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Fuels From Recycled Carbon
Published in Veera Gnaneswar Gude, Green chemistry for Sustainable Biofuel Production, 2018
Michele Aresta, Angela Dibenedetto
In this direction, catalytic pyrolysis of biomass constitutes a very attractive route for the in-situ upgrading of bio-oil as the heavy oxygenated compounds are converted into lighter fuels and chemicals. The catalysts selectively favor decarboxylation and decarbonylation reactions, thus reducing the aggressivity of bio-oil. Zeolites, mesoporous materials with uniform pore size distribution (MCM-41, MSU and SBA-15), micropo- rous/mesoporous hybrid materials doped with noble and transition metals, and base catalysts have been used in catalytic biomass pyrolysis [19]. Typically, hydrodeoxygenation (HDO) is used to remove most of the oxygen groups contained in the bio-oil under high pressure (up to 20 MPa) and temperatures in the range 570-670 K affording naphtha-like and diesel streams that can be blended in refineries with conventional transportation fuels, with yields ranging between 0.3-0.5 L of product per L of bio-oil depending on the extent of deoxygenation [18,20–25]. The used catalysts are traditional hydrodesulphurization catalysts, such as NiMo and CoMo catalysts on alumina or silica alumina supports, or metal catalysts, such as Pd/C, which need improvement for their lifetime. A strategy to minimize hydrogen consumption in HDO is to operate a series of cascade catalytic transformations so to obtain second-generation liquid biofuels from lig- nocellulosic biomass in a cost-efficient way through the use of tailored nano-catalysts.
Metal Oxide/Sulphide-Based Nanocatalysts in Biodiesel Synthesis
Published in Bhaskar Singh, Ramesh Oraon, Advanced Nanocatalysts for Biodiesel Production, 2023
Juan S. Villarreal, José R. Mora
For the hydrodeoxygenation process (HDO), metal sulphide catalysts are usually used. Ni-Mo and Co-Mo sulphide catalysts have been studied in the reaction of oleic acid and palmitic acid (Yoosuk et al., 2019). Ammonium tetrathiomolybdate and Ni(NO3)2.6H2O or Co(NO3)2.6H2O were mixed in a reactor pressurized with H2 at 28 bar and 350 °C for 60 min to synthesize the catalysts. Then, oleic acid or palmitic acid were submitted to react with pressurized H2 in the presence of the sulphide catalyst. The authors suggested the three main reactions occurring in the system:
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Published in Deniz Uner, Advances in Refining Catalysis, 2017
Although the reactions on the hydrotreating catalyst are not completely clarified, various reactions have been proposed. The removal of sulfur compounds is one of the most required reactions in refinery operations, since the sulfur content of crude oil has important effects on refining. Furthermore, most catalysts that are used for the processing of fuel products cannot handle a compound that contains sulfur and metals. In HDS reactions, the sulfur content of organic sulfur compounds such as mercaptans, sulfides, disulfides, thiophenes, benzothiophenes, and dibenzothiophenes is converted into H2S. The level of difficulty of HDS reactions depends on the type of sulfur compound. As the complexity of compounds decreases, the ease of sulfur removal increases. The ranking on the basis of ease of removal according to the type of sulfur compounds is as follows: mercaptans, sulfides, disulfides, thiophenes, benzothiophenes, and dibenzothiophenes. Removal of nitrogen is more difficult to overcome than HDS. HDN is also important for many petroleum streams, since nitrogen compounds inhibit the acidic function of the catalyst. Therefore, nitrogen removal efficiency effects further reactions such as hydrocracking. Besides nitrogen-containing compounds, metal contents also damage catalyst surface by being deposited on the hydrotreating catalyst. HDM reactions are used to remove metal contents such as vanadium and nickel. Like the metal-containing compounds, olefinic hydrocarbons affect the activity of the hydrotreating catalysts. Removal of the olefinic compounds are used to decelerate formation of coke deposits on the catalysts. Hydrodeoxygenation (HDO) reactions are used to remove phenols and/or peroxides in the feedstock by releasing water. Chemical reactions that take place in hydrotreating processes are shown in Table 5.2 [1,2,5].
