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Alkaline Catalysts

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Liejin Guo – One of the best experts on this subject based on the ideXlab platform.

Hui Jin – One of the best experts on this subject based on the ideXlab platform.

  • Effects of Alkaline Metals on the Reactivity of the Carbon Structure after Partial Supercritical Water Gasification of Coal
    Energy & Fuels, 2020
    Co-Authors: Runyu Wang, Hui Jin, Deming Zhang, Wenwen Wei, Liejin Guo
    Abstract:

    Conversion of coal, biomass, and organic waste to combustible gases H2 and CH4 in supercritical water (SCW) is an economically and environmentally favored technology. Homogeneous Alkaline Catalysts

  • Hydrogen production by catalytic gasification of coal in supercritical water with Alkaline Catalysts: Explore the way to complete gasification of coal
    International Journal of Hydrogen Energy, 2014
    Co-Authors: Hui Jin, Liejin Guo
    Abstract:

    Abstract Supercritical water gasification (SCWG) of coal is a promising technology for clean coal utilization. In this paper, hydrogen production by catalytic gasification of coal in supercritical water (SCW) was carried out in a micro batch reactor with various Alkaline Catalysts: Na2CO3, K2CO3, Ca(OH)2, NaOH and KOH. H2 yield in relation to the Alkaline catalyst was in the following order: K2CO3 ≈ KOH ≈ NaOH > Na2CO3 > Ca(OH)2. Then, hydrogen production by catalytic gasification of coal with K2CO3 was systematically investigated in supercritical water. The influences of the main operating parameters including feed concentration, catalyst loading and reaction temperature on the gasification characteristics of coal were investigated. The experimental results showed that carbon gasification efficiency (CE, mass of carbon in gaseous product/mass of carbon in coal × 100%) and H2 yield increased with increasing catalyst loading, increasing temperature, and decreasing coal concentration. In particular, coal was completely gasified at 700 °C when the weight ratio of K2CO3 to coal was 1, and it was encouraging that raw coal was converted into white residual. At last, a reaction mechanism based on oxygen transfer and intermediate hybrid mechanism was proposed to understand coal gasification in supercritical water.

E Santacesaria – One of the best experts on this subject based on the ideXlab platform.

  • main technologies in biodiesel production state of the art and future challenges
    Catalysis Today, 2012
    Co-Authors: E Santacesaria, M Di Serio, Martinez G Vicente, Riccardo Tesser
    Abstract:

    Abstract Biodiesel is a fuel safe, renewable, non-toxic, biodegradable and much less contaminant for the environment than conventional diesel. Moreover, it represents a strategic source of energy especially for the countries that have not oilfields. For these reasons, even if the cost of biodiesel is still greater than diesel from petroleum, many governments sustain this production. The cost of biodiesel is mainly affected by the cost of the feedstock but also an improvement of the adopted technology can contribute in reducing the costs. Therefore, it is imperative: to employ less expensive feedstock, that is, unrefined or waste oils; to use not edible oil coming from alternative sources as, for example, algae or Jathropa Curcas; to improve the actual technology based on the use of homogeneous Alkaline Catalysts through a better understanding of the reaction mechanism, to develop new biphasic kinetic models; to adopt techniques of process intensification; to introduce the use of heterogeneous Catalysts, possibly finding a catalyst promoting in one step both esterification of free fattfatty acids and transesterification of tri-glycerides; to find new remunerative uses for the by-product glycerol. In this paper, all the mentioned aspects will be considered by reporting some of the most relevant results obtained in the last years.

  • kinetics of free fatty acids esterification batch and loop reactor modeling
    Chemical Engineering Journal, 2009
    Co-Authors: Riccardo Tesser, M Di Serio, L Casale, D Verde, E Santacesaria
    Abstract:

