Abstract:
Digestion of cellulosic biomass solids to form a hydrolysate may be conducted with in situ catalytic reduction to transform soluble carbohydrates in the hydrolysate into a more stable reaction product. Biomass conversion systems for performing such a transformation can comprise: a hydrothermal digestion unit that also contains a first catalyst capable of activating molecular hydrogen, the first catalyst being fluidly mobile within the hydrothermal digestion unit; an optional hydrogen feed line that is operatively connected to the hydrothermal digestion unit; a fluid circulation loop comprising the hydrothermal digestion unit and a catalytic reduction reactor unit that contains a second catalyst capable of activating molecular hydrogen; and a catalyst transport mechanism external to the hydrothermal digestion unit, the catalyst transport mechanism being capable of conveying at least a portion of the first catalyst to another location from a catalyst collection zone located within the hydrothermal digestion unit.