PDF Publication Title:
Text from PDF Page: 011
Energies 2019, 12, 809 11 of 41 that only Co promotes HDO stronger than deCOx reactions. Ni and Co are often used as promoters to increase the activity of molybdenum sulfide, as it is believed that they donate electrons to Mo, which weakens the metal–sulfide bond. However, it has been found that the activity of the sulfided catalysts decreases over time due to a loss in MoS2 active sites and to the presence of water due to HDO. This means that a continuous supply of a sulfiding agent, such as H2S, is necessary in order to avoid either the oxidation of the sulfide catalyst or the reduction by H2 of the sulfide phase [88]. Kub ̆ıcka and Kaluža [72] have examined the deoxygenation of rapeseed oil over sulfided Ni, Mo and Ni–Mo catalysts supported over Al2O3 and observed that Ni produces exclusively n-C17H36 and no n-C18H38 while Mo produces only a small fraction of C17H36 and almost exclusively C8H18. This behavior implies that Ni promotes exclusively the deCOx of the fatty acids while Mo promotes their HDO. This is explained by the inherently different electronic properties of the Mo and Ni sulfided phases. In the Ni-Mo catalyst, both n-C17H36 and no n-C18H38 were observed as products in appreciable quantities with a C17/C18 weight ratio equal to 0.36 (at 260–280 ◦C, 35 bar and Liquid Hour Space Velocity, LHSV, = 0.25–0.4 h−1). Given that Ni was used as a promoter in lower concentration than Mo, it was deduced that over Ni-Mo the main product is n-C18H38 and the main reaction pathway is HDO [72]. Laurent et al. [89], examined the impact that H2O and H2S have on the HDO of guaiacyl, carboxylic and carbonyl groups, using NiMo/CoMo catalysts that were based on γ-Al2O3, and concluded that Brønsted acidity of the sulfide phase increases in the presence of H2S during the reaction. Toba et al. [80] have examined the hydrotreatment of waste cooking oil (WCO) using sulfided Ni–Mo/Al2O3, Co–Mo/Al2O3, and Ni–W/Al2O3 catalysts and observed that although all catalysts have high catalytic activity for production of C15–C18 hydrocarbons there exists a small difference in the order Ni–Mo > Ni–W > Co–Mo. At the same study, the effect of the support was examined on Ni–Mo/Al2O3 and Ni–Mo/B2O3–Al2O3 catalysts and it was shown that due to higher acidity, B2O3–Al2O3 increases the production of branched isomers and improves the cold fuel properties of the biofuel. Phosphorus has also been tried as a promoter of Mo-based catalysts during hydrotreatment of bio-oil and model compounds. It was concluded that phosphorus enhances the dispersion of Mo on to the support, helps reduce the formation of coke, favors the creation of new Brønsted and Lewis acid sites on the surface of the support and increases the packing of MoS2 crystallites [90]. As is well understood, the nature of the support can have a significant effect on the performance of a catalytic system and as a result a number of different metal oxides, such as Al2O3, TiO2, ZrO2 and CeO2 have been tested as carriers [91]. As alumina supports have been used extensively for the removal of sulfur from crude oil (upgrading of oil), a number of authors have examined its performance for hydrodeoxygenation in bio-oil upgrading. The main issues identified are the susceptibility of alumina to attack by acidic water at elevated conditions and its reaction with H2O which leads to a reduction of surface area [92]. Moreover, as alumina is not inert (as it possesses acid centers, mainly of Lewis type), promoters such as Ni and/or Co can react with Al2O3 and take up tetrahedral and octahedral sites found in the external layers [93]. As a consequence, a strong interaction develops between the support and the modifier, which in turn inhibits the dispersion of the Mo sulfide phase and affects HDO activity in a negative way [94]. The effect of the support has been examined also by Kub ̆ıcka et al. [75] who examined the hydrotreatment of rapeseed oil over Co-Mo supported on Al2O3, MCM-41 and Organized Mesoporous Alumina (OMA) and shown that the formation of branched isomers follows the order OMA > Al2O3 > MCM-41. A promising supporting material for HDO is activated carbon (AC) due to its thermal stability, high surface area and pore volume, presence of both meso and macro pores and hydrophobic nature [95,96]. Supelveda et al. [95], using a Mo2N/AC catalyst reported that the high mesoporosity of the activated carbon facilitated the diffusion of the reactants to the internal surface area, i.e., at the location of the active centers. Moreover, Echeandia et al. [96] argued that the hydrophobic nature of activated carbon prevents the water produced during HDO from being adsorbed on the catalyst’s active sites. SiO2 has also been used in HDO reactions as it is known to be inert and to have a small interaction with the sulfide phase. For example, Popov et al. [97] studying the HDO of phenolic molecules reported that the phenolic compound interacted through H bonding.PDF Image | Green Diesel: Biomass Feedstocks, Production Technologies
PDF Search Title:
Green Diesel: Biomass Feedstocks, Production TechnologiesOriginal File Name Searched:
energies-12-00809.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)