Entrained Flow Gasification of Polypropylene Pyrolysis Oil.

Petrochemical products could be produced from circular feedstock, such as waste plastics. Most plants that utilize syngas in their production are today equipped with entrained flow gasifiers, as this type of gasifier generates the highest syngas quality. However, feeding of circular feedstocks to an entrained flow gasifier can be problematic. Therefore, in this work, a two-step process was studied, in which polypropylene was pre-treated by pyrolysis to produce a liquid intermediate that was easily fed to the gasifier. The products from both pyrolysis and gasification were thoroughly characterized. Moreover, the product yields from the individual steps, as well as from the entire process chain, are reported. It was estimated that the yields of CO and H2 from the two-step process were at least 0.95 and 0.06 kg per kg of polypropylene, respectively, assuming that the pyrolysis liquid and wax can be combined as feedstock to an entrained flow gasifier. On an energy basis, the energy content of CO and H2 in the produced syngas corresponded to approximately 40% of the energy content of the polypropylene raw material. This is, however, expected to be significantly improved on a larger scale where losses are proportionally smaller.

Production of an upgraded lignin-derived bio-oil using the clay catalysts of bentonite and olivine and the spent FCC in a bench-scale fixed bed pyrolyzer.

Lignocellulosic biomass is an abundant renewable energy source that can be converted into various liquid fuels via thermochemical processes such as pyrolysis. Pyrolysis is a thermal decomposition method, in which solid biomass are thermally depolymerized to liquid fuel called bio-oil or pyrolysis oil. However, the low quality of pyrolysis oil caused by its high oxygen content necessitates further catalytic upgrading to increase the content of oxygen-free compounds, such as aromatic hydrocarbons. Among the three different types of lignocellulosic biomass components (hemicellulose, lignin, and cellulose), lignin is the most difficult fraction to be pyrolyzed because of its highly recalcitrant structure for depolymerization, forming a char as a main product. The catalytic conversion of lignin-derived pyrolyzates is also more difficult than that of furans and levoglucosan which are the main pyrolysis products of hemicellulose and cellulose. Hence, the main purpose of this study was to develop a bench-scale catalytic pyrolysis process using a tandem catalyst (both in-situ and ex-situ catalysis mode) for an efficient pyrolysis and subsequent upgrading of lignin components. While HZSM-5 was employed as an ex-situ catalyst for its excellent aromatization efficiency, the potential of the low-cost additives of bentonite, olivine, and spent FCC as in-situ catalysts in the Kraft lignin pyrolysis at 500 °C was investigated. The effects of these in-situ catalysts on the product selectivity were studied; bentonite resulted in higher selectivity to aromatic hydrocarbons compared to olivine and spent FCC. The reusability of HZSM-5 (with and without regeneration) was examined in the pyrolysis of lignin mixed with the in-situ catalysts of bentonite, olivine, and spent FCC. In the case of using bentonite and spent FCC as in-situ catalysts, there were no obvious changes in the activity of HZSM-5 after regeneration, whereas using olivine as in-situ catalyst resulted in a remarkable decrease in the activity of HZSM-5 after regeneration.

Enhanced stability of bio-oil and diesel fuel emulsion using Span 80 and Tween 60 emulsifiers.

Bio-oil (biomass pyrolysis oil) has some undesirable properties (e.g., low heating value, high corrosiveness, and high viscosity) that restrain its direct use as a transportation fuel. The emulsification of bio-oil and diesel is an effective and convenient method to use bio-oil in the present transportation fuel infrastructure. The addition of an emulsifying agent (emulsifier or surfactant) to two immiscible liquids of diesel and bio-oil is an important step in emulsification. The hydrophilic-lipophilic balance (HLB) value, according to the chemical structure and characteristics of the emulsifier, is a key parameter for selecting a surfactant. In this study, an ether treatment of raw bio-oil was carried out to separate the ether-soluble fraction of bio-oil from its heavy (dark brown and highly viscous) fraction, and the ether-extracted bio-oil (EEO) was processed further for emulsification into diesel fuel. The effects of the HLB value of the emulsifier and the contents of EEO, diesel, and emulsifier on the stability of the EEO/diesel emulsion were investigated. To optimize the HLB value of the emulsifier, different HLB values (4.3-8.8), which were prepared by mixing different amounts of Span 80 and Tween 60 as surfactants, were used for the EEO and diesel emulsification. A HLB value of 7.3 with diesel, EEO, and emulsifier contents of 90, 5, 5 wt%, and 86, 7.4, 6.6 wt% resulted in EEO/diesel emulsions (without phase separation) stable for 40 and 35 days, respectively. Measurement of the high heating value (HHV) of the emulsified fuels gave a 44.32 and 43.68 MJ/kg values for the EEO to emulsifier mass ratios of 5:5 and 7.4:6.6, respectively. The stability of emulsified EEO and diesel was verified by TGA and FT-IR methods.