1. ABOUT THE DATASET -------------------- Title: Data for Crystallisation of a Homologous Series of Single and Mixed n-Alkanes (C16 – C23) from Representative Hydrocarbon Fuel Solvents. Creator(s): Alexander S. M. Jackson [1], Dhanesh Goberdhan [2], Peter J. Dowding [2] and Kevin J. Roberts [1*] Organisation(s): [1] School of Chemical and Process Engineering, University of Leeds, Leeds, LS2 9JT, UK [2] Infineum UK Ltd, Milton Hill Business and Technology Centre, Abingdon, OX13 6BB, UK Rights-holder(s):Unless otherwise stated, Copyright 2022 University of Leeds Publication Year: 2023 Description: The data presented in this article relates to the crystallisation of 8 single n-alkanes, C16H34 – C23H48 in representative diesel solvents dodecane and toluene, as well as a mixture of these 8-alkanes with a composition representative of real diesel fuel in the same solvents. For the single alkane systems, the data was collected over a range of 5 concentrations ranging from 0.09 – 0.311xi, depending upon the system, and 4 concentrations for the 8-alkane mixture, 0.1 – 0.5 xi. Raw average crystallisation and dissolution points as a function of cooling rate (q) from a polythermal methodology are presented. Along with the equilibrium crystallisation and dissolution temperatures, van’t Hoff fitting parameters, relative critical undercooling (uc) values as a function of q as well as the calculated values of KG and αdet. Cite as: A. S. M. Jackson, D. Goberdhan, P. J. Dowding and K. J. Roberts1* (2023): Data for Crystallisation of a Homologous Series of Single and Mixed n-Alkanes (C16 – C23) from Representative Hydrocarbon Fuel Solvents. University of Leeds. https://doi.org/10.5518/1299 Related publication: Alexander S.M. Jackson, Dhanesh Goberdhan, Peter J. Dowding, Kevin J. Roberts, Solution Crystallisation of Single and Mixed n-Alkanes, within the Homologous Series C16 to C23 from Representative Hydrocarbon Fuel Solvents, Fluid Phase Equilibria, 2022, 113705 (Accepted) Alexander S.M. Jackson, Dhanesh Goberdhan, Peter J. Dowding, Kevin J. Roberts, Data for Crystallisation of a Homologous Series of Single and Mixed n-Alkanes (C16 – C23) from Representative Hydrocarbon Fuel Solvents, Data in Brief, 2023 (Submitted) Contact: K.J.Roberts@leeds.ac.uk 2. TERMS OF USE --------------- Copyright 2023 University of Leeds. Unless otherwise stated, this dataset is licensed under a Creative Commons Attribution 4.0 International Licence: https://creativecommons.org/licenses/by/4.0/.] 3. PROJECT AND FUNDING INFORMATION ---------------------------------- Title: The Nucleation Mechanism of Diesel Fuels within Fractionation Driven Crystallisation Dates: September 2017 - March 2023 Funding organisation: EPSRC, Infineum UK Ltd Grant no.: EP/L015285/1, EP/IO14446/1 and EP/IO13563/1 This research, which forms part of the doctoral studies of ASMJ “The Nucleation Mechanism of Diesel Fuels within Fractionation Driven Crystallisation”, was carried out at the EPSRC Centre for Doctoral Training in Complex Particulate Products and Processes (EP/L015285/1) as part of a collaborative project with Infineum Ltd., who we gratefully acknowledge. We also gratefully acknowledge the EPSRC for the support of the Molecules, Clusters and Crystals project (Grants EP/IO14446/1 and EP/IO13563/1). The analysis of polythermal nucleation data was inspired by Professor Dimo Kashchiev (Institute of Physical Chemistry, Bulgarian Academy of Sciences) during his sabbatical leave in Leeds (Leverhulme Trust, Grant F10100A) and we are most grateful to him for his insightful contribution to this research area. 4. CONTENTS ----------- File listing Data for Alkane Crystallisation.xlsx File contains data associated with the crystallisation of 8 alkanes from toluene and dodecane. Data is formatted into tables in 6 sheets with each sheet covering a type of data. Column "B" contains explanation of the data in adjoining tables. Sheet "Tc & Td" contains the average crystallisation and dissolution temperatures for 8 single and mixed alkanes in 2 solvents for 4-5 concentrations at 7 cooling rates. Sheet "Tc,l & Te" contains the equillibrium crystallisation and dissolution temperatures for 8 single and mixed alkanes in 2 solvents for 4-5 concentrations. Sheet "van't Hoff" contains the fitting parameters of the van't Hoff solubility model to the Te and concentration data for 8 single and mixed alkanes in 2 solvents. Sheet "Intermolecular Interactions" contains the data associated with the modelling of the interactions between a single solute and solvent molecule for 8 alkanes and 2 solvents. Sheet "KBHR" contains the data associated with the nucleation analysis from the KBHR approach. Sheet "Samples" contains the compositions of the 8 alkane mixtures and the provenance of the raw materials. 5. METHODS ---------- Experimental design, materials and methods Materials n-Alkanes, representative of the major constituents of diesel fuels, were chosen for this study, C16H34 – C23-H48. Toluene and dodecane were chosen as representative for both the aromatic and aliphatic solvent components of diesel fuels. A model 8-alkane mixture was constructed where the relative composition of C16H34 – C23H48 matched that of a real diesel fuel. Table 15 shows the relative composition of the 8-alkane mixture in mole fraction, Table 16 shows the summary of the raw materials used in this research. Equipment The polythermal crystallisation experiments were conducted using a Technobis Crystal16 crystallisation screening platform. This is a multicell crystalliser consisting of 16 individual cells which can take a 1.5mL vial of solution. 