▎ 摘　　要

NOVELTY - Preparation of xylo-oligosaccharides, dietary fiber and three-dimensional graphene based on biomass stalks involves mixing biomass stalk with solid heteropoly acid and acidic ion water, and sintering; pressing and washing slurry; mixing crude sugar solution with alkaline ion water, adding xylanase, decolorizing and drying to get xylo-oligosaccharides; cooking, mixing with alkaline ionized water, sulfite and Lewis base, performing enzymolysis with cellulase, hemicellulase and pectinase, and drying to prepare dietary fiber; and carbonizing lignosulfonate to prepare three-dimensional graphene. USE - Method for preparing xylo-oligosaccharides, dietary fiber and three-dimensional graphene (claimed). ADVANTAGE - The method ensures zero waste gas, waste liquid and waste residue, reduces production cost and improves production efficiency which fits for large scale production. It is safe and environment-friendly. DETAILED DESCRIPTION - Preparation of xylo-oligosaccharides, dietary fiber and three-dimensional graphene based on biomass stalks comprises: (A) mixing biomass stalk with solid heteropoly acid and acidic ion water, evaporating, introducing 1-5 wt.% sulfur dioxide to reactor, reacting at 160-170 degrees C and 0.6-1.2 MPa for 60-80 minutes, crushing bio-straw to 3-5 cm size, sintering, removing dust, sorting out leaves and spikes, and mixing with solid heteropoly acid, acidic ion water and sulfur dioxide; (B) subjecting slurry to multi-stage pressing and countercurrent washing at solid-liquid ratio of 1:3-5 and steaming at 50-80 degrees C to obtain steamed slag and crude sugar liquid; (C) adjusting pH of crude sugar solution at 65-75 degrees C to 4-6.0 with alkaline ion water, and adding xylanase; (D) removing solid particles to obtain clear solution; (E) decolorizing with activated carbon and drying to prepare xylo-oligosaccharides; (F) cooking at 0.6-1.2 MPa and 130-1710 degrees C for 1-2 hours, mixing cooking liquor with alkaline ionized water, sulfite and Lewis base; (G) subjecting to multi-stage countercurrent washing to obtain two-stage steamed slag and black liquor; (H) homogenizing two-stage steamed slag at 50-80 degrees C and 40-60 MPa; (I) adding acid ion water to slurry, adjusting pH to 4-5, adding cellulase with titer, hemicellulase and pectinase, performing enzymolysis at 50-85 degrees C for 6-10 hours, concentrating digested pulp, drying and packaging to prepare dietary fiber; (J) discharging fine fiber, coarse sediment and fine sediments of black liquor; (K) adding potassium hydroxide to black liquor, stirring for 2-3 hours, dissolving mixture, concentrating and drying to obtain lignosulfonate; (L) placing lignin sulfonate in tube furnace, passing through nitrogen stream for 30-50 minutes at room temperature, and cooling to room temperature; (M) placing treated lignin sulfonate in first step in atmospheric furnace, heating for 20-40 minutes to 320-360 degrees C at 1 degrees C/minute and performing deoxidation; (N) washing lignosulfonate salt for three times with deionized water to remove inorganic ions, and drying; and (O) placing dried lignosulfonate in vacuum atmosphere furnace, and subjecting to carbonization treatment to prepare three-dimensional graphene. The Lewis base is sodium hydroxide, potassium hydroxide, calcium hydroxide or aqueous ammonia.