title: A new pilot flow reactor for high-intensity ultrasound irradiation. Application to the synthesis of biodiesel.
abstract: In recent years, chemistry in flowing systems has become more prominent as a method of carrying out chemical transformations, ranging in scale from microchemistry up to kilogram-scale processes. Compared to classic batch ultrasound reactors, flow reactors stand out for their greater efficiency and flexibility as well as lower energy consumption. This paper presents a new ultrasonic flow reactor developed in our laboratory, a pilot system well suited for reaction scale up. This was applied to the transesterification of soybean oil with methanol for biodiesel production. This reaction is mass-transfer-limited initially because the two reactants are immiscible with each other, then because the glycerol phase separates together with most of the catalyst (Na or K methoxide). In our reactor a mixture of oil (1.6 L), methanol and sodium methoxide 30% in methanol (wt/wt ratio 80:19.5:0.5, respectively) was fully transesterified at about 45 degrees C in 1h (21.5 kHz, 600 W, flow rate 55 mL/min). The same result could be achieved together with a considerable reduction in energy consumption, by a two-step procedure: first a conventional heating under mechanical stirring (30 min at 45 degrees C), followed by ultrasound irradiation at the same temperature (35 min, 600 W, flow rate 55 mL/min). Our studies confirmed that high-throughput ultrasound applications definitively require flow reactors.
authors.affiliation: Departamento de Química Orgánica e Inorgánica, Universidad de Extremadura, Badajoz, Spain.
authors.forename: Pedro
authors.initials: P
authors.lastname: Cintas
authors.forename: Stefano
authors.initials: S
authors.lastname: Mantegna
authors.forename: Emanuela Calcio
authors.initials: EC
authors.lastname: Gaudino
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Cravotto
mesh_terms: D056804:Biofuels; D007221:Industry; D010865:Pilot Projects; D013010:Sonication / Q000295:instrumentation* / Q000379:methods
chemical_list: D056804:Biofuels