Co-cracking of bio-oil distillate bottoms with vacuum gas oil for enhanced production of light compounds

• Published in: Journal of analytical and applied pyrolysis Vol. 132; pp. 65 - 71
• Main Authors: Choi, Yong S., Elkasabi, Yaseen, Tarves, Paul C., Mullen, Charles A., Boateng, Akwasi A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2018
• Subjects: alkanes; alkenes; Bio-oil; biomass; biorefining; BTEX (benzene, toluene, ethylbenzene, xylene); carbon; catalysts; Coprocessing; Cracking; Delayed coking; distillation; Fast pyrolysis; fuel oils; gases; guayule; hydrogen; mixing ratio; molecular weight; oil and gas industry; oxygen; Panicum virgatum; petroleum; pyrolysis; pyrolysis oils; Residues; Spirulina; thermal cracking; viscosity; zeolites; Cracking; Residues; Fast pyrolysis; Coprocessing; Bio-oil; Delayed coking
• ISSN: 0165-2370; 1873-250X
• DOI: 10.1016/j.jaap.2018.03.014

•Tail-gas reactive pyrolysis bio-oil distillate residues were co-reacted with vacuum gas oil (VGO) using py-GCMS.•Zeolite catalysts were evaluated for efficacy (HZSM-5, Y-zeolite).•Blends of switchgrass-based residues/VGO produced up to three-fold increases of aromatic compounds.•Guayule and spirulina-based residue blends with VGO produced up to 50% increases in light olefin compounds. Seamless co-processing of pyrolysis bio-oil within existing petroleum refineries is the most synergistic and economic way to improve biorefinery output. Coprocessing bio-oil with vacuum gas oil (VGO) is one logical pathway. Bio-oil has a viscosity and molecular weight range similar to that of VGO, and the hydrogen-rich nature of VGO can chemically complement the bio-oil hydrogen deficiency. Distillation of biomass pyrolysis oils produces solid residues with a significant fraction of fixed carbon and heavy volatiles. Maximization of yields of light compounds like olefins and gasoline-range aromatics are crucial for both attainment of desired product output levels as well as to follow methods that mimic petroleum-based methods and chemistries. Herein we discuss a systematic study on the additive coprocessing of specific bio-oil distillation bottoms with VGO. Tail-gas reactive pyrolysis (TGRP) bio-oils from spirulina, switchgrass, and guayule biomasses were distilled, and their bottoms were subject to analytical experiments in mixtures with VGO over different zeolite catalysts (no catalyst, HZSM-5, Y-zeolite). Switchgrass-based bottoms exhibit greater hydrogen deficiency and higher oxygen content compared with that of spirulina or guayule. Switchgrass-based bottoms, with or without VGO, produced more aromatics and less olefins and alkanes, compared with spirulina or guayule bottoms. When compared across different mixing ratios, thermal cracking of a 10:1 guayule/VGO mixture resulted in higher aromatics yields than even the VGO by itself. Addition of more VGO up to a 1:1 ratio of VGO/switchgrass bottoms nearly tripled the production of BTEX compounds. For hydrogen-rich bottoms spirulina and guayule, LPG-range olefins yields increased nearly 50% for 1:1 VGO/bottoms blends, compared with theoretical yields.