Interconnected pyrolysis and activation with in-situ H3PO4 activation of biochar from pear wood chips in a pilot scale dual fluidized bed.

[Display omitted] • Pyrolysis and activation in a dual fluidized bed was successfully operated. • Physical and chemical activation by flue gas and H 3 PO 4 occur simultaneously. • Maximum biochar yield and iodine number were 42.3 wt% and 648.5 mg/g, respectively. • Pyrolysis and activation of one-step method is superior to two-step method in DFB. • H 3 PO 4 favors formation of pores and surface functional groups with rising ratios. Interconnected pyrolysis and activation is a novel technology for combustible gas and biochar production in dual fluidized bed (DFB). The study proposed one-step and two-step methods for pyrolysis and activation of biomass in a pilot scale DFB with capacity of 100 kg/h. Physical and chemical activation occurred simultaneously in DFB system by phosphoric acid (H 3 PO 4) impregnation pretreatment of pear wood chips, and flowing hot flue gas and steam. Stable operating parameters were observed for both methods. The one-step method was superior to the two-step method in terms of the pyrolysis gas quality, biochar pore distribution, micro- and meso-pores structures of biochar, while one-step method reduced the biochar yields. As an activation agent, H 3 PO 4 increased the yields of biochar and pyrolysis gas, promoted formation of micropores and enriched the surface functional groups of biochar with increasing ratio of H 3 PO 4. H 3 PO 4 to biomass ratio of 1:5 reached the maximum biochar yield of 42.3 wt% and highest iodine adsorption value of 648.5 mg/g, increasing by 70.6 % and 90.3 % compared to the biochar without H 3 PO 4 pretreatment, respectively. This DFB system facilitated the diversified use of fluidized beds and the co-production of biochar and product gas with energy saving and CO 2 emission reduction. [ABSTRACT FROM AUTHOR]