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Outlook and Perspective
Published in Saeed Sahebdelfar, Maryam Takht Ravanchi, Ashok Kumar Nadda, 1 Chemistry, 2022
Saeed Sahebdelfar, Maryam Takht Ravanchi, Ashok Kumar Nadda
With the advent of new feedstocks, the traditional catalysts need to be improved or novel ones to be developed. Bifunctional (or multifunctional) catalysts could be especially effective to reduce thermodynamic constraints in equilibrium limited reactions by coupling them with another reaction as tandem reactions. This approach is most suited for coupling reactions occurring optimally under similar operation conditions (especially temperature). The components of the hybrid catalyst should be tolerant to the products of reactions under operating conditions. A well-known and potentially attractive example is direct hydrogenation of carbon oxides to dimethyl ether, which should result in higher conversion compared to methanol synthesis under similar conditions. The incorporation of zeolites in catalyst formulation can further affect the catalyst performance by introducing shape-selectivity, which is useful when a wide range of bulky molecules are potential products as in hydrogenation of carbon oxides to hydrocarbons (Zhou et al., 2019).
Butane and Naphtha Hydroisomerization
Published in Mark J. Kaiser, Arno de Klerk, James H. Gary, Glenn E. Hwerk, Petroleum Refining, 2019
Mark J. Kaiser, Arno de Klerk, James H. Gary, Glenn E. Hwerk
Light paraffin hydroisomerization processes convert linear paraffins into branched paraffins of the same carbon number. The catalysts that are used are bifunctional catalysts, with both metal sites and acid sites. The only metal that is industrially employed is platinum, but three different acid support materials are employed, namely, chlorided alumina, sulfated zirconia, and mordenite. The conversion is equilibrium limited. Hydroisomerization is performed in the presence of hydrogen, which regulates the hydrogenation-dehydrogenation equilibrium and limits reactions leading to coking. Butane hydroisomerization produces isobutane and is usually employed in conjunction with aliphatic alkylation. Light naphtha hydroisomerization is employed to increase the octane number of light naphtha, which is then called “isomerate,” to be used as blendstock for motor gasoline.
Bifunctional Porous Catalysts in the Synthesis of Valuable Products
Published in Vanesa Calvino-Casilda, Antonio José López-Peinado, Rosa María Martín-Aranda, Elena Pérez-Mayoral, Nanocatalysis, 2019
Elena Pérez-Mayoral, Marina Godino-Ojer, Daniel González-Rodal
When modifying solid supports, the functions often are randomly distributed at the surface. In this respect, a significant number of papers are focused on the control of the structural properties of the multifunctional nanocatalysts. Several different approaches have been used to prepare bifunctional heterogeneous catalysts by using various supports where distinct functional groups are responsible for improved catalytic activity. Although zeolites are the preferred materials widely used in the petrochemical industry, these solids show some limitations because of their small pore sizes which restrict the scope of catalytic reactions. One example of layered zeolitic hybrid organic–inorganic material comprising acid and base centres located in the zeolitic counterpart and the organic component, respectively, is that reported by Corma et al. (2010). While the acid sites are located within micropores in the zeolitic material, the amine functions were incorporated on the bridged benzene groups in the interlayer space. This zeolitic hybrid was proved in the cascade reactions involving the acetal deprotection promoted by acid sites in the zeolitic framework, followed by consecutive Knoevenagel condensation catalysed by basic sites constituted by amine functions.
Toward estimation of upgrading of n-heptane over catalysts using robust technique
Published in Petroleum Science and Technology, 2020
Xiuling Sun, Haifeng Sun, Gaili Du
The reaction of conversion of typical petroleum light naphta feeds (C6 and C7) to the branched aliphatic hydrocarbons and aromatics is called catalytic reforming. Catalytic reforming which is widely used in petroleum refining industry to improve the temperature performance of diesel, to produce lube oils and to enhance the octane number of gasoline has been studied extensively in these years (Epron, Carnevillier, and Marécot 2005; Hamoule et al. 2011; Rahimpour, Jafari, and Iranshahi 2013; Parsafard, Peyrovi, and Rashidzadeh 2014). Bifunctional catalysts are used to improve reactions such as isomerization, cyclization, hydrocracking, hydrogenation, and dehydrogenation (Hamoule et al. 2011). Recent studies have been shown the effect of bifunctional catalysts on enhancing biomass conversion (Serrano-Ruiz and Dumesic 2011; Barbaro et al. 2012; Lee et al. 2012). More recent studies show the application of bifunctional catalysts in synthesis of liquid fuels and fine chemicals from biomass and syngas (Chheda, Huber, and Dumesic 2007; Kunkes et al. 2008; Barbaro et al. 2012). One of the most important characteristics of bifunctional catalysts which has a key role in optimizing the reaction which is depending on the utilization and intention is acidity includes acidity number and acidity strength (Hensen et al. 2010).
