Junliang Wang

Depolymerization of polycarbonate with catalyst in hot compressed water in fused silica capillary and autoclave reactors

Depolymerization of polycarbonate (PC) with the catalyst manganese acetate (Mn(Ac)2) was studied in hot compressed water (HCW) using a stainless steel batch autoclave reactor and a fused silica capillary reactor (FSCR). The phase behavior of PC in water with or without Mn(Ac)2 during the heating, reaction and cooling processes was observed. The phase behavior indicated that the dissolution time of PC in HCW to form a homogeneous liquid solution was effectively reduced by adding Mn(Ac)2 as a catalyst. For the reaction in the autoclave reactor, the main liquid products were bisphenol A (BPA) and phenol. The effects of operating parameters such as catalyst concentration (ratio of Mn(Ac)2 to PC) (0–2.5%), temperature (250–280 °C) and reaction time (5–60 min) on depolymerization of PC were investigated in the autoclave reactor. The optimal experimental conditions were found to be a temperature of 280 °C, reaction time of 20 min with the ratio of Mn(Ac)2/PC of 2.0%, giving yields of BPA and phenol of 55.25% and 18.63%, respectively. The main gaseous product CO2 in the FSCR was qualitatively and quantitatively analyzed by Raman spectroscopy. A reaction pathway for catalytic depolymerization of PC in HCW was proposed based on the experimental results.

Hydrothermal liquefaction phase behavior of microalgae & model compounds in fused silica capillary reactor

ABSTRACT 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 when Dunaliella tertiolecta used 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 the Dunaliella 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.