Catalytic conversion of biomass-derived feedstocks into olefins and aromatics with ZSM-5: the hydrogen to carbon effective ratio

Abstract

Catalytic conversion of ten biomass-derived feedstocks, i.e. glucose, sorbitol, glycerol, tetrahydrofuran, methanol and different hydrogenated bio-oil fractions, with different hydrogen to carbon effective (H/C eff ) ratios was conducted in a gas-phase flow fixed-bed reactor with a ZSM-5 catalyst. The aromatic + olefin yield increases and the coke yield decreases with increasing H/C eff ratio of the feed. There is an inflection point at a H/C eff ratio ¼ 1.2, where the aromatic + olefin yield does not increase as rapidly as it does prior to this point. The ratio of olefins to aromatics also increases with increasing H/ C eff ratio. CO and CO 2 yields go through a maximum with increasing H/C eff ratio. The deactivation rate of the catalyst decreases significantly with increasing H/C eff ratio. Coke was formed from both homogeneous and heterogeneous reactions. Thermogravimetric analysis (TGA) for the ten feedstocks showed that the formation of coke from homogeneous reactions decreases with increasing H/C eff ratio. Feedstocks with a H/C eff ratio less than 0.15 produce large amounts of undesired coke (more than 12 wt %) from homogeneous decomposition reactions. This paper shows that the conversion of biomassderived feedstocks into aromatics and olefins using zeolite catalysts can be explained by the H/C eff ratio of the feed.

Kinetics and reaction chemistry for slow pyrolysis of enzymatic hydrolysislignin and organosolv extracted lignin derived from maplewood

“…67, 68 Most biomass feedstocks have H/C eff ratios lower than 0.5 due to high oxygen contents while petroleum-based feedstocks have a value between 1-2. 69 The Maplewood has a low value, 0.06 due to high oxygen content. The organosolv lignin has H/C eff ratio five times that of original Maplewood.…”

Regional differences in the economic feasibility of advanced biorefineries: Fast pyrolysis and hydroprocessing

“…3 production (so-called drop-in biofuels because of their compatibility with the existing transportation fuel infrastructure) (Holmgren et al, 2008) and commodity chemicals production (Vispute et al, 2010;Zhang et al, 2011).…”

Aromatic Hydrocarbon Generation from a Simulated Bio-oil Fraction by Dual-stage Hydrogenation-cracking: Hydrogen Supply and Transfer Behaviors

“…The direct dehydration of CPOL produced cyclopentene and it could be cracked into lighter olefins, which then underwent aromatization. For the conversion of PDOL, because of the double-hydroxyl structure, some decarbonylation and decarboxylation occurred (Zhang et al 2011). However, according to the result of HPO hydrogenationcracking, dehydration still predominated in the PDOL cracking and complete deoxygenation was achieved to produce light olefins for aromatization.…”

“…However, direct cracking of bio-oil faces problems of low aromatic hydrocarbon yield and severe coking (Vitolo et al 1999). There are two main reasons for the coke (carbonaceous deposit) formation: the presence of large molecular weight compounds in bio-oil, such as phenolic oligomers (pyrolytic lignin), which are nonvolatile and have low cracking reactivity, resulting in easy carbonaceous deposition in the catalytic bed (Valle et al 2010); and the hydrogen-poor composition, namely the high unsaturation degree that leads to the low integral H/C ratios of final products and also favors the formation of coke (Zhang et al 2011).…”