2-Hexyne is a potential sulfur-free odorant for liquefied petroleum gas (LPG). In this study, saturated vapor pressure of 2-hexyne at 273.14-313.14 K, and bubble point pressure for three binaries, ethane–2-hexyne, propane–2-hexyne and butane–2-hexyne were measured using a static apparatus at 273.15, 303.15 and 313.15 K. The attractive parameter in the Peng–Robinson (PR) equation of state was re-determined for 2-hexyne using the saturated vapor pressure data. The attractive parameters and the excluded volumes in the PR equation were also re-determined for ethane, propane and butane using the saturated vapor pressure and liquid density data. The binary parameters were evaluated by fitting the bubble point pressure data for the three binaries. Quaternary vapor-liquid equilibrium was estimated for 45.00 kg of LPG, with the mass ratio of ethane : propane : butane = 0.6000 : 97.07 : 1.700 containing 50.00 ppm of 2-hexyne, in a household LPG cylinder with inner volume of 117.50 L. The mole fraction of 2-hexyne was evaluated as 3.939 × 10^–9 in the vapor phase at 273.15 K, and increased by 2.49 times and 3.40 times at 303.15 K and 313.15 K, respectively.

The thermal behaviors of ash components in three Vietnamese coals, anthracite from Quang Ninh (QN) province, bituminous coal from Thai Nguyen (TN) province, and brown coal from Lang Son (LS) province, were investigated using XRD, TG-DTA, and TEM measurements. QN and LS coals had very high SiO₂ and Al₂O₃ contents and low CaO content. TN coal had high CaO content and low SiO₂ and Al₂O₃ contents. The weight losses of QN, TN, and LS coals were 91, 84, and 77 % at 1200 °C under an air atmosphere, respectively. Kaolinite in SiO₂ and Al₂O₃-rich QN and LS raw coals was transformed into mullite through illite after heat treatment under an air atmosphere. Quartz was found in all QN and LS ashes. Calcite in CaO-rich TN is considered to change to anhydrite and lime after heat treatment under an air atmosphere. Pyrite in TN and LS raw coals was oxidized to hematite after heat treatment. The needle-like crystals seen in QN and LS coals are likely to be illite, although those in TN may be calcite based on the XRD and TEM results.

Utilization of visible light for the selective aerobic oxidation of organic molecules has the potential to provide an environmentally-friendly route for the synthesis of chemicals. Dye-sensitized photocatalysts are effective for the reaction under visible-light irradiation. The aggregated dyes have different molecular interactions in the excited states from the monomer; however, the effect of the aggregation on the photocatalytic activity has not been investigated in detail. In the present work, we prepared titanium dioxide (TiO₂) photocatalysts modified with tetrakis(4-carboxyphenyl)porphyrin (TCPP) dye and changed the aggregation states of TCPP by an adsorption method. The change of the Soret band shape in the diffuse-reflectance UV-vis spectra indicated that the aggregated TCPP was formed on the TiO₂ surface at high TCPP loadings. The photocatalytic activity of the TCPP-modified TiO₂ photocatalysts was investigated using photocatalytic oxidation of benzyl alcohol in air under visible light. Using the optimized reaction conditions, we found that there is a strong positive correlation between the initial reaction rate and the absorption amount of the visible light even in the different aggregation states. The result indicated that the aggregation of the TCPP molecules reduced the light absorption and thus decreased the photocatalytic activity.