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Hydrolysis
Published in Richard A. Larson, Eric J. Weber, Reaction Mechanisms in Environmental Organic Chemistry, 2018
Richard A. Larson, Eric J. Weber
Often there is confusion as to the definition of the term catalysis. A reaction is catalyzed if its rate is accelerated relative to the noncatalyzed pathway. A catalyst serves to alter the reaction mechanism of a chemical process by providing a new pathway with a lower potential-energy barrier. The Union of Pure and Applied Chemistry (IUPAC, 1981) definition of the term catalyst states “that a catalyst is a substance that increases the rate of a reaction without modifying the overall standard Gibbs energy change in the reaction; the process is called catalysis, and a reaction in which a catalyst is involved is known as a catalyzed reaction.”
Multiple Model Adaptive Control
Published in Roderick Murray-Smith, Tor Arne Johansen, Multiple Model Approaches to Modelling and Control, 2020
Kevin D. Schott, B. Wayne Bequette
Applications of MMAC have been primarily focused in three different areas: (i) aircraft and space-structure, (ii) drug delivery and (iii) chemical process control. Here we discuss important characteristics of problems in each area.
Biodiesel production from fish oil: a review
Published in Biofuels, 2023
Yaseen M. Tayib, Farooq Al–Sheikh, Zaidoon M. Shakor, William A. Anderson
A catalyst is a material that is used to speed up a chemical process that is thermodynamically possible; it is utilized in one stage of the reaction but regenerates in the following step, so it is not consumed throughout the reaction. The procedure is repeated until the reaction is finished, and neither the composition nor the characteristics of the catalyst are permanently altered [9]. The biodiesel synthesis is typically catalyzed by an alkaline homogeneous catalyst using the transesterification process to create a mixture of fatty acid methyl esters [100]. The catalyst used in these methods could be homogenous acids (H2SO4, HCl, and H3PO4), heterogeneous acids (zeolites, and sulfonic resins), enzymatic (lipases: Candida, and Pseudomonas), heterogeneous bases (MgO, and CaO) and or homogenous bases (KOH, and NaOH), the latter being often used on an industrial scale due to its ability to work under moderate settings (ambient pressure and temperatures between 60 and 70 °C) and quicker response time [7]. Figure 4 shows a classification of transesterification catalysts.
Nonisothermal reactor networks optimization using metaheuristics in a bi-level approach
Published in Chemical Engineering Communications, 2023
Victor Pádua Teixeira, Mauro Antonio da Silva Sá Ravagnani, Caliane Bastos Borba Costa
A chemical process comprises all the steps necessary to convert raw materials into a desired product. An industrial process can be synthesized based on subsystems, like the reactors network, separation network, heat exchangers network, utility plants and others. The reactor system is the first stage to be synthesized and its choice is reflected in the subsequent stages. Because of this, the choice of the reactive system and its equipment has a direct impact on the economic success or failure of a chemical plant.