Prediction of catalytic hydro conversion of normal heptane over catalysts using multi-layer perceptron artificial neural network (ANN-MLP)
Published in Petroleum Science and Technology, 2018
The reaction of conversion of typical petroleum light naphta feeds (C6 and C7) to the branched aliphatic hydrocarbons and aromatics is called catalytic reforming. Catalytic reforming which is widely used in petroleum refining industry to improve the temperature performance of diesel, to produce lube oils and to enhance the octane number of gasoline has been studied extensively in these years (Epron, Carnevillier, and Marécot 2005; Hamoule et al. 2011; Rahimpour, Jafari, and Iranshahi 2013; Parsafard, Peyrovi, and Rashidzadeh 2014). Bifunctional catalysts are used to improve reactions such as isomerization, cyclization, hydrocracking, hydrogenation and dehydrogenation (Hamoule et al. 2011). Recent studies have been shown the effect of bifunctional catalysts on enhancing biomass conversion (Serrano-Ruiz and Dumesic 2011; Barbaro et al. 2012; Lee et al. 2012). More recent studies show the application of bifunctional catalysts in synthesis of liquid fuels and fine chemicals from biomass and syngas (Chheda, Huber, and Dumesic 2007; Kunkes et al. 2008; Barbaro et al. 2012). One of the most important characteristics of bifunctional catalysts which has a key role in optimizing the reaction which is depending on the utilization and intention is acidity includes acidity number and acidity strength (Hensen et al. 2010).
Prospects of novel heterogeneous base catalysts and nanocatalysts in achieving sustainable biodiesel production
Published in International Journal of Green Energy, 2023
Dhnyaneshwar Raising Rathod, Sandesh Suresh Karkal, Akil Salim Jamadar, Aliaa M.A. Hashem, P. V Suresh, S.S Mamatha, Tanaji G. Kudre
Bifunctional catalysts are a novel promising type of catalysts generally comprising both active base and acid catalyst sites. Due to the presence of both base and acid active sites, these catalysts can catalyze both esterification and transesterification reactions with high conversion and selectivity (Mardhiah et al. 2017). The problem pertaining to biodiesel production from low-grade feedstocks such as WCO, which has high FFA and water content, can be easily overcome using modified bifunctional catalysts. Thus, biodiesel production via a two-step transesterification process can be averted. This approach might help in cost-effective and sustainable biodiesel production. Research on biodiesel production using bifunctional heterogeneous catalysts showed that the transesterification reaction required high temperature and slightly higher reaction time (Essamlali et al. 2018; Farooq, Ramli, and Subbarao 2013). Farooq et al (Farooq, Ramli, and Subbarao 2013) reported a maximum biodiesel yield of 91.4% biodiesel yield using 15 wt% Mo – Mn/γ-Al2O3 bifunctional catalysts dosage at methanol to oil molar-ratio of 27:1, reaction temperature 100°C, the reaction time of 4 h, and an agitation speed of 500 rpm. Further, the bifunctional catalyst (Mo – Mn/γ-Al2O3) was reused eight times without loss in their catalytic activity (Farooq, Ramli, and Subbarao 2013). Like Mo – Mn/γ-Al2O3, another bifunctional catalyst, Sodium-modified fluorapatite (Na/FAP), is a highly efficient, solid, bifunctional catalyst. The highest biodiesel yield of 98% was obtained from a transesterification reaction using Na/FAP bifunctional catalysts and waste cooking oil feedstock at methanol to oil molar ratio is 10:1, catalysts dosage 6 wt.%, the reaction temperature 120°C, and reaction time 8 h. Also, the catalyst displayed reusability potential for up five cycles with no significant loss of catalyst activity (Essamlali et al. 2018). (Simbi et al. 2022) obtained a biodiesel (fatty acid methyl ester) yield of 98.23% from sunflower oil using CaO/Al2O3 bifunctional catalysts. However, the bifunctional catalysts must be modified to produce biodiesel at moderate operation conditions to achieve economic and sustainable biodiesel production.