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Visbreaking
Published in Mark J. Kaiser, Arno de Klerk, James H. Gary, Glenn E. Hwerk, Petroleum Refining, 2019
Mark J. Kaiser, Arno de Klerk, James H. Gary, Glenn E. Hwerk
The concept of hydrogen donor visbreaking comes from the development work done on direct coal liquefaction. In hydrogen donor visbreaking, hydrogen is supplied in the form of a hydrogen donor solvent. The hydrogen donor solvent is co-fed with the feed to the visbreaker and it provides a source of transferable hydrogen during thermal conversion. The reaction chemistry involved in hydrogen transfer is discussed in Section 24.3.1.
Progress and utilization of biomass gasification for decentralized energy generation: an outlook & critical review
Published in Environmental Technology Reviews, 2023
Deepak Kumar Singh, Reetu Raj, Jeewan Vachan Tirkey, Priyaranjan Jena, Prakash Parthasarathy, Gordon Mckay, Tareq Al-Ansari
Liquefaction: Liquefaction involves the conversion of solid or gaseous feedstocks into liquid fuels [6]. There are two main types of liquefaction processes: direct and indirect liquefaction. Direct liquefaction: In direct liquefaction, the feedstock is reacted with a hydrogen donor solvent at high temperatures and pressures. Advantages include:Efficient conversion of a wide range of feedstocks, including coal, biomass, and waste.Production of liquid fuels that can be readily used in existing infrastructure.Potential for capturing and utilizing carbon dioxide (CO2) emissions.
1H NMR and 13C NMR characterization of n-heptane extraction of low-temperature coal tar reacted with formaldehyde
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Qiuxiang Yao, Xiangxi Kong, Xiaomin Dai, Junwen Gao, Rucheng Wang, Yujuan Zhang, Ming Sun, Xiaoxun Ma
Coal tar pitch was used to produce needle coke in the 1960s. In order to prepare needle coke with better quality, many scholars have conducted systematic researches on the relationships between the composition and structure of coal tar pitch and the characteristics of needle coke (Tang et al. 2016). Greinke and Singer (1988) had found that the components between 700 and 1200 u have the optimum reactivity and they are transition molecules, to form the stable intermediate phase after reactions. And the components whose molecular weight is greater than 1200 u are stable in the process of interphase formation, and they are inert in the carburization process. Moriyama, Hayashi, and Chiba (2004) added different contents of primary QI to A-240 pitch and then heated. It was found that the primary QI not only affected the coalescent of mesophase spherules, but also affected the nucleation rate of spherules. Yamada et al. (1982) used tetrahydroquinoline as a hydrogen-donor solvent to deal with coal pitch, to introduce naphthenic structure into coal pitch and to improve the mobility of mesophase. Finally, the contents of methyl or methylene group increase. Brozowska, Zielinski, and Machnikowski (1998) modified coal pitch by adding polyvinyl chloride and polystyrene, and made the carbonization rate increase by 3–5% and certainly improve the optical texture of samples. Lin et al. (2004) modified coal pitch by using toluenesulfonic acid (catalyst) and divinylbenzene (modifier). The carbonization rate had been increased by 10–18% after modified, and the crude mosaic structure of semi-coke had also been improved.
Hydrogen transfer during co-liquefaction of Elbistan lignite and biomass: liquid product characterization approach
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2018
Cemil Koyunoglu, Huseyin Karaca
The AS yield among the products is the other important factor. An investigation of the hydrogen donor abilities of heavy oils concluded the heavy oils containing more asphaltenes that are better hydrogen donors than resids with less asphaltenes (Ekinci et al. 1991). Therefore, the same level asphaltene yields after replacing hydrogen donor solvent tetralin with distilled water the more hydrogen transferred by manure decomposition (Stray et al. 1986). It is also believed that the hydrogen bonding and polar interactions might be responsible for the formation of the asphaltene aggregates (Tavakkoli, Chen, and Vargas 2016).