Supercritical fluid technology in biodiesel production

Abstract

Abstract:The synthesis of biodiesel has received attention as an alternative source of energy to decrease our dependence on petroleum-based fuels. The catalyzed processes present a series of limitations and drawbacks, among them the high energy required for complex purification and undesirable side reactions. Supercritical fluid (SCF) technology is being proved an efficient approach compared to traditional methods for preparing biodiesel. This review illustrates the advances, advantages, and drawbacks involved in the use of all current biodiesel production technologies.Keywords: biodiesel; catalyst; non-catalytic; supercritical fluid; transesterification. List of abbreviationsBDF, biodiesel fuel; FA, fatty acid; FFA, free fatty acid; FAAE, fatty acid alkyl ester; FAME, fatty acid methyl ester; FAEE, fatty acid ethyl

Waste to bioenergy: a review on the recent conversion technologies

“…In methanol, the hydrogen bond network is broken under supercritical conditions, this reduction in hydrogen bonding will encourage a stronger direct nucleophilic attack by methanol on the carbonyl group. The dielectric constant of methanol also decreases at supercritical state and this will lead to an elevation in reaction rate [128]. Nevertheless, the selection of alcohol is vital for evaluating the cost and performance.…”

“…Besides, alcohol with higher or branched structure is able to produce fuels with better properties. The extra carbon atom provided by ethanol can slightly increase the heat content and cetane number [128].…”

Waste to bioenergy: a review on the recent conversion technologies

“…In methanol, the hydrogen bond network is broken under supercritical conditions, this reduction in hydrogen bonding will encourage a stronger direct nucleophilic attack by methanol on the carbonyl group. The dielectric constant of methanol also decreases at supercritical state and this will lead to an elevation in reaction rate [128]. Nevertheless, the selection of alcohol is vital for evaluating the cost and performance.…”

“…Besides, alcohol with higher or branched structure is able to produce fuels with better properties. The extra carbon atom provided by ethanol can slightly increase the heat content and cetane number [128].…”

Sustainable biofuel production in Sub‐Saharan Africa: Exploring transesterification process, nonedible feedstocks, and policy implications

“…Despite these drawbacks, noncatalytic transesterification finds utility in applications where catalyst use might contaminate the final product, like biodiesel production from vegetable oils (Jung et al, 2021). Supercritical transesterification employs supercritical fluids, typically supercritical methanol, as catalysts to convert triglycerides into biodiesel, resulting in faster reaction times and higher yields (Aboelazayem et al, 2021; Hoang et al, 2013). This method simplifies production and enhances separation efficiency by promoting a single phase between reagents and triglycerides.…”

Biodiesel Production from Waste Frying Oils by Potassium Methoxide Supported on Activated Carbon Catalysts from Lignocellulosic Biomass

“…Biodiesel synthesis using WFO as feedstock is a challenging task as it typically contains some undesirable components, i.e., free fatty acids (FFA) and water (Jacobson et al, 2008). Several studies (Demirbas, 2009;Hoang et al, 2013) reported that the feedstock containing a significant amount of FFA and water may inhibit the transesterification process to optimize biodiesel production. This is because FFA would react with the catalyst to form soap and inhibit the separation of biodiesel from glycerol.…”

“…sodium hydroxide and potassium hydroxide) in the transesterification process would have some drawbacks in regards to catalyst reusability and its separation from the methyl ester. The use of heterogeneous catalysts for transesterification provides specific benefits, such as an easy separation and reuse, and soap formation reduction (Hoang et al, 2013).…”

Waste to bioenergy: a review on the recent conversion technologies

“…In methanol, the hydrogen bond network is broken under supercritical conditions, this reduction in hydrogen bonding will encourage a stronger direct nucleophilic attack by methanol on the carbonyl group. The dielectric constant of methanol also decreases at supercritical state and this will lead to an elevation in reaction rate [128]. Nevertheless, the selection of alcohol is vital for evaluating the cost and performance.…”

