A method comprising: providing cellulosic biomass solids and a slurry catalyst in a hydrothermal digestion unit, the slurry catalyst being capable of activating molecular hydrogen and the cellulosic biomass solids comprising a digestible filter aid comprising cellulosic biomass particulates capable of forming a filter cake suitable for retaining at least a portion of the slurry catalyst thereon; distributing the slurry catalyst within the cellulosic biomass solids using fluid flow; heating the cellulosic biomass solids in the hydrothermal digestion unit in the presence of the slurry catalyst, a digestion solvent, and molecular hydrogen, thereby forming a liquor phase comprising soluble carbohydrates; allowing a portion of the liquor phase to exit the hydrothermal digestion unit; forming a filter cake comprising a digestible filter aid on a solids retention mechanism configured to allow the liquor phase to pass therethrough; collecting at least a portion of the slurry catalyst on the filter cake; and performing a first catalytic reduction reaction on the soluble carbohydrates within the hydrothermal digestion unit, thereby at least partially forming a reaction product comprising a triol, a diol, a monohydric alcohol, or any combination thereof in the hydrothermal digestion unit, wherein the first catalytic reduction reaction comprises a hydrogenolysis reaction which is conducted at a temperature in a range of 110 to 300 degrees C and a pressure in a range between 1 bar (100 KPa) and 150 bar (15000 KPa), wherein the slurry catalyst is distributed in the cellulosic biomass solids using upwardly directed fluid flow. providing cellulosic biomass solids and a slurry catalyst in a hydrothermal digestion unit, the slurry catalyst being capable of activating molecular hydrogen and the cellulosic biomass solids comprising a digestible filter aid comprising cellulosic biomass particulates capable of forming a filter cake suitable for retaining at least a portion of the slurry catalyst thereon; distributing the slurry catalyst within the cellulosic biomass solids using fluid flow; heating the cellulosic biomass solids in the hydrothermal digestion unit in the presence of the slurry catalyst, a digestion solvent, and molecular hydrogen, thereby forming a liquor phase comprising soluble carbohydrates; allowing a portion of the liquor phase to exit the hydrothermal digestion unit; forming a filter cake comprising a digestible filter aid on a solids retention mechanism configured to allow the liquor phase to pass therethrough; collecting at least a portion of the slurry catalyst on the filter cake; and performing a first catalytic reduction reaction on the soluble carbohydrates within the hydrothermal digestion unit, thereby at least partially forming a reaction product comprising a triol, a diol, a monohydric alcohol, or any combination thereof in the hydrothermal digestion unit, wherein the first catalytic reduction reaction comprises a hydrogenolysis reaction which is conducted at a temperature in a range of 110 to 300 degrees C and a pressure in a range between 1 bar (100 KPa) and 150 bar (15000 KPa), wherein the slurry catalyst is distributed in the cellulosic biomass solids using upwardly directed fluid flow.