Bi-functional catalysts

Hydrogen oxidation can be done in situ, using a bi-functional catalyst (6—11), or the two processes can be separated by feeding the dehydrogenation... 

The catalyst used in the TransPlus process jointly developed by ExxonMobil and CPC uses a proprietary zeolite [76]. From the literature, the SK Energy ATA-11 catalyst appears to be based on either mordenite or beta zeolite using attenuated noble metals. The UOP TAC9 process was developed by UOP and Toray and is licensed by UOP (outside Japan and Korea). The UOP Tatoray process is based on a bi-functional catalyst with long catalyst life, minimal ring loss and hydrogen consumption in comparison with noble metal catalyst systems. 

In this study we have investigated utilizing a bi-functional catalyst with a solid base function for the aldol condensation reaction and a metal function for the hydrogenation. This work is a continuation of the study that examined the supported base catalyzed aldol condensation of acetone (5, 6). In those studies... 

Li J, Wang L, Shi F et al (2011) Quaternary ammonium ionic liquids as bi-functional catalysts for one-step synthesis of dimethyl carbonate from ethylene oxide, carbon dioxide and methanol. Catal Lett 141(2) 339-346... 

Interest in carbon deposition cm platinum surfaces has been driven by the fact that this metal and its alloys are used extensively in the reforming of petroleum naphthas. This reaction is carried out over bi-functional catalysts which consist of a single metal (e.g. Pt) or a combination of metals (e.g. Pt/Ir, Pt/Re, Pt/Sn) dispersed on an acidic support such as alumina, on which the acidity is controlled by addition of... 

In the same area, Shibasaki et al. described a new Lewis acid-Lewis base bi-functional catalyst 55 highly efficient in the cyanosilylation of aldehydes [57,58] (Table 7). 

Ag-Cs0H/Si02 Bi-functional Catalysts for Production of Methyl Methacrylate from Methyl Propionate and Methanol... 

Ag-Cs0H/Si02 Bi-functional catalysts for production of methyl methacrylate... 

For instance, metal catalysts are not in their bulk form but they are generally dispersed on a high surface area insulator (support) such as AI2O3 or SiC>2. Sometimes, both the metal and the support act as a catalyst. These are referred to as bi-functional catalysts. An example is the platinum dispersed on alumina used in the gasoline reforming. 

Climeni. MJ Conna, A Garcia, H Guil-Lopez. R Iborra. S Fomes, V. Acid-base bi functional catalysts for the preparation of fine chemicals synthesis of jasminaldchyde. Journal of Catalysis, 2001 197. 385-393. 

Heterogeneous catalysts, in particular zeolites with their various properties contribute extensively to the environmental protection in the synthesis of fine chemicals. For that a broad and very impressive range of acidic and basic catalysts is already available having all levels of properties between super acidity and super basicity. Furthermore the zeolitic materials may have shape-selective behavior. Also the possibility to prepare bi-functional catalysts will gain in importance. 

As described in this subsection, metal halides, metal complexes and water can improve the activities of ILs for the synthesis of cyclic carbonates from epoxides and CO2. A generally accepted reaction mechanism for those bi-functional catalyst systems can be drawn as Scheme 5. Because these additives have Lewis acidic nature, they would interact with the oxygen atom of the epoxide. On the other hand, the basic anion of IL would attack the less hindered carbon atom of the epoxide ring. Such cooperative activation of the epoxide should make the ring opening easier, being the reason of the promotional effects of the additives. In some cases, the additives may have a role in the activation of CO2. 

According to the function of two compositions of BMNCs in the electrocatalytic reaction, BMNCs can be divided into mono-functional catalysts and bi-functional catalysts. In mono-functional catalysts, reagents are only adsorbed on one kind of metal atoms in bi-functional catalysts, both kinds of metal atoms on the surface serve as adsorption sites for different reagents. The alloy BMNCs of Pt and early transition metals as ORR catalysts are mono-functional catalysts, in which reagent and intermediates are only adsorbed on the Pt sites and the early transition metals are introduced to modulate the electronic stmcture of the Pt and improve the ORR activity [5, 6, 8]. Pt-Ru catalysts used for methanol electro-oxidation, however, are considered as bi-functional catalysts where Pt atoms serve as the adsorption sites of the C-species and Ru atoms serve as the adsorption sites of the 0-species [9, 10]. If BMNCs are to serve as bi-functional catalysts, the synthetic approach should be specially designed to optimize the ratio of the exposed sites of each of the two metal atoms. 

Li, J. Wang, L. Shi, F. Liu, S. He, Y Lu, L. Ma, X. Deng, Y. Quaternary Ammonium Ionic Liquids as Bi-functional Catalysts for One-Step Synthesis of Dimethyl Carbonate from Ethylene Oxide, Carbon Dioxide and Methanol. Catal. Lett. 2011, 141,339-346. 

Su, M., Yang, R., Li, M., 2013. Biodiesel production from hempseed oil using alkaline earth metal oxides supporting copper oxide as bi-functional catalysts for transesterification and selective hydrogenation. Fuel 103, 398—407. Available at http //www.sciencedirect.com/ science/article/pii/S0016236112005583 (accessed 22.06.14.). 

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