NOVELTY - The method comprises fermenting a biomass with a microorganism/mutagen to produce a mixture of metabolites comprising acetone and butanol, separating acetone from butanol and ethanol or other solvents in the mixture by fractional distillation, dimerizing a portion of resultant acetone to form isopentane, trimerizing another portion of the acetone using a catalyst containing metal to form mesitylene, mixing the mesitylene with the isopentane to form the biomass-derived high-octane fuel, and performing dehydration reaction of ethanol on a calcium base in the presence of zinc oxide catalyst.    USE - The method is useful for producing bio-mass derived high-octane fuel, where the bio-mass includes sugars, celluloses, lignins, starches, lignocelluloses, hard woods, grasses, corn stover, sorghum, corn fiber and oat hulls (claimed) and the high-octane fuel is useful in internal combustion engines, automobile gasoline engines, spark-ignited engines and turbine (jet) engines.    ADVANTAGE - The method is capable of effectively and economically producing bio-mass derived high-octane renewable fuel with minimization of side reactions and controlled dimerization and trimerization reactions and without environmental pollution, while maintaining a high throughput.    DETAILED DESCRIPTION - The method comprises fermenting a biomass with a microorganism or a mutagen to produce a mixture of metabolites comprising acetone and butanol, separating the acetone from butanol and ethanol or other solvents in the mixture by fractional distillation, dimerizing a portion of resultant acetone to form isopentane, trimerizing another portion of the acetone using a catalyst containing metal to form mesitylene, mixing the mesitylene with the isopentane to form the biomass-derived high-octane fuel, and performing dehydration reaction of ethanol on a calcium base in the presence of a zinc oxide catalyst at elevated temperatures of 350 degrees C and at elevated pressures, and cooling vapors from the dehydration reaction to condense water and separate unreacted ethanol to acetone through distillation to form resultant mesitylene. The biomass is pretreated with enzymes or strong acids to break hemicellulose chains into their sugar monomers. The step of fermentation is conducted in an anaerobic reactor in the absence of oxygen. The metabolites are stripped from the fermentation when 2-3 wt.% of concentrations are obtained to avoid poisoning of the microorganism. The step of trimerizing of acetone is carried out: in gas phase by passing acetone in contact with a catalyst containing niobium oxide at elevated temperatures; and with a catalyst of niobium oxide on a base of alumina washcoat on calcined aluminized stainless steel corrugated film, niobium oxide on a base of alumina beads and niobium oxide on silica gel, and manganese nitrate on a base of alumina washcoat on calcined aluminized stainless steel corrugated film, manganese nitrate on alumina beads and manganese nitrate on silica gel. The step of dimerization of acetone is carried out in a gas phase catalytic reaction to yield isopentane. The ethanol is produced from a plant material by growing Saccharophagus degradans strain 2-40 in a first portion of the plant material, harvesting protein from Saccharophagus degradans strain 2-40, and mixing the protein with a second portion of the plant material and yeast in an aqueous mixture for producing ethanol. The aqueous mixture contains 1% and/or 10% salt.    DESCRIPTION OF DRAWING(S) - The figure shows a flow chart of a process of converting six carbon sugars to the bio-mass derived high-octane fuel.