Catalytic hydropyrolysis of lignocellulosic biomass to BTX and biofuels over zeolite beta based catalysts

Catalytic hydropyrolysis of eucalyptus leaves was investigated in a batch reactor over four catalysts (H-BEA, Ni/ BEA, Ni/Fe-BEA and Fe/BEA). HBEA catalyst exhibited a higher monoaromatic hydrocarbons (MAHs) selectivity compared to non-catalytic pyrolysis. However, the selectivity to polyaromatic hydrocarbons (PAHs) was not significantly reduced by the addition of a protonic zeolite. The highest cycloalkanes selectivity (78.5%) was observed over Ni/BEA, owing to its high concentration of Ni sites as well as acid sites, facilitating the hydro-genation and ring-opening of polyaromatic hydrocarbons together with the hydrodeoxygenation of phenols. In contrast, the Ni/Fe-BEA exhibits the highest selectivity of MAHs, suggesting the Ni-Fe species facilitate the partial hydrogenation of PAHs and hydrogenolysis of phenols but restrict the further hydrogenation of aromatic monomers. Moreover, the reduction of CO to CH4 was restricted over Ni-Fe/BEA compared to Ni/BEA. A high selectivity of phenols and PAHs was detected over Fe/BEA due to the high oxophilicity but low hydrogenation activity of Fe species, hindering the hydrogenation of PAHs and HDO of phenols. The spent Ni/BEA and spent Ni/ Fe-BEA catalysts exhibited a higher surface area and pore volume as well as lower mass of deposited carbon compared to spent HBEA and spent Fe/BEA catalysts, suggesting the catalyst deactivation was restricted by hydrogenation metal (Ni, Ni-Fe) and dissociated H species. Besides, high H2 pressure promoted the hydroge-nation and ring-opening of polyaromatic hydrocarbons, and high reaction temperature hindered the hydroge-nation of MAHs to cycloalkanes. The highest selectivity to MAHs (85.1%) with a 62% selectivity of BTEX was observed over Ni/Fe-BEA catalyst at 400 degrees C and an initial H2 pressure of 3.0 MPa.

Automated summary

The catalytic hydropyrolysis of eucalyptus leaves was investigated using four different catalysts. The selectivity towards monoaromatic hydrocarbons (MAHs) and polyaromatic hydrocarbons (PAHs) varied depending on the catalyst used. The Ni/BEA catalyst had the highest selectivity towards cycloalkanes, while the Ni/Fe-BEA catalyst had the highest selectivity towards MAHs. The reaction conditions, such as H2 pressure and temperature, also affected the selectivity of the products.