Evaluation of biomass sources on the production of biofuels from lignocellulosic waste over zeolite catalysts

Catalytic fast pyrolysis (CFP) is a promising method to convert biomass waste into sustainable bio-oils. However, the relationship gap between biomass characteristics and bio-oil quality has hindered the development of CFP technology. This study investigated the pyrolysis and CFP of ten biomass sources over zeolites, and showed that biomass sources and zeolites played important roles in bio-oil production. For noncatalytic trials, the bio-oil yield was positively related to holocellulose (R2 = 0.75) and volatiles content (R2 = 0.62) but negatively to ash content (R2 = -0.65). The bio-oil quality was dramatically improved after catalyst addition. For CFP over ZSM-5, hydrocarbons selectivity of bio-oils was increased by 1.6∼79.3 times, which was closely related to H/C ratio (R2 = 0.79). For ZSM-5@SBA-15 trials, the dependency of hydrocarbons selectivity on biomass characteristics was less clear than that in ZSM-5 counterparts, although undesirable PAHs were inhibited for most biomass sources. This study demonstrated the influence mechanism of biomass characteristics on bio-oil compositions.

A study on the association between biomass types and magnesium oxide pretreatment

This work studied the association between biomass types and MgO pretreatment using representative agricultural residues (corn stover, sorghum stalk, and wheat straw), energy crops (miscanthus, switchgrass, and big bluestem), and woody biomass (poplar). Differences in biomass chemical components (24.7-40.3% cellulose, 17.4-27.6% hemicellulose, 12.1-22.0% lignin, and 5.1-38.3% extractives) and the amount of acetic acid (1.9-5.3%) affected biomass structure and pretreatment severity. Optimal pretreatment temperature and time were 170 °C and 40 min for wheat straw and switchgrass; 180 °C and 30 min for miscanthus and poplar; and 180 °C and 40 min for corn stover, sorghum stalk, and big bluestem. Big bluestem and poplar have a larger amount of acetic acid and required more MgO loading (0.12 mol/L). Except for sorghum stalk (0.10 mol/L), the rest required less MgO loading (0.08 mol/L). Approximate MgO loading completely neutralized released acetic acid during pretreatment, reducing sugar degradation and eliminating inhibitor formation.