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Current Status and Perspectives of Biogas Upgrading and Utilization
Published in Anand Ramanathan, Babu Dharmalingam, Vinoth Thangarasu, Advances in Clean Energy, 2020
Anand Ramanathan, Babu Dharmalingam, Vinoth Thangarasu
Before describing the chemical hydrogenation process, we need to know the definition of hydrogenation. Hydrogenation means conversion of unsaturated organic components into saturated organic components with the help of hydrogen molecules in the presence of a catalyst. Catalysts are substances that are used to speed up the rate of a reaction without being consumed during the process. Catalysts used for hydrogenation reactions are metals such as nickel, ruthenium, and platinum. We can also convert double- or triple-bond hydrocarbon to single-bond hydrocarbon by adding hydrogen atoms (Ramaraj and Dussadee 2015). In this process, hydrogen is added to carbon dioxide in the presence of a catalyst. The most commonly used catalysts for hydrogenation are nickel and ruthenium. The optimum condition for the hydrogenation reaction is 473 K temperature and 50–200 bar pressure. (Xia, Cheng, and Murphy 2016).
Feedstock Chemistry in the Refinery
Published in James G. Speight, Refinery Feedstocks, 2020
A wide variety of metals are active hydrogenation catalysts; those of most interest are nickel, palladium, platinum, cobalt, iron, nickel-promoted copper, and copper chromite. Special preparations of the first three are active at room temperature and atmospheric pressure. The metallic catalysts are easily poisoned by sulfur-containing and arsenic-containing compounds, and even by other metals. To avoid such poisoning, less effective but more resistant metal oxides or sulfides are frequently employed, generally those of tungsten, cobalt, chromium, or molybdenum. Alternatively, catalysts poisoning can be minimized by mild hydrogenation to remove nitrogen, oxygen, and sulfur from feedstocks in the presence of more resistant catalysts, such as cobalt– molybdenum–alumina (Co-Mo-Al2O3). The reactions involved in nitrogen removal are somewhat analogous to those of the sulfur compounds and follow a stepwise mechanism to produce ammonia and the relevant substituted aromatic compound.
Polyalphaolefins
Published in Leslie R. Rudnick, Synthetics, Mineral Oils, and Bio-Based Lubricants, 2020
The hydrogenation is typically performed over a supported metal catalyst such as nickel/kieselguhr or palladium/alumina. Hydrogenation is necessary to give the final product enhanced chemical inertness and added oxidative stability. The term PAO is used even though the fluid is saturated in a subsequent chemical hydrogenation.
Cashew nutshell liquid and its derivatives in oil field applications: an update
Published in Green Chemistry Letters and Reviews, 2021
David Chukwuebuka Ike, Millicent Uzoamaka Ibezim-Ezeani, Onyewuchi Akaranta
Etherification of CNSL has also been reported via its reactions with alkyl halides (Figure 6(e)) (21, 24, 54). Etherification of cardanol has also been reported via the hydrolysis of epoxy product (55). Epoxidation of CNSL is carried out by reaction with epichlorohydrin in the presence of a base catalyst. The reaction of cardanol with epichlorohydrin in the presence of caustic soda as a catalyst has been reported to give a great yield of epoxy cardanol (Figure 6(f)) (55–57). Hydrogenation of unsaturation is often performed directly with hydrogen in the presence of metal catalysts such as copper, nickel, palladium, or platinum (Figure 6(g)) (50–58). CNSL has been hydrogenated using Pd/C catalyst and was applied for the synthesis of an azo dye (58).
Preparation of jet engine range fuel from biomass pyrolysis oil through hydrogenation and its comparison with aviation kerosene
Published in International Journal of Green Energy, 2019
Zeban Shah, Renato C. Veses, Julio C. P. Vaghetti, Vanessa D. A. Amorim, Rosangela da Silva
Pyrolysis oil from agricultural residues was a black sticky liquid containing various groups of compounds such as alcohol, aldehydes, nitrogenated, oxygenated compounds, phenol, ketones and hydrocarbons. An increase (40–50%) in the production of bio-oil from the pyrolysis of lignin of the wood was observed after adding discarded soybean frying oil. The aim of upgrading was to convert oxygen and nitrogen-containing compounds to hydrocarbons through hydrogenation using NiMo as a catalyst. Hydrogenation was found very useful to improve stability and fuel quality by decreasing the contents of organic acids, ketones, aldehydes as well as other reactive compounds. More than 60% oxygen and nitrogen containing compounds were converted to hydrocarbons through hydrogenation. The hydrogenated bio-oil showed very similar physico-chemical properties such as freezing point, flash point, density, viscosity and enthalpy of combustion as that of aviation kerosene. Our future work is going to use hydrogenated bio-oil in an aviation turbine to check its important characteristics such as the cetane number, ignition delay time, particulate matter (PM), nitric oxide (NO) and carbon monoxide (CO) emissions.
Experimental study on operating conditions of 2-ethylhexanol manufacturing process
Published in Materials and Manufacturing Processes, 2018
Ahad Ghaemi, Mohammad Hadi Zerehsaz
The hydrogenation reactions may occur in both liquid and gas phases. In the liquid phase, the reactions occur over a catalyst at a temperature of about 160°C and at a pressure below 30 bars. In the gas phase, the hydrogenation reactions take place over a catalyst at a temperature of approximately 170°C and at a pressure below 6 bars. Regarding the studies conducted in this area, reaction kinetics based on the species concentration can be presented as below[15,16]: where k is the reaction constant and CA and are the aldehyde concentration and hydrogen concentration, respectively. The reaction constant is shown as below[22]: