Interactions and stabilisation of acetone, sulfur dioxide and water with 1-octyl-3-methylimidazolium tetrafluoroborate [OMIM][BF4] at low temperatures.
Interactions and stabilisation of acetone, sulfur dioxide and water with 1-octyl-3-methylimidazolium tetrafluoroborate [OMIM][BF4] at low temperatures.
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DOI：
10.1039/c7fd00146k
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发表时间：
2018
影响因子：
3.4
通讯作者：
Matthew Buckley;K. Syres;Robert G. Jones
中科院分区：
文献类型：
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作者：
Matthew Buckley;K. Syres;Robert G. Jones
用视线程序升温脱附法（LOSTPD）研究了水（H_2O）、二氧化硫（SO_2）和丙酮（（CH_3）_2CO）与离子液体（IL）1-辛基-3-甲基咪唑四氟硼酸盐[OMIM][BF_4]之间的相互作用.在90 K下，通过物理气相沉积法用多层小分子物质（从气相吸附）沉积多层IL。然后进行LOSTPD，其中小分子物质首先从混合多层解吸，然后在较高温度下从金表面解吸IL。IL具有较高的脱附活化能126（6）kJ mol-1。纯丙酮的脱附活化能为38（2）kJ mol ~（-1），当在90 K下预吸附在离子液体的上覆多孔层下时，其活化能增加到45-61 kJ mol ~（-1）。稳定的丙酮被认为与含有离子部分的孔有关。还观察到失稳的丙酮，并认为其来源于含有辛基链的孔。稳定化的丙酮的量与IL的量成比例，即每IL离子对约1.1个分子。SO2和H2O与IL在90 K下共吸附，导致两者的紧密混合物。对于纯SO2，解吸能为32（2）kJ mol-1，当相对浓度高达6个SO2分子/IL离子对时，解吸能增加到40-52 kJ mol-1。在纯水中，无定形冰和结晶冰的活化能分别为49（5）kJ mol ~（-1）和43（1）kJ mol ~（-1）。当与IL共吸附的稳定化能量为42-49 kJ mol-1，但高达505个水分子每IL离子对可以稳定到一定程度。讨论了这些相互作用的脱附机理和原因。
The interactions between three small molecules, water (H2O), sulfur dioxide (SO2) and acetone ((CH3)2CO), with the ionic liquid (IL) 1-octyl-3-methylimidazolium tetrafluoroborate, [OMIM][BF4], have been determined using line of sight temperature programmed desorption (LOSTPD) from a gold surface. Multilayers of the IL were deposited by physical vapour deposition with multilayers of the small molecular species (adsorbed from the gas phase) at 90 K. LOSTPD was then carried out with the small molecular species desorbing first from the mixed multilayer, followed at higher temperatures by desorption of the IL from the gold surface. The IL had a high activation energy for desorption of 126(6) kJ mol-1. Pure acetone showed a desorption activation energy of 38(2) kJ mol-1, which increased to 45-61 kJ mol-1 when it was pre-adsorbed below an overlying porous layer of the ionic liquid at 90 K. The stabilised acetone is thought to be associated with pores containing ionic moieties. Destabilised acetone was also observed and thought to originate from pores containing octyl chains. The quantity of stabilised acetone scaled with the amount of IL, being ≈1.1 molecules per IL ion pair. SO2 and H2O were co-adsorbed with the IL at 90 K leading to an intimate mixture of the two. For pure SO2 the desorption energy was 32(2) kJ mol-1, which increased to 40-52 kJ mol-1 for relative concentrations up to 6 SO2 molecules per IL ion pair. For pure water the activation energies were 49(5) kJ mol-1 and 43(1) kJ mol-1 for amorphous and crystalline ice respectively. When co-adsorbed with the IL the stabilisation energies were 42-49 kJ mol-1, but up to 505 water molecules per IL ion pair could be stabilised to some degree. The desorption mechanisms and the reasons for these interactions are discussed.