Pretreatment of bio-oil with ion exchange resin to improve fuel quality and reduce char during hydrodeoxygenation upgrading with Pt/C
Published in Environmental Technology, 2021
Shinyoung Oh, In-Gyu Choi, Joon Weon Choi
Bio-oil, which is obtained from the fast pyrolysis of biomass, is a promising second-generation liquid fuel due to its high yield (ca. 75 wt%) and carbon-neutral features [1,2]. Notwithstanding the benefits of a fast pyrolysis system, the fuel properties of bio-oil, including its high water (15–30 wt%) and oxygen (35–40 wt%) contents (resulting in a lower calorific value (16–19 MJ/kg) in comparison to fossil fuels (40 MJ/kg)), make bio-oil unsuitable for direct application as a transportation or jet fuel [1]. Moreover, the oxygenated compounds in bio-oil, such as acids and aldehydes, result in corrosion of the engine, nozzle plugging, multiphase flow, and coke formation [2]. Therefore, to overcome these limitations and utilization of bio-oil into biofuel, an upgrade process for bio-oil is essential. Upgrading processes can be divided into physical (e.g. solvent addition, emulsification, and filtration) or catalytic (e.g. esterification, catalytic cracking, and hydrodeoxygenation) methods [2–6]. Generally, physical methods are easier to control, but the product quality is superior in catalytic methods. One of the catalytic upgrading, hydrodeoxygenation process (HDO) has been shown to be particularly promising for improving both the bio-oil quality and stability [6]. In previous studies, sulfide NiMo, sulfide CoMo, solid acid catalysts, noble metal catalysts (Pt, Ru, or Pd) or transition metal catalysts (like Ni, Mn or Zn) with various supports (active carbon, TiO2, SiO2-ZrO2, SBA-15, Al2O3, or MgO) have been typically used in the HDO reaction [2,7–11]. HDO upgrading with those catalysts could effectively reduce the pyrolytic lignin, which consisted approximately 25% of bio-oil, and one of the major factors affecting bio-oil instability via reaction with reactive monomers such as aldehydes and unsaturated compounds, and resulted in the improvement of stability [12]. Previous researchers mentioned that using HDO with a supercritical fluid is effective in removing pyrolytic lignin and enhancing bio-oil stability [13].
Production of Medium Chain Fatty Acid Ethyl Ester, Combustion, and Its Gas emission using a Small-Scale Gas Turbine Jet Engine
Published in International Journal of Green Energy, 2019
Nhan Thi Thuc Truong, Arnupong Suttichaiya, Wikanda Hiamhoen, Peerapat Thinnongwaeng, Chaloemkwan Ariyawong, Pailin Boontawan, Jürgen Rarey, Manida Tongroon, Ekarong Sukjit, Atit Koonsrisuk, Apichat Boontawan
Conversion of biomass to bio-kerosene can be classified according to the feedstock used, conversion processes, and the products obtained. Different major pathways such as Fischer-Tropsch (FT) pathway, hydroprocessing pathway, hydrothermal liquefaction (HTL) and pyrolysis pathway, hydro-treated Esters and Fatty Acids (HEFA) pathway, Direct Sugars to Hydrocarbons (DSHC) pathway, Alcohol-to-Jet (ATJ) pathway, and trans-esterification pathway are among the popular methods to produce the renewable jet fuel (Chiaramonti et al. 2014; Hari, Yaakob, and Binitha 2015; Pearlson, Wollersheim, and Hileman 2013; Vásquez, Silva, and Castillo 2017; Yang et al. 2016). Among these pathways, the hydroprocessing of vegetable oils has gained a lot of attention because the product has a very similar chemical composition to the fossil kerosene. The process is also certified by the American Society for Testing and Materials (ASTM) for commercial application. It consists of chemical conversion of triglyceride feedstock through processes, namely, hydrodeoxygenation (HDO), isomerizing/cracking, and distillation to produce jet fuel. However, the severe conditions of the production process results in a high production cost: for example, the HDO reactor required a large amount of highly flammable H2 gas, high temperature of up to 320°C, and pressure of 80 bar, while the second reactor for cracking/isomerizing reaction was carried out at 480°C, and 80 bar, respectively. Finally, the bio-derived synthetic paraffinic kerosene (Bio-SPK) was separated from light gases, naphtha, and diesel products by fractional distillation (Gutiérrez-Antonio et al. 2016). In an attempt to search for a new advanced bio-based jet fuel which possesses desired jet fuel combustion properties, another approach has been introduced. Medium-chain fatty acid containing bio-resources such as coconut oil and palm oil (Llamas et al. 2012), and oleaginous yeasts (Froissard et al. 2015; Rutter, Zhang, and Rao 2015) could be trans-esterified with alcohol in order to produce medium-chain fatty acid alkyl ester (FAAE) in a milder production condition (Röttig et al. 2010). The fraction of medium-chain FAAE which possesses the distillation range of fossil kerosene then can be distilled from the bottom fraction of long-chain FAAE (biodiesel). More importantly, combustion characteristic using a real gas-turbine engine should be investigated for the produced medium-chain FAAE without blending with fossil kerosene because it is important to compare the combustion efficiency as well as GHG emission characteristic. This is a major driver for the increasingly stringent exhaust-emission regulation imposed to improve air quality and human health (Bergthorson and Thomson 2015).