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Platinum-Free Anode Electrocatalysts for Methanol Oxidation in Direct Methanol Fuel Cells
Published in Prasanth Raghavan, Fatima M. J. Jabeen, Ceramic and Specialty Electrolytes for Energy Storage Devices, 2021
Bhagyalakhi Baruah, Ashok Kumar
Rhodium (Rh) is a silvery, hard, and durable noble element with high corrosion resistance. Although, Rh has not been recognized as a catalyst for alcohol electro- oxidation in a basic medium, numerous studies have investigated electrocatalytic applications of Rh-based materials. Owing to the oxophilic property of Rh, it can help in removal of intermediates, such as CO, by OH- ion adsorption in alkaline electrolytes [1].
Catalytic Chemical Syntheses at High Pressure
Published in Ian L. Spain, Jac Paauwe, High Pressure Technology, 2017
Oxo reactions are carried out in the liquid phase usually in a fixed-bed system. Temperatures encountered may range from about 100 to 200°C. Pressures can be from about 2000 psi to 5,000 psi (~13.8 – 34.5 MPa). With this process, soluble cobalt salts of fatty acids or naphthenates are pumped with the olefin to the top of the first reactor and flow countercurrent to the synthesis gas. The cobalt is converted to carbonyl. In the near future, rhodium catalysts will probably replace cobalt resulting in milder conditions and economic advantages.
Rh, 45]
Published in Alina Kabata-Pendias, Barbara Szteke, Trace Elements in Abiotic and Biotic Environments, 2015
Alina Kabata-Pendias, Barbara Szteke
Rhodium (Rh) is a silvery-white, hard metal of group 9 in the periodic table of elements, is the least frequent element of the platinum group metals (PGMs), and is chemically inert. It reveals both siderophilic and chalcophilic properties. Its average content in the Earth’s crust is estimated to be 0.06 µg/kg, and its contents in rocks vary within the range of 0.01–20 µg/kg. It may be accumulated in coal, up to about 100 µg/kg. It tends to occur along with deposits of PGMs and is primarily obtained as a by-product of mining and refining Pt. It is also mined from the Cu–Ni deposits, mainly in Monchegorsk area, the Kola Peninsula (Russia). The main minerals of these ores are pyrrhotite, magnetite, pentlandite, chalcopyrite, Ti magnetite, and pyrite, in which Rh contents vary from 4 to 2780 µg/kg (Gregurek et al. 1999).
Performance analysis of a hybrid lightweight vehicle with downsized engine
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Yasin Karagöz, Özgün Balcı, Onur Gezer, Sefa Kale, Hasan Köten
Nowadays, all passenger cars have after-treatment systems. It is not possible to overcome today’s forceful emission regulations without after-treatment equipment. Three-way catalytic converters are one of the most widespread after-treatment systems at gasoline engines to meet stringent emission regulations. The working principle of the system is based on absorption of the catalyst material on a metallic or ceramic-based body which reduces emissions by passing the exhaust gases (Santos and Costa 2008b). Catalytic materials are generally composed of platinum, palladium, and rhodium (Santos and Costa 2008a). Platinum and palladium are effective in the oxidation of CO and HC emissions, while rhodium plays an important role in the reduction of NOx emissions (Heo et al. 2012). TWC achieves conversion efficiency of 95% for CO, HC, and NOx (Santos and Costa 2008b). TWC efficiency is a function of temperature, substantially. The reaction speed is slow at low-converter temperatures. The reaction rate increases sharply according to the Arrhenius law at high-converter temperature (Santos and Costa 2008a). At the same time, chemical activation energy reduces at high temperature (Santos and Costa 2008a). For that reason, exhaust gas temperatures were measured experimentally for different engine speed and engine loads. Then a three-way catalytic converter conversion model was created depending on exhaust gas temperature.
A Review on the Recovery of Noble Metals from Anode Slimes
Published in Mineral Processing and Extractive Metallurgy Review, 2020
Wei Dong Xing, Seong Ho Sohn, Man Seung Lee
Cementation is one of the most effective and economic techniques for separation methods. The noble metal ions are reduced by less noble metal such as zinc, iron, copper, and aluminum (Aktas 2012; Kuntyi et al. 2013; Lee et al. 2013). Gold was recovered by the reduction of copper disc from the chloride leach liquor of anode slimes containing Au and Ag along with some base metals like Pb, Sb, Zn, Cu, and Sn (Donmez et al. 2001). A mechanistic study on the cementation of Ru(III), Rh(III), and Ir(IV) from sulfate solution by using iron ion indicated that solution pH has the most significant effect regardless of iron valence state (Coetzee et al. 2018). In recent work by Aktas (Aktas 2011), 99% of rhodium(III) was recovered by zinc powder from the waste rinsing water. However, the free acid and some other metal impurities increase the consumption of zinc powder.
The effect of using the turbulence enhancement unit before the catalytic converter in diesel engine emissions
Published in International Journal of Ambient Energy, 2018
Mohit Bhandwal, Manthan Kumar, Manish Sharma, Utkarsh Srivastava, Anmol Verma, R. K. Tyagi
Various researches and inventions have been conducted in the past years and decades for the reduction of vehicle exhaust emissions from internal combustion engines. The results from these researches and studies had given some efficient devices for emission reduction and one such example is the catalytic converter, which is found in each and every vehicle's exhaust system nowadays (Reference for Business 2013). A catalytic converter is the most effective device in the exhaust system to reduce exhaust emissions from vehicles, which works on few chemical reactions and is inexpensive too (Wright 2006). Earlier these converters were professionally used for industrial purposes for removal of harmful wastes. In those days,' removal of exhaust emissions from automobiles was not considered necessary (Chemical Heritage Foundation 2010). The catalytic converter was invented by a French mechanical engineer who lived in the United States, named Eugene Houdry (Pundir 2007; Bera and Hegde 2010). Eugene got his patent in 1950 for development of the catalytic converter for a gasoline engine (Houdry 1956, US2742437). In India, the government has made use of converters in the exhaust system of vehicles to control the exhaust emissions mandatory for all the new vehicles getting registered (Shelef and McCabe 2000; Bera and Hegde 2010). The three-way catalytic converter is structurally stable even at high operating temperatures up to 1300°C, is chemically inert, and supports less pressure drop during operation. The normal operating temperature range of the converter is 200–300°C (Wright 2006). The commonly used catalysts are rhodium, platinum, palladium, and gold, which undergo several successive chemical reactions in different phases to reduce the emissions form the exhaust of vehicles (Nice and Bryant 2009). Use of a whale filter, which is a South African patented diesel particulate filter, has also been studied for reduction of exhaust emissions of vehicles which also showed significant results (Pilusa, Mollagee, and Muzenda 2012; Tyagi et al. 2015).