4 cells are grouped into a block, resulting in 4 blocks which can be individually temperature controlled via a Peltier heat exchanger linked to a refrigerated recirculating bath. The system can cool to ca. -15°C and heat to an upper limit of 100°C at a range of cooling rates from 0.1 - 10°C/min. A dry air purging system prevents condensation when cooling below sub-ambient temperatures. Each cell holds 1mL of solution in which crystallisation and dissolution can be followed as a function of temperature and time by turbidity via a transmission turbidity red laser source/detector, with each cell being magnetically agitated with a 2x7mm stirrer bar. Polythermal crystallisation experiments were also carried out on a Mettler Toledo DSC 1 with cryogenic cooler for the purpose of determining the thermodynamic parameters of an 8-alkane mixture. Samples were prepared around 10mg in mass in a sealed standard aluminium crucible. Experimental Procedure Solution Preparation All solutions were prepared on a 5mL scale as this was a sufficient volume to provide solution to fill 4 Crystal16 cells at once to provide a full run of cooling rates. For each alkane 5 concentrations were prepared, which were unique for each alkane but ranged overall from 0.09 - 0.311 xi. Solutes were weighed out using a balance of 0.01mg accuracy. 5mL of solvent was added using a Sartorius 500-5000uL mechanical pipette. Mixtures were heated on a hotplate with a magnetic stirrer to a temperature high enough that the solution completely dissolved and were left to homogenise at this temperature for 1 hour. A Sartorius 1-1000uL mechanical pipette was used to transfer 1mL of solution to a 1.5mL glass GC vial, in which a 2x7mm PTFE stirrer bar had been placed. 16 vials were filled with 4 concentrations in 4 vials each, providing an almost complete set of concentrations to run at 7 cooling rates on the Crystal16 In the case of the 8-alkane mixture pre-determined amounts of each alkane were weighed into a large dish. This mixture was then completely melted over a water-bath, with an inverted watch-glass placed over the mixture so that any condensation formed drained away from the mixture. After homogenising for 1 hour above its melting point, the mixture was weighed into vials and dissolved as described above. Polythermal Analysis Each block was set to follow a specific temperature program of heating and cooling at prescribed rates so that each concentration would be run at 0.25, 0.5, 1, 2, 3.2, 4 and 5°C/min. 4 blocks allowed 4 cooling rates to be run simultaneously on 4 different solution concentrations. Each temperature program would begin with heating to 40°C, with this temperature being held for 30 minutes to ensure complete dissolution. The sample was then cooled at the specified rate to -15°C, before being held at this temperature for 30 minutes to ensure the system stabilised, before heating back up at the same rate to 40°C. This cycle was repeated 4 times. From this the crystallisation temperature and dissolution temperature were determined, by fitting a Boltzmann[4] curve to the transition %T vs. temperature data and determining the temperature at 99%T for Tdiss and 90%T for Tcryst from the equation of the fit. This data was then calibrated based on the linear response of the temperature of a thermocouple inside a cell containing only solvent, and the Crystal16 measured temperature for each block. With the correct block’s calibration being applied to the data that was collected on that block and with that solvent. This data was then analysed using the polythermal method of plotting average Tcryst (Tc) and average Tdiss (Td) vs cooling rate to determine the equilibrium values at q=°C/min, Tc,l and Te. The solubility was modelled with the Van’t Hoff equation along with the solute’s ideal solubility. The nucleation mechanism and associated kinetic parameters were determined using the KBHR approach. Computational Methods Intermolecular interactions were determined using dedicated software that uses grid-based modelling with a systematic search algorithm to investigate the intermolecular interactions between a target and probe molecule by calculating the interaction energy between the two at each point on a user defined grid. The molecules were constructed and optimised using the Forcite module of Materials Studio before being run in the grid search. For both solvents the optimal grid was determined by establishing the number and energy of interactions found as a function of grid size. Ideally a grid with infinitely high resolution would be used however software and hardware limited the total number of grid points to less than approx 1000. As a result, the optimal spacing of these grid points was determined to find the strongest interactions. In the case of Toluene this was a 30-30-30 (XYZ) size grid with 8-11-8 (UVW) and 972 grid points, for dodecane this was 20-20-30 (XYZ) Å size grid with 7-11-8 (UVW) grid lines. The Euler angles in all cases were 30° at all grid points. XYZ represents the physical size of the grid, UVW represents the number of grid lines in a specific direction, XYZ, from the origin