by far the main route of WCO reuse (Al-Hamamre and Yamin, 2014; Mohammad et al., 2014; Chen et al., purchase clemastine 2009). Recently, Amani and co-workers (Amani et al., 2014) investigated the transesterification of waste cooking palm oil with methanol into fatty purchase clemastine methyl esters (FAMEs) using solid acidic mixed oxide catalysts MnZr0.5yAlxO3 prepared via coprecipitation. The authors showed that the catalyst achieved a FAME content of more than 93%, and the optimal reaction conditions were as follows: reaction temperature of 150 °C, reaction time of 5 h, molar methanol-to-WCPO ratio of 14:1, and catalyst loading of 2.5 wt.%. Hamze et al. (Hamze et al., 2015) studied the transesterification of the WCO with response surface methodology (RSM) based on Box–Behnken design. The results revealed that the catalyst concentration is the most important parameter and the maximum biodiesel yield under the optimized conditions was 99.38 wt.%. It should be noted, here, that even with all the advantages, there are still some disadvantages associated with the use of biodiesel in combustion engine. Biodiesel has a 12% lower energy content than fossil diesel, which leads to an increase in fuel consumption of approximately 2–10% (Atabani et al., 2012). Moreover, biodiesel has higher cloud and pour points as well as higher nitrogen oxide emissions than fossil diesel. Biodiesel also has lower volatilities, which lead to soot formation in engines due to incomplete combustion (Atabani et al., 2012). In the past few years, some researchers have turned their interest toward fatty material-based H2. Converting WCO into H2 is a three-win alternative, simultaneously addressing pollution, food security, and energy security. Various processes have been proven theoretically and experimentally by many research groups. Pimenidou et al. (Pimenidou et al., 2010a) used a CLR process to produce H2 from WCO using a nickel-based OC. High purity H2 was produced by adding calcined dolomite as a CO2 sorbent into the reactor catalytic bed (Pimenidou et al., 2010b). Dupont et al. (Dupont et al., 2007) studied a novel process of H2 production called unmixed steam reforming (USR) using methane and sunflower oil. Dupont et al. showed that both methane and sunflower oil are suitable fuels for the USR process and that the thermal decomposition of the fuel played a significant role in early H2 production concurrent with coking conditions. This paper explores an innovative application of soybean WCO (SWCO) for H2 production via a CLR process. We believe that SWCO is a promising feedstock for renewable H2 production because of SWCO\'s low O2 content and high potential yield of H2. Moreover, SWCO is a potential alternative for H2 production due to its highly centralized generation in restaurants, various eating outlets and food industries as well as its historically low prices. SWCO may therefore have energy, environmental, and economic advantages that could be exploited. H2 obtained from SWCO has been proposed to be a low-risk end use for SWCO derived from livestock that have been removed from the food chain. Because of the complex chemical structure of SWCO, the unavailability of physical and chemical properties and the multitude of chemical reactions that can occur, no thermodynamic investigation of H2 production by CLR of SWCO has been considered in the past. Generally, an investigation of thermodynamic equilibrium is an important tool preceding experimental work. This investigation identifies thermodynamically favorable process operating conditions and predicts the equilibrium product composition. In addition, this investigation is an aid in reactor modeling, in examining kinetic schemes and reaction mechanisms, and in identifying rate-controlling processes (Shi et al., 2001). This paper aims to identify thermodynamically favorable operating conditions at which SWCO may be converted to H2 by CLR. An expanded product set is used to examine the plausible appearance of the various species in the CLR system. Coke deposits are also investigated to determine coke forming and coke-free regions. It should be noted that the thermodynamic equilibrium investigation conducted here did not consider any kinetic constraints such as concentration and/or temperature gradients occurring in the process. However, these results are still helpful in locating ranges of favorable operation conditions for the CLR system. Further refinement of the optimal conditions will require kinetic investigations.