    Abstract Biodiesel is a fuel derived from a renewable vegetable origin and is object of growing interest in recent years both as a pure fuel and as blending component to reduce exhaust pollutants of traditional diesel fuel. The conventional biodiesel production technology involves the use of Alkaline Catalysts and is therefore not compatible with large amounts of free fattfatty acids (FFAs) and moisture in the feedstock due to the formation of soaps that strongly affect the feasibility of glycerol separation by liquid–liquid splitting. A preliminary stage of acidity reduction is therefore necessary, for this process, if the starting material is characterized by a free acidity higher than 0.5% by weight often contained in cheaper feedstock which lowers the production costs. This can be pursued, for example, by means of an esterification reaction of the FFAs with methanol, catalyzed by ionic-exchange sulphonic acid resins. In the present work, the above-mentioned reaction has been studied in different reactor configurations on a model mixture composed by artificially acidified soybean oil with oleic acid using an acid exchange resiresin as catalyst. This work has been developed in two parts: (i) a kinetic study in batch conditions with the purpose of developing a suitable kinetic expression and determining the related parameters and (ii) a study of the FFAs esterification in a packed bed tubular reactor operated inside a circulation loop. The kinetic model that is developed on the basis of several batch runs is able to simulate also the behavior of dynamic tubular loop reactor, providing that the external mass transfer resistance is properly accounted for. The mass transfer coefficient is satisfactorily modeled using correlations available on literature.

  • synthesis of biodiesel via homogeneous lewis acid catalyst
    Journal of Molecular Catalysis A-chemical, 2005
    Co-Authors: M Di Serio, Riccardo Tesser, M Dimiccoli, F Cammarota, Nastasi Mario, E Santacesaria
    Abstract:

    Abstract Nowadays, most biodiesel (fatty acids methyl esters, FAME) is produced by the transesterification of triglycerides (TG) of refined/edible type oils using methanol and an homogeneous Alkaline catalyst. However, production costs are still rather high compared with the ones of petroleum-based diesel fuel. To lower costs and make biodiesel competitive less-expensive feedstocks such as waste fats or non-edible type oils could be used. The use of homogeneous Alkaline Catalysts in the transesterification of such types of fats and oils poses great difficulties due to the presence of large amounts of free fattfatty acids (FFA). This paper studies the use of carboxylic salts as a possible alternative, because these Catalysts are active also in the presence of high FFA concentrations. The most active catalyst (Cd, Mn, Pb, Zn carboxylic salts) have been individuated and a correlation of the activities with the cation acidity has been found.

Riccardo Tesser – One of the best experts on this subject based on the ideXlab platform.

  • main technologies in biodiesel production state of the art and future challenges
    Catalysis Today, 2012
    Co-Authors: E Santacesaria, M Di Serio, Martinez G Vicente, Riccardo Tesser
    Abstract:

    Abstract Biodiesel is a fuel safe, renewable, non-toxic, biodegradable and much less contaminant for the environment than conventional diesel. Moreover, it represents a strategic source of energy especially for the countries that have not oilfields. For these reasons, even if the cost of biodiesel is still greater than diesel from petroleum, many governments sustain this production. The cost of biodiesel is mainly affected by the cost of the feedstock but also an improvement of the adopted technology can contribute in reducing the costs. Therefore, it is imperative: to employ less expensive feedstock, that is, unrefined or waste oils; to use not edible oil coming from alternative sources as, for example, algae or Jathropa Curcas; to improve the actual technology based on the use of homogeneous Alkaline Catalysts through a better understanding of the reaction mechanism, to develop new biphasic kinetic models; to adopt techniques of process intensification; to introduce the use of heterogeneous Catalysts, possibly finding a catalyst promoting in one step both esterification of free fatty acids and transesterification of tri-glycerides; to find new remunerative uses for the by-product glycerol. In this paper, all the mentioned aspects will be considered by reporting some of the most relevant results obtained in the last years.

  • kinetics of free fatty acids esterification batch and loop reactor modeling
    Chemical Engineering Journal, 2009
    Co-Authors: Riccardo Tesser, M Di Serio, L Casale, D Verde, E Santacesaria
    Abstract:

    Abstract Biodiesel is a fuel derived from a renewable vegetable origin and is object of growing interest in recent years both as a pure fuel and as blending component to reduce exhaust pollutants of traditional diesel fuel. The conventional biodiesel production technology involves the use of Alkaline Catalysts and is therefore not compatible with large amounts of free fatty acids (FFAs) and moisture in the feedstock due to the formation of soaps that strongly affect the feasibility of glycerol separation by liquid–liquid splitting. A preliminary stage of acidity reduction is therefore necessary, for this process, if the starting material is characterized by a free acidity higher than 0.5% by weight often contained in cheaper feedstock which lowers the production costs. This can be pursued, for example, by means of an esterification reaction of the FFAs with methanol, catalyzed by ionic-exchange sulphonic acid resins. In the present work, the above-mentioned reaction has been studied in different reactor configurations on a model mixture composed by artificially acidified soybean oil with oleic acid using an acid exchange resin as catalyst. This work has been developed in two parts: (i) a kinetic study in batch conditions with the purpose of developing a suitable kinetic expression and determining the related parameters and (ii) a study of the FFAs esterification in a packed bed tubular reactor operated inside a circulation loop. The kinetic model that is developed on the basis of several batch runs is able to simulate also the behavior of dynamic tubular loop reactor, providing that the external mass transfer resistance is properly accounted for. The mass transfer coefficient is satisfactorily modeled using correlations available on literature.

  • synthesis of biodiesel via homogeneous lewis acid catalyst
    Journal of Molecular Catalysis A-chemical, 2005
    Co-Authors: M Di Serio, Riccardo Tesser, M Dimiccoli, F Cammarota, Nastasi Mario, E Santacesaria
    Abstract:

    Abstract Nowadays, most biodiesel (fatty acids methyl esters, FAME) is produced by the transesterification of triglycerides (TG) of refined/edible type oils using methanol and an homogeneous Alkaline catalyst. However, production costs are still rather high compared with the ones of petroleum-based diesel fuel. To lower costs and make biodiesel competitive less-expensive feedstocks such as waste fats or non-edible type oils could be used. The use of homogeneous Alkaline Catalysts in the transesterification of such types of fats and oils poses great difficulties due to the presence of large amounts of free fatty acids (FFA). This paper studies the use of carboxylic salts as a possible alternative, because these Catalysts are active also in the presence of high FFA concentrations. The most active catalyst (Cd, Mn, Pb, Zn carboxylic salts) have been individuated and a correlation of the activities with the cation acidity has been found.

Glauco F. Bauerfeldt – One of the best experts on this subject based on the ideXlab platform.

  • Biodiesel synthesis: A study of the triglyceride methanolysis reaction with Alkaline Catalysts
    Catalysis Communications, 2016
    Co-Authors: Matthieu Tubino, José Geraldo Rocha Junior, Glauco F. Bauerfeldt
    Abstract:

    Abstract The rates of soybean oil methanolysis under NaOCH 3 , KOCH 3 , NaOH and KOH catalysis were determined at 30.0, 40.0, 50.0 and 60.0 °C using a refractometric method for online monitoring of this reaction. The influences of the metallic cations and anions on the catalysis were studied. Potassium promotes faster reactions than sodium. For the reactions catalyzed by hydroxides, the rate constants are less sensitive to temperature than those catalyzed by methoxides. The proposed reaction mechanism was based on the formation of ionic pairs at the interface of the methanol and oil phases and in the methanol phase.

  • Biodiesel synthesis with Alkaline Catalysts: A new refractometric monitoring and kinetic study
    Fuel, 2014
    Co-Authors: Matthieu Tubino, José Geraldo Rocha Junior, Glauco F. Bauerfeldt
    Abstract:

    Abstract In this work, an experimental system was designed to allow the online monitoring of a chemical reaction in continuous flow leading to biodiesel synthesis using a portable digital refractometer. The proposed method was applied to the monitoring of the methanolysis of soybean oil using KOCH 3 as the catalyst at temperatures from 30 to 60 °C, allowing data acquisition in a relatively simple, reliable and cheap fashion. It was also possible to identify, discriminate and monitor the mixing (emulsification) and the reaction steps, with the former being the rate determinant. The methanolysis reaction is better represented by a zero-order kinetic scheme than by a pseudo-first-order scheme; the activation energy was determined to be (31.3 ± 1.8) kJ mol −1 . This behavior suggests that methanolysis with Alkaline Catalysts, usually considered as a homogeneous process, should in fact be assumed to be heterogeneous. Therefore, the rate of mixing controls the reaction kinetics and is a key factor in decreasing the transesterification time.