“…Besides, alcohol with higher or branched structure is able to produce fuels with better properties. The extra carbon atom provided by ethanol can slightly increase the heat content and cetane number [128].…”

Sustainable biofuel production in Sub‐Saharan Africa: Exploring transesterification process, nonedible feedstocks, and policy implications

“…Despite these drawbacks, noncatalytic transesterification finds utility in applications where catalyst use might contaminate the final product, like biodiesel production from vegetable oils (Jung et al, 2021). Supercritical transesterification employs supercritical fluids, typically supercritical methanol, as catalysts to convert triglycerides into biodiesel, resulting in faster reaction times and higher yields (Aboelazayem et al, 2021; Hoang et al, 2013). This method simplifies production and enhances separation efficiency by promoting a single phase between reagents and triglycerides.…”

Biodiesel Production from Waste Frying Oils by Potassium Methoxide Supported on Activated Carbon Catalysts from Lignocellulosic Biomass

“…Biodiesel synthesis using WFO as feedstock is a challenging task as it typically contains some undesirable components, i.e., free fatty acids (FFA) and water (Jacobson et al, 2008). Several studies (Demirbas, 2009;Hoang et al, 2013) reported that the feedstock containing a significant amount of FFA and water may inhibit the transesterification process to optimize biodiesel production. This is because FFA would react with the catalyst to form soap and inhibit the separation of biodiesel from glycerol.…”

“…sodium hydroxide and potassium hydroxide) in the transesterification process would have some drawbacks in regards to catalyst reusability and its separation from the methyl ester. The use of heterogeneous catalysts for transesterification provides specific benefits, such as an easy separation and reuse, and soap formation reduction (Hoang et al, 2013).…”

Waste to bioenergy: a review on the recent conversion technologies

“…In methanol, the hydrogen bond network is broken under supercritical conditions, this reduction in hydrogen bonding will encourage a stronger direct nucleophilic attack by methanol on the carbonyl group. The dielectric constant of methanol also decreases at supercritical state and this will lead to an elevation in reaction rate [128]. Nevertheless, the selection of alcohol is vital for evaluating the cost and performance.…”

“…Besides, alcohol with higher or branched structure is able to produce fuels with better properties. The extra carbon atom provided by ethanol can slightly increase the heat content and cetane number [128].…”

Sustainable biofuel production in Sub‐Saharan Africa: Exploring transesterification process, nonedible feedstocks, and policy implications

“…Despite these drawbacks, noncatalytic transesterification finds utility in applications where catalyst use might contaminate the final product, like biodiesel production from vegetable oils (Jung et al, 2021). Supercritical transesterification employs supercritical fluids, typically supercritical methanol, as catalysts to convert triglycerides into biodiesel, resulting in faster reaction times and higher yields (Aboelazayem et al, 2021; Hoang et al, 2013). This method simplifies production and enhances separation efficiency by promoting a single phase between reagents and triglycerides.…”

Biodiesel Production from Waste Frying Oils by Potassium Methoxide Supported on Activated Carbon Catalysts from Lignocellulosic Biomass

“…Biodiesel synthesis using WFO as feedstock is a challenging task as it typically contains some undesirable components, i.e., free fatty acids (FFA) and water (Jacobson et al, 2008). Several studies (Demirbas, 2009;Hoang et al, 2013) reported that the feedstock containing a significant amount of FFA and water may inhibit the transesterification process to optimize biodiesel production. This is because FFA would react with the catalyst to form soap and inhibit the separation of biodiesel from glycerol.…”

“…sodium hydroxide and potassium hydroxide) in the transesterification process would have some drawbacks in regards to catalyst reusability and its separation from the methyl ester. The use of heterogeneous catalysts for transesterification provides specific benefits, such as an easy separation and reuse, and soap formation reduction (Hoang et al, 2013).…”