Co-liquefaction Of Coal And Polypropylene In Supercritical Water

The phase behavior during co-liquefaction of coal andpolypropylene （PP） in a fused-silica capillary reactor （FSCR） wasobserved under a microscope. It provided evidence for the selection ofexperimental conditions for the next experiment. The co-liquefaction ofYanzhou coal and PP in supercritical water （SCW） was carried out in a50mL batch stainless steel autoclave reactor. Polymer ratio （0⁵0%）, theratio of water to reactant （20:1and30:1）, reaction temperature （360⁴30℃）, reaction time （30¹20min）, and the use of different catalysts（Mn（Ac）2and Fe-S） were used to investigate the effects on the conversionand yield of oil and gas （O+G）. The vapor products and the aqueousproducts were collected and analyzed qualitatively by FT-IR and HPLC,respectively. The co-liquefaction residues were analyzed by FT-IR andTG. The co-liquefaction mechanism of coal and PP in SCW was apreliminary investigation.The phase behavior of the co-liquefaction of coal and PP in SCW inthe FSCR was investigated during the heating, reaction and coolingstages. The phase behavior of coal and PP interacted with each other inthe process of co-liquefaction. PP swelled at134.4℃and intenerated at203.6℃. The gas bubble was generated at203.6℃and gathered at248.8℃during heating. The oil phase （i.e. yellow liquid observed bymicroscope） emerged at380℃while the oil phase separation occurred at147.1℃and then became a trail of opaque droplets at38.7℃or ambient temperature. The phenomenon did not appear in the process of coalliquefaction or PP liquefaction. The above results demonstrate that PPpromoted coal liquefaction as a hydrogen donor in SCW. It providedevidence for the selection of experimental conditions for the nextexperiment.Hydroquinone, resorcinol, phenol, paracresol and orthocresol weredetected in the aqueous phase by HPLC. The vapor phase consistedmainly of CO₂, CH₄, and C₂H₆, which was collected from the headspaceand analyzed qualitatively by FT-IR. The co-liquefied residues underdifferent reaction temperatures were analyzed by FT-IR. The resultsindicated that the peak of the C-O bonds and the C=C bonds in thearomatic ring decreased with the increasing reaction temperature andthese bonds became weaker with the addition of catalysts （Mn（Ac）2andFe-S）. The raw coal and the co-liquefied residues were analyzed by TGand the results indicated that the mass loss of the raw coal was higherthan that of co-liquefied residues.The co-liquefaction of coal and PP in SCW was carried out in abatch stainless steel autoclave reactor and the results are shown asfollows: The conversion and the yield of O+G increased with increasingpolymer ratio, increasing reaction temperature and prolonging thereaction time. It was also found that the ratio of water to reactant at20:1created a better conversion and yield of O+G than30:1. The optimalconditions of co-liquefaction in SCW are: a polymer ratio of50%, theratio of water to reactant at20:1, a reaction temperature of420℃, and areaction time of120min. The maximum conversion and the yield of O+Gwere70.92%and69.11%under the conditions, respectively.The effect of the same conditions on the conversion and the yield ofO+G with the different catalysts were investigated in the batch stainlesssteel autoclave reactor. The results indicated that the catalysts Mn（Ac）2 and Fe-S improved the co-liquefaction, and the time became shorter forthe maximum conversion and the yield of O+G to be reached. Theconversion and the yield of O+G increased with increasing reactiontemperature and prolonging reaction time. The optimal conditions ofco-liquefaction with catalyst in SCW are: a polymer ratio of50%, theratio of water to reactant at20:1, a reaction temperature of420℃, areaction time of45min and using the Fe-S catalyst. The maximumconversion and the yield of O+G were81.65%and75.71%, respectively.