Diatomite-based graded porous heat-insulating ceramic and preparation method thereof

The invention discloses a diatomite-based hierarchical porous heat insulation ceramic, which is a porous ceramic with diatomite as a three-dimensional skeleton, new micron-sized pores are formed through a pore-forming agent while most of the nano-sized pores of the diatomite are reserved, the pore size distribution is 0.05-10 [mu] m, and in-situ generated porous nano MgO with a three-dimensional structure is also distributed in the diatomite-based hierarchical porous heat insulation ceramic. The diatomite-based hierarchical porous heat-insulating ceramic is prepared from modified diatomite, dolomite, Al2O3 and V2O5, wherein the mass fraction or mass percent of each component is as follows: 450-750 parts of modified diatomite, 150-450 parts of dolomite and 100 parts of Al2O3, and the V2O5 accounts for 0.5-2% of the total mass of the modified diatomite, the dolomite and the Al2O3. The diatomite-based hierarchical porous heat-insulating ceramic prepared by the invention has the characteristics of high porosity,