Biodiesel Production from Wastes: Process Development and Quality Control Joana Maia Moreira Dias 2010 BIODIESEL PRODUCTION FROM WASTES: PROCESS DEVELOPMENT AND QUALITY CONTROL Porto, August 2010 BIODIESEL PRODUCTION FROM WASTES: PROCESS DEVELOPMENT AND QUALITY CONTROL Dissertation presented by JOANA MAIA MOREIRA DIAS for the degree of DOCTOR OF PHILOSOPHY IN ENVIRONMENTAL ENGINEERING to the Faculty of Engineering, University of Porto Thesis supervised by Professor Maria da Conceição Machado Alvim Ferraz (Chemical Engineering Department) Professor Manuel Afonso Magalhães Fonseca Almeida (Metallurgical and Materials Engineering Department) To my family and friends, for always believing in me ACKNOWLEDGEMENTS My sincere thanks to my Supervisor Maria da Conceição Machado Alvim Ferraz and my Co- supervisor Manuel Afonso Magalhães Fonseca Almeida for making this study possible, providing scientific and technical support in all phases of the work and specially for personal support always believing in my capacities, being present at all times and giving me the needed strength to carry on when difficulties appeared. Thanks to Fundação para a Ciência e a Tecnologia (Grant SFRD/BD/22293/2005) and Project QREN 3491: Fat-Value -Valorização de Subprodutos de Carne, for financial support of the work. I would also like to thank to the Chemical Engineering Department, namely to the Laboratory for Process, Environmental and Energy Engineering, and to the Metallurgical and Materials Engineer- ing department for providing the resources needed to perform the work. Also, thanks to all the professors that kindly provided help during the work, namely Maria do Carmo Pereira, Fernando Gomes Martins, Arminda Alves, Margarida Bastos and Lúcia Santos from FEUP and Beatriz Oliveira and Susana Casal from the Pharmacy Faculty of Oporto University. Thanks to my colleagues and friends from FEUP which made the work much easier to perform by the sympathy and support provided, including the friends from the office E 319: Daniela, Filipa, Herney, João, José Carlos (infiltrated), Klára, Marta, Pedro, Renato, Sofia and Vânia and E 316: Sílvia, Ana and Leonor, my dear laboratory colleagues mostly present at the execution of the work: Joana, Berta, Elisabete, Salomé, José and Rui, and to my other colleagues and friends from DEQ: Carla, Fátima, João, Marta, Martita, Sílvia, Sofia and Isabel. From those, I would like to em- phasize a very special thank to Sofia, Daniela, Vânia and José Carlos for being present and helping me in every ways possible. Thanks to my students from MIEA from whom I’ve learned throughout this year and that I will always remember. A very special thank to my boyfriend and best friend Mario who stole my heart and made my life more worthy, for helping me throughout the work, making me believe that I am capable of every- thing, giving me important advices and pretending to listen to me when sleeping; special thanks to its patience in this final period, helping me by being present and making extreme efforts during household tasks; namely creative experiments in cooking. Also a special thank to Mario’s family for all the support and friendship provided. vii A very sincere thanks to my family that provided my education and all the support throughout my life and that are the reason why this work was possible. My heart is also always with you, Mom, Dad and dear sisters. Thanks to my Mom, for always being present, being a true believer in me and in life and for very nice and entertaining phone calls; to my sisters Daniela and Ana: Daniela for giving me inspiration and for being my dear companion and friend all the time, making me laugh even in the difficult times; Ana for always being present despite far and solving all my prob- lems even before I realized that I had them! Also a special thank to my dear brother in law Miguel (Espectáculo!) and my new family in Caracas, Venezuela. To my Dad I would like to send a special and sincere thank for the precious support during the work, Dad: you made me want to be more and despite far you are with me all the time, your perfectionism and commitment are examples that I intend to follow through all my life. Finally, thanks to everyone else that participated somehow in the work and that I unfortunately forgot to mention! viii ABSTRACT The present work aimed to provide increased knowledge regarding biodiesel production by transesterifica- tion, focusing on diversifying raw materials and improving production process, in order to take advantage of current investments made in biodiesel production plants. Using sunflower oil, soybean oil and waste frying oil as raw materials and NaOH, CH3ONa and KOH as cata- lysts, the results showed that: i) biodiesel production using virgin oils results in higher yields (reaching 97 wt.