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Separation and Hydroprocessing of HZSM-5 Catalytic Olive Mill Waste Sludge Bio-oil

Ma, Bingji, Agblevor, Foster
Energy & Fuels 2016 v.30 no.12 pp. 10524-10533
Fourier transform infrared spectroscopy, acetone, biofuels, catalysts, cyclohexanes, elemental composition, food processing wastes, gas chromatography-mass spectrometry, gel chromatography, methylene chloride, nickel, nuclear magnetic resonance spectroscopy, oils, oleic acid, olives, palmitic acid, pyrolysis, sludge, solvents, stable isotopes, temperature, viscosity
The catalytic effects of HZSM-5 during olive sludge pyrolysis on the product yields and chemical composition of the bio-oil produced were investigated. Three solvents of increasing polarity (cyclohexane < methylene chloride < acetone) were used to sequentially fractionate the HZSM-5 catalytic bio-oil at 500 °C into four fractions (cyclohexane fraction, methylene chloride fraction A, methylene chloride fraction B, and acetone fraction). The yields for the four fractions cyclohexane, methylene chloride A, methylene chloride B, and acetone were 26.8%, 11.6%, 20.0%, and 39.7%, respectively. The HZSM-5 catalytic bio-oil and noncatalytic pyrolysis bio-oil were characterized by Fourier transform infrared (FT-IR) spectrometry and ¹H and ¹³C nuclear magnetic resonance (NMR) spectrometry, and their organic elemental compositions and calorific values were also determined. Furthermore, major compounds in both bio-oils were identified by gas chromatography–mass spectrometry (GC–MS). Compared with the olive sludge pyrolysis bio-oil obtained without a catalyst, the HZSM-5 catalytic bio-oil had a lower viscosity and a higher calorific value. Chemical characterization revealed that hexadecanenitrile was the major component in the HZSM-5 catalytic bio-oil (23.8%), whereas oleic acid, ethyl oleate, and hexadecanoic acid were the dominant compounds in the noncatalytic bio-oil. Furthermore, the pyrolysis temperature strongly affected the yield of hexadecanenitrile, and most of the hexadecanenitrile could be obtained in a high purity by polarity-based separation plus silica gel column chromatography. Moreover, a series of experiments was conducted at varying temperatures, pressures, catalyst contents, and residence times to study the effects of these parameters on the hydrodeoxygenation reaction in a microreactor. As a result, HZSM-5 catalytic OMWS pyrolysis oil was successfully converted to HDO-upgraded oil. The experimental results indicated that the best performance conditions were 400 °C, 550 psi, 15% catalyst content, and 45-min reaction time for nickel catalytic hydroprocessing of biocrude leading to free-flowing oil.