▎ 摘　　要

NOVELTY - Preparing composite catalyst, comprises (i) mixing graphene and boric acid crystals evenly, (ii) quenching the mixture of graphene and boric acid crystal to molten state at high temperature, along with heat preservation, diffusing B atoms and connecting to graphene and graphene to form sheet-type structure, annealing and cooling to obtain boron trioxide-graphene, (iii) adding boron trioxide-graphene into water, and boron trioxide-graphene obtains water molecules to form boric acid-graphene, and (iv) cooling water, separating out boric acid-graphene from the water to obtain final product. USE - The composite catalyst is useful for improving lactose isomerization yield and in lactose isomerization (all claimed). ADVANTAGE - The composite catalyst has high catalytic efficiency, while taking into account the decolorization performance. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for: Use of composite catalyst in lactose isomerization, comprising adding boric acid-graphene into lactose solution, reacting to obtain isomerized lactose solution, where molar ratio of lactose and boric acid-graphene is 1:0.4-1; and Composite catalyst obtained by above method, where composite catalyst is boric acid-graphene of formula (I).