Two-Step Pyrolysis Process for Producing High Quality Bio-oils

Abstract

A newly developed two-step pyrolysis process for the fractionation of lignocellulosic biomass components into sugar-rich and lignin-derived rich bio-oils by using pinewood as the feedstock has been studied. In the first step, biomass is pyrolyzed between 300°C and 350 o C decomposing cellulose and hemicellulose fibers to produce bio-oil having significantly higher selectivities towards sugars and lower selectivities towards low molecular weight oxygenated compounds, such as organic acids, aldehydes, and ketones than those of bio-oil produced from the conventional one-step pyrolysis at 500 o C. In the second step, the lignin-rich biomass remaining was pyrolyzed in the presence of HZSM-5 catalyst to produce aromatic-rich bio-oil with low selectivity towards oxygenated compounds. Comparison with the conventional one-step 500°C catalytic pyrolysis showed the advantage of biomass "heat pretreatment" in the first-step pyrolysis, which promoted the decomposition of lignin to monomeric phenolic compounds which were more easily converted to aromatics. Application of catalytic pyrolysis to both steps produced two bio-oil fractions, combined, having significantly higher selectivity towards aromatics and lower selectivity towards oxygenated compounds. Over the conventional one-step pyrolysis, by decomposing biomass components separately at different pyrolysis temperature levels, the developed two-step pyrolysis process allows more flexibility for producing bio-oils with specific composition of chemical moieties that meet the requirements for their desired end uses.

Pyrolysis of the Cellulose Fraction of Biomass in the Presence of Solid Acid Catalysts: An Operando Spectroscopy and Theoretical Investigation

“…Levoglucosany ield can be altereda nd secondary reactions suppressed significantly by optimizing the following experimental variables:s ample size, carrier/sweep gas rate, heating rate, and biomass moisture content. [16,17,[60][61][62][63][64][65] It was demonstrated that H-ZSM-5, with aS i/Al ratio of roughly3 0, gives the best selectivity to aromaticsc omparedt oa morphous silica-aluminas, other zeolites,a nd other supported metal or metal oxide catalysts. Thus, slow heating rates maximize the amount of useable levoglucosan.…”

“…Selectivity to aromatic products or value-added chemicals was determined to be af unction of catalyst/biomass weightr atio, heating rate, pore size, reactorc onfiguration, and reactiontemperature. [16,17,[60][61][62][63][64][65] It was demonstrated that H-ZSM-5, with aS i/Al ratio of roughly3 0, gives the best selectivity to aromaticsc omparedt oa morphous silica-aluminas, other zeolites,a nd other supported metal or metal oxide catalysts. [60,63,[66][67][68][69][70][71] However, physical mixtures of Siral 5, an amorphous silica-alumina, and H-ZSM-5 was shown to have as ynergistic effect on the yield of aromaticsr elative to either catalystalone.…”

Influences of zinc chloride on fast pyrolysis of pinewood

“…Zinc chloride (ZnCl2) is one of the promising catalysts to produce furfural (FF) [19]. Zinc chloride is known to affect the fast pyrolysis reaction of biomass [19], but the exact effect on fast pyrolysis of pinewood is not well known [20,21]. Qiang Lu and Zhi Wang published an article on zinc chloride impregnated corncobs and its effect on the product yield distribution from the pyrolysis.…”

Study of the Potential Uses of Hydrochar from Grape Pomace and Walnut Shells Generated from Hydrothermal Carbonization as an Alternative for the Revalorization of Agri-Waste in Chile

“…Proximate analysis was done using the same procedure as described in prior research studies [61][62][63][64][65]. Ultimate analysis was obtained using the Parikh, J. et al correlation [66], along with HHV [67].…”