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Biodiesel Production from Municipal Wastewater Sludge
Published in Ozcan Konur, Biodiesel Fuels Based on Edible and Nonedible Feedstocks, Wastes, and Algae, 2021
Muhammad Nurunnabi Siddiquee, Sohrab Rohani
Catalyst selection is an important consideration in biodiesel production. Different catalysts are used, for example, homogeneous and heterogeneous base and acid catalysts, zeolite-based catalysts, and enzymatic catalysts. Basic catalytic transesterification is very fast compared to other catalyst types and widely used commercially. But FFAs in the raw materials produce soap in the presence of a base catalyst (Reaction IV). It is not only consumed in the reaction but also inhibits the glycerine separation from biodiesel and contributes to emulsion formation during the water wash. Homogeneous acid (H2SO4, for instance) catalyzed transesterification is much slower (by approximately 4,000 times) than base catalyzed transesterification and requires excess alcohol (Demirbas, 2005). But the main advantage of an acid catalyst is that it can catalyze both the esterification and transesterification and produce more biodiesel.
Producing Fuels and Fine Chemicals from Biomass using Nanomagnetic Materials
Published in Vanesa Calvino-Casilda, Antonio José López-Peinado, Rosa María Martín-Aranda, Elena Pérez-Mayoral, Nanocatalysis, 2019
Specifically, in the aqueous systems, 5-HMF enters into a consecutive reaction sequence, taking up two molecules of water and forming levulinic and formic acid as semi-final products. In the non-aqueous system, the hydrolysis of 5-HMF can be suppressed. However, the polymerization reactions are observed in all the systems, and lead to the production of coloured soluble polymers and insoluble brown humins (Lewkowski 2001). In order to prevent the side reactions and obtain a high yield of 5-HMF, one solution involves the designing and employment of a suitable catalyst which allows the formation of 5-HMF, while not promoting the consecutive reactions. The catalysts used are generally classified as mineral acid, organic acid and solid acid catalysts, and metal-containing catalysts (Tong et al. 2010).
Grouting
Published in Bujang B. K. Huat, Arun Prasad, Sina Kazemian, Vivi Anggraini, Ground Improvement Techniques, 2019
Bujang B. K. Huat, Arun Prasad, Sina Kazemian, Vivi Anggraini
Aminoplasts consist of urea and formaldehyde. The rapid grout reaction in hot and acidic environments makes this product difficult to handle. An intermediate stage between liquid and solid urea–formaldehyde is used instead of the pure liquid phase. Aminoplasts with formaldehyde and acid catalyst contents are toxic and corrosive. In the gelled state, the aminoplast may contain leachable, unreacted formaldehyde. It is suitable for ground with a pH less than 7 (Karol, 2003; Kazemian et al., 2010).
Plant design of biodiesel production from waste cooking oil in Malaysia
Published in Biofuels, 2023
Angnes Ngieng Tze Tiong, Zuhair Khan, Valerie Chin, Osama Abdul Wahid, Regina Mbeu Wachira, Shannon Michaela Kung, Ashvin Viknesh Mahenthiran
The commonly utilized catalysts are sulfuric acid (acid catalyst), sodium hydroxide (alkali catalyst), lipase (enzyme catalyst), and sodium hydroxide in acetone (co-solvent catalyst). The lipase-catalyzed process appears to be the best among all the catalyzed processes as transesterification via lipases generates a smaller amount of waste, and it has a conversion rate of 95%. Unfortunately, this type of process has only been conducted in a lab-scale arrangement as the cost of enzyme catalyst makes it economically unfeasible at an industrial scale [43]. The co-solvent process seems to have a lower temperature requirement and results in the same yield. Nonetheless, the additional acetone solvent increases the production cost. Besides, the acetone solvent would mix with the product biodiesel, and its removal needs extra costs. The co-solvent process is also mainly being tested on a laboratory scale [44, 45].
The critical techno-economic aspects for production of B10 biodiesel from second generation feedstocks: a review
Published in International Journal of Sustainable Energy, 2022
Timothy Tibesigwa, Peter Wilberforce Olupot, John Baptist Kirabira
Homogeneous acid catalysis aids both esterification and transesterification reactions and is insensitive to high FFA in feedstock (Refaat 2010). Popular catalysts in this category are Brønsted acids that include, sulphonic, sulphuric and hydrochloric acids (Schuchardt, Sercheli, and Matheus 1998). However, compared to homogeneous base catalysis, acid catalysis has the following disadvantages: slower reaction rate; higher methanol to oil molar ratio requirement; higher process temperature; no tolerance to water concentration; corrosive in nature; catalysts are difficult to recycle; difficulty in separating catalyst form the product; economically less viable due to increased energy requirement, among others (Fattah et al. 2020; Silitonga et al. 2020). The mechanism of acid-catalysed transesterification of vegetable oil (for a monoglyceride) is presented in Figure 4 (Ejikeme et al. 2010).
Lab-scale catalytic production of biodiesel from waste cooking oil – a review
Published in Biofuels, 2020
Abdul Raqeeb Mohammed, Chakradhar Bandari
Among the homogeneous acid catalysts, sulfuric acid, hydrochloric acid and super phosphoric acid are widely used [41]. They are known for simultaneous catalysis of esterification and transesterification reactions [27]. The most commonly used acid is sulfuric acid [47]. The benefits of using acid catalyst are high conversion and low costs [68]. In the esterification of oil using acid catalyst, water is a byproduct [21]. However, the presence of water does not hinder the performance of the acid to catalyze the transesterification reaction. However, in comparison with alkaline catalysts, acid catalysts require a longer duration for reaction and are less efficient [25,42,46,69,74]. Other disadvantages of using acid catalysts are effluent disposal problems, high reaction temperature, expensive material required to construct equipment capable of handling acids, and difficulty in catalyst recovery for reuse [64,71].