Co-liquefaction of Elbistan lignite and duckweed (Lemna minor)

In this study, direct liquefaction efficiency of Elbistan lignite and biomass (duckweed) was investigated under catalytic and non-catalytic conditions The purpose of liquefaction is to increase the (H/C)atomic ratio of the fuel. Since the (H/C)atomic ratio of biomass is higher than lignite, using biomass and coal together instead of coal alone in direct liquefaction studies has a synergistic effect on the liquefaction efficiency and the reduction of environmental pollution. Therefore, duckweed (Lemna minor) was used as biomass in this study. In the first stage of the study, liquefaction process was carried out in non-catalytic conditions under N2 atmosphere with 400 oC temperature and 60 min reaction time conditions in order to determine the lignite particle size and according to the results obtained appropriate particle size was found to be 0,25 mm. In catalytic liquefaction processes, Borax Pentahydrate (Etibor-48, Na2O.2B2O3.5H2O), Etidot-67 (Na2B8O13.4H2O), Boron Oxide (B2O3, in glassy and amorphous form), Anhydrous Borax (Etibor-68, Na2O. 2B2O3), Sodium Perborate Tetrahydrate (NaBO2.H2O2.4H2O) and Borax Decahydrate (Crystal, Na2O.2B2O3.10H2O)) were used as catalyst type. Borax Decahydrate (Crystal, Na2O.2B2O3.10H2O) was chosen as the appropriate catalyst type according to the total conversion and liquid product yields obtained as a result of the liquefaction process. In liquefaction processes, the catalyst was added to the reaction medium by physical mixing. The effects of solvent/solid ratio, biomass/coal ratio, mixing speed, initial nitrogen gas pressure, reaction time and reaction temperature on total conversion and liquid product yield were investigated. According to the results regarding the appropriate process parameters, the solvent/solid ratio is 3/1, the biomass/coal ratio is 1/1, the mixing speed is 800 rpm, the initial nitrogen gas pressure is 20 bar, the reaction time is 60 min and the reaction temperature is 400 oC. In catalytic conditions, the liquefaction efficiency obtained when lignite and biomass are used together were found to be higher than non-catalytic conditions. The total conversion obtained under these conditions was found to be 79,43 %, PAS + AS efficiency 27,53 %, oil+gas yield 51,90 % and gas volume 22,0 L. The liquid products obtained at the end of the liquefaction process were separated into soluble products (Preasphalten, Asphaltene and Oil) by the solvent extraction method. Oils from soluble products were analyzed by gas chromatography - mass spectrometry (GC-MS). According to the results of GC-MS analysis, it was seen that the oils obtained consisted of aromatic and polyaromatic compounds to a great extent, these compounds mainly consist of tetralin and its derivatives, naphthalene and derivatives, benzene and derivatives, azulene. The calorific value of the oil obtained as a result of the liquefaction process carried out under appropriate process conditions was 10.088 cal/g, and the calorific value of the crude oil obtained from Batman Refinery was 10.124 cal/g. According to GC-MS and calorific value analysis of liquefaction products, it can be argued that the oils obtained in liquefaction are approximately similar to crude oil and its fractions.