Influence of hydrogen bonding on the viscosity of coal liquids

Equilibrium study on the reactive liquid–liquid extraction of 4-cyanopyridine with 4-nonylphenol

“…The length of these oligomers depends greatly on the polarity of the diluent, in polar diluents or apolar diluents saturated with water, oligomers larger than dimers or trimers are rarely found (Staszak and Prochaska, 2008;Woolley and Hepler, 1972). The oligomerization of phenol increases the viscosity of the liquid (Tewari et al, 1979), confirmed by the very high viscosity of 1300 cP of undiluted NP determined by our viscosity measurements. When saturated with water the viscosity was reduced to 300 cP, which can be explained by the reduction in the size of the NP-oligomers.…”

Effect of Process Parameters on Rheological Properties of Coal-Derived Liquids

“…20,21 Asphaltenes and oil fractions are intermolecularly associated through hydrogen bonding and are partly responsible for the increase in the viscosity of the CDLs. 22 It must be noted that the chemical and physical properties of pre-asphaltenes and asphaltenes, such as component concentration, molecular weight, and molecular interaction, strongly depend upon their source. Pre-asphaltenes and asphaltenes in CDLs dramatically vary with parent coal types and solvents.…”

“…The coefficient values in eq indicated that (i) there is a very strong correlation between pre-asphaltenes and asphaltenes and viscosity and (ii) pre-asphaltenes has a greater effect on viscosity than asphaltenes. The major contributors to the high viscosity of coal conversion products were found to be in pre-asphaltenes, , probably because the pre-asphaltenes have larger molecular weights and functionalities and a stronger ability to form multiple hydrogen-bonding systems in comparison to asphaltenes. , Asphaltenes and oil fractions are intermolecularly associated through hydrogen bonding and are partly responsible for the increase in the viscosity of the CDLs . It must be noted that the chemical and physical properties of pre-asphaltenes and asphaltenes, such as component concentration, molecular weight, and molecular interaction, strongly depend upon their source.…”

“…CDLs have higher levels of organic oxygen and nitrogen compounds compared to petroleum fractions, and more hydrogen bondings (−O−H· · ·N−) are formed between oxygen and nitrogen compounds. The increased concentration of large complexed ions formed in the transition from the hydrogen-bonded complexes (−O−H· · ·N−) to the proton-transfer complexes (−O − · · ·H + −N−) is partially responsible for the high viscosity . Therefore, the presence of the stronger association effect in CDLs than in petroleum fractions leads to inaccurate estimations of viscosities for CDLs.…”

“…The increased concentration of large complexed ions formed in the transition from the hydrogen-bonded complexes (ÀOÀH 3 3 3 NÀ) to the protontransfer complexes (ÀO À 3 3 3 H þ ÀNÀ) is partially responsible for the high viscosity. 22 Therefore, the presence of the stronger association effect in CDLs than in petroleum fractions leads to inaccurate estimations of viscosities for CDLs. The results showed that the existing correlations are unsatisfactory for the viscosity of CDLs; therefore, modification should be made when a petroleum model is applied to CDLs.…”