نمونه ترجمه تخصصی شیمی درباره انرژی زیستی

bioenergy

Bioenergy is one of the most promising energy sources that is expected to replace fossil fuels. Biodiesel, biohydrogen, biomethane, bioethanol, and biooil are the main sources of bioenergy that are mass extracted from oil seeds, agricultural wastes, and microorganisms like algae [1, 2]. While microorganisms receive more attention than other bioenergy sources thanks to their higher adaptability to different biological conditions and higher production performance, there are unsolved challenges in the way of harvesting and processing them and producing biofuel at a commercial level. The key to have a commercially viable bioenergy source is to find bio-sources with easy and inexpensive harvesting and processing methods [3, 4]. Biooil is a product that is obtained from biomasses and through a process called pyrolysis. Pyrolysis is a thermal cracking reaction without oxygen and the products are in liquid (biooil), gas (biogas), and solid (biochar) phases [5]. Factors such as high oxygen and nitrogen content, high water content, and high acidity decrease the quality of produced biooil through pyrolysis process. To improve the quality of the obtained product, catalysts are used. The Type and amount of a catalyst are two key factors [6, 7]. In this regard, pyrolysis process is categorized into direct pyrolysis and catalytic pyrolysis. No generally accepted mechanism has been introduced for catalytic pyrolysis reactions yet [8]. Some researchers believe that catalytic pyrolysis of hydrocarbon follows free radical mechanism; while some believe that these reactions follow carbonium ion mechanism in acid and alkali exchanges based on Bronsted-Lowry model. However, since catalytic pyrolysis includes catalytic cracking and thermal cracking, it follows both carbonium ion mechanism and free radical mechanism. One may say that catalytic pyrolysis reactions are functions of the both mechanisms [9]. In general, catalysts are synthesized based on the combination of two agents including the base and synthesis enhancer agents. This makes a notable improvement in catalysts’ performance. Zeolite compounds are the most common base agents and metallic oxides like molybdenum oxide, nickel oxide, and cobalt oxide are the main enhancers [10]. Jones et al. (2009) studied biooil production from three biomasses including chlorella micro-algae using zeolite catalyst. They found that zeolite deoxygenated the bio-compounds obtained in the first stage and converted them into hydrocarbons with a higher thermal value [11].