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Structurally unique ionic liquids phosphonium-phosphate and phosphonium-thiophosphate, having both phosphorus based counter ions, in which the anionic part is represented by di-aryl phosphate or di-aryl thiophosphate and cations been tetraalkylphosphonium groups, behave differently in terms of their NMR behaviour. While phosphonium-phosphates show significant changes in its 1 H, 13 C and 31 P NMR chemical shifts vis. á vis. corresponding chemical shifts for a physical mixture of tetraalkylphosphonium bromide and di-aryl phosphate, phosphonium-thiophosphates behave almost similarly in terms of NMR with their synthetic precursors, hence indicating phosphate-phosphonium interaction has a significant covalent component resembling more to a liquid ion pair while thiophosphate-phosphonium interaction is principally ionic in nature. Translational diffusion behavior studied by PFGSE-NMR experiments and ionic conductivities of these ionic liquids in chloroform solution corroborated the hypothesis. The effect of variable alkyl chain length in phosphonium cation is effectively observed in the extent of ion association. Results of this study may provide insight into the solution state behavior of these ionic liquids, would help to classify those in terms of their strength of ion association and thus potential application thereof. [ABSTRACT FROM AUTHOR]

Science of maintaining a balance between reactivity and fluidity during mesophase formation, thus production of needle coke from FCC-DO has been described in terms of correlating several structural parameters of feed to the quality of needle coke produced. [Display omitted] • A study relating str. parameters of FCC-DO with quality of produced needle coke in DCU has been carried out. • The av. str. prmts. of FCC-DO provided in-depth understanding about the science of maintaining balance between reactivity and fluidity during needle coke formation. • The role of optimum combinations of various prmts. in feeds providing good quality of cokes has been studied. • Str. prmts. have been classified into two categories according to their role- either the facilitators or obstructers to good needle coke production. A comprehensive study relating structural parameters of carbonaceous feedstock with quality of produced needle coke in delayed coker unit (DCU) has been carried out. The used feedstock, clarified oil (CLO), was studied by various analytical techniques; the results of which was then correlated with needle coke properties. The average structural parameters of CLO as determined by q-1H and q-13C NMR, class-wise distribution of aromatics by HPLC-PDA-ELSD and molecular weight distribution (MWD)-cum-estimation of individual components possessing high needle coke potential from HRMS provided in-depth understanding about the science of maintaining balance between reactivity and fluidity during needle coke production. It was observed that presence of an optimal amount of saturates and all of mono-, di-, tri-, tetra-, penta- aromatics in an optimum ratio help producing good quality needle coke. The study also reveals that while the presence of methyl-substituted aromatics and multimodal MWD are desirable, presence of long chain-substituted aromatics, heteroatoms, non-linear polyaromatics with high bay regions and uniformity in MWD are detrimental to a better mesophase formation and uni-axial rearrangement of molecules during delayed coking process. The quality of needle coke was determined, in addition to CTE values, by crystallinity index using XRD and SEM analysis. Few compositional features of CLO that appears to be critical in determining needle coke character are listed to rate them for their needle coke potential. [ABSTRACT FROM AUTHOR]

A comprehensive study using conventional 1H, 31P NMR as well as advanced PFGSE-DOSY NMR on structurally unique ionic liquids (ILs) having, in one hand, both phosphorus based counter ions called tetraalkylphosphonium diarylphosphate (PP)/diarylthiophosphate (PTP), and on the other hand polyisobutylenesuccinimide-tethered tetraalkylammonium diarylphosphate (PIBSI-P)/diarylthiophosphate (PIBSI-TP) has been carried out in order to establish their structures and interactions between the counter ions in chloroform solution. It has been noticed that the ion association increases significantly by increasing the cationic alkyl chain length in PP and moderately in PTP owing to stronger hydrophobic interactions. However in polymeric ionic liquids (POILs), PIBSI-P and PIBSI-TP, it is the hydrophobic effect of the long chain PIB backbone which dominates the course, effect of cationic alkyl chain length was not much observed. The ILs were synthesized either from an anion exchange reaction between tetraalkylphosphonium bromides and diarylphosphate/thiophosphate (former) or from a reaction of same diarylphosphate/thiophosphate with tetraalkylammonium bromide derived from polyisobutylene succinic anhydride (PIBSA) (later). The synthetic procedure is very simple, efficient and high yielding. The developed ILs are found to be effective for application as lubricant additive. Synergistic ion association-cum-hydrophobic interaction holds the counter ions together in POILs. Unlabelled Image • POILs PIBSI-P & PIBSI-TP behave differently while compared to PPs & PTPs in terms of their NMR behavior. • The concept of ion association dominates in PP & PTP whereas the effect is predominantly hydrophobic in POILs. • Diffusion behavior confirmed that comparatively smaller anion is encapsulated by long chain polymer-tethered cation in POILs. • It is the synergistic ion association-cum-hydrophobic interaction which holds the counter ions together in POILs. • The synthesized novel IL and POILs are found to be potential as a lubricant additive. [ABSTRACT FROM AUTHOR]