Petroleum-based impregnating pitches were prepared from pyrolysis fuel oil (PFO) using a two-step heat treatment without a separation process. The pressurized heat treatment, the first step, was used to improve the properties of the pitches and enhance the product yield by promoting the cracking and polymerization of the components in the PFO. An atmospheric heat treatment as the second step was used only to synthesize the impregnating pitches from the liquid pitches prepared during the first step. The prepared impregnating pitches had the properties of a commercial petroleum-based impregnating pitch. The impregnation performance was evaluated by HT-XRD and an impregnation test. The HT-XRD results showed changes in the stacked structure of the pitches at the impregnation temperature. The bulk density of the carbon block was increased to 14.3% and the porosity was reduced by 10.3% after the impregnation/recarbonization process. The high reaction temperature during the first step induced the formation of quinoline insoluble (QI) components during the second step of the treatment, and the QI components adversely affected the impregnation process.

Structural characterization of pyrolysis fuel oil (PFO) was conducted via 1H NMR and 13C NMR to elucidate its molecular structure and evaluate the feasibility of using PFO as a raw material for mesophase pitch synthesis. The average structural parameters were calculated based on the data from elemental analysis and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS), as well as 1H NMR and 13C NMR data. The resultant structural features of PFO were compared with those of fluidized catalytic cracking-decant oil (FCC-DO). Based on the calculated parameters, we proposed average molecular models of PFO and FCC-DO. The molecular model of PFO showed that it had an aromatic structure consisting of three aromatic rings and one naphthenic ring fused with one pericondensed and two catacondensed aromatic carbons, as well as a short alkyl side chain (with only a methyl group). This structural feature of PFO demonstrated that it is highly favorable for use as a raw material for mesophase pitch synthesis. The empirical findings in this study provide an in-depth understanding of the molecular structure of PFO as well as FCC-DO and can offer insights for future research on the utilization of PFO and other petroleum heavy oils.

Pitch precursors affording excellent spinnability, high-level oxidation-resistance, and good carbonization yields were prepared by bromination–dehydrobromination of various ratios of pyrolyzed fuel oil and coal tar pitch. The pitches exhibited spinnabilities that were much better than those of pitches prepared via simple distillation. A pitch prepared using a 1:2 ratio of fuel oil and coal tar pitch exhibited the best tensile strength. Pitch fibers of diameter 8.9 ± 0.1 μm were stabilized at 270 °C without soaking time after heating at a rate of 0.5 °C/min and carbonized at 1100 °C for 1 h after heating at 5 °C/min. The resulting carbon fibers exhibited a tensile strength, elongation, Young’s modulus, and average diameter of 1700 ± 170 MPa, 1.6 ± 0.1%, 106 ± 37 GPa, and 7.1 ± 0.2 μm, respectively.

바이오오일은 고품질 화학물질로 이용이 가능하며 차세대 탄화수소 연료와 석유정제업 공급 원료로 사용할 수 있기 때문에 촉망받는 신재생에너지의 하나로 상당한 관심을 받고 있다. 또한 제올라이트는 급속열분해 과정에서 크래킹 반응을 효과적으로 촉진시켜 탈산소 반응을 증가 시키고 탄화수소가 많은 안정된 바이오오일을 만든다. 그래서 본 연구에서는 백합나무 바이오오일 품질개선을 위해 촉매열분해(Control, Blackcoal, Whitecoal, ZeoliteY 및 ZSM-5)를 적용하여 특성을 조사하였다. 바이오오일의 특성 변화를 알아보기 위하여 0.3～1.4 mm 크기의 백합나무 시료 500 g을 465℃에서 1.6초 동안 촉매열분해하여 바이오오일을 제조하였다. 촉매 조건 상태에서 바이오오일의 수율은 Control(54.0%)과 비교하여 Blackcoal(56.2%)를 제외하면, Whitecoal(53.5%), ZeoliteY (51.4%), 및 ZSM-5(52.0%)로 모두 감소했다. 수분 함량이 Control(37.4%)에서 촉매 처리후 37.4~45.2%로 증가함에 따라 발열량((High heating value)은 감소했다. 그러나 다른 다른 바이오오일 특성은 개선되었다. 촉매 적용 결과 바이오오일의 회분과 전산가(TAN)가 감소했고, 특히 수송연료로 중요한 특성인 점도는 Control cP(6,933) 에서 2,578 ~ 4,627 cP로 감소했다. 또한 ZeoliteY는 방향족탄화수소를 생산하고 점도를 개선시키는데 가장 효과적이였다.

