target="_blank" rel="nofollow" href="#uffe63dd9-161d-53b5-9542-a34a7133d908">Chapter 14 overviews different reactions between a carboxylic acid (fatty acids) and alcohol (methanol and ethanol) over heterogeneous catalysts, an important step in biodiesel production. The nature of solid materials, like zeolites, heteropolyacids, materials with sulfonic groups, inorganic mixed oxides, and clays towards biodiesel production is discussed.
Chapter 15 sheds light on inedible feedstock that could be utilized for biodiesel production. Plant-based and non-plant feedstock are discussed. The waste lipid sources which are unfit for consumption are also highlighted. The chemical composition, economic viability, and sustainability of some of these feedstocks are equally explored.
Chapter 16 provides detailed information on the fabrication of biodiesel from microalgae. Specific information on the physical properties, amount of biodiesel production, and level of transesterification of biodiesel are discussed. The application of photobioreactors for the production of biodiesel with the special consideration of several factors such as flow rate, temperature, light intensity, CO2 concentration, and time is highlighted. Several techniques for the extraction of biodiesel such as supercritical CO2, physicochemical, direct transesterification, chemical solvents, and biochemical respectively are highlighted.
Chapter 17 discusses the biofuel classification in terms of origin and technological conversion of raw materials. Techniques capable of producing biodiesel on commercial scales are also presented. Furthermore, influential parameters and their roles in biodiesel production are elaborately covered. Finally, challenges and limitations confronting biodiesel uptake are presented.
Chapter 18 mainly explicates the application of nanoparticle catalysis for the high production of biodiesel. In particular, various types of catalyst nanoparticles with different synthesis strategy and their roles in enhancing the biodiesel production are discussed.
Inamuddin, Mohd Imran Ahamed, Rajender Boddulaand Mashallah Rezakazemi
1
Biocatalytic Processes for Biodiesel Production
Ubaid Mehmood1, Faizan Muneer2, Muhammad Riaz3, Saba Sarfraz4 and Habibullah Nadeem2*
1College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, China
2Department of Bioinformatics and Biotechnology, Government College University Faisalabad, Pakistan
3Department of Food Sciences, University College of Agriculture, Bahauddin Zakariya University, Multan, Pakistan
4Department of Chemistry, Government College Women University Faisalabad, Faisalabad, Pakistan
Abstract
Enzymes such as microbial lipases can be effectively used as biocatalysts for bio-diesel production in a sustainable manner. Biocatalytic processes to produce bio-diesel or biofuel is the need of time to reduce the emission of greenhouse gases produced from conventional diesel or fossil fuels. Lipases with excellent biochemical and physiological properties are most commonly used to catalyze the transesterification process for biodiesel production. Lipases obtained from microbes such as bacteria and fungi produce 70%–95% ethanol and methanol. Biodiesel is usually composed of fatty acid alkyl esters which are mono-alkyl esters of either fatty acid methyl esters or fatty acid ethyl esters depending upon the alcohol (acyl acceptor) being used in the reaction. Factors such as bioreactor type, acyl acceptor, temperature, and glycerol can affect the enzymatic transesterification reaction. Recombinant enzymes such as recombinant lipases can be employed to obtain higher percentage of biodiesel due to their high specificity and biocatalytic activity for different substrates used for biodiesel production.
Keywords: Lipases, biodiesel, biocatalysis, biofuels, Novozyme, free fatty acids, ethyl acceptors
1.1 Introduction and Background
Biofuels are crucial for the conservation of our natural environment and the climate. Biofuel such as bioethanol can be used for energy generation purposes which are currently being produced by fossil fuels such as petrol, diesel, and kerosene oil [1]. Being non-renewable energy sources, fossil fuels will not only deplete from the planet earth but will also leave a long-term impact on the globe both in terms of economy and climate change. Apart from being limited natural fuel reserves, there are countless reasons available that justify the need of natural and eco-friendly energy sources such as bio-fuels. Transportation, power generation, and house hold appliances use fuels directly or indirectly and for that purpose we are almost dependent on fossil fuels [2]. If efficient and robust methods and technologies are not worked out, we might come to a permanent stand still condition in the future when all our natural fossil fuel reserves will be vanished. The use of fossil fuel produces gases such as carbon dioxide (CO2), carbon monoxide (CO), sulfur oxides (SOx), and nitrogen oxides (NOx) which are unhealthy for human beings causing health issues such as asthma, skin diseases, and even cancers [3]. These by-products of fuel consumption affect not only human but also animals and plants on a broader view. Plant production and growth rates are highly effected by the changing environmental and climatic conditions due to heavy use of fossil fuels and their derivatives such as plastics [4].
Vehicular CO2 emission in the past decade was 20%, and it is estimated that by 2030, it will reach up to 80%. Liquide biofuels got prominence with the automobile industry. Peanut oil was used to make biofuel, i.e., biodiesel by Rudolph Diesel in 1898. Henri Ford who was the founder of Ford Company an automobile industry was also convinced by the idea of using biofuels in his automobile. During World War-II, Germany used biomass-based fuels for their machines which is the evidence of its use back in 1940s. The utilization of biofuels was presented, but after two major oil crises, first was in 1973 and second in 1978, and brought back its importance to public again. Biofuels that are produced using a large number of biomass sources are a sustainable solution for the environment and biosphere conservation. Being renewable energy resources and eco-friendly to the environment and life on earth, these are highly desirable products produced from renewable biomass substrates [5].
Currently, biofuels from various agricultural sources such as soybean oil, rapeseed oil, recycled waste oils, and waste plant residues are being studied. Depending on the feedstock type, processing technology and their developmental level, biofuels can be classified into first-, second-, and third-generation biofuels. Biofuels produced directly from edible feedstock such as crops, sugars, and edible oil using conventional techniques are considered as first-generation biofuels [6]. Non-edible feedstock such as waste crop residues like lignocelluloses and waste vegetable oils are required to produce second-generation biofuels which are comparatively economical and more sustainable as there is no food versus fuel competition. Highly advanced methods are used to produce second-generation biofuels which has certainly less flaws and ultimately improved to get greater yield [7]. We are currently in the phase of second-generation biofuels. Most of the processing techniques for second-generation biofuel production are not available at commercial level. One must think that the land dedicated for edible feedstock/crops will be compromised if we start cultivating non-edible crops in that land. Marginal lands can be used for the cultivation of grasses and other