%) compared to the production using waste frying oils (reaching 92 wt.%); ii) biodiesel kinematic viscosity and purity were important quality properties to select catalytic conditions to be used; using KOH as catalyst, minimum purity was not obtained; and iii) depending of the raw material and the sodium based catalysts used, to ensure a product with quality, 0.6 or 0.8 wt.% of catalyst should be used. Using mixtures of pork lard and soybean oil as raw materials for biodiesel production: i) using raw material mixtures the product yield varied from 81.7 to 88.8 (wt.%) and enough purity was not obtained, being how- ever close to the limit; ii) a linear model could be used to estimate the composition and some biodiesel quality properties, based on the weighted average of those properties for each component of the mixture. Biodiesel production from acid waste lard (14.57 mg KOH g-1 ) was enabled by studying a two-step process, including acid esterification followed by basic transesterification. In the two step synthesis, the best reaction conditions led to a purity of 99.6 wt.%; however, low yield was obtained (65 wt.%). Basic transesterification of a raw material mixture resulted in a yield of 77.8 wt.%, showing that blending might be an interesting alterna- tive to enable homogeneous transesterification of acid raw-materials. Several heterogeneous catalysts were studied for biodiesel production and results showed that: i) the basicity and catalyst calcination play a very important role in its performance; ii) CaO and the mixed oxide of calcium and manganese (Ca0.9Mn0.1O) presented the best results; iii) using CaO, higher reaction rates were observed compared to when using Ca0.9Mn0.1O; however, the mixed oxide catalyst needed lower activation tempera- ture; iv) carbonation was probably responsible for the deactivation of CaO catalyst whereas hydration was responsible for the deactivation of the mixed oxide of calcium and manganese; v) temperature and interac- tion between temperature and catalyst concentration mostly influenced product purity obtained from pork lard using calcium manganese oxide as catalyst; vi) calcium manganese oxide was reused without loss of activity but there were evidences of residual catalyst leaching to biodiesel; however, catalytic behaviour could be classified as essentially heterogeneous. Using different raw materials, after 8 h of reaction, heterogeneous catalysis (calcium manganese oxide) led to better product quality compared to homogeneous catalysis (NaOH); the higher reaction times might be com- pensated by reduced purification steps. The developed work can be used to improve biodiesel production using homogeneous catalysis and presents relevant results to support research regarding heterogeneous catalysis. KEYWORDS: Vegetable oils, animal fats, wastes, mixtures, transesterification, heterogeneous catalysts. ix RESUMO O presente trabalho pretendeu acrescentar conhecimento ao processo de produção de biodiesel através de transesterificação, focando-se na diversificação de matérias-primas e na melhoria do processo e traduzindo-se em possíveis adaptações às actuais fábricas, contribuindo para uma melhoria da sua viabilidade económica. Utilizando óleo de girassol, óleo de soja e óleo de fritura usado como matérias-primas e NaOH, CH3ONa, e KOH como catalisadores, os resultados mostraram que: i) utilizando óleos virgens conseguem-se maiores rendi- mentos na produção de biodiesel (atingindo 97 % (m/m)), do que utilizando óleos de fritura usados (atingindo 92 % (m/m)); ii) a viscosidade cinemática e a pureza são parâmetros de elevada importância para a selecção das condições catalíticas; utilizando KOH como catalisador, a pureza mínima não foi obtida; iii) uma concentra- ção de 0.6 ou 0.8 % (m/m) de catalisador à base de sódio foi necessária, dependendo da matéria-prima e do catalisador utilizado, de forma a assegurar um produto com qualidade. Utilizando misturas de banha de porco e óleo de soja como matérias-primas para a produção de biodiesel: i) o rendimento do produto variou entre 81.7 e 88.8 % (m/m) e a pureza mínima não foi obtida, estando no entan- to próxima do limite mínimo; ii) um modelo linear pôde ser utilizado para estimar a composição e proprieda- des do biodiesel tendo em conta a média pesada dessas propriedades nos componentes da mistura. A produção de biodiesel utilizando banha ácida, com uma acidez de 14.57 mg KOH g-1, foi possível através de um processo em dois estágios: esterificação ácida seguida de transesterificação básica. As melhores condições reaccionais permitiram a obtenção de um produto com 99.6 % (m/m) de pureza, no entanto, com um baixo rendimento (65 % (m/m)). A transesterificação básica de uma mistura de matérias-primas resultou num pro- duto