NOVELTY - Digesting (M1) cellulosic biomass solids to form and process glycol reaction product involves: providing cellulosic biomass solids; converting the cellulosic biomass solids into a reaction product comprising a glycol; at least partially drying the reaction product, thus forming a dried reaction product comprising a dried glycol; and at least partially converting the dried glycol into a monohydric alcohol.    USE - For digesting cellulosic biomass solids to form and process glycol reaction product (claimed); for converting a glycol reaction product obtained in conjunction with hydrothermal digestion of cellulosic biomass solids into a monohydric alcohol feed that can be subsequently processed.    ADVANTAGE - The digestion rate of cellulosic biomass solids is accelerated in the presence of a digestion solvent. The digestion solvent is maintained at elevated pressures that keep the digestion solvent in a liquid state when raised above its normal boiling point. The hydrothermal digestion of cellulosic biomass solids is an endothermic process, whereas catalytic reduction reactions are exothermic. Thus, the excess heat generated by the in situ catalytic reduction reaction(s) is utilized to drive the hydrothermal digestion, thus lowering the amount of additional heat energy input needed to conduct digestion. Since digestion and catalytic reduction take place in the same vessel in an in situ catalytic reduction reaction process, there is minimal opportunity for heat transfer loss to take place, as would occur if the catalytic reduction reaction(s) were to be conducted in a separate location. In addition, the in situ catalytic reduction reaction(s) may provide a growing supply of the reaction product within the hydrothermal digestion unit, which may serve as or replenish the digestion solvent. Under such conditions, there is no express need to separate and recycle the digestion solvent from the reaction product before downstream processing takes place, which may be further advantageous from an energy efficiency standpoint. The ability to use no or limited mechanical agitation techniques allow high loadings of cellulosic biomass solids relative to digestion solvent to be used, thus improves throughput and process economics.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for digesting cellulosic biomass solids (M2) to form and process glycol reaction product external to the hydrothermal digestion unit involving: providing cellulosic biomass solids and a hydrocatalytic slurry catalyst in a hydrothermal digestion unit; heating the cellulosic biomass solids in the hydrothermal digestion unit in the presence of the slurry catalyst, a digestion solvent, and molecular hydrogen, thus forming a liquor phase comprising soluble carbohydrates; performing a first catalytic reduction reaction on the soluble carbohydrates within the hydrothermal digestion unit, thus at least partially converting the soluble carbohydrates into a reaction product comprising a glycol; at least partially drying the reaction product, thus forming a dried reaction product comprising a dried glycol; and at least partially converting the dried glycol into a monohydric alcohol external to the hydrothermal digestion unit.