PDF Publication Title:
Text from PDF Page: 015
Energies 2020, 13, 420 15 of 96 cation and are realized dispersing into a polymeric matrix the functional groups devolved to enhance the ion mobility [166]. The hydrogen evolution reaction that occurs at the cathode consist on the water dissociation (Equation (17)) through the Volmer step (Equation (18)) which involves the absorption (e.g., Ni-based catalysts) or adsorption (e.g., Pt-based materials) of protons into the electrode active sites, and the hydrogen desorption via Heyrovsky (Equation (19)) or Tafel (Equation (20)) reactions. The overall oxygen evolution reaction, expressed by Equation (21), occurs at the anode. The hydroxide is oxidized involving multiple intermediate steps [171]. 2H2O + 2e− → H2 + 2OH− (overall HER reaction) (17) H2O + e− → Had + OH− (Volmer step) (18) Had + H2O + e− → H2 + OH− (Heyrovsky step) (19) 2Had → H2 (Tafel step) (20) 2OH− → 12O2 + H2O + 2e− (overall OER reaction) (21) The product gas quality is in the range of 99.5%–99.9% for H2 and can be increased up to 99.999% with gas purification treatments [154]. The operational power density is restricted to 20%–100% of the available nominal power as at low loads the crossover effect (oxygen diffuses across the diaphragm and reacts back with hydrogen) could lead to dangerous mixtures [172]. The coupling with intermittent and fluctuant energy sources is possible although problems occur when the power density is below 20% of the nominal load and during the start up of the system since the cold start time that ranges between minutes and hours is relatively high [173]. Nowadays, the research is focused on improving the efficiency of the process, reducing cell resistance and enhancing ion and electric conductivity. The main improvements are: (i) new cell configurations including a zero-gap design and low-resistance diaphragms, (ii) high operational temperature, and (iii) new catalysts such as mixed-metal coating with cobalt oxide and Raney nickel [174]. The “zero-gap” configuration or gas diffusion layer (GDL) is adopted to avoid bubble formation near the electrodes. The zero-gap design uses porous electrodes deposited onto an anion exchange membrane reducing the inter-electrode gap (lower than 0.5 mm rather than above 2 mm). The catalyst can be deposited directly on the polymeric membrane, forming the catalyst-coated membrane (CCM). Otherwise, the catalyst can be coated on a porous substrate and compressed onto the membrane, forming the catalyst-coated substrates (CCS) [175]. Zero gap solution reduces the electrolyte resistance and facilitates the gas bubbles releasing from the backside of the electrodes [176]. The gas diffusion layer is a porous layer with large carbon or nickel particles incorporated in a binder. The function is the transport of fuel and products and the electric connection between the electrodes and the external circuit. The GDL is carved into the metal body in which are placed the porous electrodes and the polymeric separator [177]. The electrolyte flow across the gas diffusion layer within a recirculation loop promoting the gas bubble detachment and removal [159]. The overpotential can also be reduced, introducing a third intermediate electrode. The hydrogen and oxygen production steps take place in successive processes obtaining a production of hydrogen of higher purity and lower ohmic resistance due to the lower thickness of the diaphragm [178]. The typical operating temperature and pressure are 70–100 ◦C and 1–30 bar, respectively [174]. The temperature enhances the entropy energy and, therefore, reduces the electric energy required [179]. The activation overpotential and ohmic drop are strictly related to operating temperatures: high temperatures positively affect the electrolyte ion-conductivity and electrode kinetics, but negatively affect the corrosion resistance of electrocatalysts [180]. At a given temperature, the pressure has to be suitably set since too high pressure induces condensation of steam, but too low pressure could result inPDF Image | Green Synthetic Fuels
PDF Search Title:
Green Synthetic FuelsOriginal File Name Searched:
energies-13-00420.pdfDIY PDF Search: Google It | Yahoo | Bing
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
IT XR Project Redstone NFT Available for Sale: NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Be part of the future with this NFT. Can be bought and sold but only one design NFT exists. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Turbine IT XR Project Redstone Design: NFT for sale... NFT for high tech turbine design with one part 3D printed counter-rotating energy turbine. Includes all rights to this turbine design, including license for Fluid Handling Block I and II for the turbine assembly and housing. The NFT includes the blueprints (cad/cam), revenue streams, and all future development of the IT XR Project Redstone... More Info
Infinity Turbine ROT Radial Outflow Turbine 24 Design and Worldwide Rights: NFT for sale... NFT for the ROT 24 energy turbine. Be part of the future with this NFT. This design can be bought and sold but only one design NFT exists. You may manufacture the unit, or get the revenues from its sale from Infinity Turbine. Royalties go to the developer (Infinity) to keep enhancing design and applications... More Info
Infinity Supercritical CO2 10 Liter Extractor Design and Worldwide Rights: The Infinity Supercritical 10L CO2 extractor is for botanical oil extraction, which is rich in terpenes and can produce shelf ready full spectrum oil. With over 5 years of development, this industry leader mature extractor machine has been sold since 2015 and is part of many profitable businesses. The process can also be used for electrowinning, e-waste recycling, and lithium battery recycling, gold mining electronic wastes, precious metals. CO2 can also be used in a reverse fuel cell with nafion to make a gas-to-liquids fuel, such as methanol, ethanol and butanol or ethylene. Supercritical CO2 has also been used for treating nafion to make it more effective catalyst. This NFT is for the purchase of worldwide rights which includes the design. More Info
NFT (Non Fungible Token): Buy our tech, design, development or system NFT and become part of our tech NFT network... More Info
Infinity Turbine Products: Special for this month, any plans are $10,000 for complete Cad/Cam blueprints. License is for one build. Try before you buy a production license. May pay by Bitcoin or other Crypto. Products Page... More Info
CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com (Standard Web Page)