Waste heavy oil sludge is considered oil waste that can be utilized as a renewable energy source. In this study, an attempt has been made to convert the mixtures of waste heavy oil sludge and sawdust into solid biomass fuels. The solid fuel pellets from waste heavy oil sludge and sawdust could be manufactured only with a press type pelletizer. The mixing ratios of waste heavy oil sludge and sawdust capable of manufacturing a solid fuel pellet were 30 : 70, 40 : 60 and 50 : 50. Ultimate analysis result revealed that these mixtures had C 50.21 ~ 54.77%, H 10.25 ~ 12.66%, O 25.84 ~ 34.83%, N 1.01 ~ 1.04%, S 1.03 ~ 1.07%. With increasing the mixing ratio of waste heavy oil sludge, the carbon and hydrogen content in solid fuel pellets were increased, while the oxygen content was decreased. But the nitrogen and sulfur content in solid fuel pellets did not show much difference. Their lower heating values ranged from 4,780 kg/kcal to 5,530 kg/kcal. The density of the solid fuel pellets was increased from 0.63 g/cm3 to 0.85 g/cm3 with increasing the mixing ratio of waste heavy oil sludge and the collapse of the solid fuel pellets occurred at a moisture content of 21%. As the mixing ratio of waste heavy oil sludge in the solid fuel pellets was increased, the reaction of thermal cracking became faster. It was also observed that the solid fuel pellets were thermally decomposed in two steps and their DTG curves were simpler with increasing the mixing ratio of waste heavy oil sludge. The activation energy and the pre-exponential factor of the solid fuel pellets ranged from 18.90 kcal/mol to 21.36 kcal/mol and from 201 l/sec to 8,793 l/sec, respectively. They were increased with increasing the mixing ratio of waste heavy oil sludge.

The large amount of waste oil sludge was generated from waste oil purification process, oil bunker, or the ocean plant. Although it has high calorific values, it should be treated as a designated waste. During the recycling process of construction and demolition wastes or the trimming process of woods, a lot of sawdust is produced. In this study, the feasibility of BOF (biomass and waste oil sludge fuel) as a renewable energy source was estimated. For manufacturing a BOF, a press type pelletizing was better than an extruder type and also 40 ~ 60% of mixing ratio in waste oil sludge was appropriate to produce a pellet. The pellet was 13 mm in diameter and 20 mm in length. There was no fixed carbon in waste oil sludge, and its carbon content and higher heating value were 63.90% and 9,110 kcal/kg, respectively. With an increse of mixing ratio of sawdust, the carbon content and heating value of the BOF were dropped, but fixed carbon content was increased. The heating value of BOF was in the range of 6,400 ~ 7,970 kcal/kg at the mixing ratio of 40 ~ 60% in waste oil sludge. It means that the BOF can be classified as the 1stgrade solid fuel. In TGA experiment carried out at heating rate of 10oC/min and under nitrogen atmosphere, thermal decomposition of sawdust was occurred in two steps, but waste oil sludge was destructed in one step. The initiated cracking temperature of sawdust and waste oil sludge was 300 and 280oC in respective and after 450oC the thermal decomposition process of sawdust was slowly progressed by 800oC in contrast to waste oil sludge. Thermal decomposition of waste oil sludge was finished around 600oC. It can be considered that this difference is due to the fixed carbon content. Thermal decomposition pattern for the pellet of mixing ratio over 50% in waste oil sludge was similar to that for waste oil sludge and thermal cracking was occurred between 300 and 350oC. As the mixing ratio of waste oil sludge in the pellet increased, the reaction of thermal cracking became fast.