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A fused silica capillary reactor combined with a heating/cooling stage, a microscope and a digital camera were used to investigate phase behavior during the hydrothermal liquefaction of microalgae (Dunaliella tertiolecta) and model compounds, including soya protein and glycine, starch, glucose and xylose, stearic acid and palmitic acid. Bubbles were generated at 246°C and disappeared at 360°C upon heating whenDunaliella tertiolectaused as feedstocks. Moreover, liquid products were generated at 300°C upon heating and oily liquid products began to separate out at 250°C upon cooling. The phase behavior of soya protein was similar to that of theDunaliella tertiolecta. Meanwhile, there only observed the bubbles generation during hydrothermal liquefaction of glycine. Heating the starch, glucose and xylose above 350°C generated black solids from carbonization. Stearic acid and palmitic acid only had the process of melting, dissolution, dispersion and precipitation. [ABSTRACT FROM AUTHOR]

The coliquefaction of coal and polystyrene (PS) in supercritical water (SCW) was carried out in a 50-mL batch stainless steel autoclave reactor, and the effects of the polymer ratio by weight (10–40%), reaction temperature (633.5–703.5 K), and reaction time (30–120 min) were investigated. The main products were analyzed qualitatively by Fourier transform infrared spectroscopy and high-performance liquid chromatography. The results show that polystyrene stimulates coal liquefaction as a hydrogen donor, and the synergistic effects during coliquefaction in SCW were confirmed. The conversion reached a maximum of 62.26% after 60 min at 673.5 K. The phase behavior during coliquefaction was observed in a fused silica capillary reactor using a combined microscope and video recorder system. [ABSTRACT FROM PUBLISHER]

Depolymerization of poly(butylene terephthalate) (PBT) in sub- and supercritical ethanol was performed both in a fused silica capillary reactor (FSCR) or a batch autoclave reactor. The phase behavior of PBT in ethanol during heating and cooling was studied in the FSCR under a microscope and captured by a digital camera. The results showed that PBT could dissolve in supercritical ethanol at 330 °C and form a homogeneous solution. Under autogenous pressure in the batch autoclave reactor, the effects of the ethanol/PBT mass ratio (8 g/2 g to 24 g/2 g), reaction temperature (200–280 °C) and reaction time (5–60 min) on depolymerization of PBT in sub- and supercritical ethanol were investigated. The main liquid products of depolymerization were identified and quantified as diethyl terephthalate (DET) and 1,4-butanediol (1,4-BD) by liquid chromatography mass spectrometry, gas chromatography mass spectrometry, and gas chromatography, respectively. PBT could be completely depolymerized at 240 °C in 60 min with an optimal ethanol/PBT mass ratio of 20 g/2 g (10:1). The highest yields of DET and 1,4-BD were 97.7% and 89.4%, respectively. Reaction kinetics analysis showed that the PBT depolymerization in sub-critical ethanol reaction was first order and activation energy was 38.8 kJ mol−1. A reaction pathway was proposed based on the experimental results. [ABSTRACT FROM AUTHOR]

Abstract: The co-liquefaction of coal and polypropylene or polystyrene in hot compressed water was carried out in a 50mL batch stainless steel autoclave reactor. The effects of the polymer ratios by weight (10–40%), reaction temperatures (360–430°C), and reaction time (30–120min) were investigated. The main products were analyzed qualitatively by Fourier transform infrared spectroscopy and high-performance liquid chromatography. The results showed that the synergistic effect was demonstrated and the polymer stimulated coal liquefaction as a hydrogen donor during co-liquefaction in hot compressed water. The reaction temperature was the critical factor because the process of oil and gas generating by hydro-cracking, ring-opening and hydrogenation clearly occurred above 400°C and the conversion and yield of oil and gas reached a maximum of 75.92% and 69.11% at 420°C, respectively. The phase behavior during co-liquefaction in a fused-silica capillary reactor was recorded by a microscope during the heating and cooling processes, demonstrating that polypropylene melted to form a liquid phase as the reaction medium and hydrogen donor during co-liquefaction. [Copyright &y& Elsevier]

Abstract: Poly(trimethylene terephthalate) (PTT) was depolymerized in hot compressed water (HCW) using a fused-silica capillary reactor (FSCR) and a batch-type autoclave reactor. The phase behavior of PTT in water during the heating, reaction, and cooling processes was observed in an FSCR with a microscope and recorded by a digital camera. It was found that PTT can dissolve in water in a temperature range of 240–320 °C and form a homogeneous aqueous solution. The effects of the reaction temperature (240–320 °C) and reaction time (5–60 min) were evaluated in a batch-type autoclave reactor. The main depolymerization products of PTT were terephthalic acid (TPA) and 1,3-propanediol (1,3-PDO), which were identified by liquid chromatography mass spectrometry, Fourier-transform infrared spectroscopy, gas chromatography mass spectrometry, Raman spectroscopy, and quantified by high-performance liquid chromatography as well as gas chromatography. Additionally, it was found that 1,3-PDO was converted to 1,5-dioxocane partly in the presence of TPA. Under optimal reaction conditions, i.e. 300 °C, 15 min, with a water/PTT ratio of 8:1 (w/w), complete depolymerization was achieved, and the yields of TPA and 1,3-PDO reached 90.5% and 69.03%, respectively. Based on the results, a reaction mechanism for PTT depolymerization in HCW was proposed. [Copyright &y& Elsevier]